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

On Tue, Mar 8, 2022 at 3:33 PM Robert Raszuk <robert@raszuk.net> wrote:

>
> 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.
>
>
>
sure! that was my re-wording of sriram's question, effectively. (or I think
that was the re-wording!)

>
>
> 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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>>>