[rbak-nsp] SEOS 6.4.1.1 and iBGP problem

David Freedman david.freedman at uk.clara.net
Mon Sep 27 12:32:11 EDT 2010


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The only other problem I can potentially see are in the communities:


>c0 080c 0000 3b41 0000 51cc 220a 220a

0000 3b41 = 0:15169
0000 51cc = 0:20940
220a 220a = 8714:8714

RFC1997 reserves communities 0x0000000 -> 0x0000FFFF , perhaps this is
being checked and rejected?

Dave.


Marcin Kuczera wrote:
> David Freedman wrote:
> Well, I notice from this output the following:
> 
>>>> c0 0708 0000 611f 0000 0000
> 
> c0 - optional transitive attribute follows
> 07 - AGGREGATOR
> 08 - of 8 bytes
> 0000611f - from AS 24863
> 00000000 - aggregated by 0.0.0.0
> 
> According to RFC4271, sec 5.1.7:
> 
>    AGGREGATOR is an optional transitive attribute, which MAY be included
>    in updates that are formed by aggregation (see Section 9.2.2.2).  A
>    BGP speaker that performs route aggregation MAY add the AGGREGATOR
>    attribute, which SHALL contain its own AS number and IP address.  The
>    IP address SHOULD be the same as the BGP Identifier of the speaker.
> 
> It is possible that SEOS considers 0.0.0.0 to be an invalid BGP
> identifier and therefore an impossible aggregator
> 
> For reference, this update covers the following prefixes:
> 
> 41.178.0.0/24
> 41.196.4.0/22
> 41.196.8.0/22
> 41.196.12.0/22
> 41.196.16.0/22
> 41.196.24.0/22
> 41.196.36.0/23
> 
> 
> with AS_PATH 24724 15412 24863
> 
> Since none of my SEOS boxes carry a full table can another SEOS operator
> with a full table confirm if they have these prefixes (and if so, what
> it shows as aggregator)
> 
> I can tell you in Cisco IOS, I accept these prefixes.
> 
> 
>> Printouts below, it seems that all aggregators here are 0.0.0.0
> 
>> 6.4.1.1 has probably some accidental bug or some unfinished function is
>> implemented here..
> 
>> Regards,
>> Marcin
> 
> 
> 
>> [bgp1]RedBack_SE100#show bgp route 41.178.0.0/24
>> BGP ipv4 unicast routing table entry: 41.178.0.0/24, version 4979776
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.4.0/22
>> BGP ipv4 unicast routing table entry: 41.196.4.0/22, version 4979779
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.8.0/22
>> BGP ipv4 unicast routing table entry: 41.196.8.0/22, version 4979773
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.12.0/22
>> BGP ipv4 unicast routing table entry: 41.196.12.0/22, version 4979775
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.16.0/22
>> BGP ipv4 unicast routing table entry: 41.196.16.0/22, version 4979767
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.24.0/22
>> BGP ipv4 unicast routing table entry: 41.196.24.0/22, version 4979769
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
>> [bgp1]RedBack_SE100#show bgp route 41.196.36.0/23
>> BGP ipv4 unicast routing table entry: 41.196.36.0/23, version 4979766
>> Paths: total 2, best path count 1, best peer 193.111.38.97
>> Advertised to non peer-group peers: 2
>>   91.195.159.30  91.195.159.138
> 
>> 15744 13293 3356 15412 24863
>>   Nexthop 212.106.159.142 (0), peer 212.106.159.142 (83.230.95.254), AS
>> 15744
>>   Origin IGP, localpref 200, med 0, weight 100, external
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 13000:9001
> 
> 
>> 24724 15412 24863
>>   Nexthop 193.111.38.97 (0), peer 193.111.38.97 (193.111.37.1), AS 24724
>>   Origin incomplete, localpref 200, med 0, weight 100, external, best
>>   aggregator: 0.0.0.0, AS 24863
>>   Community: 0:15169 0:20940 8714:8714
> 
>> [bgp1]RedBack_SE100#
> 
> 
> 
> 
> 
> 
> 
> 
> Dave
> 
> 
> Blake Willis wrote:
>>>> On Sep 27, 2010, at 2:12 PM, Marcin Kuczera wrote:
>>>>
>>>>> [bgp1]se100-test#show bgp neighbor 195.66.73.253 malform update
>>>>> Dump logged malformed UPDATE messages for ??? (1 total entries):
>>>>> Sep 27 14:09:48 Malformed UPDATE msg (nbr 195.66.73.253, context
>>>>> 0x40080002, 120 bytes, repeated 4221 times, reason: Invalid msg) -
>>>>> ffff ffff ffff ffff ffff ffff ffff ffff 0078 0200 0000 4540 0101 02c0
>>>>> 0708 0000 611f 0000 0000 5002 000e 0203 0000 6094 0000 3c34 0000 611f 4
>>>>> 003 04c1 6f26 6180 0404 0000 0000 4005 0400 0000 c8c0 080c 0000 3b41
>>>>> 0000 51cc 220a 220a 1829 b200 1629 c404 1629 c408 1629 c40c 1629
>>>>> c410 162
>>>>> 9 c418 1729 c424
>>>> Ouch.  I think it's time to open a case with the TAC.  Looks like we
>>>> won't be testing 6.4 any time soon then...
>>>>
>>>>> Is there any possibility to ignore malformed updates instead of
>>>>> dropping down whole session ?
>>>> I don't think I've seen a knob like that from any vendor so far...
>>>>
>>>>  -Blake
>>>> _______________________________________________
>>>> redback-nsp mailing list
>>>> redback-nsp at puck.nether.net
>>>> https://puck.nether.net/mailman/listinfo/redback-nsp
>>>>
> 7
> 
>>

- --

David Freedman
Group Network Engineering

david.freedman at uk.clara.net
Tel +44 (0) 20 7685 8000

Claranet Group
21 Southampton Row
London - WC1B 5HA - UK
http://www.claranet.com

Company Registration: 3152737 - Place of registration: England

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