Home page logo
/

nanog logo nanog mailing list archives

Re: Initial Route Server Stats for MAE-East
From: "Jeff Young" <young () mci net>
Date: Sun, 22 Oct 1995 21:04:19 -0400

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

-- 
+--------------------------------------------------------------------------+
| Tim Bass                           | #include<campfire.h>                | 
| Principal Network Systems Engineer |       for(beer=100;beer>1;beer++){  |
| The Silk Road Group, Ltd.          |           take_one_down();          |
|                                    |           pass_it_around();         |
| http://www.silkroad.com/           |       }                             |
|                                    |  back_to_work(); /*never reached */ | 
+--------------------------------------------------------------------------+



  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]