Policy Statement on Address Space Allocations

Robert A. Rosenberg hal9001 at panix.com
Wed Jan 31 08:17:50 UTC 1996

At 11:39 1/30/96, Iljitsch van Beijnum wrote:

>> At 6:09 1/29/96, Alex.Bligh wrote:
>> > Currently I have 2 choices as
>> >far as I can make out, give them a bit of my /19, break up my
>> >nice aggregate and ensure loads of extra announcements (and that
>> >probably none of them get routed by anyone applying prefix based
>> >filtering), or give them a new /19 all of their own (you've
>Suppose you have a customer that needs a /22 and they want to go
>multi-homed. Suppose you give them that /22 out of your /19 or /16 you
>got from the RIPE NCC. So they announce their /22 to you and to their
>other provider. But you keep announcing your /19 or /16. So if anybody
>were to filter the /22 announcement, your customer only suffers partial
>loss of connectivity, since you are still announcing an aggregate of
>their announcemnt (your original /19 or /16).
>Problem fixed. Anything else?  ;-)

Unless you announce both the /16 (or 19) AND the /22, they are not
multi-homed but only single routed (with some fallback for those who see
the /22 announcement). Anyone who gets the unfiltered /22 announcement will
used the other provider (so long as that provider is up) while you get used
only by those who get a filter routing (and as fallback when the other
provider goes down).

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