BESS Working Group Ali Sajassi Internet-Draft Samir Thoria Intended Status: Standards Track Cisco Keyur Patel Derek Yeung Arrcus John Drake Wen Lin Juniper Expires: September 4, 2018 March 4, 2018 IGMP and MLD Proxy for EVPN draft-ietf-bess-evpn-igmp-mld-proxy-01 Abstract Ethernet Virtual Private Network (EVPN) solution [RFC 7432] is becoming pervasive in data center (DC) applications for Network Virtualization Overlay (NVO) and DC interconnect (DCI) services, and in service provider (SP) applications for next generation virtual private LAN services. This draft describes how to support efficiently endpoints running IGMP for the above services over an EVPN network by incorporating IGMP proxy procedures on EVPN PEs. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html Sajassi et al. Expires September 4, 2018 [Page 1] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 2 IGMP Proxy . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 Proxy Reporting . . . . . . . . . . . . . . . . . . . . . . 6 2.1.1 IGMP Membership Report Advertisement in BGP . . . . . . 6 2.1.1 IGMP Leave Group Advertisement in BGP . . . . . . . . . 8 2.2 Proxy Querier . . . . . . . . . . . . . . . . . . . . . . . 9 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1 PE with only attached hosts/VMs for a given subnet . . . . . 10 3.2 PE with mixed of attached hosts/VMs and multicast source . . 11 3.3 PE with mixed of attached hosts/VMs, multicast source and router . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 All-Active Multi-Homing . . . . . . . . . . . . . . . . . . . . 11 4.1 Local IGMP Join Synchronization . . . . . . . . . . . . . . 12 4.2 Local IGMP Leave Group Synchronization . . . . . . . . . . . 13 4.2.1 Remote Leave Group Synchronization . . . . . . . . . . . 13 4.2.2 Common Leave Group Synchronization . . . . . . . . . . . 14 5 Single-Active Multi-Homing . . . . . . . . . . . . . . . . . . . 14 6 Selective Multicast Procedures for IR tunnels . . . . . . . . . 14 7 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.1 Selective Multicast Ethernet Tag Route . . . . . . . . . . . 15 7.1.1 Constructing the Selective Multicast Ethernet Tag route . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.2 IGMP Join Synch Route . . . . . . . . . . . . . . . . . . . 18 7.2.1 Constructing the IGMP Join Synch Route . . . . . . . . 19 Sajassi et al. Expires September 4, 2018 [Page 2] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 7.3 IGMP Leave Synch Route . . . . . . . . . . . . . . . . . . . 20 7.3.1 Constructing the IGMP Leave Synch Route . . . . . . . . 22 7.4 Multicast Flags Extended Community . . . . . . . . . . . . . 23 7.5 EVI-RT Extended Community . . . . . . . . . . . . . . . . . 24 8 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 24 9 Security Considerations . . . . . . . . . . . . . . . . . . . . 24 10 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 11 References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.1 Normative References . . . . . . . . . . . . . . . . . . . 25 11.2 Informative References . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25 Sajassi et al. Expires September 4, 2018 [Page 3] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 1 Introduction Ethernet Virtual Private Network (EVPN) solution [RFC 7432] is becoming pervasive in data center (DC) applications for Network Virtualization Overlay (NVO) and DC interconnect (DCI) services, and in service provider (SP) applications for next generation virtual private LAN services. In DC applications, a POD can consist of a collection of servers supported by several TOR and Spine switches. This collection of servers and switches are self contained and may have their own control protocol for intra-POD communication and orchestration. However, EVPN is used as way of standard inter-POD communication for both intra-DC and inter-DC. A subnet can span across multiple PODs and DCs. EVPN provides robust multi-tenant solution with extensive multi-homing capabilities to stretch a subnet (e.g., VLAN) across multiple PODs and DCs. There can be many hosts/VMs (e.g., several hundreds) attached to a subnet that is stretched across several PODs and DCs. These hosts/VMs express their interests in multicast groups on a given subnet/VLAN by sending IGMP membership reports (Joins) for their interested multicast group(s). Furthermore, an IGMP router (e.g., IGMPv1) periodically sends membership queries to find out if there are hosts on that subnet still interested in receiving multicast traffic for that group. The IGMP/MLD Proxy solution described in this draft has three objectives to accomplish: 1) Reduce flooding of IGMP messages: just like ARP/ND suppression mechanism in EVPN to reduce the flooding of ARP messages over EVPN, it is also desired to have a mechanism to reduce the flood of IGMP messages (both Queries and Reports) in EVPN. 2) Distributed anycast multicast proxy: it is desired for the EVPN network to act as a distributed anycast multicast router with respect to IGMP/MLD proxy function for all the hosts attached to that subnet. 3) Selective Multicast: to forward multicast traffic over EVPN network such that it only gets forwarded to the PEs that have interest in the multicast group(s) - i.e., multicast traffic will not be forwarded to the PEs that have no receivers attached to them for that multicast group. This draft shows how this objective may be achieved when Ingress Replication is used to distribute the multicast traffic among the PEs. Procedures for supporting selective multicast using P2MP tunnels can be found in [bum-procedure-updates] The first two objectives are achieved by using IGMP/MLD proxy on the Sajassi et al. Expires September 4, 2018 [Page 4] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 PE and the third objective is achieved by setting up a multicast tunnel (e.g., ingress replication) only among the PEs that have interest in that multicast group(s) based on the trigger from IGMP/MLD proxy processes. The proposed solutions for each of these objectives are discussed in the following sections. 1.1 Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. POD: Point of Delivery ToR: Top of Rack NV: Network Virtualization NVO: Network Virtualization Overlay VNI: Virtual Network Identifier (for VXLAN) EVPN: Ethernet Virtual Private Network IGMP: Internet Group Management Protocol MLD: Multicast Listener Discovery EVI: An EVPN instance spanning the Provider Edge (PE) devices participating in that EVPN MAC-VRF: A Virtual Routing and Forwarding table for Media Access Control (MAC) addresses on a PE Ethernet Segment (ES): When a customer site (device or network) is connected to one or more PEs via a set of Ethernet links, then that set of links is referred to as an 'Ethernet segment'. Ethernet Segment Identifier (ESI): A unique non-zero identifier that identifies an Ethernet segment is called an 'Ethernet Segment Identifier'. PE: Provider Edge device. BD: Broadcast Domain. As per [RFC7432], an EVI consists of a single Sajassi et al. Expires September 4, 2018 [Page 5] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 or multiple BDs. In case of VLAN-bundle and VLAN-based service models VLAN-aware bundle service model, an EVI contains multiple BDs. Also, in this document, BD and subnet are equivalent terms. Ethernet Tag: An Ethernet tag identifies a particular broadcast domain, e.g., a VLAN. An EVPN instance consists of one or more broadcast domains. Single-Active Redundancy Mode: When only a single PE, among all the PEs attached to an Ethernet segment, is allowed to forward traffic to/from that Ethernet segment for a given VLAN, then the Ethernet segment is defined to be operating in Single-Active redundancy mode. All-Active Redundancy Mode: When all PEs attached to an Ethernet segment are allowed to forward known unicast traffic to/from that Ethernet segment for a given VLAN, then the Ethernet segment is defined to be operating in All-Active redundancy mode. 2 IGMP Proxy IGMP Proxy mechanism is used to reduce the flooding of IGMP messages over EVPN network similar to ARP proxy used in reducing the flooding of ARP messages over EVPN. It also provides triggering mechanism for the PEs to setup their underlay multicast tunnels. IGMP Proxy mechanism consist of two components: a) Proxy for IGMP Reports and b) Proxy for IGMP Queries. 2.1 Proxy Reporting When IGMP protocol is used between host/VMs and its first hop EVPN router (EVPN PE), Proxy-reporting is used by the EVPN PE to summarize (when possible) reports received from downstream hosts and propagate it in BGP to other PEs that are interested in the info. This is done by terminating IGMP Reports in the first hop PE, translating and exchanging the relevant information among EVPN BGP speakers. The information is again translated back to IGMP message at the recipient EVPN speaker. Thus it helps create an IGMP overlay subnet using BGP. In order to facilitate such an overlay, this document also defines a new EVPN route type NLRI, EVPN Selective Multicast Ethernet Tag route, along with its procedures to help exchange and register IGMP multicast groups [section 5]. 2.1.1 IGMP Membership Report Advertisement in BGP When a PE wants to advertise an IGMP membership report (Join) using the BGP EVPN route, it follows the following rules: 1) When the first hop PE receives several IGMP membership reports Sajassi et al. Expires September 4, 2018 [Page 6] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 (Joins) , belonging to the same IGMP version, from different attached hosts/VMs for the same (*,G) or (S,G), it only sends a single BGP message corresponding to the very first IGMP Join. This is because BGP is a statefull protocol and no further transmission of the same report is needed. If the IGMP Join is for (*,G), then multicast group address along with the corresponding version flag (v1, v2, or v3) are set. In case of IGMPv3, exclude flag also needs to be set to indicate that no source IP address to be excluded (e.g., include all sources "*"). If the IGMP Join is for (S,G), then besides setting multicast group address along with the version flag v3, the source IP address and the include/exclude flag must be set. It should be noted that when advertising the EVPN route for (S,G), the only valid version flag is v3 (i.e., v1 and v2 flags must be set to zero). 2) When the first hop PE receives an IGMPv3 Join for (S,G) on a given BD, it advertises the corresponding EVPN Selective Multicast Ethernet Tag (SMET) route regardless of whether the source (S) is attached to itself or not in order to facilitate the source move in the future. 3) When the first hop PE receives an IGMP version-X Join first for (*,G) and then later it receives an IGMP version-Y Join for the same (*,G), then it will re-advertise the same EVPN SMET route with flag for version-Y set in addition to any previously-set version flag(s). In other words, the first hop PE does not withdraw the EVPN route before sending the new route because the flag field is not part of BGP route key processing. 4) When the first hop PE receives an IGMP version-X Join first for (*,G) and then later it receives an IGMPv3 Join for the same multicast group address but for a specific source address S, then the PE will advertise a new EVPN SMET route with v3 flag set (and v1 and v2 reset). Include/exclude flag also need to be set accordingly. Since source IP address is used as part of BGP route key processing, it is considered as a new BGP route advertisement. 5) When a PE receives an EVPN SMET route with more than one version flag set, it will generate the corresponding IGMP report for (*,G) for each version specified in the flag field. With multiple version flags set, there should be no source IP address in the receive EVPN route. If there is, then an error should be logged. If v3 flag is set (in addition to v1 or v2), then the include/exclude flag needs to indicate "exclude". If not, then an error should be logged. The PE MUST generate an IGMP membership report (Join) for that (*,G) and each IGMP version in the version flag. Sajassi et al. Expires September 4, 2018 [Page 7] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 6) When a PE receives a list of EVPN SMET NLRIs in its BGP update message, each with a different source IP address and the multicast group address, and the version flag is set to v3, then the PE generates an IGMPv3 membership report with a record corresponding to the list of source IP addresses and the group address along with the proper indication of inclusion/exclusion. 7) Upon receiving EVPN SMET route(s) and before generating the corresponding IGMP Join(s), the PE checks to see whether it has any CE multicast router for that BD on any of its ES's . The PE provides such check by listening for PIM hellos on that AC (i.e, ). If it has router's ACs, then the generated IGMP Join(s) are sent to those ACs. If it doesn't have any router's AC, then no IGMP Join(s) needs to be generated because sending IGMP Joins to other hosts can result in unintentionally preventing a host from joining a specific multicast group for IGMPv1 and IGMPv2 - i.e., if the PE does not receive a join from the host it will not forward multicast data to it. Per [RFC4541], when an IGMPv1 or IGMPv2 host receives a membership report for a group address that it intends to join, the host will suppress its own membership report for the same group. In other words, an IGMPv1 or IGMPv2 Join MUST NOT be sent on an AC that does not lead to a CE multicast router. This message suppression is a requirement for IGMPv1 and IGMPv2 hosts. This is not a problem for hosts running IGMPv3 because there is no suppression of IGMP Membership reports. 2.1.1 IGMP Leave Group Advertisement in BGP When a PE wants to withdraw an EVPN SMET route corresponding to an IGMPv2 Leave Group (Leave) or IGMPv3 "Leave" equivalent message, it follows the following rules: 1) For IGMPv1, there is no explicit membership leave; therefore, the PE needs to periodically send out an IGMP membership query to determine whether there is any host left who is interested in receiving traffic directed to this multicast group (this proxy query function will be described in more details in section 2.2). If there is no host left, then the PE re-advertises EVPN SMET route with the v1 version flag reset. If this is the last version flag to be reset, then instead of re-advertising the EVPN route with all version flags reset, the PE withdraws the EVPN route for that (*,G). 2) When a PE receives an IGMPv2 Leave Group or its "Leave" equivalent message for IGMPv3 from its attached host, it checks to see if this host is the last host who is interested in this multicast group by sending a query for the multicast group. If the host was indeed the last one, then the PE re-advertises EVPN SMET Multicast route with the corresponding version flag reset. If this is the last version Sajassi et al. Expires September 4, 2018 [Page 8] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 flag to be reset, then instead of re-advertising the EVPN route with all version flags reset, the PE withdraws the EVPN route for that (*,G). 3) When a PE receives an EVPN SMET route for a given (*,G), it compares the received version flags from the route with its per-PE stored version flags. If the PE finds that a version flag associated with the (*,G) for the remote PE is reset, then the PE generates IGMP Leave for that (*,G) toward its local interface (if any) attached to the multicast router for that multicast group. It should be noted that the received EVPN route should at least have one version flag set. If all version flags are reset, it is an error because the PE should have received an EVPN route withdraw for the last version flag. If the PE receives an EVPN SMET route withdraw, then it must remove the remote PE from the OIF list associated with that multicast group. 4) When a PE receives an EVPN SMET route withdraw, it removes the remote PE from its OIF list for that multicast group and if there are no more OIF entries for that multicast group (either locally or remotely), then the PE MUST stop responding to queries from the locally attached router (if any). If there is a source for that multicast group, the PE stops sending multicast traffic for that source. 2.2 Proxy Querier As mentioned in the previous sections, each PE need to have proxy querier functionality for the following reasons: 1) To enable the collection of EVPN PEs providing L2VPN service to act as distributed multicast router with Anycast IP address for all attached hosts/VMs in that subnet. 2) To enable suppression of IGMP membership reports and queries over MPLS/IP core. 3) To enable generation of query messages locally to their attached host. In case of IGMPv1, the PE needs to send out an IGMP membership query to verify that at least one host on the subnet is still interested in receiving traffic directed to that group. When there is no reply to three consecutive IGMP membership queries, the PE times out the group, stops forwarding multicast traffic to the attached hosts for that (*,G), and sends a EVPN SMET route associated with that (*,G) with the version-1 flag reset or withdraws that route. Sajassi et al. Expires September 4, 2018 [Page 9] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 3 Operation Consider the EVPN network of figure-1, where there is an EVPN instance configured across the PEs shown in this figure (namely PE1, PE2, and PE3). Lets consider that this EVPN instance consist of a single bridge domain (single subnet) with all the hosts, sources and the multicast router shown in this figure connected to this subnet. PE1 only has hosts connected to it. PE2 has a mix of hosts and multicast source. PE3 has a mix of hosts, multicast source, and multicast router. Further more, lets consider that for (S1,G1), R1 is used as the multicast router. The following subsections describe the IGMP proxy operation in different PEs with regard to whether the locally attached devices for that subnet are: - only hosts/VMs - mix of hosts/VMs and multicast source - mix of hosts/VMs, multicast source, and multicast router +--------------+ | | | | +----+ | | +----+ H1:(*,G1)v1 ---| | | | | |---- H6(*,G1)v2 H2:(*,G1)v1 ---| PE1| | IP/MPLS | | PE2|---- H7(S2,G2)v3 H3:(*,G1)v2 ---| | | Network | | |---- S2 H4:(S2,G2)v3 --| | | | | | +----+ | | +----+ | | +----+ | | H5:(S1,G1)v3 --| | | | S1 ---| PE3| | | R1 ---| | | | +----+ | | | | +--------------+ Figure 1: 3.1 PE with only attached hosts/VMs for a given subnet When PE1 receives an IGMPv1 Join Report from H1, it does not forward this join to any of its other ports (for this subnet) because all these local ports are associated with the hosts/VMs. PE1 sends an Sajassi et al. Expires September 4, 2018 [Page 10] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 EVPN Multicast Group route corresponding to this join for (*,G1) and setting v1 flag. This EVPN route is received by PE2 and PE3 that are the member of the same BD (i.e., same EVI in case of VLAN-based service or in case of VLAN-aware bundle service). PE3 reconstructs IGMPv1 Join Report from this EVPN BGP route and only sends it to the port(s) with multicast routers attached to it (for that subnet). In this example, PE3 sends the reconstructed IGMPv1 Join Report for (*,G1) to only R1. Furthermore, PE2 although receives the EVPN BGP route, it does not send it to any of its port for that subnet - namely ports associated with H6 and H7. When PE1 receives the second IGMPv1 Join from H2 for the same multicast group (*,G1), it only adds that port to its OIF list but it doesn't send any EVPN BGP route because there is no change in information. However, when it receives the IGMPv2 Join from H3 for the same (*,G1), besides adding the corresponding port to its OIF list, it re-advertises the previously sent EVPN SMET route with the version-2 flag set. Finally when PE1 receives the IMGMPv3 Join from H4 for (S2,G2), it advertises a new EVPN SMET route corresponding to it. 3.2 PE with mixed of attached hosts/VMs and multicast source The main difference in here is that when PE2 receives IGMPv3 Join from H7 for (S2,G2), it does not advertises it in BGP because PE2 knows that S2 is attached to its local AC. PE2 adds the port associated with H7 to its OIF list for (S2,G2). The processing for IGMPv2 received from H6 is the same as the v2 Join described in previous section. 3.3 PE with mixed of attached hosts/VMs, multicast source and router The main difference in here relative to the previous two sections is that Join messages received locally needs to be sent to the port associated with router R1. Furthermore, the Joins received via BGP need to be passed to the R1 port but filtered for all other ports. 4 All-Active Multi-Homing Because a CE's LAG flow hashing algorithm is unknown, in an All- Active redundancy mode it must be assumed that the CE can send a given IGMP message to any one of the multi-homed PEs, either DF or non-DF - i.e., different IGMP Join messages can arrive at different PEs in the redundancy group and furthermore their corresponding Leave messages can arrive at PEs that are different from the ones received Sajassi et al. Expires September 4, 2018 [Page 11] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 the Join messages. Therefore, all PEs attached to a given ES must coordinate IGMP Join and Leave Group (x, G) state, where x may be either '*' or a particular source S, for each BD on that ES. This allows the DF for that [ES, BD] to correctly advertise or withdraw a Selective Multicast Ethernet Tag (SMET) route for that (x, G) group in that BD when needed. All-Active multihoming PEs for a given ES MUST support IGMP synch procedures described in this section if they want to perform IGMP proxy for hosts connects to that ES. 4.1 Local IGMP Join Synchronization When a PE, either DF or non-DF, receives, on a given multihomed ES operating in All-Active redundancy mode, an IGMP Membership Report for (x, G), it determines the BD to which the IGMP Membership Report belongs. If the PE doesn't already have local IGMP Join (x, G) state for that BD on that ES, it instantiates local IGMP Join (x, G) state and advertises a BGP IGMP Join Synch route for that [ES, BD]. Local IGMP Join (x, G) state refers to IGMP Join (x, G) state that is created as the result of processing an IGMP Membership Report for (x, G). The IGMP Join Synch route carries the ES-Import RT for the ES on which the IGMP Membership Report was received. Thus it may only go to the PEs attached to that ES (and not any other PEs). When a PE, either DF or non-DF, receives an IGMP Join Synch route it installs that route and if it doesn't already have IGMP Join (x, G) state for that [ES, BD], it instantiates that IGMP Join (x,G) state - i.e., IGMP Join (x, G) state is the union of local IGMP Join (x, G) state and installed IGMP Join Synch route. If the DF is not currently advertising (originating) a SMET route for that (x, G) group in that BD, it does so now. When a PE, either DF or non-DF, deletes its local IGMP Join (x, G) state for that [ES, BD], it withdraws its BGP IGMP Join Synch route for that [ES, BD]. When a PE, either DF or non-DF, receives the withdrawal of an IGMP Join Synch route from another PE it removes that route. When a PE has no local IGMP Join (x, G) state and it has no installed IGMP Join Synch routes, it removes IGMP Join (x, G) state for that [ES, BD]. If the DF no longer has IGMP Join (x, G) state for that BD on any ES for which it is DF, it withdraws its SMET route for that (x, G) group in that BD. I.e., A PE advertises an SMET route for that (x, G) group in that BD Sajassi et al. Expires September 4, 2018 [Page 12] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 when it has IGMP Join (x, G) state in that BD on at least one ES for which it is DF and it withdraws that SMET route when it does not have IGMP Join (x, G) state in that BD on any ES for which it is DF. 4.2 Local IGMP Leave Group Synchronization When a PE, either DF or non-DF, receives, on a given multihomed ES operating in All-Active redundancy mode, an IGMP Leave Group message for (x, G) from the attached CE, it determines the BD to which the IGMPv2 Leave Group belongs. Regardless of whether it has IGMP Join (x, G) state for that [ES, BD], it initiates the (x, G) leave group synchronization procedure, which consists of the following steps: 1) It computes the Maximum Response Time, which is the duration of (x, G) leave group synchronization procedure. This is the product of two locally configured values, Last Member Query Count and Last Member Query Interval (described in Section 3 of [RFC2236]), plus delta, the time it takes for a BGP advertisement to propagate between the PEs attached to the multihomed ES (delta is a consistently configured value on all PEs attached to the multihomed ES). 2) It starts the Maximum Response Time timer. Note that the receipt of subsequent IGMP Leave Group messages or BGP Leave Synch routes for (x, G) do not change the value of a currently running Maximum Response Time timer and are ignored by the PE. 3) It initiates the Last Member Query procedure described in Section 3 of [RFC2236]; viz, it sends a number of Group-Specific Query (x, G) messages (Last Member Query Count) at a fixed interval (Last Member Query Interval) to the attached CE. 4) It advertises an IGMP Leave Synch route for that that [ES, BD]. This route notifies the other multihomed PEs attached to the given multihomed ES that it has initiated an (x, G) leave group synchronization procedure; i.e., it carries the ES-Import RT for the ES on which the IGMP Leave Group was received. It also contains the Maximum Response Time and the Leave Group Synchronization Procedure Sequence number. The latter identifies the specific (x, G) leave group synchronization procedure initiated by the advertising PE, which increments the value whenever it initiates a procedure. 5) When the Maximum Response Timer expires, the PE that has advertised the IGMP Leave Synch route withdraws it. 4.2.1 Remote Leave Group Synchronization When a PE, either DF or non-DF, receives an IGMP Leave Synch route it Sajassi et al. Expires September 4, 2018 [Page 13] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 installs that route and it starts a timer for (x, G) on the specified [ES, BD] whose value is set to the Maximum Response Time in the received IGMP Leave Synch route. Note that the receipt of subsequent IGMPv2 Leave Group messages or BGP Leave Synch routes for (x, G) do not change the value of a currently running Maximum Response Time timer and are ignored by the PE. 4.2.2 Common Leave Group Synchronization If a PE attached to the multihomed ES receives an IGMP Membership Report for (x, G) before the Maximum Response Time timer expires, it advertises a BGP IGMP Join Synch route for that [ES, BD]. If it doesn't already have local IGMP Join (x, G) state for that [ES, BD], it instantiates local IGMP Join (x, G) state. If the DF is not currently advertising (originating) a SMET route for that (x, G) group in that BD, it does so now. If a PE attached to the multihomed ES receives an IGMP Join Synch route for (x, G) before the Maximum Response Time timer expires, it installs that route and if it doesn't already have IGMP Join (x, G) state for that BD on that ES, it instantiates that IGMP Join (x,G) state. If the DF is not currently advertising (originating) a SMET route for that (x, G) group in that BD, it does so now. When the Maximum Response Timer expires a PE that has advertised an IGMP Leave Synch route, withdraws it. Any PE attached to the multihomed ES, that started the Maximum Response Time and has no local IGMP Join (x, G) state and no installed IGMP Join Synch routes, it removes IGMP Join (x, G) state for that [ES, BD]. If the DF no longer has IGMP Join (x, G) state for that BD on any ES for which it is DF, it withdraws its SMET route for that (x, G) group in that BD. 5 Single-Active Multi-Homing Note that to facilitate state synchronization after failover, the PEs attached to a multihomed ES operating in Single-Active redundancy mode should also coordinate IGMP Join (x, G) state. In this case all IGMP Join messages are received by the DF and distributed to the non- DF PEs using the procedures described above. 6 Selective Multicast Procedures for IR tunnels If an ingress PE uses ingress replication, then for a given (x, G) group in a given BD: 1) It sends (x, G) traffic to the set of PEs not supporting IGMP Sajassi et al. Expires September 4, 2018 [Page 14] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 Proxy. This set consists of any PE that has advertised an Inclusive Multicast Tag route for the BD without the "IGMP Proxy Support" flag. 2) It sends (x, G) traffic to the set of PEs supporting IGMP Proxy and having listeners for that (x, G) group in that BD. This set consists of any PE that has advertised an Inclusive Multicast Tag route for the BD with the "IGMP Proxy Support" flag and that has advertised an SMET route for that (x, G) group in that BD. If an ingress PE's Selective P-Tunnel for a given BD uses P2MP and all of the PEs in the BD support that tunnel type and IGMP, then for a given (x, G) group in a given BD it sends (x, G) traffic using the Selective P-Tunnel for that (x, G) group in that BD. This tunnel will include those PEs that have advertised an SMET route for that (x, G) group on that BD (for Selective P-tunnel) but it may include other PEs as well (for Aggregate Selective P-tunnel). 7 BGP Encoding This document defines three new BGP EVPN routes to carry IGMP membership reports. This route type is known as: + 6 - Selective Multicast Ethernet Tag Route + 7 - IGMP Join Synch Route + 8 - IGMP Leave Synch Route The detailed encoding and procedures for this route type is described in subsequent section. 7.1 Selective Multicast Ethernet Tag Route An Selective Multicast Ethernet Tag route type specific EVPN NLRI consists of the following: Sajassi et al. Expires September 4, 2018 [Page 15] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 +---------------------------------------+ | RD (8 octets) | +---------------------------------------+ | Ethernet Tag ID (4 octets) | +---------------------------------------+ | Multicast Source Length (1 octet) | +---------------------------------------+ | Multicast Source Address (variable) | +---------------------------------------+ | Multicast Group Length (1 octet) | +---------------------------------------+ | Multicast Group Address (Variable) | +---------------------------------------+ | Originator Router Length (1 octet) | +---------------------------------------+ | Originator Router Address (variable) | +---------------------------------------+ | Flags (1 octets) (optional) | +---------------------------------------+ For the purpose of BGP route key processing, all the fields are considered to be part of the prefix in the NLRI except for the one- octet optional flag field (if included). The Flags fields are defined as follows: 0 1 2 3 4 5 6 7 +--+--+--+--+--+--+--+--+ | reserved |IE|v3|v2|v1| +--+--+--+--+--+--+--+--+ The least significant bit, bit 7 indicates support for IGMP version 1. The second least significant bit, bit 6 indicates support for IGMP version 2. The third least significant bit, bit 5 indicates support for IGMP version 3. The forth least significant bit, bit 4 indicates whether the (S, G) information carried within the route-type is of Include Group type (bit value 0) or an Exclude Group type (bit value 1). The Exclude Group type bit MUST be ignored if bit 5 is not set. This EVPN route type is used to carry tenant IGMP multicast group information. The flag field assists in distributing IGMP membership interest of a given host/VM for a given multicast route. The version Sajassi et al. Expires September 4, 2018 [Page 16] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 bits help associate IGMP version of receivers participating within the EVPN domain. The include/exclude bit helps in creating filters for a given multicast route. 7.1.1 Constructing the Selective Multicast Ethernet Tag route This section describes the procedures used to construct the Selective Multicast Ethernet Tag (SMET) route. Support for this route type is optional. The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The value field comprises an IP address of the PE (typically, the loopback address) followed by a number unique to the PE. The Ethernet Tag ID MUST be set as follows: EVI is VLAN-Based or VLAN Bundle service - set to 0 EVI is VLAN-Aware Bundle service without translation - set to the customer VID for that BD EVI is VLAN-Aware Bundle service with translation - set to the normalized Ethernet Tag ID - e.g., normalized VID The Multicast Source length MUST be set to length of multicast source address in bits. In case of a (*, G) Join, the Multicast Source Length is set to 0. The Multicast Source is the Source IP address of the IGMP membership report. In case of a (*, G) Join, this field does not exist. The Multicast Group length MUST be set to length of multicast group address in bits. The Multicast Group is the Group address of the IGMP membership report. The Originator Router Length is the length of the Originator Router address in bits. The Originator Router Address is the IP address of Router Originating the prefix. It should be noted that using the "Originating Router's IP address" field is needed for local-bias procedures and may be needed for building inter-AS multicast underlay tunnels where BGP next hop can get over written. Sajassi et al. Expires September 4, 2018 [Page 17] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 The Flags field indicates the version of IGMP protocol from which the membership report was received. It also indicates whether the multicast group had INCLUDE or EXCLUDE bit set. IGMP protocol is used to receive group membership information from hosts/VMs by TORs. Upon receiving the hosts/VMs expression of interest of a particular group membership, this information is then forwarded using Ethernet Multicast Source Group Route NLRI. The NLRI also keeps track of receiver's IGMP protocol version and any "source filtering" for a given group membership. All EVPN SMET routes are announced with per-EVI Route Target extended communities. 7.2 IGMP Join Synch Route This EVPN route type is used to coordinate IGMP Join (x,G) state for a given BD between the PEs attached to a given ES operating in All- Active (or Single-Active) redundancy mode and it consists of following: +--------------------------------------------------+ | RD (8 octets) | +--------------------------------------------------+ | Ethernet Segment Identifier (10 octets) | +--------------------------------------------------+ | Ethernet Tag ID (4 octets) | +--------------------------------------------------+ | Multicast Source Length (1 octet) | +--------------------------------------------------+ | Multicast Source Address (variable) | +--------------------------------------------------+ | Multicast Group Length (1 octet) | +--------------------------------------------------+ | Multicast Group Address (Variable) | +--------------------------------------------------+ | Originator Router Length (1 octet) | +--------------------------------------------------+ | Originator Router Address (variable) | +--------------------------------------------------+ | Flags (1 octet) | +--------------------------------------------------+ For the purpose of BGP route key processing, all the fields are considered to be part of the prefix in the NLRI except for the one- octet Flags field, whose fields are defined as follows: Sajassi et al. Expires September 4, 2018 [Page 18] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 0 1 2 3 4 5 6 7 +--+--+--+--+--+--+--+--+ | reserved |IE|v3|v2|v1| +--+--+--+--+--+--+--+--+ The least significant bit, bit 7 indicates support for IGMP version 1. The second least significant bit, bit 6 indicates support for IGMP version 2. The third least significant bit, bit 5 indicates support for IGMP version 3. The fourth least significant bit, bit 4 indicates whether the (S, G) information carried within the route- type is of Include Group type (bit value 0) or an Exclude Group type (bit value 1). The Exclude Group type bit MUST be ignored if bit 5 is not set. The Flags field assists in distributing IGMP membership interest of a given host/VM for a given multicast route. The version bits help associate IGMP version of receivers participating within the EVPN domain. The include/exclude bit helps in creating filters for a given multicast route. 7.2.1 Constructing the IGMP Join Synch Route This section describes the procedures used to construct the IGMP Join Synch route. Support for this route type is optional. If a PE does not support this route, then it MUST not indicate that it supports 'IGMP proxy' in Multicast Flag extended community for the EVIs corresponding to its multi-homed Ethernet Segments. An IGMP Join Synch route is advertised with an ES-Import Route Target extended community whose value is set to the ESI for the ES on which the IGMP Join was received. The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The value field comprises an IP address of the PE (typically, the loopback address) followed by a number unique to the PE. The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet value defined for the ES. The Ethernet Tag ID MUST be set as follows: EVI is VLAN-Based or VLAN Bundle service - set to 0 EVI is VLAN-Aware Bundle service without translation - set to the customer VID for the BD EVI is VLAN-Aware Bundle service with translation - set to the normalized Ethernet Tag ID - e.g., normalized VID Sajassi et al. Expires September 4, 2018 [Page 19] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 The Multicast Source length MUST be set to length of multicast source address in bits. In case of a (*, G) Join, the Multicast Source Length is set to 0. The Multicast Source is the Source IP address of the IGMP membership report. In case of a (*, G) Join, this field does not exist. The Multicast Group length MUST be set to length of multicast group address in bits. The Multicast Group is the Group address of the IGMP membership report. The Originator Router Length is the length of the Originator Router address in bits. The Originator Router Address is the IP address of Router Originating the prefix. The Flags field indicates the version of IGMP protocol from which the membership report was received. It also indicates whether the multicast group had INCLUDE or EXCLUDE bit set. 7.3 IGMP Leave Synch Route This EVPN route type is used to coordinate IGMP Leave Group (x,G) state for a given BD between the PEs attached to a given ES operating in All-Active (or Single-Active) redundancy mode and it consists of following: Sajassi et al. Expires September 4, 2018 [Page 20] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 +--------------------------------------------------+ | RD (8 octets) | +--------------------------------------------------+ | Ethernet Segment Identifier (10 octets) | +--------------------------------------------------+ | Ethernet Tag ID (4 octets) | +--------------------------------------------------+ | Multicast Source Length (1 octet) | +--------------------------------------------------+ | Multicast Source Address (variable) | +--------------------------------------------------+ | Multicast Group Length (1 octet) | +--------------------------------------------------+ | Multicast Group Address (Variable) | +--------------------------------------------------+ | Originator Router Length (1 octet) | +--------------------------------------------------+ | Originator Router Address (variable) | +--------------------------------------------------+ | Leave Group Synchronization # (4 octets) | +--------------------------------------------------+ | Maximum Response Time (1 octet) | +--------------------------------------------------+ | Flags (1 octet) | +--------------------------------------------------+ For the purpose of BGP route key processing, all the fields are considered to be part of the prefix in the NLRI except for the Maximum Response Time and the one-octet Flags field, whose fields are defined as follows: 0 1 2 3 4 5 6 7 +--+--+--+--+--+--+--+--+ | reserved |IE|v3|v2|v1| +--+--+--+--+--+--+--+--+ The least significant bit, bit 7 indicates support for IGMP version 1. The second least significant bit, bit 6 indicates support for IGMP version 2. The third least significant bit, bit 5 indicates support for IGMP version 3. The fourth least significant bit, bit 4 indicates whether the (S, G) information carried within the route- type is of Include Group type (bit value 0) or an Exclude Group type (bit value 1). The Exclude Group type bit MUST be ignored if bit 5 is not set. Sajassi et al. Expires September 4, 2018 [Page 21] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 The Flags field assists in distributing IGMP membership interest of a given host/VM for a given multicast route. The version bits help associate IGMP version of receivers participating within the EVPN domain. The include/exclude bit helps in creating filters for a given multicast route. 7.3.1 Constructing the IGMP Leave Synch Route This section describes the procedures used to construct the IGMP Join Synch route. Support for this route type is optional. If a PE does not support this route, then it MUST not indicate that it supports 'IGMP proxy' in Multicast Flag extended community for the EVIs corresponding to its multi-homed Ethernet Segments. An IGMP Join Synch route is advertised with an ES-Import Route Target extended community whose value is set to the ESI for the ES on which the IGMP Join was received. The Route Distinguisher (RD) SHOULD be a Type 1 RD [RFC4364]. The value field comprises an IP address of the PE (typically, the loopback address) followed by a number unique to the PE. The Ethernet Segment Identifier (ESI) MUST be set to the 10-octet value defined for the ES. The Ethernet Tag ID MUST be set as follows: EVI is VLAN-Based or VLAN Bundle service - set to 0 EVI is VLAN-Aware Bundle service without translation - set to the customer VID for the BD EVI is VLAN-Aware Bundle service with translation - set to the normalized Ethernet Tag ID - e.g., normalized VID The Multicast Source length MUST be set to length of multicast source address in bits. In case of a (*, G) Join, the Multicast Source Length is set to 0. The Multicast Source is the Source IP address of the IGMP membership report. In case of a (*, G) Join, this field does not exist. The Multicast Group length MUST be set to length of multicast group address in bits. The Multicast Group is the Group address of the IGMP membership report. Sajassi et al. Expires September 4, 2018 [Page 22] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 The Originator Router Length is the length of the Originator Router address in bits. The Originator Router Address is the IP address of Router Originating the prefix. The Flags field indicates the version of IGMP protocol from which the membership report was received. It also indicates whether the multicast group had INCLUDE or EXCLUDE bit set. 7.4 Multicast Flags Extended Community The 'Multicast Flags' extended community is a new EVPN extended community. EVPN extended communities are transitive extended communities with a Type field value of 6. IANA will assign a Sub- Type from the 'EVPN Extended Community Sub-Types' registry. A PE that supports IGMP proxy on a given BD MUST attach this extended community to the Inclusive Multicast Ethernet Tag (IMET) route it advertises for that BD and it Must set the IGMP Proxy Support flag to 1. Note that an [RFC7432] compliant PE will not advertise this extended community so its absence indicates that the advertising PE does not support IGMP Proxy. The advertisement of this extended community enables more efficient multicast tunnel setup from the source PE specially for ingress replication - i.e., if an egress PE supports IGMP proxy but doesn't have any interest in a given (x, G), it advertises its IGMP proxy capability using this extended community but it does not advertise any SMET route for that (x, G). When the source PE (ingress PE) receives such advertisements from the egress PE, it does not replicate the multicast traffic to that egress PE; however, it does replicate the multicast traffic to the egress PEs that don't advertise such capability even if they don't have any interests in that (x, G). A Multicast Flags extended community is encoded as an 8-octet value, as follows: Sajassi et al. Expires September 4, 2018 [Page 23] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=0x06 | Sub-Type=TBD | Flags (2 Octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The low-order bit of the Flags is defined as the "IGMP Proxy Support" bit. A value of 1 means that the PE supports IGMP Proxy as defined in this document, and a value of 0 means that the PE does not support IGMP proxy. The absence of this extended community also means that the PE doesn not support IGMP proxy. 7.5 EVI-RT Extended Community The 'EVI-RT' extended community is a new EVPN extended community. EVPN extended communities are transitive extended communities with a Type field value of 6. IANA will assign a Sub-Type from the 'EVPN Extended Community Sub-Types' registry. A PE that supports IGMP synch procedures for All-Active (or Single- Active) multi-homed ES, MUST attach this extended community to either IGMP Join Synch route (sec 7.2) or IGMP Leave Synch route (sec 7.3). This extended community carries the RT associated with the EVI so that the receiving PE can identify the EVI properly. The reason standard format RT is not used, is to avoid distribution of these routes beyond the group of multihoming PEs for that ES. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=0x06 | Sub-Type=TBD | RT associated with EVI | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RT associated with the EVI (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 8 Acknowledgement 9 Security Considerations Same security considerations as [RFC7432]. Sajassi et al. Expires September 4, 2018 [Page 24] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 10 IANA Considerations IANA has allocated the following EVPN Extended Community sub-types in [RFC7153], and this document is the only reference for them. 0x09 Multicast Flags Extended Community [this document] 0x0A EVI-RT Extended Community [this document] This document requests the following EVPN route types from IANA registry. + 6 - Selective Multicast Ethernet Tag Route + 7 - IGMP Join Synch Route + 8 - IGMP Leave Synch Route 11 References 11.1 Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4360] S. Sangli et al, ""BGP Extended Communities Attribute", February, 2006. [RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", February, 2015. 11.2 Informative References [ETREE-FMWK] Key et al., "A Framework for E-Tree Service over MPLS Network", draft-ietf-l2vpn-etree-frwk-03, work in progress, September 2013. [PBB-EVPN] Sajassi et al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn- 05.txt, work in progress, October, 2013. [RFC4541] Christensen, M., Kimball, K., and F. Solensky, "Considerations for IGMP and MLD snooping PEs", RFC 4541, 2006. Authors' Addresses Ali Sajassi Cisco Email: sajassi@cisco.com Sajassi et al. Expires September 4, 2018 [Page 25] INTERNET DRAFT IGMP Reports Aggregation in EVPN March 4, 2018 Samir Thoria Cisco Email: sthoria@cisco.com Keyur Patel Arrcus Email: keyur@arrcus.com Derek Yeung Arrcus Email: derek@arrcus.com John Drake Juniper Email: jdrake@juniper.net Wen Lin Juniper Email: wlin@juniper.net Sajassi et al. Expires September 4, 2018 [Page 26]