[j-nsp] What does AS path attribute problem mean?

[Jerry Jones]

Looks like JUniper issued a note today on this.

PSN-2011-09-380



On Sep 20, 2011, at 9:45 AM, Juniper GOWEX wrote:

Hi Experts,

The attributes problems have appearedagain:

      /Sep 19 20:46:43 router1.net LEV[2625]: bgp_path_attr_error: NOTIFICATION sent to 149.X.X.X (External AS XXX): code 3 (Update Message Error) subcode 11 (AS path attribute problem)/



and looking at the Juniper KB I found a workaround :


      /"In order to stop the BGP session flaps, a per-neighbor
      configuration option exists that will cause JUNOSe to ignore any
      illegal or incorrectly formatted attributes:
      /

          /ERX(config)#*router bgp*//<AS#>
          ERX(config-router)#*neighbor*//<x.x.x.x>*  lenient*/

      /Provided log category |*bgpMessages*| has been set to log
      severity warning by configuring:
      /

          /ERX(config)#*log severity warning bgpMessages*/

      /a message will still be logged when an illegal attribute is
      received:

      |WARNING 01/01/2008 19:34:52 bgpMessages (default,10.0.0.2):
      UPDATE message from peer 10.0.0.2 in core: new-as-path contains
      segment type confed-sequence (not allowed). "|
      /

http://kb.juniper.net/InfoCenter/index?page=content&id=KB13623&actp=RSS



Does anyone know or configuredthis workarround ? . Do you think this could avoid the BGP session flaps?

Thanks in advance for your support




Best Regards

Isidoro



El 09/09/2011 18:58, Andrew Parnell escribió:
> We noticed this as well on a couple of our M7i running 9.x series
> code, but not on others running 10.x.  This is being caused by a
> particular prefix (212.118.142.0/24):
> 
> rpd[5239]: xx.xx.253.192 (Internal AS xx) Received BAD update for
> family inet-unicast(1), prefix 212.118.142.0/24
> 
> The easy solution is to simply filter out the offending prefix.  There
> are many ways this can be done, but the following did the trick for
> us:
> 
> policy-options {
>     prefix-list bad-prefixes {
>         212.118.142.0/24;
>     }
>     policy-statement BGP-Import {
>         term block-bad-prefixes {
>             from {
>                 prefix-list bad-prefixes;
>             }
>             then reject;
>         }
> }
> 
> Apply something like this to your BGP import and/or export policy as
> appropriate and you should be fine.
> 
> Andrew
> 
> On Fri, Sep 9, 2011 at 11:41 AM, Markus<universe at truemetal.org>  wrote:
>> All of a sudden without changing anything in the config I'm getting the
>> following on a M7i running 8.0R2.8:
>> 
>> rpd[3019]: bgp_read_v4_update: NOTIFICATION sent to 89.146.xx.49 (External
>> AS xxxx): code 3 (Update Message Error) subcode 11 (AS path attribute
>> problem)
>> 
>> The other end (Cisco) is getting:
>> 
>> %BGP-3-NOTIFICATION: received from neighbor 89.146.xx.50 3/11 (invalid or
>> corrupt AS path) 0 bytes
>> 
>> This is causing the BGP session to flap. It happens at arbitrary intervals,
>> sometimes once a minute, sometimes just once in an hour. CFEB and RE CPU are
>> at steady 100% when it happens.
>> 
>> What can I do about this and what could be the cause? Help! :)
>> 
>> Thanks!
>> Markus
>> 
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