Re: [aqm] ping loss "considered harmful"

Mikael Abrahamsson <swmike@swm.pp.se> Mon, 02 March 2015 04:05 UTC

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Date: Mon, 2 Mar 2015 05:05:18 +0100 (CET)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Dave Taht <dave.taht@gmail.com>
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Cc: "aqm@ietf.org" <aqm@ietf.org>, "cerowrt-devel@lists.bufferbloat.net" <cerowrt-devel@lists.bufferbloat.net>, bloat <bloat@lists.bufferbloat.net>
Subject: Re: [aqm] ping loss "considered harmful"
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On Sun, 1 Mar 2015, Dave Taht wrote:

> but wow, it never occurred to me - in all these years - that ping was 
> the next core metric on simple tests. I can be really dumb.
>
> How can we fix this user perception, short of re-prioritizing ping in
> sqm-scripts?

People will make all kinds of judgement calls based on things that are not 
very relevant.

Some people think a traceroute with few hops in it to be better than one 
with more hops in it. So a lot of providers use their MPLS networks and 
make the intermediate nodes not show up in traceroute.

I don't know how many times I have experienced people have used PING and 
opened trouble tickets when a core router had ICMP ping packet loss (even 
though all core router platforms have rate limiters for ICMP).

When you say that you de-prioritize ping, do you mean only ECHO REQUEST 
and ECHO REPLY, or do you mean all ICMP? Perhaps a solution would be to 
assure 5% of the link bandwidth for ICMP?

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se