Hi Sasha,

In your case, the route type 5 would use the RD of the IP-VRF. I don’t think 
any implementation would do anything different.

RFC9136 says the RD has to be used in the same way it is defined in RFC7432, 
but the text refers to the recommendation of using a type 1 RD and its 
uniqueness, in fact the spec says that you take the RD from a mac-vrf or an 
ip-vrf. This could have been explicitly written, but I don’t think it creates 
any interop issue at all. We’ve been testing this across vendors for quite some 
time now, and I don’t see issues.

RFC9136 allows using the RD of a mac-vrf in a few cases where the there is no 
ip-vrf and a route type 5 is generated, but in the ip-vrf-to-ip-vrf cases you 
would use the RD of the IP-VRF.

My 2 cents.

Thanks.
Jorge

From: Alexander Vainshtein <alexander.vainsht...@rbbn.com>
Date: Sunday, December 10, 2023 at 2:39 AM
To: Jorge Rabadan (Nokia) <jorge.raba...@nokia.com>, Wim Henderickx (Nokia) 
<wim.henderi...@nokia.com>, Ali Sajassi (sajassi) 
<sajassi=40cisco....@dmarc.ietf.org>, John E Drake 
<jdrake=40juniper....@dmarc.ietf.org>, w...@juniper.net <w...@juniper.net>, 
ssa...@cisco.com <ssa...@cisco.com>, stho...@cisco.com <stho...@cisco.com>
Cc: bess@ietf.org <bess@ietf.org>
Subject: RE: A minor contradiction between RFC 9135 and RFC 9136?

CAUTION: This is an external email. Please be very careful when clicking links 
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Hi all,
A gentle reminder…

Regards,
Sasha

From: Alexander Vainshtein
Sent: Sunday, November 19, 2023 2:22 PM
To: Rabadan, Jorge (Nokia - US/Mountain View) <jorge.raba...@nokia.com>; 
wim.henderi...@nokia.com; Ali Sajassi (sajassi) 
<sajassi=40cisco....@dmarc.ietf.org>; John E Drake 
<jdrake=40juniper....@dmarc.ietf.org>; w...@juniper.net; ssa...@cisco.com; 
stho...@cisco.com
Subject: FW: A minor contradiction between RFC 9135 and RFC 9136?

Hi all,
The email expansions for the authors of RFC 9135 and RFC 9136 do not work 
anymore.
Therefore, I forward my email to you individually.

Regards,
Sasha

From: Alexander Vainshtein
Sent: Sunday, November 19, 2023 2:08 PM
To: 
draft-ietf-bess-evpn-prefix-advertisem...@ietf.org<mailto:draft-ietf-bess-evpn-prefix-advertisem...@ietf.org>;
 
draft-ietf-bess-evpn-inter-subnet-forward...@ietf.org<mailto:draft-ietf-bess-evpn-inter-subnet-forward...@ietf.org>
Cc: bess@ietf.org<mailto:bess@ietf.org>
Subject: A minor contradiction between RFC 9135 and RFC 9136?
Importance: High

Hi all,
I see what looks to me as a contradiction between Section 9.1.1 of RFC 
9315<https://datatracker.ietf.org/doc/html/rfc9135#section-9.1.1> and Section 
4.4.1 of RFC 9136<https://datatracker.ietf.org/doc/html/rfc9136#section-4.4.1>:


The former:

Defines a Symmetric IRB as an interface connecting an IP-VRF to an EVPN 
Broadcast Domain (a MAC-VRF or a specific BBD within a MAC-VRF that implements 
VLAN-Aware service interface)

Describes an IP Prefix (EVPN Type 5, a.k.a. RT-5) route advertised for the 
subnet of a Symmetric EVPN IRB and states that RD in the NLRI of this route is 
the RD of IP-VRF that contains that the IRB in question

The latter describes the Interface-less IP-VRF to IP-VRF model:

To the best of my understanding, this model deals with just Symmetric IRBs

The RFC states that the NVE/DGW will, for each of its prefixes, advertise an 
RT-5 with RD in its NLRI as defined in RFC 
7432<https://www.rfc-editor.org/rfc/rfc7432.html>. Since RFC 7432 does not 
refer to IP-VRFs at all, this strongly suggests to me that it means RD of a 
MAC-VRF .

The following diagram shows why this difference may be meaningful:

[cid:image001.png@01DA2B65.E342FB80]
In this diagram PE-1, PE-2 and PE-3 can only exchange L2VPN/EVPN routes but not 
VPN-IP routes.
Suppose that IP-VRF in PE-1 and PE-2 are configured with a static route to SN-. 
In this case:

PE-1 and PE-2 can advertise RT-5 for SN-1 using either RDs of IP-VRFs or RDs of 
MAC-VRF

If RT-5 uses RDs of containing IP-VRF, bi-directional connectivity between 
devices in SN-1 and SN-2 can be established

If RT-5 uses RDs of MAC-VRF in its NLRI, PE-3 cannot advertise RT-5 for SN-2 
because there is no MAC-VRF in this PE.


What, if anything,  do I miss?

Your timely feedback would be highly appreciated.

Regards, and lots of thanks in advance,
Sasha



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