Conectivity Testing

[ppucci]

Friends,

I have a customer who is experiencing some packet loss problems. I logged into his router and did some testing. When I ping the WAN far-end, I have 100% success. However, if I try an extended ping, I miss every other ping (!.!.!.!). I already checked the routing table for bad routes, but nothing unnusual.

Anybody have any tips?

Rgds,

Persio

[svermill]

I seem to recall seeing this problem a while back. I think that it was a bad route being load balanced across. You already checked that though. Could it be a bad route on the return path?

[svermill]

On further thought, you might want to try an extended ping an specify more than the default 2 second timeout and see what happens. I once set the bandwidth (not the speed) on an asynch interface to 64kbps but acutally had it configured for only 9.6kbps. I think I was running OSPF. It caused some serious issues with load balancing and I wound up with a response on every other ping. Extending the response time "fixed" the problem until I figured out my mistake.

Also, don't forget that you can turn on "debug IP ICMP" to get a better idea of what is going on. Even if a ping times out, the response will still arrive at the pinging router (assuming all in the network/routing tables is OK). The debug option will tell you when those late responses arrive.