Has anyone else noticed a significant increase in latency within Comcast's network? -- LR Mack McBride Network Administrator Alpha Red, Inc. _______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog
On Tue, 29 Apr 2008 23:43:46 -0500 mack <mack@exchange.alphared.com> wrote:
Has anyone else noticed a significant increase in latency within Comcast's network?
On one quick test, it looks normal to me from my house. --Steve Bellovin, http://www.cs.columbia.edu/~smb _______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog
On Wed, Apr 30, 2008 at 8:14 AM, Steven M. Bellovin <smb@cs.columbia.edu> wrote:
On Tue, 29 Apr 2008 23:43:46 -0500 mack <mack@exchange.alphared.com> wrote:
Has anyone else noticed a significant increase in latency within Comcast's network?
On one quick test, it looks normal to me from my house.
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. Look, I've always been a big fan of Comcast.... but at this point I suspect they have just about over-engineered their network. -Jim P. _______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog
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. _______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog
-----Original Message----- From: John Osmon [mailto:josmon@rigozsaurus.com] 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.
The delay was probably introduced by an adaptive jitter buffer on one of the VoIP end points. It is supposed to reduce the buffer as network conditions improve. When it "fell apart" the buffer was increased until it was long enough to reorder all of the packets. It would be interesting to see if a call between those same end points would reduce the size of their buffers after the network stabalized again. Mike
As luck would have it, I have been running Smokeping from my home connection (Comcast Business) pointed towards Comcast Residential (and other broadband providers) routers for a few weeks. I'm not sure when you saw the latency increase, but if it has been in the past few weeks, I might actually have useful data for you. If you (or others) are interested in access, please contact me off-list. Dave On Tue, Apr 29, 2008 at 9:43 PM, mack <mack@exchange.alphared.com> wrote:
Has anyone else noticed a significant increase in latency within Comcast's network?
-- LR Mack McBride Network Administrator Alpha Red, Inc.
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participants (6)
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Big Wave Dave -
Jim Popovitch -
John Osmon -
mack -
Mike Fedyk -
Steven M. Bellovin