Re: [aqm] ping loss "considered harmful"

Joe Touch <touch@isi.edu> Mon, 02 March 2015 21:53 UTC

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Date: Mon, 02 Mar 2015 13:53:13 -0800
From: Joe Touch <touch@isi.edu>
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Subject: Re: [aqm] ping loss "considered harmful"
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On 3/2/2015 1:40 AM, Brian Trammell wrote:
...
> The real solution is to create a utility called "ping" that uses 
> traffic that gets prioritized the same way as the traffic you care
> about instead of ICMP echo request/reply. Users don't care about
> the packets on the wire so much as they do that you're supposed to
> ping things.

There are three separate problems:

1. a ping that doesn't use ICMP
	there are dozens of these

2. needing a reflector
	ping gets around this only because the reflector is widely
	deployed (and integrated into most OSes)

3. using the same port as the traffic you care about
	transport protocol is only one problem (ICMP being a "transport
	protocol" by virtue of using the IP protocol number field)

	the other is differential prioritization based on port number

	there's no easy solution to that;
	every service would need an integrated
	ping reflector

I suspect #3 is the ultimate killer of this idea.

Joe