Hi Aaron, If you were already using MTU above 1508 for your CMTS to ME3600 links than you would not need to change anything.
The issue with CMTS to ASR9K only exist if you have configured the very same MTU on both sides. You need to check that your "IOS-XR" MTU is equal to your "IOS" MTU + 14 bytes. (You need two 4-bytes labels for MPLS VPN so if you are using Ethernet your "IOS" MTU should be 1508 at least) Cheers, JF De : aar...@gvtc.com A : Jean-Francois Dube <jean-francois.d...@videotron.com>, Cc : cisco-nsp@puck.nether.net Date : 2013-03-29 15:21 Objet : Re: [c-nsp] converting cmts from pure ip routing to mpls pe - uBR7246VXR Thanks JF, is there a reason why this would be required for CMTS to asr9k, but not required for CMTS to me3600x ? My CMTS PE to me3600 p is running fine, I didn't make any Mtu changes there. Aaron ----- Original Message ----- From: Jean-Francois Dube <jean-francois.d...@videotron.com> To: cisco-nsp@puck.nether.net Sent: Fri, 29 Mar 2013 09:18:33 -0400 (EDT) Subject: Re: [c-nsp] converting cmts from pure ip routing to mpls pe - uBR7246VXR Hi Aaron, It sounds like you may be having MTU issue. At least that is my experience when you can ping and only browse "some" websites. Your CMTS is running IOS and your ASR9K is running IOS-XR. In IOS-XR you need to account for the L2 header of 14 bytes so the "default" MTU is 1514. If you are running MPLS you'll need to increase the MTU even higher to account for the extra headers/labels. That means your CMTS interfaces should be using something like 1516 and your ASR9K would be 1530. Cheers, JF Jean-François Dubé Technicien, Opérations Réseau IP Ingénierie Exploitation des Réseaux Vidéotron cisco-nsp-boun...@puck.nether.net a écrit sur 2013-03-28 15:24:42 : > De : "Aaron" <aar...@gvtc.com> > A : <cisco-nsp@puck.nether.net>, > Date : 2013-03-28 15:31 > Objet : [c-nsp] converting cmts from pure ip routing to mpls pe - uBR7246VXR > Envoyé par : cisco-nsp-boun...@puck.nether.net > > I have (5) cmts's (uBR7246VXR) ..4 operational and 1 in lab for testing. > > > > We have a new mpls network comprised of asr901's, me3600's and asr9k's > functioning as p's and pe's. > > > > I wanted to move my cmts's off my traditional routed/switched network to my > new mpls network. I wanted to have cmts's function as pe's so as to > potentially take advantage of the mpls LxVPN's > > > > I successfully converted one of my cmts's to pe and it's running nicely, > uplinked into p box (me3600). What I did was basically convert wan uplink > to mpls, remove igp and replace with core mpls network igp process, and then > bring up the expected mp-ibgp and vrf stuff, and then convert all those > traditional routing interfaces and services (ntp, logging, aaa and tacacs) > to be vrf based..works. > > > > Now for the second cmts that I wanted to convert to pe, I've tried twice now > and have seen similar strange behavior. wan uplink utilization drops to > about 50% of what was previously seen before change..cpu utilization drops > from 30-40% utilization to about 0-10%....given those observations on the > first attempt last week, I left it that way, thinking not too much of it as > it was 2:30 a.m. in the morning and was thinking that low utilization at > that hour is conceivable. later I got woken up with a phone call from one of > my front-line noc network analysts at 7:15 a.m. saying that we had several > subs calling in saying that they could not get to most internet web pages > but only some were reachable.. (I think the web pages they could get to were > our local company web site hosted on-net, and some of our local Akamai and > other cached pages)..strangely I could ping and trace to and from those > subnets on that cmts to and from internet route server (looking glass) test > locations.. I didn't know what to make of this..i couldn't find a problem, > so was forced to hurry up and throw the cmts back to old switched/routed > network. > > > > ..i tried again a few nights ago and saw similar drop in wan utilization and > cpu load..not knowing what to make of it, and concerned that subs would be > unable to get to web sites that following morning, I moved it back. I don't > have a test modem off of this cmts to test with but will need to get one out > there if I try again. > > > > .I have a tac case open, and I am going to try to reproduce this in the test > cmts. (but all previous tests on the lab cmts show good results.and as I > mentioned, the other cmts is running fine in mpls net) > > > > Difference between the one that worked and the one that doesn't is one is > uplinked into me3600 (working one) and the one that didn't work is uplinked > into asr9k > > > > Interestingly, the module in the asr9k that I uplink that second cmts into, > crashed a couple weeks ago..it took a double ecc error and ios xr showed a > forced reset on that module..strange.. tac ios xr team said that it's > probably an isolated (transient) error and shouldn't happen again, but if it > does, they will RMA that 2/20 module in that asr9k. ..several connections > are still working on that asr9k linecard and so I didn't think that this > second cmts being mpls uplinked through there would be an issue..but I had > to mention it since I'm seeing weirdness.. > > > > Any thoughts or input would be appreciated. > > > > Aaron > > > > > > _______________________________________________ > cisco-nsp mailing list cisco-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/