nanog mailing list archives
RE: why not AS number based prefixes aggregation
From: Paul Francis <francis () cs cornell edu>
Date: Tue, 9 Sep 2008 14:02:57 -0400
Sorry, my question was not clear. By "entries" I meant "routes" or "prefixes". For instance, some ISPs today deaggregate in order to load-balance, so they advertise multiple prefixes or routes instead of one. Of course, the "right" number would vary from ISP to ISP (as someone already pointed out to me), but I'm not even sure what the criteria would be for how many routes one needs to load balance...i.e. depends on the number of AS neighbors?, depends on the number of depends on the number of BGP neighbors?, depends on your load balancing mechanism (MEDs versus path prepending versus ....???)? The point is this...BGP seems to give use two tools...a machete (AS numbers) and a scalpel (prefixes). If I want to cut a steak (load balance), the machete is too coarse, the scalpel is too fine. What's the right tool??? PF
-----Original Message----- From: Jean-François Mezei [mailto:jfmezei () vaxination ca] Sent: Monday, September 08, 2008 10:21 PM To: nanog () nanog org Subject: Re: why not AS number based prefixes aggregation Paul Francis wrote:AS, or even dozens. So I'm curious...if we could wave a magic wandandcontrol the exact number of entries any AS needs to advertise, whatwouldfolks consider to be roughly the right number of entries?Wouldn't this greatly depend on the span/breath of your network ? If you are a large nationwide (or even international) ISP/network, then you want to be able to distribute your network so that someone on west coast trying to reach one of your west coast IP addresses will have a pretty direct route into your west coast infrastructure instead of funnelling all traffic into one central location. But a smaller ISP based in only one city would not need to distribute traffic through different entry points since traffic from each transit provider would end up on the same router. So I am not sure one could draw any "right number of entries".
Current thread:
- Re: why not AS number based prefixes aggregation, (continued)
- 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)
- RE: why not AS number based prefixes aggregation Boyd, Benjamin R (Sep 08)