North American Network Operators Group
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RE: Pinging routers for network status

  • From: Blaine Christian
  • Date: Mon Dec 18 10:43:19 2000 
Hello,

One thing to keep in mind is that even if you escape being process
switched you still have ECMP and variants to contend with.  Some vendors
reliably switch packets through certain paths based on source/destination
hashes.  This means a probe THROUGH a router using a single source 
address could well report good things while an adjacent source prefix
could be screwed by riding a congested path.  The only way to be
absolutely sure is to either stop using ECMP or run your tests from
enough devices to be hashed over all possible paths.

All the above in mind, ICMP is quite useful and while it is not 100%
accurate it is a pretty good way to identify possible issues.

Regards,

Blaine