looping traceroutes
Marshall Eubanks
tme at 21rst-century.com
Wed Sep 19 11:32:04 UTC 2001
>
>From AS 16517 one seems normal, one does not. In both
cases eBGP seems normal. I cannot ping to the non-normal
one, so a black hole is possible. Maybe they
are running an iBGP with a loop.
Regards
Marshall Eubanks
NORMAL
multicasttech-2>trace 200.13.39.1
Type escape sequence to abort.
Tracing the route to 200.13.39.1
1 207.ATM1-0.GW2.DCA8.ALTER.NET (157.130.46.53) 4 msec 4 msec 4 msec
2 0.so-3-0-0.XL2.DCA8.ALTER.NET (146.188.162.194) [AS 701] 8 msec 4 msec 24
msec
3 0.so-3-0-0.TR2.DCA8.ALTER.NET (152.63.144.29) [AS 701] 4 msec 4 msec 4 msec
4 115.at-6-0-0.TR2.HOU7.ALTER.NET (146.188.141.142) [AS 701] 64 msec 56 msec
60 msec
5 186.at-1-0-0.XR2.HOU7.ALTER.NET (152.63.97.233) [AS 701] 60 msec 52 msec
56 msec
6 182.ATM5-0.GW4.HOU7.ALTER.NET (152.63.100.133) [AS 701] 60 msec 56 msec
60 msec
7 avental-gw.customer.ALTER.NET (157.130.133.206) [AS 701] 72 msec 72 msec
72 msec
8 200.33.208.206 [AS 6503] 100 msec 84 msec 92 msec
9 ar6.mexmdf.avantel.net.mx (200.33.209.29) [AS 6503] 92 msec 100 msec 88
msec
10 na-62-239.na.avantel.net.mx (200.39.239.62) [AS 6503] 112 msec 96 msec 88
msec
11 200.13.38.129 [AS 3561] 144 msec 136 msec 128 msec
multicasttech-2>show ip bgp 200.13.39.1
BGP routing table entry for 200.13.39.0/24, version 155431
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
192.168.1.2
701 6503
157.130.46.53 from 157.130.46.53 (137.39.4.99)
Origin IGP, localpref 100, valid, external, best
1239 1239 1239 5511
160.81.38.225 from 160.81.38.225 (144.228.242.54)
Origin IGP, metric 48, localpref 100, valid, external
NOT NORMAL
multicasttech-2>trace 198.146.21.26
Type escape sequence to abort.
Tracing the route to 198.146.21.26
1 207.ATM1-0.GW2.DCA8.ALTER.NET (157.130.46.53) 4 msec 12 msec 4 msec
2 0.so-3-0-0.XL1.DCA8.ALTER.NET (146.188.162.198) [AS 701] 4 msec 8 msec 8
msec
3 189.at-1-0-0.XR1.DCA6.ALTER.NET (152.63.33.77) [AS 701] 4 msec 8 msec 24
msec
4 0.so-2-1-0.XL1.DCA6.ALTER.NET (152.63.38.85) [AS 701] 8 msec 8 msec 8 msec
5 POS6-0.BR4.DCA6.ALTER.NET (152.63.41.229) [AS 701] 32 msec 12 msec 4 msec
6 204.255.169.98 [AS 701] 8 msec 8 msec 8 msec
7 wdc-core-01.inet.qwest.net (205.171.24.37) [AS 209] 8 msec 8 msec 4 msec
8 dca-core-02.inet.qwest.net (205.171.8.209) [AS 209] 4 msec 8 msec 8 msec
9 atl-core-02.inet.qwest.net (205.171.8.153) [AS 209] 28 msec 24 msec 24 msec
10 atl-edge-05.inet.qwest.net (205.171.21.54) [AS 209] 44 msec 24 msec 28 msec
11 63.144.0.110 [AS 209] 36 msec 40 msec 32 msec
12 * * *
13 208.63.129.1 [AS 19956] 32 msec 32 msec 32 msec
14 208.63.129.3 [AS 19956] 56 msec * 32 msec
15 208.63.129.1 [AS 19956] 36 msec 36 msec 32 msec
16 *
208.63.129.3 [AS 19956] 32 msec *
17 208.63.129.1 [AS 19956] 32 msec 100 msec 96 msec
18 *
208.63.129.3 [AS 19956] 36 msec *
19 208.63.129.1 [AS 19956] 36 msec 32 msec 32 msec
20 208.63.129.3 [AS 19956] 32 msec * 32 msec
21 208.63.129.1 [AS 19956] 32 msec 36 msec 44 msec
22 * *
208.63.129.3 [AS 19956] 40 msec
23 208.63.129.1 [AS 19956] 32 msec 40 msec 32 msec
24 *
208.63.129.3 [AS 19956] 32 msec *
25 208.63.129.1 [AS 19956] 36 msec 36 msec 40 msec
26 208.63.129.3 [AS 19956] 32 msec * 32 msec
27 208.63.129.1 [AS 19956] 32 msec 36 msec 40 msec
28 *
208.63.129.3 [AS 19956] 36 msec *
29 208.63.129.1 [AS 19956] 36 msec 36 msec 52 msec
30 * * *
multicasttech-2>show ip bgp 198.146.21.26
BGP routing table entry for 198.146.21.0/24, version 696388
Paths: (2 available, best #1, table Default-IP-Routing-Table)
Advertised to non peer-group peers:
192.168.1.2
701 209 19956 16473
157.130.46.53 from 157.130.46.53 (137.39.4.99)
Origin incomplete, localpref 100, valid, external, best
1239 1239 1239 209 19956 16473
160.81.38.225 from 160.81.38.225 (144.228.242.54)
Origin incomplete, metric 8, localpref 100, valid, external
multicasttech-2>
multicasttech-2>ping 198.146.21.26
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.146.21.26, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
multicasttech-2>
>
>the most interesting thing is that the rtt increases..
>
>and it does so by regular amounts, about 30ms in each hop
>
>i'd guess there is a routing loop going on there for sure, i'd also guess
>its between two routers that are 30ms apart!
>
>perhaps it could be being caused by some sort of nat on the router so
>there are actually two routers looping but one or both of the addresses
>get nat'd as the replies come to you
>
>Steve
>
>On Tue, 18 Sep 2001, Ratul Mahajan wrote:
>
>>
>>
>>
>> while playing around with traceroutes for a measurement study of bgp, i
>> often come across the traceroute outputs similar to those appended below.
>> i don't have a reasonable explanation of such behaviour (i don't think
>> these are routing loops; they are not transient in any case). i am hoping
>> someone on the list has a hang of traceroute implementations, and provide
>> insights into under what circumstances this might happen.
>>
>> thanks,
>> -- ratul
>>
>> --------------
>>
>> $ traceroute 200.13.39.1
>> traceroute to 200.13.39.1 (200.13.39.1), 30 hops max, 38 byte packets
>> 1 regina-GE1-2.cac.washington.edu (128.95.219.100) 1.098 ms 1.233 ms
>> 2 uwbr2-GE3-0.cac.washington.edu (140.142.153.24) 0.349 ms 0.377 ms
>> 3 cnsp1-wes-GE1-0.pnw-gigapop.net (198.107.150.1) 1.561 ms 1.005 ms
>> 4 so-1-2-2.a07.sttlwa01.us.ra.verio.net (204.203.3.1) 21.690 ms 6.076
>> 5 ge-6-2-0.r03.sttlwa01.us.bb.verio.net (129.250.28.1) 8.481 ms 8.756
>> 6 p4-7-2-0.r06.plalca01.us.bb.verio.net (129.250.3.138) 29.934 ms
>> 7 p16-3-0-0.r00.plalca01.us.bb.verio.net (129.250.2.162) 26.740 ms
>> 8 p4-0.francetelecom.plalca01.us.bb.verio.net (129.250.9.134) 23.058 ms
>> 9 P4-3.DALBB1.Dallas.opentransit.net (193.251.132.221) 84.523 ms
>> 10 P5-1.FWHBB2.Fort-worth.opentransit.net (193.251.132.213) 86.653 ms
>> 11 Sr9-0-0.FWHAR1.Fort-worth.opentransit.net (193.251.132.227) 88.507 ms
>> 12 193.251.133.117 (193.251.133.117) 115.472 ms * 116.554 ms
>> 13 193.251.133.117 (193.251.133.117) 145.386 ms 147.224 ms 148.333 ms
>> 14 193.251.133.117 (193.251.133.117) 178.751 ms 172.224 ms *
>> 15 193.251.133.117 (193.251.133.117) 208.640 ms 203.841 ms 199.946 ms
>> 16 193.251.133.117 (193.251.133.117) 231.618 ms 233.234 ms 229.844 ms
>> 17 193.251.133.117 (193.251.133.117) 259.227 ms 258.488 ms 262.034 ms
>> 18 193.251.133.117 (193.251.133.117) 288.661 ms 292.598 ms 288.129 ms
>> 19 193.251.133.117 (193.251.133.117) 321.982 ms 320.806 ms 318.364 ms
>> 20 193.251.133.117 (193.251.133.117) 350.245 ms 349.834 ms 540.883 ms
>> 21 193.251.133.117 (193.251.133.117) 539.971 ms 410.838 ms 419.743 ms
>> 22 193.251.133.117 (193.251.133.117) 468.291 ms 409.761 ms 406.256 ms
>> 23 193.251.133.117 (193.251.133.117) 432.990 ms 439.589 ms 434.184 ms
>> 24 * 193.251.133.117 (193.251.133.117) 466.399 ms 465.287 ms
>> 25 193.251.133.117 (193.251.133.117) 500.719 ms 498.601 ms 499.957 ms
>> 26 193.251.133.117 (193.251.133.117) 530.089 ms 527.642 ms 528.999 ms
>> 27 193.251.133.117 (193.251.133.117) 556.208 ms 555.552 ms 557.387 ms
>> 28 193.251.133.117 (193.251.133.117) 586.776 ms 584.171 ms 586.944 ms
>> 29 193.251.133.117 (193.251.133.117) 608.677 ms 610.789 ms 618.232 ms
>> 30 193.251.133.117 (193.251.133.117) 641.141 ms 643.149 ms 639.050 ms
>>
>> ----------
>>
>> $ traceroute 198.146.21.26
>> traceroute to 198.146.21.26 (198.146.21.26), 30 hops max, 38 byte packets
>> 1 regina-GE1-2.cac.washington.edu (128.95.219.100) 4.395 ms 0.986 ms
>> 2 uwbr2-GE2-0.cac.washington.edu (140.142.155.24) 0.326 ms 0.310 ms
>> 3 cnsp1-wes-GE1-0.pnw-gigapop.net (198.107.150.1) 1.305 ms 1.113 ms
>> 4 so-1-2-2.a07.sttlwa01.us.ra.verio.net (204.203.3.1) 4.219 ms 4.308
>> 5 ge-6-2-0.r03.sttlwa01.us.bb.verio.net (129.250.28.1) 4.096 ms 6.462
>> 6 p4-5-0-0.r06.plalca01.us.bb.verio.net (129.250.3.89) 25.469 ms
>> 7 p4-0-0.r05.plalca01.us.bb.verio.net (129.250.2.129) 23.593 ms 22.371
>> 8 svl-brdr-01.inet.qwest.net (205.171.4.45) 24.093 ms 25.967 ms
>> 9 svl-core-03.inet.qwest.net (205.171.14.109) 27.487 ms 22.669 ms
>> 10 svl-core-01.inet.qwest.net (205.171.14.121) 22.500 ms 24.719 ms
>> 11 chi-core-03.inet.qwest.net (205.171.8.50) 62.208 ms 55.153 ms
>> 12 chi-core-01.inet.qwest.net (205.171.20.173) 57.742 ms 54.672 ms
>> 13 chi-edge-01.inet.qwest.net (205.171.20.34) 54.261 ms 58.971 ms
>> 14 208.46.63.202 (208.46.63.202) 88.583 ms 69.619 ms 67.605 ms
>> 15 208.63.128.3 (208.63.128.3) 70.551 ms 67.581 ms 69.375 ms
>> 16 208.63.128.1 (208.63.128.1) 65.115 ms 70.951 ms 66.083 ms
>> 17 208.63.128.3 (208.63.128.3) 67.628 ms 65.488 ms 68.418 ms
>> 18 208.63.128.1 (208.63.128.1) 72.197 ms 71.422 ms 69.517 ms
>> 19 208.63.128.3 (208.63.128.3) 68.539 ms 68.976 ms 67.911 ms
>> 20 208.63.128.1 (208.63.128.1) 72.373 ms 67.838 ms 66.468 ms
>> 21 208.63.128.3 (208.63.128.3) 67.040 ms 69.136 ms 67.631 ms
>> 22 208.63.128.1 (208.63.128.1) 66.317 ms 83.947 ms 70.693 ms
>> 23 208.63.128.3 (208.63.128.3) 66.865 ms 69.521 ms 69.760 ms
>> 24 208.63.128.1 (208.63.128.1) 69.604 ms 67.534 ms 70.447 ms
>> 25 208.63.128.3 (208.63.128.3) 68.285 ms 69.772 ms 67.721 ms
>> 26 208.63.128.1 (208.63.128.1) 71.915 ms 69.530 ms 72.403 ms
>> 27 208.63.128.3 (208.63.128.3) 111.475 ms 69.670 ms 69.267 ms
>> 28 208.63.128.1 (208.63.128.1) 68.883 ms 67.147 ms 72.106 ms
>> 29 208.63.128.3 (208.63.128.3) 69.842 ms 67.889 ms 66.944 ms
>> 30 208.63.128.1 (208.63.128.1) 70.986 ms 73.124 ms 68.452 ms
>>
>>
>>
>>
>
>--
>Stephen J. Wilcox
>IP Services Manager, Opal Telecom
>http://www.opaltelecom.co.uk/
>Tel: 0161 222 2000
>Fax: 0161 222 2008
>
>
Marshall Eubanks
tme at 21rst-century.com
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