Re: [bess] A couple of question about draft-ietf-bess-evpn-ac-aware-bundling

[Alexander Vainshtein <[e-mail]>]

Hi,
Regarding my Q2:

I have encountered deployments in which an EVPN IRB is configured with multiple IP subnets while the single attachment circuit of the broadcast domain it uses is delimited by a single VLAN.

Regards,
Sasha

From: Alexander Vainshtein
Sent: Tuesday, February 6, 2024 3:51 PM
To: [e-mail]
Cc: [e-mail]
Subject: A couple of question about draft-ietf-bess-evpn-ac-aware-bundling
Importance: High

Hi,
I have a couple of question about the AC-aware bundling draft<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-ac-aware-bundling-04> .
The background for these questions is given below.


1.       Section 6.2 of RFC 7432<https://datatracker.ietf.org/doc/html/rfc7432#section-6.2> that defines VLAN Bundle Service Interface says that "MAC addresses MUST be unique across all VLANs for that EVI in order for this service to work" .

a.       This requirement is not limited to multihomed PEs

b.       No mechanisms for enforcement of this requirement (e.g., by detecting and handling of possible violations) are defined

c.       Any manipulation of VLAN tags is strictly prohibited with this service interface

2.       The draft in question defines a similar requirement and effectively provides a way to enforce it. However:

a.       Detection of misconfiguration is explicitly limited to just multihomed PEs (as can be seen from the title of Section 5)

b.       The draft does not impose any limitations on VLAN manipulation (this is expected in the case of inter-subnet traffic (with each subnet differentiated by a VLAN) within a single broadcast domain)

c.       The draft seems to deal just with the situation in which multiple subnets in the same broadcast domain are differentiated by VLANs.

And now my questions:

Q1: What is the rationale for restricting detection and handling of violation of the above-mentioned rule to just multi-homed PEs?
Q2: Does the draft support the situations in which multiple IP subnets in the same broadcast domain are NOT differentiated by different VLANs?
Q3: Is VLAN translation with AC-aware bundling service interface allowed for intra-subnet traffic that undergoes "pure Layer 2 switching" in the single broadcast domain?

Your feedback would be highly appreciated.

Regards, and lots of thanks in advance,
Sasha

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