Unlike static networks, ad-hoc networks have no spatial hierarchy and su er from frequent link failures which prevent mobile hosts from using traditional routing schemes. Under these conditions, mobile hosts must nd routes to destinations without the use of designated routers and also must dynamically adapt the routes to the current link conditions. This paper proposes a distributed adaptive routing protocol for nding and maintaining stable routes based on signal strength and location stability in an ad-hoc network and presents an architecture for its implementation.
Loss of the routing protocol messages due to network congestion can cause peering session failures in routers, leading to route flaps and routing instabilities. We study the effects of traffic overload on routing protocols by quantifying the stability and robustness properties of two common Internet routing protocols, OSPF and BGP, when the routing control traffic is not isolated from data traffic. We develop analytical models to quantify the effect of congestion on the robustness of OSPF and BGP as a function of the traffic overload factor, queueing delays, and packet sizes. We perform extensive measurements in an experimental network of routers to validate the analytical results. Subsequently we use the analytical framework to investigate the effect of factors that are difficult to incorporate into an experimental setup, such as a wide range of link propagation delays and packet dropping policies. Our results show that increased queueing and propagation delays adversely affect BGP's resilience to congestion, in spite of its use of a reliable transport protocol. Our findings demonstrate the importance of selective treatment of routing protocol messages from other traffic, by using scheduling and utilizing buffer management policies in the routers, to achieve stable and robust network operation.
BGP is
the
inter-domain routing protocol used in the Internet today. During the course of its evolution, the Internet has gone from being a simple and small network to one that is run at its core by large service providers constantly battling with bigger and bigger topologies forcing the routing community to invent ways of scaling both interior and exterior routing protocols.
Route-reflectors
and
confederations
have turned out to be the weapons of choice in scaling BGP to these large topologies. This paper takes a close look at these two mechanisms and seeks to compare them.
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