As link bandwidth affect the transmission capacity, variable transmission capacity presents a problem in networks in terms of ensuring the throughput for which the network is designed. From a mobile backhaul application point of view, this becomes particularly important at places in the network with a high amount of aggregated traffic or when ring or mesh topologies are deployed due to geographical and resiliency considerations (i.e. unreliable transmission media, etc.). A network 100 with variable link capacity is illustrated in FIG. 1. Network 100 includes nodes 110, 120, 130, 140, 150 and 160 (having corresponding switches 112, 122, 132, 142, 152 and 162) and variable or fixed bandwidth links 170 between the various nodes. Service paths 180 may be established over at least some of the links 170.
At present, the main packet transport networks are Ethernet and MPLS (Multi Protocol Label Switching). However, new technologies such as MPLS-TP (Transport Profile) are likely to be deployed in telecommunications transport networks. These technologies are generally clients of the physical transport layers which could be copper, ether or optical fiber. In networks that utilize microwave links for transport of Ethernet or MPLS packets, degradation due to environmental conditions or other impairments could result in loss of traffic on the microwave links.
New packet transport technologies are also being deployed over the physical layers such as fiber, copper or Ether. In microwave transport networks, degradation on microwave links can result in catastrophic loss of services. Existing solutions use protection switching where redundancies of these microwave links are deployed. However, this is an expensive solution.
Several technologies operating on variable link bandwidth networks do not take full advantage of the offered bandwidth. The links are often dimensioned for a guaranteed bandwidth which is a threshold for the availability of the entire link. If the threshold is exceeded, the link is made inoperable and will not be used for user traffic. Such static service allocation is illustrated in FIG. 2.
A link threshold 240 for guaranteed service may be pre-determined (corresponding approximately to 62.5% in this exemplary scenario). In state 210, the full bandwidth is available (i.e. greater than the 62.5% threshold) for the services allocated on the link. Therefore, no problems are encountered. In state 220, the link bandwidth has decreased to approximately 65% (still greater than the threshold) and some bandwidth is not available (35%). In this state, less bandwidth is made available to the best effort services (i.e. not guaranteed service) and best effort end-users can potentially experience a slower connection (i.e. service degradation). Guaranteed service end-users can still be provided service.
In state 230, the link bandwidth has decreased to a level where it is not possible to sustain the guaranteed services (i.e. less than 62.5%). As the services compete for the same resources, they could potentially all experience service degradation or even a service break down. Since it is not possible to operate in this state, the link can be shut down. A command signal needs to be sent to all services to take an alternate route. Transmitting such a signal may not always be possible as bandwidth may not be available to cater for extra bandwidth needed by the service.
A need exists, therefore, for facilitating a desirable throughput solution directed to networks having links with variable capacity.