BGP Timers

Answered Question
Oct 28th, 2007
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I have a lab setup simulating 2 routers connected to 2 different service providers. I am forcing all traffic to go through router1 using weight values.


I am simulating link failures by pulling the WAN connection on router1. The routing changes over quickly to router2. Doing a continuous ping from a windows box, the icmp echo only times out once.


When simulating a LAN link failure on router 1(pull the Ethernet cable), routing does not change over to router 2 until the BGP hold timers expire, which is 180 seconds.


Why does the LAN link failure take longer than the WAN? I can change the timers between the LAN peer group to speed this up, but I don't understand why I don't see the same results on the WAN failure.




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Correct Answer by htarra about 9 years 4 months ago

The reason why the LAN failure takes time is it needs to wait for the dead interval time 180secs to detect it. If LAN is connected to a switch if its directly connected to a router the time will be different.

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Correct Answer
htarra Thu, 11/01/2007 - 17:11
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The reason why the LAN failure takes time is it needs to wait for the dead interval time 180secs to detect it. If LAN is connected to a switch if its directly connected to a router the time will be different.

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