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Gaultheria pumila (L.f.) D.J.Middleton è una pianta della famiglia delle Ericaceae diffusa in Sud America.

Note

Altri progetti

Ericaceae


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Past President Judy Patterson Passes Away
Some long time members with the YCCC from years gone by will remember Judy Patterson. Judy lost her battle with Cancer on Friday December 6th 2019. Judy was in her mid 60s.
Read more: Past President Judy Patterson Passes Away
Ted Blake Award Winner
The winner of this year's Ted Blake award is someone who has worked in the background of the club for many years.
The club is lucky enough to have a website that has an amazing number of different features that allow for the sharing of information, communicating with club members and even signing up for trips and events. It is hard to imagine our club functioning as well as it does without our website.
Gatineau Park Ski/Snowshoe Passes
The National Capital Commission has given RA Canoe club members a group discount on Gatineau Park Ski and Snowshoe season passes. The discount is worth up to $20 over the presale prices. In order to get the discount club members must purchase the pass before November 16, 2019.
Ted Blake Award Nominations 2019
Your club executive is looking for nominations for the Ted Blake award which is a beautiful paddle inscribed with the names of the winners. This annual award is given to club members who have made outstanding contributions to the club, usually over the course of several years.
Do you know someone who has made a really big difference to the club? If so, please submit your nomination to any member of the club executive. Nominees should be current members of the club and cannot have won the award in the past.
Nominations can be submitted to any member of the club executive not later than Wednesday Oct 16, 2019.
History of the award
The award was created 2003 in recognition of the long and dedicated service given to the club by Ted Blake. He joined the club (then the Y Canoe Club) in 1978 – before the club even had a boathouse. It was he who negotiated a deal with the YM/YWCA to get the club's first boathouse and to organize club members to build it. He remained active with the club until his death in 2011. Click here for more information about him.
Club member Dot B created the beautiful award paddle.
Click on "Read more" to see a list of previous winners.
New Kayak
By now many of you will have noticed that the club has a new sea kayak. This is thanks to club member Margaret M. who kindly donated hers to the club. We are all very grateful to her for her generosity.
Mark Scott
Family Program Trip Reports 2019
Family Trip - Constance Creek - May 5, 2019
Family Paddle on Rideau Canal - May 26, 2019
Rideau River PP Family Trip - June 7-9, 2019
Lac La Pêche Fathers Day BBQ - June 16, 2019
Posting a Trip to the Club Calendar
The club encourages trip leaders to post all club trips on the calendar. Using the calendar is easy (see attachment). This makes them readily available to all members and gets them included in the weekly Canoebytes.
A handy feature of the calendar is that you can use it to have people register for the trip.
2019 Club Orientation Session Presentation
See attachment from the 2019 Club Orientation Session. It gives a useful overview on how the club operates.
RACCC_Orientation_2019.pdf [ ] 1049 kB
This year's open house was a big success. We had over 70 new club members and 28 people sign up for training courses.
Welcome to all of our new members and thank you to everyone who made the night go so well.
Mark - RACCC Chairperson
Accepting Canoe Club Memberships for 2019
Memberships are being accepted for 2019. Click here for more information.
Some modifications to the Canoe Club membership procedures for 2019 are listed below.
1) Members only have to pay the membership to join the RA once unless they let it lapse in which case they have to pay it again. Members however will be given a three month grace period during which the RA membership fee will be waved.
2) Canoe Club annual memberships now run for 12 months from the date that a member joined. The RA will send a reminder email to a member one month before their Canoe Club membership expires.
3) If a Canoe Club membership is not renewed by the expiry date, there will be no grace period. The member will be removed from the Canoe Club membership list and their access to the Canoe Club website will be blocked. If they renew after the expiry date, their access to the website will be promptly restored.
4) New members will get a $25 discount on their course fee if they register for a training course costing $130 or more at the same time as joining the Canoe Club.
February 04, 2019 Seminar Cancelled
Because of the freezing rain forecast the Feb 04 seminar on Lac Manicouagan has been cancelled. At thispint we do not know if it will be rescheduled.

redpajama_set_name: RedPajamaCommonCrawl


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Grants Pass Parks & Recreation
September 24, 2020 - The Spray Park will close for the season on October 1, 2020.
September 10, 2020 - The Spray Park is now open from 12 p.m. to 7 p.m. daily, with restrictions.
June 12, 2020 - The Skate Park is now open. New signage has been placed at the park alerting users to the social distancing restrictions established by state mandate. Park users must maintain 6-foot distancing. Groups of more than 10 people in the same party are prohibited. The park will be closed if distancing is not maintained or any vandalism occurs.
Vehicles must leave spaces between other cars when parking. Visitors must enter and exit vehicles without lingering or congregating in the parking lot. Parks visitors should bring their own water and hand sanitizer and avoid touching any surfaces. Restrooms may be closed or have fewer than twice per day cleanings.
June 3, 2020 - The BLM has reopened access to Dollar Mountain at NW Crescent.
May 29, 2020 - Effective immediately the tennis courts, pickleball courts and dog parks are officially open. Locks have been removed and new signage in regards to proper social distancing will be up by June 1.
Basketball courts, fields, pavilions and playgrounds remain closed at this time.
Groups of more than 10 people are prohibited. Park users should bring their own water and hand sanitizer, avoid touching shared surfaces, and are prohibited from gathering or lingering in parking lots.
For other restrictions due to Covid-19 and future updates, go to the city's COVID-19 Information page,
The City of Grants Pass contracts with Recreation Northwest, Inc. to coordinate and schedule recreation opportunities for our public.
Quarterly Recreation Guide
Recreation Northwest, Inc. provides a recreation guide for winter, spring, summer and fall. This guide lists all the activities and events, and the recreation provides.
Open the current recreation guide (PDF).
Open the current list of providers (PDF).
Fields and Courts
Recreation Northwest, Inc. works with leagues, community groups, and schools to coordinate the schedules of fields and courts.
Recreation Northwest, Inc. helps the public reserve facilities in our parks, the River Vista House for weddings, and the Street Banners on 6th and 7th streets.
Find the facilities you want to reserve.
Check out the River Vista wedding site details.
Go to the Street Banner page to find a date to schedule your banner.
Parks are open 7:00 a.m. to 7:00 p.m.
Courts and fields with lighting are open until 10:30 p.m.
Gilbert Creek Park
1750 NW Hawthorne Avenue
Park Surveys
Go to the Park Surveys page.
Loudspeaker Policy
As of June 18, 2018, the following rules and regulations for Outdoor Loudspeakers and/or Concerts in public parks apply:
Outdoor Loudspeaker/Concert Policy (PDF)
Loudspeaker Permit (PDF)
City Parks and Reservable Facilities
Caveman Pool
Dog Park Use Rules
Park Use Rules
Street Banners Reservations


While somewhat brand-new to the market, Nectar has successfully become one of the bestselling online mattresses due to its low rates and exceptional characteristics. By cutting out the middleman, salespersons, and sellers, Nectar is able to sell high caliber mattresses at economical costs.
The Nectar mattress is an 11-inch thick all foam mattress including a multitude of memory foam layers plus a soft top layer. Having a weight of 84 pounds, it is thicker and heavier than a lot of its rivals. The medium firm mattress is created for front, back, or side sleepers as well as deals with all sorts of understructures, including box springtimes, divan bases, typical structures, adjustable bases, as well as platforms.
The Nectar mattress is made of quality elements as well as layers for coziness, support, and also shape. Flexible memory foam gives rebound and also bounce, together with a breathable base layer bolsters the other layers and also supplies a stable structure. The Nectar mattress, which comes in one firmness solution, gives for appropriate spine placement, making it a perfect solution for people with back conditions.
Certipur-US Certified, the Nectar mattress is made without ozone depleters, harmful chemicals as well as gasses, PBDE flame retardants, TDCPPs, heavy metals, formaldehyde, phthalates, or volatile organic compounds. The cover, which is without a doubt resistant to bedbugs and also allergens, can be spot cleaned with a mild detergent and will certainly be replaced by the business at no cost.
The Nectar mattress is thicker and also higher profile than the majority of others and also consists of a lot more layers of foam. The quilted cooling gel layer is one-of-a-kind to the Nectar mattress.
Unlike a lot of its rivals, the Nectar mattress is Chinese-made. The firm has been given bad press for shipping hold-ups as well as bad customer care. The delivery hold-ups have actually been associated to the unforeseen popularity of the mattress, which led to an initial space in supply and also need that has actually since been fixed.
Comparing the Nectar mattress to the Purple mattress, one of its rivals, there are some likenesses and distinctions. While both brand names are made to offer pressure relief and proper support at an inexpensive rate, they are made from different types of fabrics and also have feel different.
While the Nectar mattress's memory foam layers provide it the feeling of a typical memory foam mattress, the Purple mattress's exclusive gel grid has a springier, stronger and also a lot more responsive feel. The Nectar mattress is softer; while the Purple mattress is firmer.
Nectar mattresses are 11 inches thick and have 5 layers, while Purple mattresses are 9.5 inches thick and contain 3 layers, a 2-inch purple smart comfort grid constructed from hyper-elastic polymer, a 3.5-inch layer of plush comfort foam, and also a 4-inch layer of polyfoam. The covers are very close, although the Nectar mattress's cover has actually memory foam quilted right into it.
If you are picking between both, the Nectar mattress is probably the very best decision if you are a side sleeper, if you like the sensation of memory foam, or if you choose a softer mattress. It is additionally far better with motion isolation, pressure relief, and is much less expensive. The Purple mattress might be the better selection if you are a back or stomach sleeper or like a stronger mattress.


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Cradle: a dreamlike exploration game set in the strange plains of sci-fi Mongolia
By Philippa Warr 2013-07-31T18:00:03.211Z
There's a very good chance that watching the latest trailer for Cradle will leave you absolutely none the wiser as to what that game's about. Flying buses, a dude in a Groucho Marx disguise, amnesia, a half-built mechanical girl and so many cubes that part of the game world could probably be twinned with Minecraft. This seemed like exactly the time to get in touch with Ilya Tolmachev, Creative Director of Cradle developer Flying Cafe for Semianimals and ask "Wait, what?"
You play as 18-year-old Enebish who has grown up in a yurt amongst the desert hills of Mongolia, explains Tolmachev. Ordinarily he spends his time digitising and selling flowers and ignoring the neglected entertainment park nearby, but when he loses his memory during an inexpertly performed medical procedure he gains new curiosity about his surroundings. That curiosity is only enhanced when Tolmachev discovers a neuroprocessor containing the digitised consciousness of a girl called Ida. He connects Ida's consciousness to a flower vase built in the form of a mechanical girl, and proceeds to try to unravel her story by exploring the park - the only thing she appears to recognise.
The game trailers and teasers released so far ooze a poetic strangeness which pegs the title firmly into "art game" territory, and seems to delight in obscurantism. Asking Tolmachev about the game's influences yields the following literary recipe:
"The story in Cradle has combined the mood and ideas from books of several writers: from Albert Camus the story of Cradle received the taste of bitterness and [the] absurd; from Vladimir Sorokin, an eerie feeling of permanent hostility coming out of the reality; from Andrey Platonov, the feeling of empathy and pity directed towards don't know who, having no specific addressee; from the Strugatsky brothers, the humanistic confidence in the inevitable triumph of human essence over the animal one."
The game itself is intended to feel like a dream but translating liminality into a coherent ruleset for the player is no easy feat. According to Tolmachev, the team hopes that the consistent internal logic of the game world will ground players. "The entire world of the game is built so that under the first impression it looks surreal," he says. "However, as the story develops the player unfolds strict logical links between the objects and phenomena of this universe. That makes the game transform from a metaphoric parable to a logically convincing realistic story."
By holding the player at the pivot point between two aesthetically different environments Flying Cafe aims to achieve dreaminess. It's about here that we touch on the cubes. "The glowing cubes pavilion is an integral part of our idea to immerse the player into the complex, specific state of sleep where you are peeping at someone else's life." The idea is that navigation of the apparently-voyeuristic cube world can be used to find answers to some of the players' questions.
In terms of when we might actually get to explore these Mongolian landscapes and entwined cube worlds, Cradle was previously reported for release in spring of 2012 but the departure of game designer Pavel Mikhailov over ' ideological controversies ' saw that date pushed to summer 2013. Now Flying Cafe are offering a tentative spring 2014 release date. I ask about the effect of Mikhailov's departure on the project.
"The development process has been the same hell difficult as it used to be," says Tolmachev. Over the course of development several other people departed the project and the nature of Cradle itself causes problems. "The idea behind it is ephemeral and tough to document - it is hardly possible to physically keep its sensation with you constantly." Tolmachev also admits to moments of self-doubt - a creeping coldness which accompanies exhaustion. "Then I produce a pack of old notepads where I used to work out the concept of Cradle, and everything quickly gets back in order."
The game's success on Greenlight provided a confidence boost to the team and offered proof that Cradle would be in demand but one of the side effects was that the developers now have an added sense of pressure to release - "This is an unpleasant feeling," says Tolmachev.
Speaking frankly, bringing the project to completion for 2014 - or indeed at all - might still be a challenge. With the Greenlight success in mind, one of my last questions is whether the team has considered a Kickstarter campaign. "We are indeed tempted about it as we are a bit short of funds to complete the project. In case we can't find an alternative way to procure the funding, perhaps we make a call for the community to help us with the finances."
All being well, Cradle will launch in spring 2014 on PC and Linux with a Mac port to follow.
Flying Cafe for Semianimals


I recently completed a commissioned job for St. George's University of London. The brief was to come up with a selection of pictures they could use as wall art for their new open plan Registry office. Four options with six different pictures were presented to the Registry staff to vote on with the winning set installed a few days ago. Photos of the most popular arrangement can be viewed below.


Donate to Urban League Of Greater Madison, Inc.
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Click below to go to my new store. Get some great back to school centers, reading graphic organizers and graphing activities for the whole year!
If you have items that you would love to sell, Teacher's Notebook is great.
Thanks for the free downloads! I love your activities!
I love the G.O. Book idea!! Thanks so much for sharing, yet another, wonderful idea! Where do you find the poems that you use weekly? I haven't had that much success with finding enough poems to introduce weekly for my first graders.
Kristy- I've been doing this for 11 years so I have collected lots of poems over the years on the internet that match my theme. Go to http://just4teachers.blogspot.com. She has a whole blog dedicated to poems.


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Flex Program: "You Are Not Alone" When Dealing with Stress
Homepage Local
October 28, 2021 November 4, 2021 Lily Nguyen
Juliana Luong and Luella Harding also contributed to this article.
It is now approaching the end of October, and students have begun to experience the academic rigor of high school—an inevitably drastic change from the previous virtual school year.
In high school, stress is multifaceted. It can stem from having to practice rigorously in dedication to a sport, sending in countless college applications, caring for siblings while taking on a pile of homework, dealing with sudden onsets of assessments, and too many other factors. Students are then left facing a difficult question: how can they balance school and life?
As students and faculty alike adjust to an altered school setting, Malden High School has sought to address these concerns with the introduction of Flex Block this year.
Flex Block is an 85-minute period divided into two segments: the first is "Enrichment", where students concentrate on academic tasks/project-based learning; and after that is "Joy", where they can take part in one of many staff-hosted activities of their choice. The block occurs on Gold Days, allowing high schoolers to temporarily escape from academic distress and do something they enjoy.
Flex Block is divided into cycles, where students can access a selection of Enrichment and Joy sessions from the "Edficiency" website, only one click away from Malden High School's Clever portal. They can apply for a session that piques their curiosity. Each cycle is expected to last around three weeks and cut to two after the new year, allowing students to experience more activities.
The program, which commenced in early September this year, was designed to offer students both additional academic enrichment opportunities and another avenue to explore their interests. During its creation, Principal Chris Mastrangelo voiced understanding for how academically demanding high school is and found it "unfortunate witnessing the amount of pressure students put on themselves." Academic stress then became an important foundation of building Flex Block. Mastrangelo has felt "incredibly pleased" with the outcome thus far and can say likewise for other faculty members who helped build the program.
Caitlin Quinn, guidance counselor of Holland house for grades 10-12 who assumed Flex leader alongside Ms. Jessica Bisson, expressed her enthusiasm for Flex Block as a "huge win." She emphasized the socializing aspect of the program, "something [students and teachers] have missed from a world before the pandemic," and hoped that the opportunity for new interactions with peers will "continue in the hallways and in future classes."
Brian Wong playing music from different decades as a part of his sessions. Photo by Juliana Luong
English teacher Brian Wong voiced his feelings about his "Hip Hop Legends" Joy session, saying "It is important to expose people to music from different decades," and that he "found that many students haven't heard things outside of a very narrow band of music." The reason why he set it up is for students to "talk about music...there's just so much music out there that students might actually like if they heard it."
Adding to the importance of the Flex Block, Shauna Campbell, a marine biology teacher who is hosting fish tank setups for Enrichment and board games for Joy block, said "[She] thinks Flex Block is a good way to learn about things in a more student-centered way because the groups are small and students can dictate what we are doing."
Spanish teacher Elena Mayer is offering Capoeira for her Joy block, which is an Afro-Brazilian martial art form. Mayer explains that "It involves songs in Portuguese, various rhythms that dictate different styles of playing, self-defense, gymnastics, and swag," and "is all about decolonization and familiar to many students already because [Malden High has] such a large Brazilian-American community here." Furthermore, she emphasizes that "students can work out, play some music, sing, and learn another language all at once. Most importantly, it's fun."
Elena Mayer playing a Berimbau as the students are doing Capoeira martial arts
For her Enrichment period, senior Yusra Tafraoui is taking Play Production Workspace. Being in Play Production since her sophomore year, she loves having the opportunity to take this time during the day to "work on rehearsing lines and choreography." Currently, the group is working on practicing for their production of Gypsy the Musical, and "after a year not being able to participate in Play Production," she appreciates having this extra time to work on her big role with others in preparing for their upcoming performance in November.
Another aspect of Flex Block that many seniors have found helpful is having the opportunity to work on college applications and think about other post-graduation-related plans during the school day. Senior Mackenzie Brennen is currently taking the College/Career Application Support for her Enrichment period with Holland house guidance counselor Caitlin Quinn, and says that she likes it because "it allows [her] to get direct help from Ms. Quinn without having to make an appointment." She explained that having this time built into the school day has made it easier to get feedback on her application.
Taryn Belowsky, a Brunelli guidance counselor, hosts a similar Enrichment period where she provides college and career preparation for seniors and acknowledges the great opportunity for "students to have additional support" and "bond with them more regularly." Also the co-coordinator of an outdoor walking and talking session alongside Ms. Fornash for Joy, Belowsky loves "being able to get out of the building for a little while" and "continue bonding with students" with the conversational aspect of the activity.
For his Joy block, sophomore Harrison Ashley appreciates how it "lets [him] take a break from the academic aspect of school for a little [while]." Ashley is currently taking stress-relief and coloring with Melanie Cabral, and he enjoys having the time to "chill out during the day" as well as being able to socialize with friends he doesn't normally have classes with.
Other students find "joy" in being able to do more activities that interest them. Freshman Marc Naceus is one of many students partaking in racquet sport activities hosted by Mark Gagnon in the gymnasium. Naceus appreciates that it has "taken off some of the weight" from academic stress, and "if it didn't bring enough heat, [he] can change it in [the next cycle]." Junior Jose Mejia Guerrero, who is participating in a study for Enrichment and board games for Joy, also adds "[He] does not have any complaints about the Flex Block."
Melissa Sheehan, English teacher and hosting a grade nine English support for Enrichment and silent reading space for Joy, says "[She] thinks one thing that could be improved about Flex Block is how [teachers] take attendance and hold students accountable to their sessions," and that "[She] has a lot of students on [her] roster who have never shown up."
The Flex Block options filling up quickly have also had a large impact on how students feel about going to their Enrichment and Joy blocks in general, perhaps being a reason for this attendance issue. An anonymous junior at Malden High brought up that "for the waiting list, some people are really looking forward to joining a certain block, but then other people already fill it up." If these blocks become filled up, students are placed in a completely random class that they are not able to switch out of until the three weeks is up. Additionally, she explains that "if [they] don't choose on time, people end up choosing for [them], so [they] really don't enjoy [Flex Block] for the time being and then it ends up being a very extended amount of time that [they are] just bored."
Along with there not being enough room in many of the popular Joy and Enrichment classes, junior Christel Jean-Baptiste points out how "there aren't enough options to choose what [students] are really interested in." She suggests having more options for popular Joy and Enrichment blocks that students are more interested in and want to be a part of.
Junior Michelle Dang feels that "the short time for Flex Block is jarring and should be improved." Similarly, senior Danny Du agrees that "having two split blocks as Enrichment and Joy . . . should just be one block."
Sophomore Victor Desouza says that overall he likes that Flex Block gives him "some time to pursue what [he wants] to do." However, similar to Dang, he also mentions that "if [they] were given more time during Flex Block, it would be a lot better." Desouza brings up the suggestion to switch periods 3 or 6 and Flex Block. "Instead of whatever class [they] have determining what lunch [they] have, instead, [they would] have the class where Flex Block is and Flex Block during [the lunch period]."
Another aspect of Flex Block that many students think there should be improvements to is the website Edficiency. Senior Mateus Flaherty states that "[he thinks] that the interface is really annoying." This past cycle, for his Joy block, Flaherty originally signed up for video games with teacher Gregory Simone. However, not knowing that this class had filled up, "[he] had no idea [he] was in [another] class until the day of." Flaherty "feel[s] like [they] should at least get better notification when [they're] not in a class," and if they don't get into their first choice, they are given the option to choose another class.
Flex has currently entered its third rotation, where students can continue exploring the several Enrichment and Joy sessions offered. Still a relatively new application in the schedule, Mr. Mastrangelo had acknowledged that "[Flex Block] was a big undertaking and may requirebe one or two cycles away from its optimum," but he envisioned that the program will be well-conditioned in Malden High's future.
flex, local, malden high school, mhs
Changes to Midyear Assessments Week
January 30, 2023 January 30, 2023 Mack Keating
Previous: Lisa Marino Aids the PACE Program
Next: Student Voices at MHS on Gender-Neutral Bathrooms


Shane and Josephine Finnegan - brother and sister - shared fond memories of home cooked dinners that eventually fueled their own passion for cooking.
Over time, they realized that they shared the same frustration when it came to affordable and reliable cookware. It seemed that there were only two options - buy cheap and fully anticipate discarding the cookware within a few months, or purchase overpriced cookware at a speciality kitchen shop. Brigade Kitchen was born out of Shane and Josephine's own desire to the fulfill the need for affordable, high quality cookware that enabled them to do what they loved - cook.
Utilizing lean distribution and cutting out the middle man, Brigade Kitchen offers home cooks everywhere the chance to purchase cookware that boasts the quality of today's luxury brands but at half the cost.
Their cookware is made of 5-ply 18/10 stainless steel which might cost upwards of $130 individually elsewhere but they are able to offer it to their customers for a fraction of the cost, starting at $70. Customers can buy directly from Brigade and also build their own cookware set with the added perk of 10% off if they purchase three or more units.
Shane and Josephine's mission is to make great home cooked meals accessible for everyone.
Their favorite part about building Brigade Kitchen?
"We're lucky enough to do what we love everyday and build a brand we believe in, all while working with family."
Use code "OUTGIFT" for 10% off your purchase.


Yahara Lakes 101: Salt and our freshwater lakes Join us for Yahara Lakes 101 to learn about the issues that impact our lakes! About this Talk Road salt is often thought of as an 'environmentally safe' chemical. However, at high concentrations, chloride can alter aquatic ecosystems by stressing freshwater species, and deteriorate drinking water sources. For 70+ years, we have applied road salt (sodium chloride) to paved surfaces, without any regard for the environmental consequences. In this month's Yahara Lakes 101 talk, Hilary Dugan will discuss long-term chloride trends and the state of our lakes across the Midwest and Northeast United States with regard to chloride contamination. We'll also learn what is currently being done locally to curtail further environmental damage. Additionally, representatives from Wisconsin Salt Wise, a partnership with agencies in Dane County including the Land & Water Resources Department, Madison Metropolitan Sewerage District, and the Madison Water Utility, will be on hand to discuss proper ways to use salt at a home or business. About our Speaker Hilary Dugan is an assistant professor at the Center for Limnology at the University of Wisconsin – Madison. As a limnologist, Hilary studies how terrestrial and atmospheric changes, such as warming air temperatures or land use patterns, alter biogeochemical fluxes and aquatic processes in lakes. Her research balances field based programs, which rely heavily on sensor networks, with the use and development of analytical models, and the application of geophysical and geospatial tools. Her research focus is on temperate and polar lakes, with sites spanning from Wisconsin to Antarctica. One of Hilary's recent research projects examined long-term chloride trends in over 500 lakes in North America and Europe. She found that many urban lakes in North America have undergone considerable long-term salinization stemming from road salt application. Event Details The event is held at The Edgewater. Come at 7:30 a.m. for a meet-and-greet and to enjoy coffee, pastries, and fruit. The program begins at 8 a.m., and class is dismissed by 9 a.m. Complimentary event parking will be available at The Edgewater. Admission is FREE for Friends of Clean Lakes. If you are not a Friend, admission is $10 per event. Registration for each event is requested for all attendees. Yahara Lakes 101 Lecture Series Yahara Lakes 101 is a series of educational events open to the public and a great chance for residents to learn more about the science behind the issues that affect our lakes. Each month we feature a different expert to make the science accessible and interesting to non-technical audiences. The series is produced in partnership with the UW-Madison Nelson Institute for Environmental Studies, with hosting sponsor The Edgewater, presenting sponsor First Weber Group, supporting sponsor The Evjue Foundation, and media sponsor The Isthmus.
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Passport: Syrians Are Now Eating Everything From Cats to Leaves to Survive Syrians Are Now Eating Everything From Cat...
Syrians Are Now Eating Everything From Cats to Leaves to Survive
CAIRO – In a town that lies less than eight miles from the center of Damascus, Syrians are starving to death. Some children in Muadamiyah have resorted to eating leaves to survive, while a group of Muslim clerics also issued a fatwa that the consumption of dogs and cats was permissible for the area's residents. ...
By David Kenner
| October 28, 2013, 6:45 PM
Spencer Platt/Getty Images
CAIRO – In a town that lies less than eight miles from the center of Damascus, Syrians are starving to death. Some children in Muadamiyah have resorted to eating leaves to survive, while a group of Muslim clerics also issued a fatwa that the consumption of dogs and cats was permissible for the area's residents. Meanwhile, videos showing emaciated children's corpses continue to filter out — victims of a siege by the Syrian regime that prevents the entry of either food or medical care.
In an article for Foreign Policy on Friday, Secretary of State John Kerry condemned the Syrian security forces' denial of humanitarian aid to places like Muadamiyah, calling on the world to "act quickly and decisively" to pressure the Assad regime to allow assistance to reach civilians. For some of the aid workers on the conflict's front lines, however, the United States and its allies have been all talk and no action.
"Secretary Kerry and others give support in a gray, non-focused way," said Khaled Erkoussi, the head of emergency operations at the Syrian Arab Red Crescent (SARC). "It's not enough now to say, 'we support you, Syrian Red Crescent.' What we want you to say is, 'You must get your hands off the Syrian Arab Red Crescent, stop shooting at them, let them go to the areas [in need] with the support with the U.N.'"
Erkoussi wants the international community to single out the SARC as an organization whose operations must be protected inside Syria. He also wants a renewed focus on the humanitarian angle of the crisis, citing the Aug. 21 chemical weapons attack in Damascus as an example of the world's misplaced priorities.
"Our reaction as a humanitarian organization was to get the ambulances and the first aid workers ready to go there. Others' reaction was to issue a statement from the Security Council demanding an investigation," he said. "Usually, if a murder happens, don't you save the victims first before finding a killer? The whole priority of things nowadays, I think it's sometimes screwed up a little bit."
The U.N. Security Council issued a non-binding statement this month calling for increased aid delivery in Syria — Western members opted for the statement over a resolution to avoid a veto by Assad's allies on the council, Russia and China. Despite the diplomatic action, however, Erkoussi said that Syrian regime checkpoints were still denying SARC aid workers access to Muadamiyah, even after they received the proper approvals from the authorities. Meanwhile, a ceasefire in the town – designed to allow civilians to evacuate — collapsed earlier this month, as the Syrian military shelled the evacuation point. It is unclear who fired first.
But access to stricken areas isn't the only aspect of the Syrian humanitarian crisis – there also simply aren't enough resources to go around. The U.N. Syria Humanitarian Assistance Response Plan estimates that there are 6.8 million Syrians in need within the country, and requested $1.4 billion to provide for their needs in 2013. However, states have provided a mere 56 percent, or less than $800 million, of that funding request. The United States has contributed by far the largest amount of any state to fulfilling the U.N. request.
However, the deficit means that aid organizations have been forced to make tough decisions about who they can help in Syria. While the United States estimates that there are 5 million internally displaced persons in Syria, Erkoussi says that food parcels to feed only 2.1 million people are getting into Syria each month. That has forced the Red Crescent to limit aid to needy families, reducing them to a single parcel every two months.
And then, Erkoussi says, some of the aid earmarked for Syria simply isn't getting to the people in need.
"We are asking and demanding to donors to be tough, to monitor more," he said. "I hate it when I see people from international organizations staying in four-star hotels or wasting money on armored vehicles in situations where there is no need for it. People with some of the NGOs inside Damascus, they use armored vehicles — while the rest of us can walk."
Tags: Arab World, Middle East, Syria
Fukuyama: Expect More Violence Before America Returns to Sanity


Tara Liddle is a licensed pediatric physical therapist and is currently the regional director of pediatric therapy at MOTION PT Group. She received both her BS in Physical Therapy and a Master's Degree in Physical Therapy Management of Developmental Disabilities from New York University. She wrote the first edition of Why Motor Skills Matter in 2003; the second edition is scheduled to be released in July 2018. Books two and three are currently in the works. Tara is also pursuing her Doctoral Degree in Pediatric Physical Therapy and hopes to have her degree by the fall of 2019.
Tara began her clinical experience at Rusk Institute in NYC, working in pediatric rehabilitation. She then moved over to Lenox Hill Hospital to start a therapy program in the neonatal intensive care unit and a neonatal follow-up program with a pediatrician. In 1989, she also began her private practice in NYC, serving children with special abilities, neurological syndromes, developmental coordination disorders, sensory processing disorders, developmental delays, and torticollis. In addition, Tara has worked within early intervention programs (children 0 to 3) and with The Board of Education.
While treating pediatric patients in her private practice, many of their parents suggested she write a book based on the ongoing questions they had.
Tara is a frequent speaker at hospitals, schools, and parenting groups. She hopes her message regarding the importance of motor and sensory development will give children the tools they need to be more confident, self-aware, and assured throughout their lives. Her "back to basics" approach with simple techniques and toys are easily adapted into daily activities.
Tara draws on her more than 30 years of experience as a pediatric physical therapist working with children ages 0 to 18 to provide an understanding of the sensory system, the importance of touch, the roles of movement and play, and the effects these activities have on neurodevelopment and social development in early childhood.
She cares about the future success of children. Her dream is to help them have a sense of confidence in navigating the world around them.
Tara's passion for helping children and her love of animals goes beyond her professional life and has led her to board affiliations with Girls Learn International, Crutches4Kids, and Empowers Africa. She is also involved with many other charities focused on helping children and animals. Each month Tara plans to donate a percentage of proceeds from her book to a designated charity.
She is the mother of two children and resides in NYC with her husband. Besides spending time with her family, Tara also enjoys fitness, cooking, reading, the outdoors, traveling, and supporting the arts.


text:
Football: Aztec duo to play together one last time
Vongni Yang
Visalia Times-Delta
Farmersville quarterback Sam Metcalf and Aztec wide receiver Joseph De La Cruz will get the chance to play together for one last time.
Metcalf and De La Cruz are East teammates and both will play in the 48th annual Tulare-Kings County All-Star Football Game on Saturday at Golden West's Community Stadium.
Metcalf and De La Cruz linked up for 1,689 yards and 23 touchdowns in their final season at Farmersville.
Sam Metcalf wrapped up his career at Farmersville High as one of the most decorated passers in Central Section history.
The recent Aztec grad threw for a record-setting 11,913 yards and 140 touchdowns during his four years as a starter, but he still had his fair share of critics saying he only posted those ridiculous numbers because he played against "lower-tier" competition.
"You hear that all the time," Metcalf said.
But no more, hopefully.
Metcalf will get his chance to possibly prove his naysayers wrong when he showcases his skills against some of the best players in Kings and Tulare counties. The 6-foot, 185-pounder will quarterback the East squad in the 48th annual Tulare-Kings County All-Star Football Game on Saturday at Golden West's Community Stadium. Kickoff is at 8 p.m.
Metcalf, who threw for 3,360 yards and 42 scores in 10 games as a senior, is projected to start and will split time with the only other signal-caller on the roster, Michael Nava of Cesar Chavez.
Metcalf will operate out of CVC and East coach Mason Hughes' pro-style offense.
"Sam is incredible," Hughes said. "Sam is very good. He's every bit as good as any of the hype that anyone has ever had on him. He has an incredible work ethic — at least out here from what I've seen. He's been awesome. He's a good leader and he can make all the throws. He's very athletic."
Metcalf attended his first county all-star game after his freshman year in 2012.
Knowing he had to be dedicated if he ever wanted to don an East Jersey, Metcalf went to work.
"When I heard about the game as a freshman, I was pretty excited," Metcalf said. "During my freshman and sophomore years, I came to watch the all-star games, and I thought, 'I want to work hard one day and hopefully play in it.' "
Metcalf won't only play in it, but he hopes he can put his arm on display like he did at Farmersville, if given the opportunity.
What's working in Metcalf's favor is that he'll have a familiar face on the receiving end of his passes: Joseph De La Cruz.
Metcalf and De La Cruz have been on the same team since the fifth grade, and they only got better as they got older. As Aztec teammates, the duo formed one of the section's top quarterback-receiving combos and terrorized opposing secondaries.
In 2014, the duo hooked up 84 times for 1,689 yards and 23 touchdowns.
"For us to play one last game together is cool," De La Cruz said. "We grew up with each other and we know each other real well. It's crazy that it's finally coming to an end."
While Metcalf attracted some recruiting attention, De La Cruz went nearly unnoticed by college coaches despite having a stellar career.
"Honestly, I gave up on football," De La Cruz said. "I was ready to go to Fresno State and just be a student."
But a phone call in May changed everything.
A Montana State Northern coach made contact with De La Cruz and offered a partial scholarship after their conversation on the phone. The very next day, they spoke again, and the shifty 5-foot-8, 160-pound wide receiver gave his verbal commitment.
"I was really happy because football is one of the things that I enjoy the most," De La Cruz said. "And to be able to keep playing football is probably the best feeling ever."
In 10 regular season games in 2014, De La Cruz posted eight games of 100 yards or more. He eclipsed the 200-yard mark four times and had three four-touchdown games.
His numbers may be eye-opening, but his on-field work with Metcalf has Hughes gleaming.
"Joseph is a very good receiver," Hughes said. "I mean there's a connection that those two have. It's just very fun to see. They're very good high school football players, and they'll probably be very good at the next level too. I've just been very impressed."
De La Cruz reports to camp on Aug. 5 at Montana Northern, an NAIA program, and will major in criminology. He hopes to become a police officer after completing his degree.
For Metcalf, the gunslinger is headed for Minnesota State Moorhead, an NCAA Division II university. But before he departs, he has some unfinished business. He wants to strap on a Farmersville helmet for one last time.
"I put a lot of pride in that town and in that school," Metcalf said. "So to be able to represent it in an all-star game, it's pretty special."
The 48th annual Tulare-Kings County All-Star Football Game is Saturday at Visalia Community Stadium. Tickets are $10 for adults and $5 for children 12 and under. Gates open at 5:30 p.m., and kickoff is at 8 p.m.


The North Central Regional (NCR) 197 committee was established in 2000 by the National Institute of Food and Agriculture, to utilize the land-grant research and extension systems, in conjunction with agricultural producers, to reduce agricultural work-related property losses, injuries, illnesses, and deaths. The NCR 197 committee was reappointed and renamed the North Central Education/Extension Research Activity (NCERA) 197 in 2005 and reappointed again in 2011.
the prevention of secondary injuries.
rural fire prevention and response.
evaluation of the effectiveness of safety and training curricula.
address the issues of low literacy rates, secondary injuries, and injuries to youth.
Click HERE to view the National Agenda for Action for complete details about the 12 priority areas of the committee.


Kyrie and LeBron Bromance are back!
Can Harden maintain his dominance?
NBA has recorded more than three times more than Russell Westbrook in history .
After Monday night he played 21.2 points, 11.1 rebounds and 11.2 points.


text:
Teen court coming to Washington Middle School
Washington Middle School is looking to start teen court.
Teen court coming to Washington Middle School Washington Middle School is looking to start teen court. Check out this story on greenbaypressgazette.com: http://gbpg.net/2wwUw4k
Samantha Hernandez, USA TODAY NETWORK-Wisconsin Published 10:33 a.m. CT Aug. 6, 2017
Washington Middle School(Photo: USA TODAY NETWORK-Wisconsin)Buy Photo
GREEN BAY - Washington Middle School is looking to make its students part of a solution to student discipline problems with the introduction of a teen court this school year.
A teen court, also known as a peer court, can take different forms. It generally includes an element where student offenders, who agree to take part, go before their trained peers to receive their punishment. Often the sentence calls for the student to make amends in some way.
The teen court was proposed by Brown County Assistant District Attorney Cynthia Vopal and Elisabeth Stockbridge, assistant state public defender with the Green Bay Trial Office. They came to the school after Green Bay School District Superintendent Michelle Langenfeld asked the public to help find solutions for ongoing issues with disruptive and at times dangerous student behavior throughout the district.
The impetus for Langenfeld's call to action came in June in the form of Kerstin Westcott's resignation from her position at Washington Middle School and her claim that the middle school was not a safe place.
RELATED: School District gets mixed reviews on Washington improvement plan
RELATED: Former Green Bay teacher demands action on school safety
In the days leading up to the new school year, Vopal and Stockbridge are working with district administrators to figure out what form the teen court will take. Different types of teen courts enlist different numbers of students and varying levels of adult involvement.
Stockbridge's children attended Washington Middle School.
"My kids had a good experience at Washington, and that's part of the reason I do care about the school," Stockbridge said. "My kids still go to Green Bay public schools. I really want to make sure that I'm involved in the school community not just parental involvement but community involvement is so important."
The teen court will be at no cost to Washington Middle School and Vopal and Stockbridge are donating their services, said Vicki Bayer, director of special education and pupil services for the school district.
Over the years, peer courts have been shown to be positive in a number of ways.
"It's bigger than just the discipline piece, it's allowing our students to learn about decision making and learn about career opportunities," Bayer said.
There is also room for student growth.
"The leadership skills, the listening skills, the ability to think on their feet and to work as role models in the building because they themselves are being empowered to be a role model and have a positive influence on their peers is all a part of it," said Nancy Anne Miller, Vilas County University Wisconsin-Extension youth agent and founding president of the Wisconsin Teen Court Association.
Miller has seen teens who went through the program as a defendant come back to take on a role in the court.
"Historically, and on the national level, recidivism rates are lower through the program. It's not for everyone. It's not 100 percent all the time, but it is a successful program," Miller said.
One of the reasons for the success is the student must have admitted fault before going to court.
"They have already admitted their guilt and they are there to make up for their mistakes," Miller said.
Bayer said the Washington teen court will not be part of the Teen Court Association.
Any incidents rising to the level of possible suspension or expulsion will continue to be handled by the administration, Bayer said.
There is also a restorative justice piece to the courts.
"The restorative justice part increases our options of possible interventions," Bayer said.
She gave the example of a student writing on a wall. Using the restorative justice path the student would work with the building engineer to improve the environment around campus.
This is not the first time the Green Bay School District or the county has had a teen court.
Southwest High School had a teen court 20 or 30 years ago, Bayer said.
According to Miller, Brown County also had a teen court until the early 2000s.
The goal is to have a mix of Washington Middle School students participating in the court, Bayer said.
A teen court should reflect the student body and be inclusive, Miller said.
The court should not be only made up of honor students, she said. If a student is a good communicator they might be a good fit to take part in the court.
Students will be chosen after the start of school year, Bayer said.
Read or Share this story: http://gbpg.net/2wwUw4k
If Packers win, Dick's Sporting Goods will reopen tonight with NFC champions gear
KGB throws in towel, advises ally to sign bond and get out of jail


text:
\section*{Acknowledgments}
\vspace{-1mm}
We want to express our gratitude for the support and feedback received from the
networking community via mailing lists and private communication, in particular
Randy Bush,
Greg Hankins,
Jakob Heitz,
Maria Matějka,
Donald Sharp,
Henk Smit
and Stefan Wahl.
We thank the reviewers and anonymous shepherd for their constructive
input and guideance.  This work supported in part by NSF grant
CNS-1855614, the European Research Council (ERC)
Starting Grant ResolutioNet (ERC-StG-679158),
by the German Ministry for Education and Research (BMBF) as BIFOLD - Berlin Institute for the Foundations of Learning
and Data (01IS18025A, 01IS18037A),
and performed while the first author held an NRC Research Associateship award at the Naval Postgraduate School.
Views and conclusions are those of the authors and
should not be interpreted as representing the official policies or
position of the U.S.\ government, the NSF, ERC, or BMBF.

\balance
\bibliographystyle{ACM-Reference-Format}

\section{introduction}

Border Gateway Protocol (BGP), the Internet's inter-domain routing protocol, is
fundamental to the operation, policies, and economics of the network.
Unsurprisingly, the real-world behavior of BGP has been subject to intense
scrutiny~\cite{griffin1999analysis,10.1145/248156.248160,roughan201110}. As an
extensible protocol, BGP and its usage have evolved in response to operator needs.
BGP communities \cite{rfc1997,BenoitOnBGPCommunities} are one such
example of an optional attribute that adds new meta-information
to routing messages.

Communities
are used to conveniently tag (an aggregate of) prefixes to enable particular
actions or policies.  However, community values and semantics are not
standardized -- the meaning of a specific community value is defined by
individual autonomous systems (ASes).  Benoit \emph{et~al.}\xspace first defined a taxonomy where, broadly speaking,
communities are used to tag received prefixes to aid an AS's internal routing
decisions, or added to outbound announcements as a convenient signaling
mechanism~\cite{BenoitOnBGPCommunities}.  Today, communities are known to encode
location
identifiers~\cite{Inferring-Complex-AS-Relationships:IMC2014,CoNEXT2015-P2F}
express policy preferences
upstream~\cite{IXP-communities-BGP-passive:Globecom2013},
enable selective advertisement in Internet Exchange Points
(IXPs)~\cite{IMC2014-RS,Inferring-Multilateral-Peering:CONEXT2013}, and as a
DDoS
mitigation signal~\cite{IMC2017-blackholing,Blackholing:PAM2016} (e.g.\xspace BGP
blackholing~\cite{rfc7999,Cisco-remotely-triggered-black-hole-filtering}).

BGP communities have been widely adopted.  Streibelt \emph{et~al.}\xspace found a
250\% increase in the number of unique communities and a 200\% increase in the
number of ASes that
use communities as seen in BGP advertisements between 2010 and 2018~\cite{IMC2018-Communities-attacks}.
Giotsas \emph{et~al.}\xspace~\cite{SIGCOMM2017-peering-infrastrutcure-outages} report that around 50\% of IPv4 and 30\% of
IPv6 BGP announcements in 2016 include at least one location-tagged BGP community.

Despite the rich literature on BGP and BGP communities,
prior work has not investigated the unintended impact of communities on the
\emph{volume} of BGP message traffic in the wild.
Isolating and decoupling the traffic impact of communities from other
mechanisms and variables in the complex Internet without ground-truth
configurations is challenging.
In this work, we take a first step towards this larger goal by examining
changes in AS paths and communities in billions of update messages at 500+ peers over 10 years.
We find that updates with no path change are common throughout the entire
measurement period and are rooted in widespread community deployment,
increasingly interconnected networks, and lack of community filtering.
More specifically, we find:

\begin{enumerate}

\item Around 50\% of announcements in March 2020 signal no path change, while
half of these exhibit a community change. We consider these announcements
\textit{unnecessary}. %

\item In laboratory experiments and in the wild, we show that community
geo-tagging in combination with missing or ineffective filtering can lead to an
increase of update messages.

\item Among 10 tested router implementations, all but two forward
communities by default. Also, 7 routers generate duplicates due to filtering
communities at egress.

\item By utilizing beacon prefixes we show that more than 60\% of all encoded
information in community attributes is revealed during global withdrawals,
as a result of path exploration.

\end{enumerate}

We publicize and validate our work through
mailing lists and online documentation~\cite{url:communityexploration}. Our
findings resonated with the community, in particular with router
developers, and helped identify a source of duplicates in a current
popular BGP implementation.
For reproducibility we publish code to identify unnecessary
announcements and router configuration of all tested routers.
Our findings afford a better understanding of routing instabilities in the
Internet, unnecessary load on the system, and may help foster detection of
anomalous communities in the future. We conclude by discussing
implications on routing
message archival and suggest future work.

\section{Background and Related Work}
\label{sec:background}

This section provides details
of BGP relevant to understanding our work on communities, as well as
a summary of
prior research.  We assume working familiarity with BGP;
see~\cite{roughan201110} for a broad overview.

\vspace{1mm}
\noindent \textbf{Path Exploration:}
The BGP decision process is
complicated, involving iBGP, eBGP and IGP interaction,
is governed by individual network policies, and beholden to BGP
implementation particulars.  There is a basic tension between
propagating reachability information quickly and sending
it prematurely, i.e.\xspace, before the AS has converged on a new best
state.  %
In practice, implementations and configurations of BGP often delay
sending messages.
Thus, updates often occur in bursts.

Several prior works analyze network stability, path exploration, and
the trade off in withholding updates~\cite{10.1145/248156.248160}.  Mechanisms such as route
dampening and MRAI timers~\cite{deshpande2004impact} have been
explored, but may offer sub-optimal performance in reacting to routing
events~\cite{wang2006measurement}.  Thus, these mechanisms are
selectively deployed.
Indeed, we show that path exploration, combined
with BGP community use, is a significant contributor to BGP update
traffic.

\vspace{1mm}
\noindent \textbf{Communities:}
BGP messages are relatively simple and include prefix \emph{updates}
(often termed an ``announcement'') as well as prefix
\emph{withdrawals} (indicating that the prefix should be removed from
the routing table).  In addition, BGP messages can include multiple
optional attributes, among them the next-hop, MED, and community.
Among these, BGP communities are notable because they are transitive
-- meaning that they are an optional attribute that may be
propagated.  Communities are the focus of our study.  As we will
show, not only are BGP communities in common use, but they are a
primary contributor to overall BGP message traffic.

BGP communities are simply a 32-bit value, however a common convention
is that the upper two bytes encode the ASN of the AS that ``owns'' the
community, while the lower two bytes define the meaning of the
community.  Because communities have no well-defined semantics, it is
up to each individual AS to define the meaning of the lower two bytes
corresponding to their community space.   Note that while large and
extended communities have since been added~\cite{rfc8092,rfc8195}, for
instance to accommodate 32-bit ASNs and to communicate additional bits
of information, these are in infrequent use.  Hence, our study focuses
on traditional BGP communities.

Benoit \emph{et~al.}\xspace provides a taxonomy of BGP communities
in~\cite{BenoitOnBGPCommunities}.  As a contemporary convention, BGP
communities can be broadly divided into informational communities and
action communities~\cite{rfc8195}.  Informational communities are
typically added to ingress routing announcements to tag aggregates of
routes in a common way in order for an AS to make internal policy and
routing decisions.  For instance, a common informational community
used by large ASes is to encode the physical geographic location
where a prefix is received,
e.g.\xspace ``North
America, Dallas, TX.''

In contrast, action communities are frequently added to egress
announcements to implement in-band signaling
to a different AS.
For instance, a common use of action communities is the blackhole
community which indicates that a provider should stanch traffic for a
particular IP or prefix that is experiencing a DDoS attack.

With the growth in BGP community adoption, researchers have
in recent years explored community prevalence and
security~\cite{BenoitOnBGPCommunities, IMC2018-Communities-attacks},
as well as the information they leak about connectivity, attacks, and
outages~\cite{SIGCOMM2017-peering-infrastrutcure-outages,
IMC2017-blackholing}.  However, less attention has been given to the
unintended impacts of communities on the volume of BGP message traffic
in general, and updates in particular -- these are the focus of the
present research.

\vspace{1mm}
\noindent \textbf{Duplicate Updates:} As with the protocol itself, BGP update behavior has been extensively studied, for
instance to understand routing dynamics~\cite{LiBGPRoutingDynamics},
understand convergence and forwarding behavior~\cite{MaoBGPBeacons},
quantify path performance~\cite{wang2006measurement}, and locate
origins of instabilities~\cite{FeldmannLocatingInstabilities}.  Of
most relevance to our present study are so-called ``duplicate'' BGP
updates, superfluous messages that do not update routing state. First
identified by Labovitz in 1998~\cite{labovitz1998internet}
and
believed to be attributable to buggy implementations, Park \emph{et~al.}\xspace
subsequently demonstrated that iBGP/eBGP interaction was the primary
cause of these duplicates~\cite{park2010investigating}.
As we also find,
when a router receives an internal update with a changed
attribute, that attribute may be removed or replaced prior to announcing to an
eBGP peer, resulting in a duplicate.
Hauweele \emph{et~al.}\xspace later verified in both real and
lab experiments that MED, next-hop, and community attribute changes induce these
duplicates~\cite{hauweele2018parrots}.

While duplicate updates have been a recognized issue for decades, we first show
via controlled lab experiments in~\S\ref{sec:controlledexperiments} the
propagation, update, and duplication implications of communities specifically.
Second, our work attempts to quantify the impact of communities on BGP message
traffic in the wild and over time. Our findings in~\S\ref{sec:analysis}
highlight the effects of increased BGP community use on update generation.
We show that BGP geolocation communities are a primary source of unnecessary
updates, and induce inter-AS message traffic even when communities are filtered.

\section{Controlled Experiments}\label{sec:controlledexperiments}

To validate our findings and inferences, as well as gain a deeper
understanding of BGP update root causes,
we conduct a series of experiments in a
controlled laboratory setting.

For each experiment run, we configure all
routers depicted in Figure~\ref{fig:lab1} to use one of the following
routing software: Cisco IOS (12.4(20)T), IOS XR (v6.0.1),
Juniper Junos (Olive 12.1R1.9),
Nokia SR OS (20.7.R2),
BIRD (v1.6.6 and v2.0.7)~\cite{url:bird},
FRRouting (v6.0.2)~\cite{url:frrouting},
OpenBGPD (v5.2 and v6.6)~\cite{url:openbgpd}
or Quagga (v1.2.4)~\cite{url:quagga}.
While Cisco and Juniper routers dominate the core router market, for example
BIRD is used in many large IXPs \cite{IMC2014-RS,euroix-2015}.
FRRouting and Quagga are used in RouteViews\xspace and RIPE\xspace collectors to
listen for BGP updates and dump them to Multi-Threaded Routing Toolkit
(MRT)~\cite{rfc6396} files. Our list of routing software is not comprehensive.

We run IOS, Junos and SR OS in emulation. By using these router images,
as well as routing daemons, we can gain insight into real-world BGP
implementation behavior.
Because we find identical behaviors for most of the experiments, we report only
on the common behavior and where it deviates.

The lab topology is crafted to test several scenarios, with and
without communities and filtering, to understand the conditions that generate BGP
update messages and when those update messages are propagated.  The
topology consists of four ASes: $X,Y,Z$ and $C$.  Router
$C_1$ mimics a route collector, while $Z_1$ originates the prefix $p$.
The links in the topology correspond to both physical connections and
eBGP and iBGP sessions.  AS $Y$ has three routers within its network;
both $Y_2$ and $Y_3$ peer with AS $Z$.

Prior to running our experiments, we verify that only BGP keep alive
messages, i.e.\xspace, pairwise heartbeats to test liveness, are sent once the network
has converged.
In the following experiments, we are interested in BGP messages that carry
announcements and withdrawals.
We use tools like tcpdump and generated logs to inspect this message exchange.

\begin{figure}[t]
\center
\includegraphics[width=0.8\linewidth]{figures/ lab1.pdf}
\vspace{-3mm}
\caption{Laboratory topology to understand conditions generating
BGP update messages}
\label{fig:lab1}
\vspace{-4mm}
\end{figure}

\begin{itemize}[leftmargin=*]
\item \textbf{Exp1}: We begin without any BGP communities to characterize
default behavior.
Note that border router $Y_1$ has two paths to reach $p$.  In the
absence of any policy, the BGP tie breaker selects $Y_2$ as the next
hop.  Therefore, to induce BGP updates, we disable the $Y_1$ to $Y_2$
link, and perform a packet capture of all messages arriving at the
collector $C_1$ and between $X_1$ and $Y_1$.

Without BGP communities, when $Y_1$ chooses a new next hop of $Y_3$,
it sends an update message to $X_1$ even though the AS path has not
changed.
(Note: Junos and SR OS do not generate duplicates).
However, this update is ignored by $X_1$ and
not propagated further -- no update message is observed at the
collector.

\item \textbf{Exp2}: Next, we consider the common scenario where AS $Y$ implements
communities that geographically tag incoming advertisements.  $Y_2$
adds community \texttt{Y:300} on ingress while $Y_3$ adds \texttt{Y:400}.
Because $Y_2$ is preferred, and no community filtering is implemented
in this network, the collector sees $p$ with \texttt{Y:300}.  We
again disable the $Y_1$ to $Y_2$ link.

Again, this induces an update
message from $Y_1$ to $X_1$. While the AS path is unchanged, this
update includes a changed community value of \texttt{Y:400}.  Because
the community value changed (implicit withdrawal), $X_1$ also sends an update which is
seen at the collector. Note that while updates sent by $Y_1$ can be due to an
internal next-hop change (as in Exp1), in the case of $X_1$ the next-hop does
not change. Thus, a change in the community attribute is the sole trigger
for the update. (Note: IOS needs explicit configuration to forward communities
on eBGP sessions).

\item \textbf{Exp3}: We implement community filtering on $X_1$ by configuring
it to remove all communities on egress.  We again flap the $Y_1$ to
$Y_2$ link to generate the update message.  Surprisingly, even
though $X_1$ is removing communities, it still sends an update to
the collector
(Note: Junos, SR OS and OpenBGPD v6.6 do not generate duplicates).
Note that this update has an unchanged AS path and
includes no communities -- i.e.\xspace, it is an arguably unnecessary
message.

\item \textbf{Exp4}: We then repeat experiment 3, but modify $X_1$
to filter communities on ingress from $Y_1$.  In this case, the
spurious update message is not sent as the communities are not
contained in the router's RIB.  This shows that we can differentiate
between ingress and egress community filtering.
\end{itemize}

\footnotesize
\begin{table}
\caption{Overview of experiments and results.}
\vspace{-3mm}
\label{tab:labsummary}
\centering
\begin{tabular}{|c|p{1.2cm}|p{1.2cm}|p{1.2cm}|p{1.2cm}|}
\hline
Routing software
 & Exp1: $Y_1$ sends dups (next-hop change)
 & Exp2: $X_1$ forwards communities set by $Y_1$
 & Exp3: $X_1$ cleans at egress, sends dups
 & Exp4: $X_1$ cleans at ingress, no dups generated\\\hline
\hline
Cisco IOS & & & & \\
12.4(20)T & true & \textbf{false} & true & true \\
XR v6.0.1 & true & \textbf{false} & true & true \\\hline
Juniper Junos & & & & \\
Olive 12.1R1.9 & \textbf{false} & true & \textbf{false} & true \\\hline
Nokia SR OS & & & & \\
20.7.R2  & \textbf{false} & true & \textbf{false} & true \\\hline
BIRD & & & & \\
v1.6.6 & true & true & true & true \\
v2.0.7 & true & true & true & true \\\hline
FRRouting & & & & \\
v6.0.2 & true & true & true & true \\\hline
OpenBGPD & & & & \\
v5.2 & true & true & true & true \\
v6.6 & true & true & \textbf{false} & true \\\hline
Quagga & & & & \\
v1.2.4 & true & true & true & true \\
\hline
\end{tabular}
\end{table}
\normalsize

\noindent \textbf{Summary:}
Table~\ref{tab:labsummary} summarizes the experiments and results.
Among the tested software, by default, only Junos and SR OS
prevent duplicates from being generated by, e.g.\xspace internal changes or community
filtering on egress.
OpenBGPD v6.6 suppresses duplicates when the community changes but not when the
next-hop changes.
Furthermore, all routers generate updates that are triggered only due a change
in the community attribute, if communities are not filtered at ingress.
Our findings imply that this behavior is transitive.
For reproducibility, we publish the relevant configurations for
each tested router software~\cite{url:communityexploration}.

We note that sending updates with no changes contradicts BGP specifications.
According to RFC4271~\S9.2~\cite{rfc4271}: ``A BGP speaker SHOULD
NOT advertise a given feasible BGP route from its Adj-RIB-Out if it would
produce an UPDATE message containing the same BGP route as was previously
advertised.''
In reality, maintaining the Adj-RIB-Out requires keeping significant state
which
is a major concern for operators when making tradeoffs
between convergence speed and resource usage.
Also, vendors and developers design their software with different default
configurations.
While for example Junos maintains the Adj-RIB-Out by default, BIRD requires
explicit configuration by the user.
The open-source implementations are not only feature rich, but also
they can operate on many different hardware architectures with
different memory capacities.
Thus, default configurations are kept at a minimum setting leaving the
responsibility to the user.

\section{Unnecessary Updates}
\label{sec:analysis}

Next, we study communities in
update messages with no path change and their impact on update propagation.
We focus on announcements and withdrawals for individual beacon prefixes
($d_{beacon}$\xspace) visible in BGP sessions over 24 hours.

\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.long-ext.20200315.rrc00.84-205-64-0-24.a1.pdf}
\vspace{-5mm}
\caption{Announcement types per BGP session for beacon prefix $84.205.64.0/24$, collector: rrc00, March 15, 2020}
\label{fig:long-ext.20200315.rrc00.84-205-64-0-24.a1}
\end{figure}

\textbf{BGP Sessions.}
We begin by investigating how peers of a routing collector perceive
the different announcement types, i.e.\xspace
\textit{pc}, \textit{pn}, \textit{nc}, \textit{nn}, \textit{xc}, and \textit{xn}.
We note that a peer AS sends only the best path via BGP sessions to the
collectors.
The stacked bar plot in Figure~\ref{fig:long-ext.20200315.rrc00.84-205-64-0-24.a1}
includes each of the BGP sessions of RIPE\xspace collector \texttt{rrc00}.
The sessions are sorted by number of announcements visible for prefix $84.205.64.0/24$~$\in$~$d_{beacon}$\xspace
and colored to indicate the announcement type.
We observe that each session shows a different
number of announcements. But more interesting is the fact that each
session shows a diverse distribution of announcements types, despite looking
\textit{only} at a single beacon prefix.
We characterize the peer ASes later in this section.
To this end, the root causes, i.e., why
\textit{nc} and \textit{nn} announcements are sent in the first place,
are
unclear. In the following we take a closer look at those announcement types.

\textbf{Community Exploration.}
To highlight the conditions that can lead to \textit{nc}
announcements in the wild,
we present an example using the view of a single BGP session.
\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.long-ext.20200315.rrc00.84-205-64-0-24.c3.17.1.pdf}
\vspace{-5mm}
\caption{Announcement types over time with prefix $84.205.64.0/24$ and AS path (\texttt{20205 3356 174 12654}). Geo-tagging induces \textit{nc} announcements.}
\label{fig:long-ext.20200315.rrc00.84-205-64-0-24.c3.17.1}
\end{figure}
In Figure~\ref{fig:long-ext.20200315.rrc00.84-205-64-0-24.c3.17.1} we show the cumulative sum of announcements over 24 hours of March 15, 2020.
We plot all announcements for the same prefix $84.205.64.0/24$~$\in$~$d_{beacon}$\xspace via a single AS path (\texttt{20205 3356 174 12654}).
Vertical yellow lines indicate the arrival of a withdrawal message for that prefix, confirming the withdrawal interval for routing beacons.

All announcements for this particular route and day show up only
during the withdrawal phases, i.e.\xspace at around 02:00, 06:00, 10:00, etc.
We deduce that this particular route was never a best path during that day (all time best path: \texttt{20205 6939 50304 12654}).
During the six withdrawal phases we observe a total of 19 announcements:
Starting with a \textit{pc} update (6 total), i.e., an announcement with changed path and community,
followed by multiple (13 total) \textit{nc}'s, announcements with changing community only.
Peer AS20205 does not set any communities.
However, it does not clean communities from its neighbor either:
The changing communities in \textit{nc} announcements represent
encoded ingress locations set presumably by AS3356.
We observe a total of 9 locations encoded in 19 announcements:
9 city communities, two country and two geographical regions, i.e., Europe and North America.
Per withdrawal phase, the location communities are mostly unique.

Due to distinct location communities attached to a single route,
multiple \textit{nc} announcements occur (comparable to Exp2 in
\S\ref{sec:controlledexperiments}). Analogously to path exploration,
we refer to this behavior as \textit{community exploration}:
Instead of multiple paths being announced, multiple communities for a single path are announced.
Also, the example above demonstrates that setting communities by one AS,
can impact the update behavior of a different AS, if no proper filtering is in
place (comparable to Exp4).

\textbf{Duplicate Announcements.}
Next, we explore a possible reason for the occurrence of \textit{nn} updates.
Therefore, we choose a route similar to the previous community exploration example.
However, we replace the peer AS with one that removes all communities (in $>$99\% of the cases).
\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.long-ext.20200315.rrc10.84-205-64-0-24.c3.2.1.pdf}
\vspace{-3mm}
\caption{Announcement types over time with prefix $84.205.64.0/24$ and AS path (\texttt{20811 3356 174 12654}). Cleaning at egress generates \textit{nn} announcements.}
\label{fig:long-ext.20200315.rrc10.84-205-64-0-24.c3.2.1}
\vspace{-0mm}
\end{figure}
Figure~\ref{fig:long-ext.20200315.rrc10.84-205-64-0-24.c3.2.1} shows the cumulative sum of announcements over the day of March 15, 2020.
We plot announcements for the same prefix $84.205.64.0/24$, but via a different AS path (\texttt{20811 3356 174 12654}).
Vertical yellow lines represent withdrawal messages for that prefix, again in accordance with the predefined intervals.
Again, all 31 announcements occur during the withdrawal phases.
Also, the phases begin with a path change (6 total), here \textit{pn}, followed by
a series of \textit{nn} announcements (25 total).

Deduced from our previous observations, we speculate that during the withdrawal
phase AS20811 simply reannounces multiple \textit{nc}'s from AS3356 (as an
implicit withdrawal) and removes the existing communities prior to announcing,
thus inducing \textit{nn} announcements.
Note, we have demonstrated such behavior in lab experiments (Exp3).
We manually re-visit the raw BGP data and confirm that no other attribute towards the collector, e.g., the MED,
has changed and no other prefix is included in the updates.
However, since our observations are limited to inter-AS changes,
we do not exclude the possibility for other sources of \textit{nn}
announcements, e.g.\xspace streams of updates due to intra-AS changes,
misconfiguration, or rate limiting -- in large and complex networks, the interplay
of these multiple internal factors may lead to unnecessary updates.

\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.longall.phases.overTime.pdf}
\caption{Revealed unique community attributes during withdrawal phases of all RIPE\xspace beacon prefixes over time.}
\label{fig:communityChanges.longall.phases.overTime}
\end{figure}

\textbf{Revealed Information.}
We have shown that geo-tagging can lead to bursts of announcements just updating
the community attribute, which can lead to re-announcements by neighboring ASes,
in a lab experiment and in the wild.
Given the information hiding character of BGP, we next investigate how
community exploration impacts the amount of information that is
revealed by
community attributes.
We utilize the fixed announcement and
withdrawal phases of the beacon prefixes, and label all announcements
~$\in$~$d_{beacon}$\xspace according to their appearances in any of the predefined phases,
or outside them. We consider all announcements that appear withing 15 minutes
of the respective phase begins, e.g., between 2:00 to 2:15 UTC for the first
withdrawal phase.

In March 15, 2020, we identify a total of 21,398 unique community attributes.
62\% of all community attributes are revealed exclusively during the
withdrawal phases. Only 17\% are revealed during the announcement phases and
$<$1\% outside both phases. The remaining attributes show up ambiguously.
Historically, this distribution is stable, as can be seen in
Figure~\ref{fig:communityChanges.longall.phases.overTime}. While the number of
unique community attributes per day during withdrawal phases increased multifold
in the last ten years, so did the total number, resulting in a stable ratio
of about 60\%.
A reason for this high number is the global increase in connectivity between
and within ASes and thus more alternative routes are explored during the
withdrawal intervals.
We note that tagged prefix aggregates are not reachable during global
withdrawals.

\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.mrtReduction.all.pdf}
\caption{Update message reduction of all MRT update files used in this work,
across all time and all collectors.}
\label{fig:communityChanges.mrtReduction.all}
\end{figure}
\textbf{Update message reduction.}
Another aspect to consider about unnecessary announcements is their impact on
message archival.
In order to investigate the update message overhead caused
by unnecessary announcements, we return to our source data, i.e.,
all (251,493) update MRT files from which we have generated the data sets
$d_{hist}$\xspace, $d_{mar20}$\xspace and $d_{beacon}$\xspace.
For each individual update file, we parse all the updates
and check if they contain unnecessary announcements.
Note that a single BGP update can contain multiple prefix announcements,
as well as withdrawals for the same AS path.
Given a single update file, we discard any update that contains only
unnecessary announcements, e.g., no path changes or withdrawals.
Since it is difficult to attribute a single prefix to the update message size,
we conservatively count the full update message, even if it includes some
unnecessary announcements.

Figure~\ref{fig:communityChanges.mrtReduction.all} shows the relative reduction
of update messages over all MRT update files.
We note that the distribution does not depend on the time or the collector.
Still, since RouteViews\xspace and RIPE\xspace use a different a binning
(96 and 288 update files per day, respectively)
to archive the updates, here we distinguish between them.
Around 50\% of all RIPE\xspace update files are reduced by 20\%+ update messages.
While RouteViews\xspace show a slightly higher reduction effect (mean=24.8\%),
the overall reduction is comparable to RIPE\xspace (mean=20.8\%).
We note that the uncompressed file size correlates positively with the number of
updates message it includes. Their ratio is almost constant for all update files
per day, per collector (with a $\sigma$ of less than 0.05). Thus, we conclude
that by removing updates containing only unnecessary announcements, the
uncompressed data volume of update files can be reduced by 20-25\%.

\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.long-ext.20200315.badASes.as2types.pdf}
\vspace{-4mm}
\caption{Unnecessary announcement (\textit{nc} vs. \textit{nn}) behavior of peer ASes in $d_{mar20}$\xspace. No correlation with AS type.}
\label{fig:communityChanges.long-ext.20200315.badASes.as2types}
\vspace{-1em}
\end{figure}
\textbf{Peer AS characterization.}
Next, we take a closer look at ASes that send unnecessary updates, i.e.\xspace,
\textit{nn} and \textit{nc} announcements.
Thereby, we focus only on ASes peering with collectors, since they provide
the only ground-truth information in our data set.
We note that not all peer ASes send updates on a given day.
From the 581 peers in $d_{mar20}$\xspace, we select 451 that actually send updates
to collectors.
Figure~\ref{fig:communityChanges.long-ext.20200315.badASes.as2types} shows the
number of \textit{nc} announcements (x-axis) and \textit{nn} announcements
(y-axis) for those peers (both axes in log scale).
We observe that while 162 (36\%) peers send \textit{nn} announcements only
(x=0), the majority of peers (285 / 63\%) send both, \textit{nc} and
\textit{nn} announcements. Only 4 peer ASes send no unnecessary announcements
(x and y=0).
Interestingly, the cluster between 10K and 1M indicates a duality in the
behavior of ASes:
there are peers that send 10K+ of \textit{nn} announcements only (x=0),
and there are peers that send 10K+ of both, \textit{nn} and \textit{nc}
announcements.
In fact, there is not a single peer that sends \textit{nc} announcements only,
implying that when communities are forwarded duplicates are always involved.
We believe this is the result of different community propagation and filtering
behavior of the peer ASes.

We further assign an AS type to each of the peers by utilizing CAIDAs as2types
data set \cite{caida:as2type}: We identify 355 Transit/Access, 49 Content, and 34 Enterprise
ASes; for 13 peer ASes no type is available. We see that the different AS types
spread across both dimensions. Thus, we conclude that the AS type does not
correlate with the propagation and filtering behavior of ASes.

\section{Discussion} \label{sec:discussion}

As the Internet's core inter-domain routing protocol, the BGP has been extensively studied.  While previous work has
found duplicate updates in the wild~\cite{labovitz1998internet} and identified potential
causes~\cite{park2010investigating,hauweele2018parrots}, we show that BGP communities play a large role in the
generation of unnecessary updates.  First, as a transitive property of BGP messages, communities can induce updates to
propagate through the entire routing system even when the path information is unchanged, the routing decision algorithm
is unaffected, and the receiving AS does not recognize the community.  Second, even when communities are filtered by an
intermediate AS, common implementations still generate a duplicate update, just without the community.  While duplicate
updates without communities do not continue to propagate, we show that they represent a sizable fraction of BGP messages
seen at route collectors and are unnecessary traffic.

Due to the surprising scale of our findings, we were interested to know if
networkers and developers are aware of the behavior we observe and
whether they consider it undesired.
As part of our validation process, we created a website
documenting our research efforts, including case studies, laboratory
experiments, and open questions directed to the
community~\cite{url:communityexploration}.
We published this website on various mailing lists
(NANOG~\cite{url:nanog.list},
BIRD~\cite{url:bird.list},
FRRouting~\cite{url:frr.list},
and OpenBGPD~\cite{url:bgpd.list})
and got into contact with various developers of routing daemons
and two vendors.
We have also directly contacted two operators of ASes involved in
the propagation of unnecessary announcements, one of which, a large Tier-1 ISP,
responded and confirmed one of our findings that only geolocation communities
are forwarded to, e.g., customer ASes, while other communities are filtered.
While the reaction of the community was affirmative of our findings,
we highlight two perspectives on the generation of unnecessary updates.
First, developers care about default configurations and to what degree they
should predefine the behavior of a router. Indeed, as we show in
laboratory experiments (\S\ref{sec:controlledexperiments}) the default behavior
deviates among different implementations. Also, through internal E-Mail
communication we learn that even among the same vendor different teams of
developers work separately on different implementations.
Second, network operators need to weigh off between memory usage due to state
keeping and the CPU overhead of processing unnecessary update messages. We find
that a system wide increase of processing due to communities has not been
anticipated by the community.

Prior work has shown that the lack of filtering and widespread propagation of BGP communities can leak information about
networks' operation and practices~\cite{SIGCOMM2017-peering-infrastrutcure-outages, IMC2017-blackholing}
and peering~\cite{Inferring-Complex-AS-Relationships:IMC2014,CoNEXT2015-P2F}, and can even be exploited to attack the
routing system~\cite{IMC2018-Communities-attacks}.  Our findings in this work demonstrate an additional motivation for more
rigorous community filtering: reducing unnecessary duplicate update traffic.  Not only does the unnecessary traffic
impact router load and convergence times~\cite{agarwal2004impact}, it increases the load and storage requirements of
systems that monitor BGP traffic including route collectors.
We show that by removing unnecessary announcements from update messages archived
by RIPE\xspace and RouteViews\xspace at least 20\% of data volume can be saved, (\S\ref{sec:analysis}).
As the global use of communities increases and ASes become increasingly
interconnected, the impact of not filtering will place even more strain on the
system.

However, we note several other implications of our findings that we plan to study in future work.  First, communities
are somewhat paradoxical to BGP's emphasis on scalability and information hiding.  For instance, the updates we observe
often allow us to remotely infer the number of interconnections between two ASes and the location where they peer.  Second, from
observing updates and lack of updates at multiple points in the network, we can make rough guesses as to the way
different ASes handle communities. Using more sophisticated network tomography techniques, we plan to classify per-AS
community behavior, for instance those that tag, filter, and ignore.
We hope to use this information to estimate the contribution of ASes that do not
peer with collectors to the generation of unnecessary announcements.
Finally, we believe that communities can enrich
our understanding of anomalous behavior in the routing system beyond existing approaches.  By characterizing the way
ASes observe and process communities, our work provides a first step toward predicting anomalous communities.

\section{Data Sets}
\label{sec:datasets}

\begin{table}
\caption{Overview $d_{mar20}$\xspace data set}
\label{tab:datasetsoverview}
\centering
\begin{tabular}{|l|r||l|r|}
\hline
IPv4 prefixes & 1,071,150 & Announcements & 1,008M  \\ 				%
IPv6 prefixes & 99,141 & w/ communities & 737.0M \\				%
ASes & 68,911 & ~~~uniq. 16 bits & 5,778 \\
Sessions & 1,504 & uniq. AS paths & 43.9M \\					%
Peers & 581 & Withdrawals & 38.5M \\						%
\hline
\end{tabular}
\end{table}

To study the impact of BGP communities on update message propagation
in the wild, we use publicly available archived routing traffic from
the RouteViews\xspace~\cite{routeviews} and RIPE\xspace~RIS~\cite{riperis} BGP collector projects.
We obtain all MRT formatted update (251,493) and RIB (9,539) files from all
collectors, inclusive of both IPv4 and IPv6 prefixes as well as withdrawals,
for a full day every 3 months (2019-03-15, 2019-06-15, 2019-09-15, etc.)
across a ten-year span (2010 to 2020).
While our analyses are based on update messages only, we use the RIB snapshots
to detect peer ASes that do not occur in the update files.

Prior to analyzing the raw data, we first perform basic
filtering, cleaning, and normalization, so as to not impart unintentional
bias.
Using current and historical allocation information from the regional
registries, we remove messages that contain an unallocated ASN or prefix at
the time of the message.
We do not aggregate overlapping prefixes, and we keep all prefixes, regardless
of their length.
We note that 7 peer ASes do not prepend their ASN to the AS path when
advertising routes to the collector, i.e., the $FROM$ field in the update
message differs from the left-most AS in the AS path. Those ASes are IXP
route servers.
To avoid overcounting peer ASes and avoid ambiguity when processing the data,
we add the ASN of the route server to the AS path.
Finally, only 4 BGP collectors (RouteViews\xspace: \texttt{route-views3, eqix,
linx, sfmix}) record update messages at a microsecond granularity, as of March
2015.
All other collectors use a single second granularity for received updates.
When multiple messages arrive within the same second for these collectors,
we preserve the message ordering and assume that each subsequent message arrives
1$\mu$s after the previous.

In the remainder of this paper, we refer to the resulting data set as $d_{hist}$\xspace.
We use $d_{mar20}$\xspace to point to the most recent data in our measurements, which is March 15, 2020.
Table~\ref{tab:datasetsoverview} provides an overview of $d_{mar20}$\xspace.
The data set includes 1,504 sessions across 581 unique peer ASes.
The number of BGP sessions at these two collector projects has roughly
doubled over the past ten years.
We note that not all the peers send updates on any day.
In $d_{mar20}$\xspace, we find updates for 451 of the 581 peer ASes.

\textbf{Routing Beacons:}
Routing beacons are prefixes announced and
withdrawn at periodic intervals~\cite{MaoBGPBeacons}.
Beacons can help network operators and researchers investigate the
routing system and routing anomalies by providing
a source of predictable and known behavior.
RIPE\xspace operates routing beacons~\cite{url:risbeacons} with an
update pattern of a single announcement every 4 hours, starting at
00:00 UTC, and a single withdrawal every 4 hours, starting at 02:00 UTC.
One specific IPv4 and IPv6 beacon prefix is announced per RIPE\xspace route collector.

From 39 available RIPE\xspace beacon prefixes, we remove 4 IPv4 beacons that are
either not active or too noisy. Then, we select all announcements and withdrawals
that are associated with the remaining 35 beacons.
We observe 660,567 announcements and 115,892 withdrawals spread over 998
sessions, 354 peers, and 34 collectors.
We refer to this subset as $d_{beacon}$\xspace.

\section{Announcement Types}
\label{sec:updatecategories}

To better understand announcements in our studied data sets, we first group them
by the prefix and the BGP session (the \texttt{<peer AS, next-hop>} tuple), in arriving
order.
Then, from one announcement to the next, we look for changes (or no changes)
in the community attribute and in the AS path. In the AS path, we further
distinguish between a change in the set of ASNs, and a change in path prepending,
i.e., inflation or deflation of an identical set; it cannot be both.
From three possible observations in the AS path attribute and two in the
community attribute, we define six different combinations of two letters to
label the \textit{announcement type}:
The first letter indicates the AS path (\textit{p} = path change,
\textit{n} = no path change, \textit{x} = path prepending),
and the second letter indicates
the community attribute (\textit{c} = community change, \textit{n} =
no community change):
\textit{pc},
\textit{pn},
\textit{nc},
\textit{nn},
\textit{xc},
\textit{xn}.

An announcement with a path change only is in the category $pn$.
If there is a change in path prepending (the set of ASes are
equal), it is in $xn$.
If, in addition to the path also the community attribute changes, the
announcement is in $pc$ (or $xc$ in case of path prepending).
While we intuitively expect $pn, pc, xn$ and $xc$ updates,
we also see updates without a path change:
$nc$ and $nn$ cover all announcements with no path change,
while the former also includes changes in the community attribute.
We note that $nn$ also includes two empty community attributes in succession.
Also, we acknowledge that the MED attribute for a the \texttt{<peer AS, next-hop>}
tuple can change towards the collector
as a reason for an \textit{nn} announcement.

\textbf{Statistics:}
\begin{table}[t]
\caption{Announcement types (share in $d_{mar20}$\xspace and $d_{beacon}$\xspace)}
\vspace{-3mm}
\label{tab:updateTypes.overview}
\centering
\begin{tabular}{|c|l|r|r|}
\hline
\textbf{type} & \textbf{observed changes} & $d_{mar20}$\xspace & $d_{beacon}$\xspace \\\hline
\hline
$pc$ & path $+$ community & 33.7\% & 44.6\% \\
$pn$ & path only & 15.1\% & 29.9\% \\
\rowcolor{Gray}
\textbf{nc} & \textbf{community only} & \textbf{24.5\%} & \textbf{13.8\%} \\
\rowcolor{Gray}
\textbf{nn} & \textbf{no change} & \textbf{25.7\%} & \textbf{11.2\%} \\
$xc$ & path prepending $+$ comm. & 0.3\% & 0.2\% \\
$xn$ & path prepending only & 0.7\% & 0.3\% \\\hline
\end{tabular}
\vspace{-4mm}
\end{table}
Table~\ref{tab:updateTypes.overview} provides a break-down of the possible
observations in $d_{mar20}$\xspace.
We note that $nc$ and $nn$ -- the only types that do not include a path change --
make up more than half of all announcements (24.5\% and 25.7\% respectively).
The largest group of announcements is of type \textit{pc} with a share of 33.7\%,
while \textit{pn} announcements constitute 15.1\%.
The number of announcements that either inflate or deflate a given AS path is
negligibly small, contributing around 1\%.
For comparison, we also provide the share of types in $d_{beacon}$\xspace. Here, we see
a different distribution. While \textit{nc} and \textit{nn} together contribute
25\% to all announcements, \textit{pc} is the most dominant type with a share
of 44.6\%, followed by \textit{pn} with 29.9\% share. Again, \textit{xn} and
\textit{xc} are low in numbers.
Recall that beacon prefixes provide us with a more controlled view on the
update behavior since they are announced and withdrawn at stated intervals.
In the wild, however, unpredictable changes at the origin AS can add to the
dynamics of update propagation at all downstream paths.

\begin{figure}[t]
\centering
\includegraphics[width=1.0\linewidth]{figures/ communityChanges.overTimeUpdateTypes.longall.share.pdf}
\vspace{-1.8em}
\caption{Share of daily announcements per type and total announcements in $d_{hist}$\xspace.}
\label{fig:overTimeUpdateTypes.longall.share}
\end{figure}
Next, we investigate the longitudinal behavior of announcement types, using
$d_{hist}$\xspace.
In Figure~\ref{fig:overTimeUpdateTypes.longall.share}, we show the share
of the individual constituents on the left y-axis, and the total number of
announcements on the right y-axis, over time.
First, we note that the overall number of announcements show a 40-fold increase
from around 26M in 2009 to 1.1B in 2019.
Except for the spike\footnote{The spike of \textit{nn} activity in June 2012 is an
artifact of peer AS821 at the \texttt{route-views2} collector sending more than
1220 duplicate announcements for more than 210K prefixes throughout a single day.} in
2012, the number is below 250M until 2015, after which it roughly
doubles to 500M in 2018, followed by another doubling in 2019 to 1B. This
increase can be explained by the parallel increase of peer ASes that send
update messages to the collectors, but also by the overall increase of routing
activity.
Second, looking at the share of the individual announcement types, we observe
some amount of variability in the distribution over time.
The standard deviation over all time points ranges between 0.047 and 0.119 for
the individual types.
The median of (\textit{pc}, \textit{pn}, \textit{nc}, \textit{nn})
announcements over the last ten years is (26\%, 24\%, 15\%, 31\%), respectively.
We note that $d_{hist}$\xspace is limited to a full day of update data per quarter year.
In a separate analysis, using ten consecutive days in February 2020, we find
less variability ($\sigma < 0.04$) on a daily basis.

redpajama_set_name: RedPajamaArXiv