What is routing loops?
What is routing loops
Routing loop is a network problem in which the packet continues to be routed in a circle without reaching to its destination network. A routing loop is a condition in which a packet is continuously transmitted within a series of routers without reaching to its destination. A routing loop can occur when two or more routers have incorrect routing information to destination network. Each time a packet forwarded back around the loop, it multiplies number of packet crossing that link. When any error occurs in the operation of routing algorithm and the path to the destination forms a loops.
The routing loop can occur because of:
1. Configured static routes are incorrect.
2. Route redistribution configured incorrect. Redistribution is a process of handling the routing information from one routing protocol to other routing protocol.
3. Because of slow convergence inconsistent routing table not being updated, it creates loops.
4. Because of wrong default gateway is used.
5. because of administrative changes to the routing protocol.
6. When one of two routers has no route for the destination and uses default route to forward the packet, back to the router the packet was received from, creating a loop.
In the link state routing protocol like OSPF routing loops disappear when the new topology is flooded to all the router in the routing area.BGP and EIGRP uses the algorithms that assure that routing loop can not be create.
A routing loop can create the following conditions:
1. Link bandwidth will be use between the routers in a loop.
2. A router’s CPU will be burdened with the useless packets forwarding that will affect the convergence of the network changing.
3. Routing updates not processed in a timely manner and these conditions introduces the additional routing loop.
4. Packets lost in ‘black holes’, never reaching their own destination network.
5. Routing loop increase the network traffic load by forwarding traffic within the loop.
There are many strategies that can be applied to reduce the routing loops. There is a method placing a limit of the number of the hops a packet takes between routers, found in RIP (Routing Information Protocol).
The mechanism use to prevent routing loops are:
1. Maximum hop count
2. Hold-down timers
3. Split horizon
4. Route poising or poison reverse
5. Triggered update
No related posts.