Hi Sasha, The reason is because the hot standby procedure is used for ingress replication or p2mp as defined in the EVPN-BFD draft.. and when we discussed this, the feedback from the WG (mostly Greg) was to add a reference to the EVPN-BFD draft.
Thanks. Jorge From: Alexander Vainshtein <Alexander.Vainshtein=40rbbn....@dmarc.ietf.org> Date: Sunday, October 27, 2024 at 4:05 AM To: draft-ietf-bess-evpn-redundant-mcast-source....@ietf.org <draft-ietf-bess-evpn-redundant-mcast-source....@ietf.org> Cc: bess@ietf.org <bess@ietf.org>, rtg-...@ietf.org <rtg-...@ietf.org>, Zheng Zhang <zhang.zh...@zte.com.cn> Subject: [bess] Re: [EXTERNAL] [RTG-DIR]Rtgdir early review of draft-ietf-bess-evpn-redundant-mcast-source-10 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. Hi all, I have looked up the draft, and I do not understand the reference to the EVPN-VFD draft in Section 5.2 of the draft<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-redundant-mcast-source-10#section-5.2>. This section says: In addition to using the state of the EVPN A-D per EVI, EVPN A-D per ES or S-PMSI A-D routes to modify the Reverse Path Forwarding check on (*,G)/(S,G) as discussed in Section 5<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-redundant-mcast-source-10#sect-5>, Bidirectional Forwarding Detection (BFD) protocol MAY be used to monitor the status of the multipoint tunnels used to forward the Single Flow Group packets from the redundant G-sources. The BGP-BFD Attribute is advertised along with the S-PMSI A-D or Inclusive Multicast Ethernet Tag routes (depending on whether Inclusive PMSI or Selective PMSI trees are used) and the procedures described in [I-D.ietf-bess-evpn-bfd] [I-D.ietf-mpls-p2mp-bfd] are used to bootstrap multipoint BFD sessions on the downstream PEs. If the purpose of using BFD is “to monitor the status of the multipoint tunnels used to forward the Single Flow Group packets from the redundant G-sources”, why is not the mechanism defined in the BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP draft<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-p2mp-bfd-08> not sufficient? Regards, Sasha From: Zheng Zhang via Datatracker <nore...@ietf.org> Sent: Thursday, October 24, 2024 7:38 AM To: rtg-...@ietf.org Cc: bess@ietf.org; draft-ietf-bess-evpn-redundant-mcast-source....@ietf.org Subject: [EXTERNAL] [RTG-DIR]Rtgdir early review of draft-ietf-bess-evpn-redundant-mcast-source-10 Reviewer: Zheng Zhang Review result: Ready Hello I have been selected to do a routing directorate “early” review of this draft. https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-redundant-mcast-source/<https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-redundant-mcast-source> The routing directorate will, on request from the working group chair, perform an “early” review of a draft before it is submitted for publication to the IESG. The early review can be performed at any time during the draft’s lifetime as a working group document. The purpose of the early review depends on the stage that the document has reached. Document: draft-ietf-bess-evpn-redundant-mcast-source-10.txt Reviewer: Zheng Zhang Review Date: Oct 24th, 2024 Intended Status: Standards Track Summary: No issues found. This documents is ready to proceed to next step. Comments: Generally, the draft written clearly. Please consider the comments listed to improve the draft. Overall, please replace the [I-D.ietf-bess-evpn-irb-mcast] with [RFC9625]. Please find the comments below with ZZ>. Multicast Source Redundancy in EVPN Networks draft-ietf-bess-evpn-redundant-mcast-source-10 Abstract ...... 1. Introduction ...... The solution provides support for Warm Standby and Hot Standby redundancy. Warm Standby is defined as the redundancy scenario in which the upstream PEs, attached to the redundant sources of the same tenant, make sure that only one source of the same flow can send multicast to the interested downstream PEs at the same time. In Hot Standby mode, the upstream PEs forward the redundant multicast flows to the downstream PEs, and the downstream PEs make sure only one flow is forwarded to the interested attached receivers. ZZ> It's better to move the Warm Standby and Hot Standby explaination to Terminology section. ...... 4. Warm Standby (WS) Solution for Redundant G-Sources The general procedure is described as follows: ZZ> It's better to add a 'specification' sub-section for the solution procedure description. 1. Configuration of the upstream PEs ...... 2. Signaling the location of a G-source for a given Single Flow Group ...... * The S-PMSI A-D route is imported by all the PEs attached to the tenant domain. In order to do that, the route will use the SBD-RT (Supplementary Broadcast Domain Route Target) in addition to the BD-RT (Broadcast Domain Route Target) of the Broadcast Domain over which the G-traffic is received. The route SHOULD also carry a Designated Forwarder Election Extended Community and a flag indicating that it conveys an SFG. The Designated Forwarder Election extended community and its use is specified in [RFC8584]. ZZ> Since the SBD-RT may not existed if there is no multiple BDs, please add "if the SBD exists" to the SBD-RT description. ...... 4.1. Warm Standby Example in an OISM Network ...... The Warm Standby solution works as follows: ...... 2. Signaling the location of S1 and S2 for (*,G1) Upon receiving (S1,G1) traffic on a local Attachment Circuit, PE1 and PE2 originate S-PMSI A-D (*,G1) routes with the SBD-RT (Supplementary Broadcast Domain Route Target), Designated Forwarder Election Extended Community and a flag indicating that it conveys a Single Flow Group. ZZ> The "a flag" indicates the "Single Flow Group (SFG) flag" defined in Multicast Flags Extended Community Flag, right? Please replace the 'a flag' with the "SFG flag". ...... The end result is that, upon receiving reports for (*,G1) or (S,G1), the downstream PEs (PE3 and PE5) will issue SMET routes and will pull the multicast Single Flow Group from PE1, and PE1 only. Upon a failure on S1, the Attachment Circuit connected to source S1 or PE1 itself will trigger the S-PMSI A-D (*,G1) withdrawal from PE1 and PE2 will be promoted to Single Forwarder. ZZ> Please add "IGMP/MLD" in front of "reports for (*,G1) or (S,G1)" in the first sentence. ...... 5. Hot Standby Solution for Redundant G-Sources ZZ> It's better to add a 'specification' sub-section for the solution procedure description. 1. Configuration of the PEs ...... Contrary to what is specified in the Warm Standby method (that is ...... The downstream PEs will locally select an Ethernet Segment Identifier for a given Single Flow Group, and will program a Reverse Path Forwarding check to the (*,G)/(S,G) state for the Single Flow Group that will discard (*,G)/(S,G) packets from the rest of the Ethernet Segment Identifiers. The selection of the Ethernet Segment Identifier for the Single Flow Group is based on local policy. ZZ> So different downstream PEs may select different upstream PE, this may be described explicitly in the paragraph. ...... 3. Distribution of DCB (Domain-wide Common Block) ESI-labels and G-source ES routes ...... b. The EVPN A-D per EVI and A-D per ES routes MUST include the route target SBD-RT since they have to be imported by all the PEs in the tenant domain. ZZ> Since the SBD may not existed, please add "if the SBD exists" to indicate. ...... 5.3. Hot Standby Example in an OISM Network ...... 2. PE1 and PE2 advertise S-PMSI A-D (*,G1) and EVPN ES, A-D per ES and A-D per EVI routes Based on the configuration of step 1, PE1 and PE2 advertise an S-PMSI A-D (*,G1) route each. The route from each of the two PEs will include TWO ESI Label Extended Communities with ESI-1 and ESI-2 respectively, as well as route target BD1-RT plus SBD-RT and a flag that indicates that (*,G1) is a Single Flow Group. ZZ> Same with previous comments, please replace "a flag" with "SFB flag". And in the sentence 'The route from each of the two PEs will include TWO ESI Label Extended Communities with ESI-1 and ESI-2 respectively,' please use lower case for the "TWO", if it has no special meaning. [End of Review] 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. 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