Routing Table inconsistencies

Tue Jun 19 05:56:59 UTC 2001

At 19:28 18/06/01 -0400, Marshall Eubanks wrote:

>Hello All;
>
>   We had a problem with a domain with two different AS paths in the BGP 
> table, so I wrote a script to
>look for such problems.
>
>There are two prefixes in the current MBGP tables here with such problems :

Go to route-views.oregon-ix.net:

route-views.oregon-ix.net>sho ip mbgp sum | excl NoNeg|Active
BGP router identifier 198.32.162.100, local AS number 6447
MBGP table version is 552946
4874 network entries and 29094 paths using 1500666 bytes of memory
658329 BGP path attribute entries using 34233108 bytes of memory
504166 BGP AS-PATH entries using 12495820 bytes of memory
408 BGP community entries using 10324 bytes of memory
27226 BGP filter-list cache entries using 435616 bytes of memory
Dampening enabled. 62 history paths, 3305 dampened paths
BGP activity 391384/274126 prefixes, 54115708/50018963 paths

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ 
Up/Down  State/PfxRcd
129.250.0.6     4  2914 1974401   36393   552946    0    0 4d09h        3936
129.250.0.11    4  2914 1378596   36399   552946    0    0 1w6d         3936
155.229.0.36    4  4565  122639   30255   552946    0    0 1w5d           23
198.32.8.252    4 11537  136322   36119   552946    0    0 1w3d         3543
203.181.248.242 4  7660  189814   71618   552946    0    0 05:34:54     1863
204.42.253.253  4   267 1251009   36379   552946    0    0 1w6d         3941
204.212.44.131  4   234  979924   36399   552946    0    0 1w6d         3938
205.215.45.50   4  4006 3332093   55271   552946    0    0 5d16h        2738
206.220.240.222 4 10764 2326042   69592   552946    0    0 05:33:12     4760
216.140.2.63    4  6395 1776339   36347   552946    0    0 4d20h         118
216.140.8.63    4  6395 1598580   36337   552946    0    0 4d20h         118
216.140.14.127  4  6395 1631400   36135   552946    0    0 3d19h         118

A simple count via:
route-views.oregon-ix.net>sho ip mbgp inc | incl >
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
*>                  129.250.0.11             5             0 2914 3549 i
*>                  206.220.240.222                        0 10764 145 195 i
*>                  206.220.240.222                        0 10764 145 195 i
*>                  206.220.240.222                        0 10764 145 195 i
*>                  129.250.0.6             22             0 2914 i
*>                  129.250.0.11            16             0 2914 1800 i
*>                  129.250.0.6             22             0 2914 i
*>                  129.250.0.11            16             0 2914 i
*>                  129.250.0.11            16             0 2914 i
*>                  129.250.0.11             9             0 2914 i
*>                  129.250.0.11            12             0 2914 i
*>                  129.250.0.11             5             0 2914 i
*>                  129.250.0.11             8             0 2914 i
*>                  129.250.0.11             9             0 2914 i
*>                  206.220.240.222                        0 10764 145 195 i
*>                  206.220.240.222                        0 10764 145 195 i

shows 16 prefixes that are inconsistent AS origin within the MBGP tables 
(if anyone knows the reg-exp for seeing the actual prefixes - 1 per line 
and not just the best path - I'd like to know :-)).  As we see in the 
larger BGP tables (close to 500 inconsistent ASs), not too many ISPs care 
about this.

-Hank

>  Date of BGP Dump  Mon Jun 18 15:39:46 EDT 2001
>
>  ROUTING INCONSISTENCY Detected for Prefix =  198.9.201.0       :
>
>*> 198.9.201.0      160.81.38.225           75             0 1239 10888 i
>*                   204.147.129.89                         0 145 24 i
>
>  ROUTING INCONSISTENCY Detected for Prefix =  198.9.202.0       :
>
>*  198.9.202.0      204.147.129.89                         0 145 24 i
>*>                  160.81.38.225           75             0 1239 10888 i
>
>And a total of 488 prefixes in the BGP tables with such problems !!!!!
>
>The complete lists are contained in
>
>http://www.multicasttech.com/status/mbgp.inconsistency and
>http://www.multicasttech.com/status/bgp.inconsistency
>
>I could update these regularly if there was any demand.
>
>I may be obtuse, but I cannot see how this could be a good thing.
>
>                                  Regards
>                                  Marshall Eubanks
>
>
>
>T.M. Eubanks
>Multicast Technologies, Inc
>10301 Democracy Lane, Suite 410
>Fairfax, Virginia 22030
>Phone : 703-293-9624       Fax     : 703-293-9609
>e-mail : tme at multicasttech.com
>http://www.on-the-i.com
>
>Test your network for multicast : http://www.multicasttech.com/mt/
>  Check the status of multicast in real time :
>  http://www.multicasttech.com/status/index.html