nanog mailing list archives
Re: why not AS number based prefixes aggregation
From: "yangyang. wang" <wyystar () gmail com>
Date: Tue, 9 Sep 2008 00:04:24 +0800
Thank you, Scott. TE is a key reason for using specific prefixes. I think that most TEs are deployed in intra-domain, and the inter-domain TEs applied to downstream AS multihomed to many different upstream ASes could be made thru AS number based aggregation. The TE between two ASes with many links (for load balance) may be implemented by layer-2 filter list staticly configured. 2008/9/8 Scott Brim <swb () employees org>
Excerpts from yangyang. wang on Mon, Sep 08, 2008 09:20:38PM +0800:Hi, everyone: For routing scalability issues, I have a question: why not deploy AS number based routing scheme? BGP is path vector protocol and theshortestpaths are calculated based on traversed AS numbers. The prefixes in thesameAS almost have the same AS_PATH associated, and aggregating prefixes according to AS will shrink BGP routing table significantly. I don't know what comments the ISPs make on this kind of routing scheme. -yangIt might be the right level of granularity for policy but is too coarse for routing. You want to be able to route on prefixes (even if not everyone does it) for flexibility/TE. Also, ASNs are not aggregatable so we can't use them to represent a large number of independently routed networks.
Current thread:
- why not AS number based prefixes aggregation yangyang. wang (Sep 08)
- Re: why not AS number based prefixes aggregation Nathan Ward (Sep 08)
- Re: why not AS number based prefixes aggregation Scott Brim (Sep 08)
- Re: why not AS number based prefixes aggregation Owen DeLong (Sep 08)
- Re: why not AS number based prefixes aggregation yangyang. wang (Sep 08)
- Re: why not AS number based prefixes aggregation Dave Israel (Sep 08)
- Re: why not AS number based prefixes aggregation Benson Schliesser (Sep 08)
- Re: why not AS number based prefixes aggregation William Herrin (Sep 08)
- Re: why not AS number based prefixes aggregation Christopher Morrow (Sep 08)
- Re: why not AS number based prefixes aggregation Jeroen Massar (Sep 08)
- Re: why not AS number based prefixes aggregation Ricardo Oliveira (Sep 08)
- RE: why not AS number based prefixes aggregation Paul Francis (Sep 08)
- Re: why not AS number based prefixes aggregation Jean-François Mezei (Sep 08)
- RE: why not AS number based prefixes aggregation Paul Francis (Sep 09)
- RE: why not AS number based prefixes aggregation Paul Francis (Sep 08)
- <Possible follow-ups>
- RE: why not AS number based prefixes aggregation Boyd, Benjamin R (Sep 08)