Suppose that IP space were not a problem. When IPv6 comes up all around, it certainly won't be then. You can have and waste all the IP space you could imagine, since we'll be numbering every atom in the known universe.
And suppose we have ASNs a plenty.
Would Sprint, Digex, and AGIS still be trying to cut out so many routes?
It has nothing to do with available IP address space. It is purely the number of routes in the "global" BGP routing table. Doing rout filtering a la Sprint is one way to enforce better aggregation and cut down on route table size. Also, in general, the longer the prefix, the more a route tends to flap. Route filtering is one way to help cust down on the number of BGP updates.
Are any other ISPs doing this filtering?
Yes. -- Eric Kozowski VP Internet Services eric@structured.net Structured Network Systems, Inc. (800)390-5945 Support A Verio Affiliate (800)881-0962 Sales/Info http://www.structured.net/ PGP Key fingerprint = 0A E4 91 B8 BD CB 3E 95 42 12 04 4E 14 DF 86 76 'They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.' -- Benjamin Franklin 1759
Eric Kozowski writes...
It has nothing to do with available IP address space. It is purely the number of routes in the "global" BGP routing table. Doing rout filtering a la Sprint is one way to enforce better aggregation and cut down on route table size.
But it has everything to do with your network size. And those who have worked hard to keep their network size small get screwed. Should it be network size based? I say it should not be. Next question: will Sprint and other providers unfilter routes smaller than their policy *IF* you connect to THEIR network but use that smaller net you got from another provider? I want to figure out just what the actual impact of being a poorly routed member of an aggregate really will be.
Also, in general, the longer the prefix, the more a route tends to flap. Route filtering is one way to help cust down on the number of BGP updates.
Why is that? Is there a technical reason, or is it just that longer prefixes tend to be associated with unstable networks?
Are any other ISPs doing this filtering?
Yes.
My point remains, why is it that the criteria on deciding which routes are worthy of propogating over the net, and which ones are not, has to be based on the network size ... or how much they are wasting? This kind of thing certainly will end up invoking some federal investigations here in the US. This kind of practice doesn't let newcomers into the business of providing nationwide or worldwide services, since such a newcomer can't get working multi-homing without using/wasting a huge chunk of IP space, and can't get lots of business to make legit usage of such a space without the multi-homing. Whether the big boys intended to cut out the little guys or not, the impact is the same, and the investigations will be the same (maybe the conclusions might be different, but we obviously have people crying foul and in many cases citing federal statutes). Solutions? I don't have them. I haven't been around this stuff long enough to know all the ins and outs. It _seems_ to me that 45,000 routes should be manageable with good code and proper resources. But clearly unabated that number won't hold at all. The only real solution I see is find/develop a better routing algorithm and abandon BGP4. -- Phil Howard KA9WGN +-------------------------------------------------------+ Linux Consultant | Linux installation, configuration, administration, | Milepost Services | monitoring, maintenance, and diagnostic services. | phil at milepost.com +-------------------------------------------------------+
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Phil Howard