How WAN Interfaces Handle Ping's

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Jul 9th, 2008
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could someone please explain the following to help me understand how it works??

I have 2 routers connected via a serial p2p link and configured with /30 ip's at both ends. If I connect to 1 router and ping its own local WAN interface, the ping request actually traverses the wan link to the B end and returns instead of just going internally directly to the wan interface. If I ping an ip on the remote router, the avg response time is say 90ms however if I ping the local wan interface the avg response time is about double at 180ms. I switched debugging on on this interface and confirmed it to be correct.

Any feedback would be helpful??

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a.alekseev Wed, 07/09/2008 - 03:18
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Yes, this is a common behaviour for WAN interfaces.

Ping for local WAN interfaces goes through remote side.

edsantos1 Wed, 07/09/2008 - 03:21
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is it only for WAN interfaces?? and is it for all types of WAN interfaces??

a.alekseev Wed, 07/09/2008 - 03:26
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ppp, frame-relay, hdlc...

sdoremus33 Wed, 07/09/2008 - 18:37
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Every time a hop traverses a router in its path = response time also the ttl is decremented by 1 every time a hop traversed through a router

Ex rtra --> rtrb+rtrc+rtrd-->rtrd

rtra 2 hops ttl decremented by 2


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