Hi all, I would highly appreciate a clarification regarding signaling of the preferred PW CW in EVPN encapsulation as discussed in Section 7.11 and Section 18 of the 7432bis draft.
Section 7.1 of the draft says: When the L2-Attr Extended Community is received from a remote PE, the control word C flag MUST be checked against local control word enablement. If there is a mismatch, the local PE MUST NOT add the remote PE as the EVPN destination for any of the corresponding service instances. The text above does not make any differentiation between known unicast and BUM traffic. Section 18 of the draft says: If a network uses deep packet inspection for its ECMP, then the following rules for "Preferred PW MPLS Control Word" [RFC4385<https://www.rfc-editor.org/info/rfc4385>] apply: ยท It MUST be used with the value 0 (e.g., a 4-octet field with a value of zero) when sending unicast EVPN-encapsulated packets over an MP2P LSP The text above: 1. Does not say anything about usage of the all-zeroes PW CW in EVPN encapsulation of broadcast and multicast traffic. It is worth noting that, if encapsulated without the PW CW, such traffic would not ever be misinterpreted as IPv4 or IPv6 traffic because the first octet of a multicast MAC address is always an odd number 2. Does not differentiate between "known unicast" traffic (that is sent to a specific remote PE) and "unknown unicast" traffic. Section 12 of the draft says that such traffic: * MAY be flooded in the same way as broadcast and multicast traffic * Alternatively, its flooding MAY be suppressed (in which case CW usage in it encapsulation becomes irrelevant). IMHO the following needs clarification: Is a PE that signals usage of the CW in the EVPN encapsulation in accordance with Section 7.11 of the draft: 1. Include the CW in the EVPN Encapsulation of broadcast and multicast traffic when using ingress replication with MP2P LSPs it floods? 2. Expect presence of the CW in the EVPN Encapsulation of broadcast and multicast traffic it receives if the remote PEs use ingress replication with MP2P LSPs? 3. If the answers to (1) and (2) above are negative, can possible reordering of unknown unicast traffic (sent without the CW in EVPN encapsulation) be tolerated? Your timely feedback would be highly appreciated. Regards, and lots of thanks in advance, Sasha 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.
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