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RE: Next hop issues inside AS577 to AS852?

  • From: Mike Tancsa
  • Date: Sat Jul 31 14:19:36 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: [email protected] [mailto:[email protected]] On Behalf Of
Mike Tancsa
Sent: Saturday, July 31, 2004 7:52 AM
To: [email protected]
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,                            [email protected]
Providing Internet since 1994                    www.sentex.net
Cambridge, Ontario Canada                         www.sentex.net/mike