Subject: Comments on RFC2283

From: Kunihiro Ishiguro <[email-masked]>
Date: Fri, 20 Mar 1998 20:24:18 +0900 (JST)

Hi this is Kunihiro Ishiguro.

I know before I-D becomes RFC, there was a period of time to read and
comment about it.  But after RFC2283 Multiprotocol Extentions for
BGP-4 was published we (me and Mr. Ikuo Nakagawa) carefully reread it
and realize we have to comment on one of the part of it.

At the end of section 4 of RFC2283.

>                                  If such a message is received from an
>   external peer, the local system shall check whether the leftmost AS
>   in the AS_PATH attribute is equal to the autonomous system number of
>   the peer than sent the message. If that is not the case, the local
>   system shall send the NOTIFICATION message with Error Code UPDATE
>   Message Error, and the Error Subcode set to Malformed AS_PATH.

In case of one of the peer is BGP Route Server, this may be always
happen.  Some BGP Route Server doesn't insert it's own AS number in
the AS path to emulate direct peering.  This may become a obstacle to
those who are developing BGP protocol Route Server like us.

I'm not sure the original intent of this part is security
consideration or preventing masquerading other AS number but I think
sometimes leftmost AS number is different case exists.

'shall' can be taken various means I hope people take it as optional
and configurable.

P.S. If the day every router implementation take above strategy come,
     we can rid all of the left most AS from update packet's AS_PATH
     value because receiver already knows it.

Sorry for very late comment.
--
Kunihiro Ishiguro