[5427] in North American Network Operators' Group
Re: hole punching reality check
daemon@ATHENA.MIT.EDU (Curtis Villamizar)
Fri Oct 18 14:59:16 1996
To: randy@psg.com (Randy Bush)
cc: nanog@merit.edu
Reply-To: curtis@ans.net
In-reply-to: Your message of "Wed, 16 Oct 1996 19:07:00 PDT."
<m0vDhrl-0007zlC@rip.psg.com>
Date: Fri, 18 Oct 1996 14:56:47 -0400
From: Curtis Villamizar <curtis@ans.net>
In message <m0vDhrl-0007zlC@rip.psg.com>, Randy Bush writes:
> Provider P allocates a block of address space A to customer, I an ISP.
>
> I allocates a /24, call it B, out of that block to one of their customers, C.
>
> C later leaves ISP I and gets a wire directly from provider P.
>
> I wishes to give C time to renumber.
>
> I would expect the world to see the following announcements.
>
> A - I announcing a shorter prefix, A
> B - P announcing a more specific for the /24 allocated to C
>
> Is this not what we all expect?
>
> Why I ask is we have provider P telling I that they should stop announcing A
> and instead announce a bunch of prefixes around the /24.
>
> randy
Let's get the whole picture:
before the move:
P announces A'/L1 to <the world>
B announces A/L2 to P (where L2 > L1)
C announces B/24 to B
There is no reason for P to announce anything more specific than A'/L1
to the rest of the world unless B is multihomed. If there is no A'/L1
aggregate then never mind.
after the move (if B is single homed to P):
P announces A'/L1 to <the world>
B announces A/L2 to P (where L2 > L1, L2 < 24)
C announces B/24 to B
There is no need for P to announce anything more specific than A'/L1
if B is not multihomed. If A'/L1 doesn't exist, there is still no
reason to announce anything more specific than A/L2.
if B is multihomed:
P announces A'/L1 to <the world>
B announces A/L2 to P (where L2 > L1, L2 < 24)
B announces A/L2 to <other provider O>
P announces A/L2 to <the world>
O announces A/L2 to <the world>
C announces B/24 to B
P announces B/24 to <the world>
The last part is unfortunate.
Curtis
