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Re: barak-online.net icmp performance vs. traceroute/tcptraceroute, ssh, ipsec

  • From: Joe Maimon
  • Date: Sun May 06 21:14:58 2007



Lincoln Dale wrote:


I did include icmp echo directly to each hop as a comparison. 


i guess what i'm saying is that you can't read much from the backscatter of
what a either:
 - ping of each hop
 - eliciting a response from each hop (as traceroute does)
as the basis for determining much.

you can perhaps derive SOME meaning from it, but that meaning rapidly
diminishes when there are multiple intermediate networks involved, some of
which you have no direct connectivity to verify problems with easily, likely
different return path for traffic (asymmetric routing) etc.

When the cards consistently fall in certain patterns, you can actually read them quite easily.

The standard control plane arguments dont apply when the pattern holds all the way through to equipment under your {remote-}control.

In this specific instance, I find interesting the disparity of results between each hop ICMP echo and traceroute time exceeded processing, all the way up to the final hop.

I wouldnt care if the application protocols rode well, but they dont seem to.


as i said before, if you have such terrible ssh/IPSec type performance, far
less than you think is reasonable, then my money is on a MTU issue, and
probably related to your DSL-based final hops.


cheers,

lincoln.