Anyone considered this could simply be a case of a customer ds3 provisioned into a mpls ccc/l2ckt style upstream aggregate? Ie. Ppp/hdlc in mpls.
It seems best to first contact Q and ask exactly how this thing is provisioned. -Tk On 9/27/08, Frank Bulk <[EMAIL PROTECTED]> wrote: > It would be quite the poorly implemented ATM-based transport system if > DS-3's were over-provisioned. We're not talking about packet-based service, > it should be transported as traditional SONET-mapped. > > Frank > > -----Original Message----- > From: Ben Plimpton [mailto:[EMAIL PROTECTED] > Sent: Friday, September 26, 2008 2:35 PM > To: mike > Cc: nanog@nanog.org > Subject: Re: high latency ds3 issue on unloaded line > > We've had a similar issue with a few of our Qwest DS3's. The solution > has been 1 of the following.... > > 1) Qwest has over-provisioned the transit links on their atm network > that the DS3 is riding and the during peak times of the day, the > transit link becomes congested causing high latency not related to our > traffic levels. So the congestion could be appearing beyond your > local loop. > > 2) We also had an instance where qwest had an issue with the PVC on > the atm switch that we connected into that was causing > 500ms of > latency. Like you, we are in a small town served by older ATM > switches, so you might just see if they can rebuild both sides to see > if that clears it up. Sounds quacky, but after 12 hours of > troubleshooting, that was the fix. > > Ben > > On Sep 26, 2008, at 12:59 PM, John Lee wrote: > >> Mike, >> >> Your latencies which suddenly appear for several hours and then go >> away and do this on a regular basis sounds like a layer 2, facility >> switching issue. As you indicated " the problem comes on during the >> day and then lets up late in the evening" sounds like the under >> lying facility is being switched back around the "long side" of the >> SONET ring or other facility. Some carrier facilities are scheduled >> for "one path or direction" say during the day that are supposed to >> be for lower latency time periods for interactive work and then >> switch for a lower cost, higher latency path in the evening when >> computer to computer backups do not care. If you can plot the times >> the issues start and end and that these occur daily during the week >> and not on weekends etc that would be a strong indicator. >> >> John (ISDN) Lee >> >> ________________________________________ >> From: mike [EMAIL PROTECTED] >> Sent: Friday, September 26, 2008 12:04 PM >> To: nanog@nanog.org >> Subject: high latency ds3 issue on unloaded line >> >> Hello, >> >> I have a ds3 from qwest which has daily issues with insane >> point-to-point latencies sometimes exceeding 1000ms for hours on end, >> and which suddenly disappear, and does not appear to correspond with >> actual measured link utilization (less than 20mbps most days). >> >> To make a long investigation short, the problem comes on during the >> day and then lets up late in the evening. I have tested and examined >> everything at the ip layer and no it's not high utilization, an ACL, >> router cpu or bad hardware, no line errors or other issues visible >> from >> interface or controller stats. yes I have flushed all hardware, and I >> have a 7204vxr/npe-400 with this single ds3. The only clue seems to be >> millions of 'output drops' from qwest's side. And at night I can hit >> popular ftp mirrors from a directly attached server and observe my >> interface reporting about %100 utilization combined with my users and >> customers, so yeah it really is a full line rate ds3. And historically >> Mrtg always shows around 20mbps or less utilization and it's only >> smokeping that goes off, usually in the afternoon when the point to >> point latencies between my router and qwest start heading north, and >> consistently at that. I also have another in house tool that takes 30 >> second snapshots of my ds3 interface in order to catch short bursts >> that >> would be smoothed out with mrtg's 5 minute average, but during these >> high latency times there aren't any spikes noted. And for added >> confusion (or fun!), the latency can start at any utilization level - >> I've observed it while we were pulling just 12mbps, and I have not had >> it while we were doing 34mbps, only the time of day seems to be the >> common factor. >> >> Qwest has not been able to identify the issue, only note that - >> yeah, this really is happening when there is otherwise no real load on >> the line - and I am certain we have done everything to rule out the ip >> layer. They have put in a 'request' to move me to another router, >> but I >> am not hopeful of a resolution that way as the router we're >> currently on >> doesn't appear otherwise to have the problem with any other >> subscriber. >> >> What I want to know, is it possible that the underlaying atm/sonet >> that carries my ds3 from my facility is somehow oversubscribed or >> misconfigured? We have an OC12 fiber entrance and this is the only >> circuit provisioned on it, and in our small tiny town the only other >> user on the ring with us is comcast (according to the att network >> engineer who installed this). I don't know enough about atm/sonet to >> imagine conditions that would cause the issues I am seeing here , but >> every ip layer tool I have only ever tells me there isn't an ip issue >> here. I can issue ping from my router directly to the attached qwest >> router and get > 1000ms and then other times (out of the problem >> window), I am getting 4ms. >> >> If anyone has laughs or beers to offer me, send 'em on cuz I could >> use both right about now.... >> >> Mike- >> > > > > >