RE: more specific routes in today reality
- Date: Wed, 10 Oct 2001 00:51:37 -0400
> >
> > Great! Now we have to collect routing policies from
> thousands of small LIRs
> > 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.
> >
> > Now more and more major ISPs are filtering out routes from
> other ISPs (
> > 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.
> > 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.
> > 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@localhost
