29-05-2013, 11:51 AM
Multiple Routing Configurations For Fast IP Network Recovery
Multiple Routing.pdf (Size: 519.59 KB / Downloads: 24)
Abstract
Now A Days Internet plays a major role in day to day communication,if a network gets failed the recovery is becoming a major problem. It takes a much time to re-establish the Link 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 pure connectionless, and assumes only destination based peer-to-peer 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,shortest path discovery, 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.
INTRODUCTION
Inrecent years the Internet has been transformed from a special purpose network to an ubiquitous platform for a wide range of everyday communication services. 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.
MRC OVERVIEW
MRC is based on building a small set of backup routing configurations, that are used to route recovered traffic on alternate paths after a failure. Our MRC approach is threefold. First, we create a set of backup configurations, so that every network component is excluded from packet forwarding in one configuration. Second, for each configuration, a standard routing algorithm like OSPF is used to calculate configuration specific shortest paths and create forwarding tables in each router, based on the configurations The use of a standard routing algorithm guarantees loop-free forwarding within one configuration.
In our approach, we construct the backup configurations so that for all links and nodes in the network, there is a configuration where that link or node is not used to forward traffic. Thus, for any single link or node failure, there will exist a configuration that will route the traffic to its destination on a path that avoids the failed element. In Section III, we formally describe MRC and how to generate configurations that protect every link and node in a network.
RECOVERY LOAD DISTRIBUTION
MRC recovery is local, and the recovered traffic is
routed in a backup configuration from the point of failure
to the egress node. This shifting of traffic from the
original path to a backup
path affects the load distribution in the network, and
might lead to congestion. If MRC is used for fast
recovery, the load distribution in the network during the
failure depends on three factors:
(a) The link weight assignment used in the normal
Configuration C0,
(b) The structure of the backup configurations, i.e.,
which links and nodes are isolated in each Ci
{C1,……Cn},
© The link weight assignments used in the
backbones B1…….Bn of the backup
configurations.
RELATED WORK
MRC operates without knowing the root cause of failure, i.e., whether the forwarding disruption is caused by a node or link failure. This is achieved by using careful link weight assignment according to the rules we have described. The link weight assignment rules also provide basis for the specification of a forwarding procedure that successfully solves the last hop problem. The performance of the algorithm and the forwarding mechanism has been evaluated using simulations. We have shown that MRC scales well: 3 or 4 backup configurations is typically enough to isolate all links and nodes in our test topologies. MRC backup path lengths are comparable to the optimal backup path lengths—MRC backup paths are typically zero to two hops longer. MRC thus achieves fast recovery with a very limited performance penalty.
Multiple Routing.pdf (Size: 519.59 KB / Downloads: 24)
Abstract
Now A Days Internet plays a major role in day to day communication,if a network gets failed the recovery is becoming a major problem. It takes a much time to re-establish the Link 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 pure connectionless, and assumes only destination based peer-to-peer 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,shortest path discovery, 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.
INTRODUCTION
Inrecent years the Internet has been transformed from a special purpose network to an ubiquitous platform for a wide range of everyday communication services. 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.
MRC OVERVIEW
MRC is based on building a small set of backup routing configurations, that are used to route recovered traffic on alternate paths after a failure. Our MRC approach is threefold. First, we create a set of backup configurations, so that every network component is excluded from packet forwarding in one configuration. Second, for each configuration, a standard routing algorithm like OSPF is used to calculate configuration specific shortest paths and create forwarding tables in each router, based on the configurations The use of a standard routing algorithm guarantees loop-free forwarding within one configuration.
In our approach, we construct the backup configurations so that for all links and nodes in the network, there is a configuration where that link or node is not used to forward traffic. Thus, for any single link or node failure, there will exist a configuration that will route the traffic to its destination on a path that avoids the failed element. In Section III, we formally describe MRC and how to generate configurations that protect every link and node in a network.
RECOVERY LOAD DISTRIBUTION
MRC recovery is local, and the recovered traffic is
routed in a backup configuration from the point of failure
to the egress node. This shifting of traffic from the
original path to a backup
path affects the load distribution in the network, and
might lead to congestion. If MRC is used for fast
recovery, the load distribution in the network during the
failure depends on three factors:
(a) The link weight assignment used in the normal
Configuration C0,
(b) The structure of the backup configurations, i.e.,
which links and nodes are isolated in each Ci
{C1,……Cn},
© The link weight assignments used in the
backbones B1…….Bn of the backup
configurations.
RELATED WORK
MRC operates without knowing the root cause of failure, i.e., whether the forwarding disruption is caused by a node or link failure. This is achieved by using careful link weight assignment according to the rules we have described. The link weight assignment rules also provide basis for the specification of a forwarding procedure that successfully solves the last hop problem. The performance of the algorithm and the forwarding mechanism has been evaluated using simulations. We have shown that MRC scales well: 3 or 4 backup configurations is typically enough to isolate all links and nodes in our test topologies. MRC backup path lengths are comparable to the optimal backup path lengths—MRC backup paths are typically zero to two hops longer. MRC thus achieves fast recovery with a very limited performance penalty.