Subject: RE: issue 63

From: "Natale, Jonathan" <[email-masked]>
Date: Fri, 18 Oct 2002 13:20:52 -0400

What will neighborAS(n) return the if the route is learned via IBGP and the
other IBGP speaker originated the route? (0 ???)

-----Original Message-----
From: Yakov Rekhter [mailto:[email-masked]] 
Sent: Friday, October 18, 2002 1:06 PM
To: [email-masked]
Subject: issue 63

63) Clarify MED Removal Text
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Following suggestion from Curtis, here are the changes:

In 5.1.4 replace:

   An implementation MAY also (based on local configuration) alter the
   value of the MULTI_EXIT_DISC attribute received over EBGP.
   If it does so, it shall do so prior to determining the degree of
   preference of the route and performing route selection (decision
   process phases 1 and 2).

with:

   An implementation MAY also (based on local configuration) alter the
   value of the MULTI_EXIT_DISC attribute received over EBGP.
   This MAY be done prior to determining the degree of preference
   of the route and performing route selection (decision process phases
   1 and 2). See section 9.1.2.2 for necessary restricts on this.
      
In 9.1.2.2 replace:

   Similarly, neighborAS(n) is a function which returns the neighbor
   AS from which the route was received.
      
with:

   Similarly, neighborAS(n) is a function which returns the
   neighbor AS from which the route was received.  If the route is  
   learned via IBGP, it is the neighbor AS from which the other
   IBGP speaker learned the route, not the local AS.

   If a MULTI_EXIT_DISC attribute is removed before redistributing
   a route into IBGP, the MULTI_EXIT_DISC attribute may only be      
   considered in the comparison of EBGP learned routes, them
   removed, then the remaining EBGP learned route may be compared    
   to the remaining IBGP learned routes, without considering the    
   MULTI_EXIT_DISC attribute for those EBGP learned routes whose
   MULTI_EXIT_DISC will be dropped before advertising to IBGP.
   Including the MULTI_EXIT_DISC of an EBGP learned route in the
   comparison with an IBGP learned route, then dropping the
   MULTI_EXIT_DISC and advertising the route has been proven to
   cause route loops.

In the absence of objections I'll make the above changes.

Yakov.

---

From: Yakov Rekhter <[email-masked]>
Date: Fri, 18 Oct 2002 11:25:57 -0700

Jonathan,

> other IBGP speaker originated the route? (0 ???)

the local AS.

with this in mind, (and taking into account your editorial comments)
here is proposed text:

In 5.1.4 replace:

with:

In 9.1.2.2 replace:

with:

   Similarly, neighborAS(n) is a function which returns the neighbor
   AS from which the route was received.  If the route is learned
   via IBGP, and the other IBGP speaker didn't originate the route,
   it is the neighbor AS from which the other IBGP speaker learned
   the route. If the route is learned via IBGP, and the other IBGP
   speaker originated the route, it is the local AS.

   If a MULTI_EXIT_DISC attribute is removed before re-advertising
   considered in the comparison of EBGP learned routes, then

Yakov.