Strowes, Stephen D.
Compact routing for the future internet.
PhD thesis, University of Glasgow.
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The Internet relies on its inter-domain routing system to allow data
transfer between any two endpoints regardless of where they are
located. This routing system currently uses a shortest path routing algorithm
(modified by local policy constraints) called the Border Gateway
Protocol. The massive growth of the Internet has led to large routing
tables that will continue to grow. This will present a serious
engineering challenge for router designers in the long-term,
rendering state (routing table) growth at this pace unsustainable.
There are various short-term engineering solutions that may slow the
growth of the inter-domain routing tables, at the expense of increasing
the complexity of the network. In addition, some of these require manual configuration, or
introduce additional points of failure within the network. These solutions may
give an incremental, constant factor, improvement. However,
we know from previous work that all shortest path routing algorithms
require forwarding state that grows linearly with the size of the
network in the worst case.
Rather than attempt to sustain inter-domain routing through a
shortest path routing algorithm, compact routing algorithms exist that
guarantee worst-case sub-linear state requirements at all nodes by
allowing an upper-bound on path length relative to the theoretical
shortest path, known as path stretch. Previous work has shown
the promise of these algorithms when applied to synthetic graphs
with similar properties to the known Internet
graph, but they haven't been studied in-depth on Internet topologies
derived from real data.
In this dissertation, I demonstrate the consistently strong
performance of these compact routing algorithms for inter-domain routing by performing
a longitudinal study of two compact routing algorithms on the Internet
Autonomous System (AS) graph over time.
I then show, using the k-cores graph decomposition algorithm, that
the structurally important nodes in the AS graph are highly stable
over time. This property makes these nodes suitable for use as the
"landmark" nodes used by the most stable of the compact routing
algorithms evaluated, and the use of these nodes shows similar strong
Finally, I present a decentralised compact routing algorithm for
dynamic graphs, and present state requirements and message overheads
on AS graphs using realistic simulation inputs.
To allow the continued long-term growth of Internet routing state, an
alternative routing architecture may be required. The use of the
compact routing algorithms presented in this dissertation offer
promise for a scalable future Internet routing system.
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