Modern OSI Model
Modern OSI Model
[A light gray shape that surrounds seven stacked dark gray rectangles centered above each other, all with labels. The light gray shape is connected but sometimes only on one side of the dark rectangles. It goes above and below the top and bottom rectangles. At the top there is a heading:] Modern OSI Model
[The first black rectangle has two lines of text. It is supported by the light gray shape on both sides:] Application (Facebook)
[Pulling the second rectangle out to the right would collapse the tower, with the top tipping to the right:] Presentation
[Pulling the third rectangle out to the left would collapse the tower, with the top tipping to the left:] Session
[The fourth rectangle is supported on both sides:] Transport
[Pulling the fifth rectangle out to the left would collapse the tower making it tip to the left:] Network
[Between the fifth and sixth dark rectangles is a label for the entire light gray shape:] Google & Amazon
[The sixth rectangle is supported on both sides:] Data link
[The seventh rectangle is supported on both sides:] Physical

The Open Systems Interconnection (OSI) Model is a conceptual model for network communications that defines 7 layers of functionality, where higher layers add increasing complexity to lower layers through associated protocols and standards.  The 7 layers in the standard OSI Model are:
In practice, the OSI model abstracts the communication between two end points, like a Facebook client and Facebook servers all the way from the application layer on the server, down to the wire on which the data is transmitted, and back up to the application layer where the user views the data. As Facebook is one of the most used websites in the world with more than a billion users, Randall claims that the "application" layer (what the client sees and uses) is mostly Facebook .
A light gray shape labeled "Google & Amazon" surrounds all seven layers of the model in an irregular shape indicating that Google and Amazon, by dint of their size and dominance at multiple layers of the model influence the entire structure. An example of Google's influence would be their introduction of new protocols like QUIC and SPDY as replacements for the existing TCP protocol that was a foundation of the web, and their accompanying modifications of the original HTTP protocol.
The significance of the irregular pattern of the "Google & Amazon" blob isn't clear. It is likely that it is in reference to the irregular way in which their modifications to the OSI stack have evolved. Potentially with extensions to the left representing the influence of Google, and extension to the right representing the influence of Amazon. However, it is also notable that the irregular structure of the stack is reminiscent of a Jenga tower. Jenga is a game in which blocks are removed from a vertical stack and added back to the top until the whole collapses. This may be a commentary on the instability of the network stack in general, or on how Google and Amazon's additions and changes to it have destabilized the networking protocols.  Or, the specific blocks to be pulled out (presentation, session, and network) may be the ones whose removal collapses the tower while the other ones can be easily removed and replaced (like the center blocks in Jenga), implying that between Google and Amazon, even if these were pulled out, the tower would remain standing.  What this says about the three layers that would destabilize the tower is unclear.
The title text refers to Horcruxes used by Voldemort in the Harry Potter book series. A Horcrux is a magical artifact used to house a wizard's soul, preventing them from dying if their body is destroyed. Since they can only be created by murdering other people, they are heavily forbidden, and before Voldemort it was unheard of for a wizard to use more than one. Voldemort used seven -- the same number of layers in the OSI model. However, while Voldemort hid his seven Horcruxes in different places to make himself that much harder to kill, Randall's have all been collected in Google and Amazon, defeating the purpose of using more than one. Alternatively, transforming each layer of the OSI model into a horcrux may be regarded as a strategy to prevent them from being destroyed since doing so would destroy networking. This strategy would fail in the modern world, since some of the envisioned layers were not used in the more common modern TCP/IP networking model and in the case of cloud infrastructure potential exists to provide even more shortcuts.
The title text may also be a reference to a prior comic about Randall mixing up things that come in groups of seven, like data layers and Horcruxes.
[A light gray shape that surrounds seven stacked dark gray rectangles centered above each other, all with labels. The light gray shape is connected but sometimes only on one side of the dark rectangles. It goes above and below the top and bottom rectangles. At the top there is a heading:] Modern OSI Model
[The first black rectangle has two lines of text. It is supported by the light gray shape on both sides:] Application (Facebook)
[Pulling the second rectangle out to the right would collapse the tower, with the top tipping to the right:] Presentation
[Pulling the third rectangle out to the left would collapse the tower, with the top tipping to the left:] Session
[The fourth rectangle is supported on both sides:] Transport
[Pulling the fifth rectangle out to the left would collapse the tower making it tip to the left:] Network
[Between the fifth and sixth dark rectangles is a label for the entire light gray shape:] Google & Amazon
[The sixth rectangle is supported on both sides:] Data link
[The seventh rectangle is supported on both sides:] Physical
