> Date: Mon, 16 Feb 2009 09:38:25 -0500 > From: Danny Mayer <[email protected]> > Sender: [email protected] > > Uwe Klein wrote: > > Danny Mayer wrote: > >> Be warned that ping uses ICMP and not UDP so the costs are different. > > > > > > Danny, > > > > we are looking at the physical transport layer i.e. > > "physical link layer" which does not care about protocol. > > > > Latencies on a DSL line are impacted by packet size, > > effective datarate, lookahead error correction > > and some ancilary stuff _per_ direction. > > > > Aditionally depending on configuration up and down stream > > utilisation can have impact on the opposite path. > > > > uwe > > Yes, I know all that. Nevertheless routers and the like also treat ICMP > packets differently from UDP and TCP. There are lots of reasons to do so > but we are getting far afield from the original question at this point.
Routers treat ICMP differently when destined to the router processor, supervisor or routing engine. (These are similar things in different routers.) I know of no commercial router with hardware based forwarding that treats transit ICMP any different from transit UDP or anything else. It is possible to use CoS and multiple hardware queues to do such a thing, but I doubt it is common practice as there is little reason to do so and it is fairly complex to set up (depending on the particular router involved). But we are digressing badly from the topic at hand. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: [email protected] Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751 _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
