[104206] in North American Network Operators' Group
Re: [NANOG] Comcast latency
daemon@ATHENA.MIT.EDU (John Osmon)
Wed Apr 30 19:32:59 2008
Date: Wed, 30 Apr 2008 17:31:48 -0600
From: John Osmon <josmon@rigozsaurus.com>
To: Jim Popovitch <yahoo@jimpop.com>
In-Reply-To: <7ff145960804300646t43d3eec1y38f5e0924ea45394@mail.gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Wed, Apr 30, 2008 at 09:46:38AM -0400, Jim Popovitch wrote:
> Looks can sometimes be deceiving. ;-) I've seen Comcast drop packets
> left and right, but show 8Mbs/2Mbs on speed test sites. Other times
> I've seen the opposite, zero PL but extremely high latency (seconds,
> double digits!)... all the while non-dynamic web pages (probably
> cached upstream) loaded just fine.
I had mrt running across a Comcast connection that indicated a
14000 ms RTT for one packet out of several hundred. I wasn't sure
that was a trustworthy measurement, but it sure suprised me.
Another time, I had a VOIP conversation fall apart once with somone on a
Comcast link. When the jitter finally fell into a reasonable
range, the call sounded *great* again -- but there was a
4 second latency that had been introduced. It was wild. I kept
wondering -- "where was this buffered? Are we on a satellite
backup route?" We kept the conversation going for a while just for the
sheer novelty.
Overall, my data points on Comcast point to a pretty solid
service -- but the outliers are pretty impressive in their
own right.
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