Next hop issues inside AS577 to AS852?

Mike Tancsa mike at sentex.net
Sat Jul 31 18:21:31 UTC 2004


At 08:27 AM 31/07/2004, Krichbaum, Eric wrote:

>If it's every 60 seconds, I'd suspect the BGP timer is the root.  They
>probably forgot to use next-hop self or a static route to a peer.  The
>end result being that the route to the bgp peer is learned via bgp
>itself...

Maybe.  Hard to say if thats what their default hold time is.  I am still 
seeing the odd hit in their network.  For the sites we connect with inside 
Bell, the tunnel LQR expire is 10 seconds and we have seen 2 big bounces 
since routing around this morning.  I emailed their noc, but no 
response.   The Bell looking glass doesnt seem to have any flap statistics 
so I dont know if things are bouncing inside :(

It is looking different once again.  Via Cogent to me,
194# traceroute 199.212.134.1
traceroute to 199.212.134.1 (199.212.134.1), 64 hops max, 44 byte packets
  1  HSE-MTL-ppp12931.qc.sympatico.ca (209.226.183.241)  266.986 
ms  229.511 ms  209.679 ms
  2  Hamilton-ppp278329.sympatico.ca (206.172.130.250)  419.439 ms  219.614 
ms  199.657 ms
  3  kitcorr01-fe0-0-0.15.in.bellnexxia.net (206.47.229.8)  219.461 
ms  239.605 ms  187.514 ms
  4  badBellDNS (64.230.241.125)  221.605 ms  209.597 ms  199.655 ms
  5  badBellDNS (64.230.242.194)  219.439 ms  227.155 ms  202.135 ms
  6  core2-chicago23-pos10-0.in.bellnexxia.net (206.108.103.118)  229.386 
ms  249.620 ms  346.174 ms
  7  bx1-chicago23-pos11-0.in.bellnexxia.net (206.108.103.125)  228.434 
ms  234.041 ms  219.645 ms
  8  p13-0.core01.ord01.atlas.cogentco.com (154.54.11.29)  249.438 
ms  239.589 ms  199.658 ms
  9  p15-0.core02.ord01.atlas.cogentco.com (66.28.4.62)  239.441 
ms  249.618 ms  229.679 ms
10  p5-0.core01.yyz01.atlas.cogentco.com (66.28.4.214)  249.409 ms  237.480 
ms  231.808 ms
11  g0-1.na01.b011027-0.yyz01.atlas.cogentco.com (66.250.14.230)  251.504 
ms  259.618 ms  219.669 ms
12  1572534Ontario.demarc.cogentco.com (38.112.5.166)  239.467 ms  249.593 
ms  219.660 ms
13  tor-hespler-360-dslgate.sentex.ca (64.7.143.43)  229.489 ms  249.606 
ms  214.908 ms
14  hespler-tor-360-i4.sentex.ca (64.7.143.46)  241.707 ms  229.615 
ms  219.680 ms
15  ns.sentex.ca (199.212.134.1)  259.436 ms  239.613 ms  215.514 ms

Hops 6 and 8 were coming back as * * * on the traceroute a few hrs ago, but 
packets were getting to and from me.  Hopefully someone from Bell will pipe 
up on or offlist as to what the problem was / is and if its resolved. Telus 
is my main transit, and I dont like having to use such a blunt approach to 
working around this issue :(

         ---Mike


>Eric Krichbaum, Chief Engineer
>MCSE, CCNP, CCDP, CCSP, CCIP
>
>-----Original Message-----
>From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On Behalf Of
>Mike Tancsa
>Sent: Saturday, July 31, 2004 7:52 AM
>To: nanog at nanog.org
>Subject: Next hop issues inside AS577 to AS852?
>
>
>Unfortunately, I am not a direct customer of AS577 otherwise I would
>open a ticket with them, but we have a lot of sites inside Bell Canada
>that need to reach us.
>
>Starting suspiciously at maintenance window time, we were seeing
>sporadic reachability issues coming at us from Bell. I am pretty sure
>its to us, and not the other way around as exiting out, I always prefer
>my GT/360 link and depending on the source IP it always works.  The path
>back to me was via
>AS852 (telus) but I had to massively prepend to force it via someone
>else to get things working.
>
>But here are 2 traceroutes from inside AS577 (Bell) back to me
>
>
>Traceroute a)
>194# traceroute -n 64.7.153.1
>traceroute to 64.7.153.1 (64.7.153.1), 64 hops max, 44 byte packets
>   1  209.226.183.241  266.863 ms  219.712 ms  199.588 ms
>   2  206.172.130.250  219.408 ms  219.700 ms  209.619 ms
>   3  206.47.229.8  239.433 ms  195.376 ms  193.984 ms
>   4  64.230.241.125  229.460 ms  199.675 ms  209.669 ms
>   5  64.230.242.150  209.415 ms  189.707 ms  199.627 ms
>   6  154.11.3.25  239.440 ms  219.684 ms  208.091 ms
>   7  154.11.6.17  241.001 ms  217.379 ms  231.976 ms
>   8  64.7.143.44  229.456 ms  199.648 ms  189.635 ms
>   9  64.7.143.45  224.784 ms  194.333 ms  189.678 ms 10  64.7.153.1
>229.431 ms  209.654 ms  209.672 ms
>
>traceroute b)
>194# traceroute -n 64.7.153.1
>traceroute to 64.7.153.56 (64.7.153.56), 64 hops max, 44 byte packets
>   1  209.226.183.241  278.871 ms  221.986 ms  189.687 ms
>   2  206.172.130.250  219.433 ms  229.680 ms  339.650 ms
>   3  206.47.229.19  239.447 ms  189.621 ms  195.621 ms
>   4  64.230.241.121  223.483 ms  209.663 ms  199.695 ms
>   5  64.230.242.97  329.445 ms  209.667 ms  229.666 ms
>   6  64.230.242.181  239.463 ms  196.798 ms  192.568 ms
>   7  * * *
>   8  * * *
>
>
>Every 60 seconds or so the path back to me inside AS577 would change
>back and forth between a) and b).  I dont know what Hop 7 on b) is. It
>could be another peer to AS852 (Telus) or just another internal router
>at Bell (AS577).  Suffice to say, when taking path b) packets never get
>back to me.
>
>To work around it, I had to prepend out my AS852 link so that Bell comes
>back at me via GT/360 or Cogent.
>
>Anyone from Bell or Telus around to clarify where the problem is?
>Sadly, this is a holiday long weekend here in Canada :(  The wheels fell
>off around 4:30 AM EST.
>
>          ---Mike
>
>
>
>--------------------------------------------------------------------
>Mike Tancsa,                                      tel +1 519 651 3400
>Sentex Communications,                            mike at sentex.net
>Providing Internet since 1994                    www.sentex.net
>Cambridge, Ontario Canada                         www.sentex.net/mike




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