I may be missing something but.. presumably their rate-limiting involves some form of queuing/buffering.. in which case assuming the ping is the only thing occuring, when the rate hits the limit it will queue, delay and slow down the echo/reply and no packets should be lost? on the other hand, if as is i think suggested below theres no buffer ie when it hits the limit it starts dropping then i dont think thats a good way of rate limiting as it only works for tcp and the network really needs to provide a way to slow the ip layer down. i cant see how that will provide a usable service... Steve -- Stephen J. Wilcox IP Services Manager, Opal Telecom http://www.opaltelecom.co.uk/ Tel: 0161 222 2000 Fax: 0161 222 2008 On Mon, 15 Jul 2002, Phil Rosenthal wrote:
Hello Alex,
I'd say this sounds obvious, but may be deceptively so... If you are taking a pipe capable of 1000 mbit, and rate-limiting it to 311 mbit, the logic used may be:
In the last 1000 msec have there been more than 311mbits? If yes: drop.
What you want is to shape the traffic, so the rule would be: In the last 1000 msec have there been more than 311 mbits? If yes: store until the msec period is up, then transmit.
If you are pushing 100 mbits over this link, it is entirely likely that there will be a few sub-second burts up to 1000 mbit, and a few sub-second drops to 0mbit.
An option for you would be to just figure out what the exact rate-limiting rules are, and then shape it into those rules on your side of the link -- assuming they wont change it to a shaping rule.
--Phil
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Alex Rubenstein Sent: Monday, July 15, 2002 10:48 PM To: nanog@merit.edu Subject: fractional gigabit ethernet links?
Hello,
I'm trying to troubleshoot a problem with a fractional (311 mbit/second) gigabit-ethernet line provided to me by a metro access provider. Specifically, it is riding a gig-e port of a 15454.
The behavior we are seeing is an occasional loss of packets, adding up to a few percent. When doing a cisco-type ping across the link, we were seeing a consistent 3 to 4 percent loss.
For fun, the provider brought it up to 622 mbit/second, and loss dropped considerably, but still hangs at about 1 to 2 percent.
There is no question in my mind the issue is with the line, as we've done a wide variety of tests to rule out the local equipment (MSFC2s, FYI).
Any clues would be exceptional.
-- Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben -- -- Net Access Corporation, 800-NET-ME-36, http://www.nac.net --