On 11/29/06, Jim Popovitch <jimpop@yahoo.com> wrote:
On Thu, 2006-11-30 at 00:06 -0500, Jim Popovitch wrote:
Question: What could cause the first trace below to succeed, but the second trace to fail?
$ mtr 69.61.40.35 HOST: blue Loss% Snt Last Avg Best Wrst 1. 192.168.3.1 0.0% 1 4.3 4.3 4.3 4.3 2. 73.62.48.1 0.0% 1 10.6 10.6 10.6 10.6 3. 68.86.108.25 0.0% 1 11.4 11.4 11.4 11.4 4. 68.86.106.54 0.0% 1 9.8 9.8 9.8 9.8 5. 68.86.106.9 0.0% 1 20.5 20.5 20.5 20.5 6. 68.86.90.121 0.0% 1 11.3 11.3 11.3 11.3 7. 68.86.84.70 0.0% 1 27.7 27.7 27.7 27.7 8. 64.213.76.77 0.0% 1 24.5 24.5 24.5 24.5 9. 208.50.254.150 0.0% 1 39.4 39.4 39.4 39.4 10. 208.49.83.237 0.0% 1 46.6 46.6 46.6 46.6 11. 208.49.83.234 0.0% 1 40.7 40.7 40.7 40.7 12. 69.61.40.35 0.0% 1 43.9 43.9 43.9 43.9
$ mtr 69.61.40.34 HOST: blue Loss% Snt Last Avg Best Wrst 1. 192.168.3.1 0.0% 1 1.1 1.1 1.1 1.1 2. 73.62.48.1 0.0% 1 9.9 9.9 9.9 9.9 3. 68.86.108.25 0.0% 1 9.3 9.3 9.3 9.3 4. 68.86.106.54 0.0% 1 9.6 9.6 9.6 9.6 5. 68.86.106.9 0.0% 1 9.0 9.0 9.0 9.0 6. 68.86.90.121 0.0% 1 18.2 18.2 18.2 18.2 7. 68.86.84.70 0.0% 1 23.9 23.9 23.9 23.9 8. ??? 100.0 1 0.0 0.0 0.0 0.0
Taking the 69.61.40.33/28 subnet a bit further, .36 drops at 68.86.84.70 but .37 - .39 make it. .40 drops at 68.86.84.70, but .41 makes it.
Crazy.
Btw, the problem has now been resolved, however I'm still curious as to what scenario could have caused that.
-Jim P.
eBGP multihop peering across a pair of 10 gigE links with static routes pointing to the remote router loopback; one link goes south, but the interface still shows as up/up, and voila, depending upon the hash, your packets may go across the good link, or they may disappear into the black hole of oblivion. This is why multipath is a good thing, and eBGP multihop with static routes is a Bad Thing(tm). Matt