Hello again,
[snip]
>>> 2) Fig 1, IMO, needs additional information about which AS/ ASes
>>> are used for Ingress and Egress SR Domains (Guess AS1 and AS2
>>> respectively, but it has to be shown). Current version looks a bit
>>> confusing, for example, why we need AS3 on Fig.1?
>>
>> I'm looking at the figure and I don't understand your confusion: sorry.
>> The ASes are not used for Ingress and Egress SR Domains. The two
>> domains are marked separately.
>> Packets are routed from the Ingress SR domain to the Egress SR
>> domain through the Gateways (also marked) and across the ASes
>> that provide connectivity.
>
> BKH> The text after Fig.1 says about limitations of BGP Add-Path
> especially in Inter-AS case with ASBRs in regards to GW identity,
> but Fig.1 also have AS3, it makes some dissonance with that
> message, IMO. That is why I was confused. May be I was just too
> focused on details :)
I’m not sure. Maybe if we had numbered the ASes differently so that the obvious
least AS-hops (“shortest”) path was through AS1, and AS2/AS3 was the path that
would lose the GW identities?
But I still don’t see the problem you are raising, and I really want to.
The figure shows that there are multiple possible routes from ingress domain to
egress domain:
* GW-AS3-GW2
* GW-AS1-[choice of ASBRs]-AS2-GW1
* GW-AS1-[choice of ASBRs]-AS2-GW2
The text notes that:
* Add-Paths enables the presentation of {AS3} and {AS1, AS2} as paths
* Add-Paths loses the identities and so choice of GW1 and GW2 in the
{AS1, AS2} case
>>> 3) If new Tunnel Encapsulation is defined as SR Tunnel, will
>>> ietf-idr-tunnel-encaps be updated accordingly? 15th version
>>> does not have it so far
>>
>> I don't believe that other document needs to be updated.
>> The code point has already been assigned for this draft. You can see
>> it at
>> https://www.iana.org/assignments/bgp-parameters/bgp-parameters.xhtml#tunnel-types
>
> Adrian, sorry, one last question:
> Part 3. SR Domain GW AD
>...
> To avoid the side effect of applying the Tunnel Encapsulation
> attribute to any packet that is addressed to the GW itself, the GW
> SHOULD use a different loopback address for the two cases.
> Am I correct that these two cases do mean:
> 1) Loopback for AD route
> 2) Loopback for other purposes (i.e. receiving packets addressed
> to the GW itself) ?
> So GW should advertise 2 different loopbacks, one with Tunnel
> Encapsulation attribute and another without it.
Yes, you got it.
Best,
Adrian
_______________________________________________
BESS mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/bess
