Subject: issue 67

From: Yakov Rekhter <[email-masked]>
Date: Thu, 17 Oct 2002 06:34:02 -0700

67) Counting AS_SET/AS_CONFED_*
  ----------------------------------------------------------------------------
  Status: No Consensus
  Change: Potentially
  Summary: Is how we count AS_SET/AS_CONFED_* covered suffiecently in the
    current draft? 
  
  Discussion:
  
  Jonathan brought up some questions on how current implementations count
  AS_SET and AS_CONFED_*
  
  There were a variety of resposnes to this, answering his questions.
  Curtis pointed out that this behavior is covered in:
  
  That's in 9.1.2.2:
  
        a) Remove from consideration all routes which are not tied for
        having the smallest number of AS numbers present in their AS_PATH
        attributes. Note, that when counting this number, an AS_SET counts
        as 1, no matter how many ASs are in the set, and that, if the
        implementation supports [13], then AS numbers present in segments
        of type AS_CONFED_SEQUENCE or AS_CONFED_SET are not included in
        the count of AS numbers present in the AS_PATH.
  
  Jonathan replied that this might be at odds with what Juniper does,
  although he was unsure, and asked for clarification.
  
  This was discussed in the "New Issue AS path" thread.

The issue of route selection in the present of confederations
belongs *not* to the base spec, but to the spec that describes
BGP Confeds. With this in mind I would suggest to change in 9.1.2.2 from

        a) Remove from consideration all routes which are not tied for
        having the smallest number of AS numbers present in their AS_PATH
        attributes. Note, that when counting this number, an AS_SET counts
        as 1, no matter how many ASs are in the set, and that, if the
        implementation supports [13], then AS numbers present in segments
        of type AS_CONFED_SEQUENCE or AS_CONFED_SET are not included in
        the count of AS numbers present in the AS_PATH.
to

        a) Remove from consideration all routes which are not tied for
        having the smallest number of AS numbers present in their AS_PATH
        attributes. Note, that when counting this number, an AS_SET counts
        as 1, no matter how many ASs are in the set. 

and ask the authors of BGP Confeds to update their document to
cover how the presence of confeds impact route selection.

Yakov.

---

From: Mathew Richardson <[email-masked]>
Date: Thu, 17 Oct 2002 10:04:15 -0400

> Yakov Rekhter <[email-masked]> [Thu, Oct 17, 2002 at 06:34:02AM -0700]:

<snip>

>        as 1, no matter how many ASs are in the set. 

<snip>

I agree both with this change, and with the logic behind it :)

mrr