[j-nsp] BGP session going down on "invalid attribute list"

[Rutger Bevaart]

Hello list,

Yesterday we had a BGP session fall away under our feet, and we don't
completely understand why. We have a Juniper M7i running JUNOS 7.4.

Logging shows:
Jan  3 16:37:18 juniper rpd[2727]: bgp_read_v4_update: NOTIFICATION sent
to *.21 (External AS X): code 3 (Update Message Error) subcode 1 (invalid
attribute list)
Jan  3 16:37:18 juniper rpd[2727]: bgp_event: peer .21 (External AS X) old
state Established event RecvUpdate new state Idle
Jan  3 16:37:26 juniper rpd[2727]: bgp_pp_recv: rejecting connection from
.21 (External AS X), peer in state Idle

We checked with our peer, and it seems that they received an advertisement
containing a private AS:

our peer (AS X) <---> peer 1 <---> peer 2 <---> AS65422.

We do filter on private-AS'es using:

    policy-statement filter-private-as {
        from as-path private;
        then reject;
    }

Our Cisco router has a BGP session to the same peer AS (and must have
received the same invalid attribute). However, the BGP session did not go
down.

a) Has anybody seen this behaviour before?

b) Does an upgrade of JUNOS resolve the issue of the BGP session going
down, or is that expected behaviour?

c) Can I apply alternative filtering to make sure routes with a private AS
in the path are always rejected?

Regards
Rutger