[rbak-nsp] BGP Flapping after update with malformed ASPATH

[Marcin Kuczera]

On 2018-05-29 14:19, Marcin Kuczera wrote:
> On 2018-05-29 13:07, Wojciech Wrona wrote:
>> Marcin Can You tell anything more? I didn't notice any problem in
>> decoded aspath in update message (my post before) what did i wrong ? :)
> AS Path was in fact empty, all ASes in {} brackets were taken from
> confederation, but AS-Path itself was empty, and that should not be
> sent from RouteServer.
An update - after deeper analysing, according to RFC - update was
correct, and SEOS should accept it but:
- this is a very interesting case of misconfiguration that should not
happen in normal usage cases
- can only happen in IX when connected to RS that removes it's AS as
first AS from AS-patch
- it looks like RFC bug, because such config was never considered as
possible and maybe RFC needs to be updated in future to avoid such cases.

Regards,
Marcin


>
> Marcin
>
>>
>> Best regards,
>> -- 
>> Wojciech Wrona
>> W dniu 29.05.2018 o 12:41, Marcin Kuczera pisze:
>>>
>>> Fixed.
>>> The problem was located in TPIX, and had been fixed.
>>> And that was not a SEOS fault. SEOS behaves correctly. Question is
>>> why Juniper passed malformed update...
>>>
>>> Regards,
>>> Marcin
>>>
>>> On 2018-05-29 10:58, Wojciech Wrona wrote:
>>>> Hi everyone,
>>>> It looks like we've managed to find another strange problem with
>>>> BGP on SEOS. In the night one of our peers session started to flap
>>>> with following message:
>>>> May 29 10:52:01: [0001]: %BGP-6-INFO: 195.149.233.1 UP
>>>> May 29 10:52:15: [0001]: %BGP-6-INFO: 195.149.233.1 DOWN -
>>>> Notification sent
>>>> May 29 10:52:15: [0001]: %BGP-6-INFO: 195.149.233.1 send
>>>> NOTIFICATION: 3/11 (update: malformed ASPATH) with 21 byte data.
>>>> mxReadMs=1555
>>>>
>>>> It does not look like previously mentioned attribute flag error.
>>>> Does anyone had something simillar ? It is a session with route
>>>> server, so i know about "no enforce first-as" option and it is
>>>> turned on, it was working fine till this night with no
>>>> configuration change on our side.
>>>>
>>>> "show bgp malform update" looks like this:
>>>> May 29 10:52:15 Malformed UPDATE msg (nbr 195.149.233.1, context
>>>> 0x40080001, 77 bytes, repeated 5 times, reason: Invalid msg) -
>>>>  ffff ffff ffff ffff ffff ffff ffff ffff 004d 0200 0000 3240 0101
>>>> 0040 0212 0104 0000 17d9 0000 183e 0000 1840 0000 1967 4003 04c3
>>>> 95e9 6480 0404 0000 0000 c007 0800 0073 5fc3 95ef ff16 c395 ec
>>>>
>>>> SEOS version SEOS-12.1.1.11p7-Release
>>>>
>>>> Thanks in advance,
>>>> Best regards,
>>>>
>>>
>>> -- 
>>>
>>> Marcin Kuczera / Wiceprezes Zarządu / CTO
>>> +48 32 440 80 71/ marcin.kuczera at leon.pl <mailto:marcin.kuczera at leon.pl>
>>>
>>> Leon Sp. z o.o.
>>> ul. Kilińskiego 33d, 44-200 Rybnik
>>> http://www.leon.pl/
>>>
>>> INTERNET | TELEWIZJA | TELEFON
>>>
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>>>
>>>
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>>
>>
>>
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>
>
> -- 
>
> Marcin Kuczera / Wiceprezes Zarządu / CTO
> +48 32 440 80 71/ marcin.kuczera at leon.pl <mailto:marcin.kuczera at leon.pl>
>
> Leon Sp. z o.o.
> ul. Kilińskiego 33d, 44-200 Rybnik
> http://www.leon.pl/
>
> INTERNET | TELEWIZJA | TELEFON
>
> KRS 0000223101 Sąd Rejonowy w Gliwicach
> Kapitał zakładowy 576.700 zł
> NIP: 6332068698
>
>
>
> _______________________________________________
> redback-nsp mailing list
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-- 

Marcin Kuczera / Wiceprezes Zarządu / CTO
+48 32 440 80 71/ marcin.kuczera at leon.pl <mailto:marcin.kuczera at leon.pl>

Leon Sp. z o.o.
ul. Kilińskiego 33d, 44-200 Rybnik
http://www.leon.pl/

INTERNET | TELEWIZJA | TELEFON

KRS 0000223101 Sąd Rejonowy w Gliwicach
Kapitał zakładowy 576.700 zł
NIP: 6332068698

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