by all means, ping all you like. please do realize that routers have other things to do besides answer pings when they're busy. just because a router doesn't respond to 15% of its pings doesn't mean that it's dropping 15% of its packets or that there is a 15% loss on a line. router load is not router load, process switched packets are not the same as card-level switched or cache switched. there aren't any easy answers. perhaps we should all just implement "ping" servers in pops ( a 386 running linux or bsd might suffice). Jeff Young young@mci.net
On Sat, 21 Oct 1995, Mike O'Dell wrote:
remember that using pings to sample connectivity to a very busy cisco router is not a very reliable probe for several reasons. Returning pings is a low-priority task in the first place, and they are rate-limited, so if the processor is busy processing lots of BGP updates and several folks are fribbling with it using ping or SNMP, it is less than clear what they will see.
-mo
Michael A. Nasto quips:
OK! Agreed. So then, what would you use?
Have you ever been in a classroom and had a student raise his hand, answer every question, ask intelligent questions, etc. just to prove to the class how smart he or she is. This is the premise of the 'Two Mike's Interchange' above. One says, HEY! I know ping packets are a lower priority than everything else in a *CISCO* router LOOK AT ME (wave wave). Then another kid in the class quips... if PING is not what you would use, give us a better utility.
In fact... EVERYONE ( okay 99.73 percent :-) uses PING. After all router LOAD is router LOAD.... and if a few ICMP packets can't get back in a subjectly reasonable time.. then DUH.... "da network is busy......" BGP updates take bandwidth just like any other packet.
Of course the 0.27 percent, zen routing gods of the universe just feel the load and the harmonic BGP update patterns and PING between the BGP updates.... for a better answer.
Sorry, I could not resist.... and apologize for the satire. PING!! PING!! PING!!
Tim
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