Re: [GROW] draft-white-grow-overlapping-routes-00

["White, Russell" <[e-mail]>]

>> not PA... With PA, if a provider is stupid
>> enough to give the inbound traffic to one of their customers to a
>> competing provider, then go ahead.
> 
> It will not ! Because wise provider do not suppress anything on inbound
> within his network he carries his more specific prefixes just fine. It
> is just outbound to his upstream he advertises his single PA space. 4
> 
>> I can't imagine doing that as a
>> provider. If I'm providing the PA space, I want to be the primary
>> entry point into the customer's network.
> 
> And you still are .. of course provided that customer will not convince
> some other ISP with sufficient $$$ to advertise part of your PA space.

Okay, there are three cases I can see:

1. A provider who is giving a customer PA space in parts, but that PA space is not being advertised anyplace other than to that provider. In this case, pulling traffic overlapping routes doesn't matter, because the provider who allows the use of PA space is going to take them out by not advertising the longer prefixes from their own space. In this case, the draft we've proposed would work, as well.

2. A provider who is giving a customer PA space and allowing the customer to advertise that same PA space through another provider. In this case, if the provider is not advertising the PA space at the same length as the customer is to an alternate provider, the alternate provider will consume all the inbound traffic to the customer. This is dumb on the part of the provider giving out the PA space.

3. A customer who has PI space and is advertising different bits in different places. Again, best practice would say to advertise a shorter covering route as well, to guard against failures. If the end AS is advertising longer and shorter prefixes that overlap, the draft we've proposed works --even if they're advertising them in different places, what we've proposed will take the longer prefix out once it no longer draws traffic along a different path than the shorter prefix.

So, I'm a bit confused as to what case you think isn't covered... I thought you were saying it was normal operation for a provider to give out PA space, allow the customer to break that space up, and then only advertise the shorter block covering the space given to the customer. I don't care how you jiggle local pref if you do this, longer prefix wins, and the alternate provider consumes the traffic --even from your AS.

:-)

Russ