Re: [Sidrops] [GROW] IXP Route Server question

On Tue, Mar 8, 2022 at 3:15 PM Robert Raszuk <robert@raszuk.net> wrote:

> Well I think the answer is - it depends.
>
> First IXP fabric can be used as pure L3 share LAN or can be used (and it
> is often the case) as a p2p emulated VLAN over such L3 shared LAN.
>
> Now if this is L3 shared LAN still customer and ISP may peer directly and
> no third party traffic would be accepted at either end.
>
> If we talk about emulating L2 IXP fabric becomes just an emulated circuit
> and from the perspective of routing it a p2p interface.
>
> Sure the other aspects of the IXP quality, port monitoring,
> oversubscription etc... always will apply but there are ways to mitigate or
> handle those in real IXPs.
>
>
I don't dispute your content here, except that Sriram's question was about
seeing 'customer routes via the RS'... which I think would obviate the
emulation examples you provided.
(well in a bunch of cases it would, you COULD hook up some tomfoolery to
get this to work, but... that sounds complex and prone to disaster)

> Best,
> R.
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> On Tue, Mar 8, 2022 at 9:05 PM Christopher Morrow <
> christopher.morrow@gmail.com> wrote:
>
>>
>>
>> On Tue, Mar 8, 2022 at 2:36 PM Sriram, Kotikalapudi (Fed)
>> <kotikalapudi.sriram=40nist.gov@dmarc.ietf.org> wrote:
>>
>>> This question has relevance to the ASPA method for route leak detection.
>>>
>>> Is it possible that an ISP AS A peers with a customer AS C via a
>>> non-transparent IXP AS B?
>>> IOW, the AS path in routes propagated by the ISP A for customer C's
>>> prefixes looks like this:  A B C.
>>> I.e., can the AS of a non-transparent IXP/RS appear in an AS path in the
>>> middle between an ISP and its customer?
>>>
>>>
>> it seems unlikely to me that an ISP would pick up a 'customer' (someone
>> that pays them to transport packets) at an IXP fabric.
>> Might it happen? sure? is it messy? yes!
>>
>> 1) that's probably a shared port
>> 2) there are other folk feeding routes and packets into the mix
>> 3) how many came through the 'customer' port (which you can't really know
>> easily) vs other participants on the ix
>> 4) what capacity planning could the 'customer' do here? (none, basically
>> with respect to the remote ISP port)
>>
>> Your question might work also as:
>>   "ISP A has a customer C on a direct link in location Y.
>>    ISP A is present at IXP-Z, so is customer C, though they do not
>> bilaterally peer (not do they interconnect at the IXP).
>>   ISP A can still see Customer C's routes through the IXP-Z Route Server."
>>
>> that seems plausible, but not a desired outcome for the ISP :) since they
>> will be unlikely to collect pesos for the traffic
>> which MAY pass across that interconnect.
>>
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>