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Great! Now we have to collect routing policies from

thousands of small LIRs

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while still have to deal with thousands of small prefixes.

So? There is no difference between thousands of PI prefixes and "thousands of small LIRs", except that the latter actually have to *pay* for what they cause.

To syncronize between the major RIRs is already dufficult enough, to make sure thousands of small LIRs all have correct info is not worth the problem it is trying to solve.

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Now more and more major ISPs are filtering out routes from

other ISPs (

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becuase we don't have transit agreements) so the multi-homed customer have to have their own AS.

No. This is an interesting arguments, but the fact that C&W has problems with some of their peers doesn't mean "the whole world has to drown in multihomed ASes". Get your contracts right.

Maybe you will carry other ISP's transit routes and they can dump about several GB of traffic for you to pass thru. And you are asking ISP to spend tons of money to carry the traffic that other ISPs are making money of ? Compared to this solution I think multihomed ASes is more acceptable.

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And if the major ISPs stop listening to the more specfic routes then even using the address from PI space won't work (unless you are big enough).

Yes. This is what it's all about. Small PI space really hurts people.

The thing is any ISP can decide to only accept /20 and above and claim any routes beyond those are not important. The truth is the INTERNET is bandwidth oriented and business like IX and webhosting are high bandwidth but not prefixes hungry. But they are hurting because someone think they are not wasting IP addresses enough. So the advice is if for any reason you need a backup link from different ISPs you better claim a /20 even a /24 is enough.

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All these solutions kind of imply that if you can't have /20 prefix then you can't be multi-homed. What happen if a customer want to have an OC-48 multi-homed link but only use prefix < /20 (that happens to the Internet Exchange people a lot ) ?

So announce it to the internet exchange. Why does it have to be visible in the whole world?

Letting "the whole world" see a /16 (from the upstream) and the direct peers a /24 (or whatever) means global routing will just work fine (over the upstream's PA block) and and IX routing will also work just fine (using the more specific).

Bad example.

So if a end-user uses one ISP's /24 from their PA space and he want to divide 50-50 traffic with a second ISP then what ? The second ISP will say no /24 allowed so can you ask the first ISP to assign a /20 ? (Don't worry CW will happily accept your /24) Even worse example. Ping Lu Cable & Wireless USA Network Tools and Analysis Group W: +1-703-292-2359 E: plu@cw.net