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

[Andrew Parnell]

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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