Re: BGP Homing Question

[Joe Provo <nanog-post () rsuc gweep net>]

[copius snips]

On Fri, Aug 27, 2004 at 11:16:40AM -0400, Patrick W Gilmore wrote:
> On Aug 27, 2004, at 8:58 AM, Joe Abley wrote:
> > On 27 Aug 2004, at 08:13, Rick Lowery wrote:
> > > I know?they would not be?good Internet citizen, but?if they needed to 
> > > do this for a temp basis does anyone see an issue?

Registering everything appropriately in the IRR will help prevent 
things from smelling fishy.

> It is your netblock, you get to use it as needed.  This 
> is much better than getting another /20 for an EU site that only needs 
> a /24.

Well, for something short term it is even less complex to get
provider-allocated space.  That is, you can plan the non-temporary
long-term around your PI space and have a clean transition out
of PA space.  Depending on your needs -and the provider's policies-
that might be the least-disruptive path for your traffic.

> Also, filtering will not be an issue, if you are careful.  Anyone who 
> does not hear the /24 will hear the /20.  Packets for the /24 will go 
> to your US upstream.  

Good advice in general for anyone concerned with more-specifics.
Reachability (and more forgiving damening) over long dstances is most 
assured by making sure you are sourcing your least-specific. Lots of
networks trade more-specifics for better geographical dispersion, but
don't expect them to propagate further than those who agree to do so.

> As long as your US upstream peers with your EU 
> upstream, and does not filter the /24 being announced over that peering 
> link, they will send the bits where they belong.  Since this is much 
> more common than the alternative, you will likely have full 
> connectivity.
>
> Anyone knows who filters these days?  

Lots of folks; manually though? Few.  Be sure your data is accurate in 
[a trusted limb of] the IRR and it should be a non-issue.

> Sprint stopped when Sean left.  Verio stopped when Randy left.  

Tying these policies to individuals is incorrect. Sprint, NTT/Verio and
others have slid their filter windows over time, roughly in step with
RIR allocation boundaries.  For example, as recently as April of this 
year Verio was using /22 in classical A and B space.

The baseline expectation that the DFZ carries rechability data and any 
more-specific data of interest is exchanged between parties who want it,
request it, or pay for it still holds true. "Being conservative in
what you send" also applies to anticipating *others* not being "liberal
in what they receive".

Joe
-- 
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