The problem is almost certainly between AS2548 (Digex/Intermedia/icix) and AS1 (Genuity/bbnplanet). But I think the reason that the Intermedia hop times look like Swiss cheese in the return trace is tricky. My guess is that Intermedia and Genuity have two physical paths between their networks in Dallas, and that Intermedia is splitting traffic to AS1 between the two paths based on a combination of source and destination IP address. One of the paths is overloaded going from AS2548 to AS1 -- the other is not. In the forward direction, where the outgoing trace packets going from AS2548 to AS1 all have the same source and destination addresses, there is a clean transition. In the reverse direction, where the source address of the ICMP error message changes with every hop, the round trip time may be very short or very long, depending on the router involved. (Check out hop 11 in the return trace.) -steve Dashbit -- The Leader In Internet Topology www.dashbit.com www.traceloop.com ************************************************************************** Here are the traces with AS transitions called out: 4 gw-swbell.digex.net (206.181.161.153) 8 ms 9 ms 10 ms 5 aus1-core3-pos1-0.atlas.icix.net (165.117.68.210) 9 ms 6 ms 7 ms 6 dfw3-core2-pos2-2.atlas.icix.net (165.117.68.218) 18 ms 15 ms 14 ms 7 dfw3-core1-pos7-0.atlas.icix.net (165.117.48.121) 28 ms 14 ms 14 ms AS2548 to AS1 8 a3-0-14.crtntx1-cr12.bbnplanet.net (4.24.147.53) 1366 ms 1336 ms 1360 ms 9 p6-0.crtntx1-br2.bbnplanet.net (4.24.9.253) 1404 ms 1352 ms 1381 ms 10 p15-0.crtntx1-br1.bbnplanet.net (4.24.10.113) 1374 ms 1327 ms 1359 ms 11 p2-0.crtntx1-cr1.bbnplanet.net (4.24.5.2) 1368 ms 1392 ms 1364 ms 12 p3-0-0.aperian3.bbnplanet.net (4.24.104.98) 1423 ms 1328 ms 1369 ms 13 morannon.the-infinite.org (216.139.208.190) 1423 ms 1383 ms 1374 ms $ ... and the reverse ... 4 183.at-2-0-0.XR1.DFW7.ALTER.NET (152.63.96.241) 28 ms 28 ms 28 ms 5 191.ATM10-0-0.BR1.DFW7.ALTER.NET (146.188.241.177) 29 ms 30 ms 21 ms AS701 to AS2548 -- Hop 6 is a UUNET address on an Intermedia router) 6 137.39.52.34 (137.39.52.34) 29 ms 28 ms 28 ms 7 dfw3-core1-pos6-0.atlas.icix.net (165.117.48.133) 1370 ms 1377 ms 1369 ms 8 dfw3-core2-pos6-0.atlas.icix.net (165.117.48.122) 1306 ms 1357 ms 1353 ms 9 aus1-core3-pos3-0.atlas.icix.net (165.117.68.217) 36 ms 36 ms 36 ms 10 aus1-core1-pos9-0-0.atlas.icix.net (165.117.68.209) 37 ms 37 ms 37 ms AS2548 to AS7293 -- Hop 11 is Intermedia addresses on (a) SW Bell router(s) 11 206.181.161.30 (206.181.161.30) 37 ms 38 ms austin-gw.swbell.com (206.181.161.154) 1363 ms 12 ded1-fa1-0-0.austtx.swbell.net (151.164.20.243) 38 ms 38 ms 37 ms 13 seton-medical-center-638746.cust-rtr.swbell.net (151.164.22.46) 34 ms 34 ms 34 ms On Fri, 4 May 2001, Dominic J. Eidson wrote:
So who replaced Intermedia's routers with a lump of cheese? :
4 gw-swbell.digex.net (206.181.161.153) 8 ms 9 ms 10 ms 5 aus1-core3-pos1-0.atlas.icix.net (165.117.68.210) 9 ms 6 ms 7 ms 6 dfw3-core2-pos2-2.atlas.icix.net (165.117.68.218) 18 ms 15 ms 14 ms 7 dfw3-core1-pos7-0.atlas.icix.net (165.117.48.121) 28 ms 14 ms 14 ms 8 a3-0-14.crtntx1-cr12.bbnplanet.net (4.24.147.53) 1366 ms 1336 ms 1360 ms 9 p6-0.crtntx1-br2.bbnplanet.net (4.24.9.253) 1404 ms 1352 ms 1381 ms 10 p15-0.crtntx1-br1.bbnplanet.net (4.24.10.113) 1374 ms 1327 ms 1359 ms 11 p2-0.crtntx1-cr1.bbnplanet.net (4.24.5.2) 1368 ms 1392 ms 1364 ms 12 p3-0-0.aperian3.bbnplanet.net (4.24.104.98) 1423 ms 1328 ms 1369 ms 13 morannon.the-infinite.org (216.139.208.190) 1423 ms 1383 ms 1374 ms $
... and the reverse ...
4 183.at-2-0-0.XR1.DFW7.ALTER.NET (152.63.96.241) 28 ms 28 ms 28 ms 5 191.ATM10-0-0.BR1.DFW7.ALTER.NET (146.188.241.177) 29 ms 30 ms 21 ms 6 137.39.52.34 (137.39.52.34) 29 ms 28 ms 28 ms 7 dfw3-core1-pos6-0.atlas.icix.net (165.117.48.133) 1370 ms 1377 ms 1369 ms 8 dfw3-core2-pos6-0.atlas.icix.net (165.117.48.122) 1306 ms 1357 ms 1353 ms 9 aus1-core3-pos3-0.atlas.icix.net (165.117.68.217) 36 ms 36 ms 36 ms 10 aus1-core1-pos9-0-0.atlas.icix.net (165.117.68.209) 37 ms 37 ms 37 ms 11 206.181.161.30 (206.181.161.30) 37 ms 38 ms austin-gw.swbell.com (206.181.161.154) 1363 ms 12 ded1-fa1-0-0.austtx.swbell.net (151.164.20.243) 38 ms 38 ms 37 ms 13 seton-medical-center-638746.cust-rtr.swbell.net (151.164.22.46) 34 ms 34 ms 34 ms $