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

Right - but IMO route leaking can happen both in the Internet or in
customer <- via IXP -> content provider interconnects.

And in the latter case - especially for those with open peering policy -
often going via RS. After all this is how route servers are mainly used
today :) So both sides will be peering to IXP RS while IXP RS will (in most
cases) not appear in the AS_PATH.

Kind regards,
R.

On Tue, Mar 8, 2022 at 9:26 PM Christopher Morrow <
christopher.morrow@gmail.com> wrote:

>
>
> 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.
>>
>>
>>
>>
>>
>>
>>
>>
>> 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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>>>
>>