Multi-Homed Routing

Haesu haesu at
Tue Sep 2 07:46:37 PDT 2003

>   Plus, some have suggested just advertising your existing assignments
> from your other provider.  Bad idea.  Most providers address allocated
> is not portable.  Check WHOIS for "ADDRESSES WITHIN THIS BLOCK ARE
> NON-PORTABLE".  Besides, even if your existing provider's IP blocks work,
> and your provider allows you to do this (you should always ask first),
> you'll be advertising a more specific prefix of one of their larger
> blocks.  Guess what that will do?

Obviously you have not had enough experience working with BGP customers.
Longer matches always win. Your provider announces the aggregate.

It's funny to say I've had up to /20 being announced elsewhere with provider's
permission even when whois shows ADDRESSES WITHIN THIS BLOCK ARE NON-PORTABLE.
Most providers will not care as long as you can justify why you want to 
announce the block elsewhere, and as long as you properly register them at IRR.

Yes IRR routing registry is only as good as the networks that use it. But you
know what? Major carriers do use them, and those who filter routes on RIR
registration boundaries either a) point a default route to elsewhere or b) build
filter based on IRR.

Try peering with some big national carrier-- they will not peer with you if you
do not use IRR -- especially in US.

Frankly, if you are a backbone filtering /24s, you obviously don't know where
to get to the internet if you are not even using IRR. Even our good old
friends at Verio is accepting our announced /24's now as long as registered in
the IRR.

>   But you need to know what you doing.  If you dump the routing table,
> you'll see that many networks can't even do basic route summaries.

You mean aggregation? I don't follow.


  Haesu C.
  TowardEX Technologies, Inc.
  E-mail: haesu at
  Cell: (978) 394-2867

> > -hc
> >
> > --
> > Sincerely,
> >   Haesu C.
> >   TowardEX Technologies, Inc.
> >   WWW:
> >   E-mail: haesu at
> >   Cell: (978) 394-2867
> Tom
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