Jorge, Lots of thanks for your email. I can easily imagine the case in which different BDs in a VLAN-aware bundle MAC-VRF serve tenant spaces with overlapping ranges of IP addresses. In this case GW IP addresses used in RT-5 would have to be differentiated by Ethernet Tag IDs for recursive resolution. I cannot say if such configurations exist in real deployments, but I definitely can build such a setup in the Lab.
IMHO the bottom line is that usage of Ethernet Tag ID in RT-5 is not specified in 9136, and this issue should be addressed if/when somebody starts working on 9136bis😉. Regards, Sasha Get Outlook for Android<https://aka.ms/AAb9ysg> ________________________________ From: Jorge Rabadan (Nokia) <jorge.rabadan=40nokia....@dmarc.ietf.org> Sent: Thursday, June 5, 2025 4:15:39 PM To: Alexander Vainshtein <alexander.vainsht...@rbbn.com>; Jeffrey (Zhaohui) Zhang <zzh...@juniper.net> Cc: bess@ietf.org <bess@ietf.org> Subject: [EXTERNAL] Re: Ethernet Tag ID in EVPN type-5 routes Hi Sasha, Jeffrey, I hope you're both doing well. Based on my understanding, there isn't a specification that mandates the use of the Ethernet Tag ID in the IP Prefix route for recursive resolution to a gw-ip or MAC overlay index. When RFC9136 was drafted, the inclusion of the Ethernet Tag ID in the IP Prefix route was primarily for consistency with other route types that advertise reachability for a given tenant. However, the assumptions you've mentioned were never really assumed or written. Regarding recursive resolution to a gw-ip, I believe that the Ethernet Tag ID doesn't add any significant value since the gw-ip is a unique IP within the tenant space. For recursive resolution to a MAC overlay index, I can understand how it might be beneficial if the MAC resides in a VLAN-aware bundle BD. That being said, I haven't come across any implementations similar to what you have described. If such implementations exist, it would be worthwhile to discuss them within this WG. Thanks, Jorge From: Alexander Vainshtein <Alexander.Vainshtein=40rbbn....@dmarc.ietf.org> Date: Wednesday, June 4, 2025 at 11:54 PM To: Jeffrey (Zhaohui) Zhang <zzh...@juniper.net> Cc: bess@ietf.org <bess@ietf.org> Subject: [bess] Re: Ethernet Tag ID in EVPN type-5 routes CAUTION: This is an external email. Please be very careful when clicking links or opening attachments. See the URL nok.it/ext for additional information. Jeffrey and all, I think that Ethernet Tag ID in the NLRI RT-5: - Is only relevant if RT-5 in question requires recursive resolution - Is used to identify the specific EVPN route to be used for recursive resolution - Can be non-zero only if advertised by one of the BDs in an EVI that implements VLAN-aware bundling - in which case it identifies the specific BD within this EVI. E.g., if, as per the rules of Table 1 of RFC 9136, the GW IP Address has to be used as the key for recursive resolution of a received RT-5, recursive resolution can only be provided by a received RT-2 for an IP-->MAC pair such that: - IP address in the NLRI of RT-2 matches the GW IP Address in the NLRI of RT-5 - Ethernet Tag ID in the NLRI of RT-2 matches the Ethernet Tag ID of RT-5. The same applies for other cases of recursive resolution. If recursive resolution is not needed, Ethernet Tag ID in the NLRI of an RT-5 can be ignored. Regards, Sasha -----Original Message----- From: Jeffrey (Zhaohui) Zhang <zzh...@juniper.net> Sent: Thursday, June 5, 2025 12:40 AM To: bess@ietf.org<mailto:bess@ietf.org> Subject: [bess] Ethernet Tag ID in EVPN type-5 routes Hi, For the Ethernet Tag ID in the type-5 routes, RFC 9136 gives two examples of Tag ID 0 and mentions the following: * The Route Distinguisher (RD) and Ethernet Tag ID MUST be used as defined in [RFC7432] and [RFC8365]. Obviously, RFC7432/8365 won't have text about the tag used in EVPN type-5 routes, so I have the following assumptions: A particular tenant has one IP VRF and one or more EVIs (Mac VRFs) on a PE. In the case of vlan-aware bundle EVI, the Ethernet tag ID identifies a BD, and the mac address in a particular BD can be used as the overlay index for a type-5 route. In this case, the tag id in the type-5 route will be set to the ethernet tag ID that identifies the BD. This also assumes that the type-5 routes (with non-zero tag) are tied to one (of all) vlan-aware EVI, or there are some other means of identifying which vlan-aware EVI will be used together with the ethernet tag ID in the type-5 routes. In particular, a non-zero ethernet tag id will only be used in type-5 routes in the vlan-aware model when the overlay index is a MAC address in a particular BD. Is my understanding correct? Thanks. Jeffrey Juniper Business Use Only Disclaimer This e-mail together with any attachments may contain information of Ribbon Communications Inc. and its Affiliates that is confidential and/or proprietary for the sole use of the intended recipient. Any review, disclosure, reliance or distribution by others or forwarding without express permission is strictly prohibited. If you are not the intended recipient, please notify the sender immediately and then delete all copies, including any attachments.
_______________________________________________ BESS mailing list -- bess@ietf.org To unsubscribe send an email to bess-le...@ietf.org
