Subject: RE: New Issue - Outbound Loop Detection

From: "Natale, Jonathan" <[email-masked]>
Date: Fri, 18 Oct 2002 13:37:28 -0400

Yakov,

OK, you are correct on both counts.

-Jonathan

-----Original Message-----
From: Yakov Rekhter [mailto:[email-masked]] 
Sent: Friday, October 18, 2002 1:32 PM
To: Natale, Jonathan
Cc: [email-masked]
Subject: Re: New Issue - Outbound Loop Detection 

Jonathan,

> This paper (thanks Jeff) 
> http://www.research.microsoft.com/scripts/pubs/view.asp?TR_ID=MSR-TR-2
> 000-08
> indicates that it is better to do the loop detection outbound as well 
> inbound. The current draft indicates that it only needs to be done
inbound. 
> IOS does it inbound as well as outbound. GateD/Juniper does it (did it
???) 
> only inbound.
> 
> So I propose we add:
> "An implementation MAY choose to not advertise routes to EBGP peers if 
> these routes contain the AS of that peer in the AS path."
> after:
> "If the autonomous system number appears in the AS path the route may 
> be stored in the Adj-RIB In, but unless the router is configured to 
> accept routes with its own AS in the AS path, the route shall not be 
> passed to the BGP Decision Process."

First of all, if we add the text you proposed it should go into 9.1.3, and
not in 9 (as Section 9 deals with processing UPDATE messages, while Seciton
9.1.3 deals with advertising routes to peers. 

Second, we could add this sentence only if there are at least two
implementations that support it. So, folks who implement the outbound loop
detection please drop an e-mail within a week.

Yakov.