03-12-2012, 01:58 PM
Multiple Routing Configurations for Fast IP Network Recovery (IEEE-2009)
Abstract:
As the Internet takes an increasingly central role in our communications infrastructure,
the slow convergence of routing protocols after a network failure becomes a growing problem.
To assure fast recovery from link and node failures in IP networks, we present a new recovery
scheme called Multiple Routing Configurations (MRC). Our proposed scheme guarantees
recovery in all single failure scenarios, using a single mechanism to handle both link and node
failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and
assumes only destination based hop-by-hop forwarding. MRC is based on keeping additional
routing information in the routers, and allows packet forwarding to continue on an alternative
output link immediately after the detection of a failure. It can be implemented with only minor
changes to existing solutions. In this paper we present MRC, and analyze its performance with
respect to scalability, backup path lengths, and load distribution after a failure. We also show
how an estimate of the traffic demands in the network can be used to improve the distribution
of the recovered traffic, and thus reduce the chances of congestion when MRC is used.
Existing System:
The demands on Internet reliability and availability have increased accordingly. A
disruption of a link in central parts of a network has the potential to affect hundreds of
thousands of phone conversations or TCP connections, with obvious adverse effects. The ability
to recover from failures has always been a central design goal in the Internet. IP networks are
intrinsically robust, since IGP routing protocols like OSPF are designed to update the forwarding
information based on the changed topology after a failure. This network-wide IP reconvergence
is a time consuming process, and a link or node failure is typically followed by a
period of routing instability. During this period, packets may be dropped due to invalid routes.
Proposed System:
In this paper we present a new scheme for handling link and node failures in IP
networks. Multiple Routing Configurations (MRC) is a proactive and local protection mechanism
that allows recovery in the range of milliseconds. MRC allows packet forwarding to continue over preconfigured alternative next-hops immediately after the detection of the failure. Using
MRC as a first line of defense against network failures, the normal IP convergence process can
be put on hold. This process is then initiated only as a consequence of non-transient failures.
Since no global re-routing is performed, fast failure detection mechanisms like fast hellos or
hardware alerts can be used to trigger MRC without compromising network stability. MRC
guarantees recovery from any single link or node failure, which constitutes a large majority of
the failures experienced in a network. MRC makes no assumptions with respect to the root
cause of failure, e.g., whether the packet forwarding is disrupted due to a failed link or a failed
router.