PIM Working Group Yisong Liu Internet Draft Huawei Technologies Intended status: Standards Track M. McBride Expires: December 20, 2019 T. Eckert Futurewei June 20, 2019 PIM Assert Message Packing draft-liu-pim-assert-packing-01 Status of this Memo This Internet-Draft is submitted 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on December 20, 2019. Copyright Notice Copyright (c) 2019 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. Liu, et al. Expires December, 2019 [Page 1] Internet-Draft PIM Assert Packing June 2019 Abstract In PIM-SM shared LAN networks, there is typically more than one upstream router. When duplicate data packets appear on the LAN from different routers, assert packets are sent from these routers to elect a single forwarder. The PIM assert packets are sent periodically to keep the assert state. The PIM assert packet carries information about a single multicast source and group, along with the metric-preference and metric of the route towards the source or RP. This document defines a standard to send and receive multiple multicast source and group information in a single PIM assert packet in a shared network. This can be particularly helpful when there is traffic for a large number of multicast groups. Table of Contents 1. Introduction ................................................ 2 1.1. Requirements Language .................................. 3 1.2. Terminology ............................................ 3 2. Use Cases ................................................... 3 2.1. Enterprise network ..................................... 3 2.2. Video surveillance ..................................... 4 2.3. Financial Services ..................................... 4 2.4. IPTV broadcast video ................................... 4 2.5. Summary ................................................ 4 3. Solution .................................................... 5 3.1. PIM Assert Packing Hello Option ........................ 5 3.2. PIM Assert Packing Simple Type ......................... 5 3.3. PIM Assert Packing Aggregation Type .................... 5 4. Packet Format ............................................... 6 4.1. PIM Assert Packing Hello Option ........................ 6 4.2. PIM Assert Simple Packing Format ....................... 7 4.3. PIM Assert Aggregation Packing Format .................. 8 5. IANA Considerations ........................................ 11 6. Security Considerations .................................... 11 7. References ................................................. 11 7.1. Normative References .................................. 11 7.2. Informative References ................................ 11 8. Acknowledgments ............................................ 12 1. Introduction In PIM-SM shared LAN networks, there is typically more than one upstream router. When duplicate data packets appear on the LAN, from different upstream routers, assert packets are sent from these routers to elect a single forwarder according to [RFC7761]. The PIM Liu, et al. Expires December, 2019 [Page 2] Internet-Draft PIM Assert Packing June 2019 assert packets are sent periodically to keep the assert state. The PIM assert packet carries information about a single multicast source and group, along with the corresponding metric-preference and metric of the route towards the source or RP. This document defines a standard to send and receive multiple multicast source and group information in a single PIM assert packet in a shared LAN network. It can efficiently pack multiple PIM assert packets into a single message and reduce the processing pressure of the PIM routers. This can be particularly helpful when there is traffic for a large number of multicast groups. 1.1. Requirements Language 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. 1.2. Terminology RPF: Reverse Path Forwarding RP: Rendezvous Point SPT: Shortest Path Tree RPT: RP Tree DR: Designated Router BDR: Backup Designated Router 2. Use Cases PIM Assert will happen in many services where multicast is used and not limited to the examples described below. 2.1. Enterprise network When an Enterprise network is connected through a layer-2 network, the intra-enterprise runs layer-3 PIM multicast. The different sites of the enterprise are equivalent to the PIM connection through the shared LAN network. Depending upon the locations and amount of groups there could be many asserts on the first hop routers. Liu, et al. Expires December, 2019 [Page 3] Internet-Draft PIM Assert Packing June 2019 2.2. Video surveillance Video surveillance deployments have migrated from analog based systems to IP-based systems oftentimes using multicast. In the shared LAN network deployments, when there are many cameras streaming to many groups there may be issues with many asserts on first hop routers. 2.3. Financial Services Financial services extensively rely on IP Multicast to deliver stock market data and its derivatives, and current multicast solution PIM is usually deployed. As the number of multicast flows grows, there are many stock data with many groups may result in many PIM asserts on a shared LAN network from publisher to the subscribers. 2.4. IPTV broadcast video PIM DR and BDR deployments are often used in host-side network for IPTV broadcast video services. Host-side access network failure scenario may be benefitted by assert packing when many groups are being used. According to [RFC7761] the DR will be elected to forward multicast traffic in the shared access network. When the DR recovers from a failure, the original DR starts to send traffic, and the current DR is still forwarding traffic. In the situation multicast traffic duplication maybe happen in the shared access network and can trigger the assert progress. 2.5. Summary In the above scenarios, the existence of PIM assert process depends mainly on the network topology. As long as there is a layer 2 network between PIM neighbors, there may be multiple upstream routers, which can cause duplicate multicast traffic to be forwarded and assert process to occur. Moreover as the multicast services become widely deployed, the number of multicast entries increases, and a large number of assert messages may be sent in a very short period when multicast data packets trigger PIM assert process in the shared LAN networks. The PIM routers need to process a large number of PIM assert small packets in a very short time. As a result, the device load is very large. The assert packet may not be processed in time or even is discarded, thus extending the time of traffic duplication in the network. Additionally, future backhaul, or fronthaul, networks may want to connect L3 across an L2 underlay supporting Time Sensitive Networks (TSN). The infrastructure may run DetNet over TSN. These transit L2 Liu, et al. Expires December, 2019 [Page 4] Internet-Draft PIM Assert Packing June 2019 LANs would have multiple upstreams and downstreams. This document is taking a proactive approach to prevention of possible future assert issues in these types of environments. 3. Solution The change to the PIM assert includes two elements: the PIM assert packing hello option and the PIM assert packing method. There is no change required to the PIM assert state machine. Basically a PIM router can now be the assert winner or loser for multiple packed (S, G)'s in a single assert packet instead of one (S, G) assert at a time. An assert winner is now responsible for forwarding traffic from multiple (S, G)'s out of a particular interface based upon the multiple (S, G)'s packed in a single assert. 3.1. PIM Assert Packing Hello Option The newly defined Hello Option is used by a router to negotiate the assert packet packing capability. It can only be used when all PIM routers, in the same shared LAN network, support this capability. This document defines two packing methods. One method is a simple merge of the original messages and the other is to extract the common message fields for aggregation. 3.2. PIM Assert Packing Simple Type In this type of packing, the original assert message body is used as a record. The newly defined assert message can carry multiple assert records and identify the number of records. This packing method is simply extended from the original assert packet, but, because the multicast service deployment often uses a small number of sources and RPs, there may be a large number of assert records with the same metric preference or route metric field, which would waste the payload of the transmitted message. 3.3. PIM Assert Packing Aggregation Type When the source or RP addresses, in the actual deployment of the multicast service, are very few, this type of packing will combine the records related to the source address or RP address in the assert message. * A (S, G) assert only can contain one SPT (S, G) entry, so it can be aggregated according to the same source address, and then all SPT Liu, et al. Expires December, 2019 [Page 5] Internet-Draft PIM Assert Packing June 2019 (S, G) entries corresponding to the same source address are merged into one assert record. * A (*, G) assert may contain a (*, G) entry or a RPT (S, G) entry, and both entry types actually depend on the route to the RP. So it can be aggregated further according to the same RP address, and then all (*, G) and RPT (S, G) entries corresponding to the same RP address are merged into one assert record. This method can optimize the payload of the transmitted message by merging the same field content, but will add the complexity of the packet encapsulation and parsing. 4. Packet Format This section describes the format of new PIM messages introduced by this document. The messages follow the same transmission order as the messages defined in [RFC7761] 4.1. PIM Assert Packing Hello Option 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OptionType = TBD | OptionLength = 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Packing_Type | +-+-+-+-+-+-+-+-+ - OptionType: TBD - OptionLength: 1 - Packing_Type: The specific packing mode is determined by the value of this field: 1: indicates simple packing type as described in section 2.2 2: indicates aggregating packing type as described in section 2.3 3-255: reserved for future Liu, et al. Expires December, 2019 [Page 6] Internet-Draft PIM Assert Packing June 2019 4.2. PIM Assert Simple Packing Format 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |PIM Ver| Type |SubType| Rsvd | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Number of Assert Records (M) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Assert Record [1] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Assert Record [2] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | . . . | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Assert Record [M] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ PIM Version, Reserved, Checksum Same as [RFC7761] Section 4.9.6 Type The new Assert Type and SubType values TBD Number of Assert Records The number of packed assert records. A record consists of a single assert message body. Liu, et al. Expires December, 2019 [Page 7] Internet-Draft PIM Assert Packing June 2019 The format of each record is the same as the PIM assert message body of section 4.9.6 in [RFC7761]. 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address (Encoded-Group format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| Metric Preference | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.3. PIM Assert Aggregation Packing Format This method also extends PIM assert packets to carry multiple records. The specific assert packet format is the same as section 4.2, but the records are divided into two types. The (S, G) assert records are organized by the same source address, and the specific message format is: 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| Metric Preference | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Number of Groups (N) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address 1 (Encoded-Group format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address 2 (Encoded-Group format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address N (Encoded-Group format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Source Address, Metric Preference, Metric and Reserved Liu, et al. Expires December, 2019 [Page 8] Internet-Draft PIM Assert Packing June 2019 Same as [RFC7761] Section 4.9.6, but the source address MUST NOT be set to zero. Number of Groups The number of group addresses corresponding to the source address field in the (S, G) assert record. Group Address Same as [RFC7761] Section 4.9.6, but there are multiple group addresses in the (S, G) assert record The (*, G) assert records are organized in the same RP address and are divided into two levels of TLVs. The first level is the group record of the same RP address, and the second level is the source record of the same multicast group address, including (*, G) and RPT (S, G), and the specific message format is: 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RP Address (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1| Metric Preference | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Number of Group Records(O) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Group Record [1] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Group Record [2] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | . . . | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . Liu, et al. Expires December, 2019 [Page 9] Internet-Draft PIM Assert Packing June 2019 . Group Record [O] . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ RP Address The address of RP corresponding to all of the contained group records. The format for this address is given in the encoded unicast address in [RFC7761] Section 4.9.1 Metric Preference, Metric and Reserved Same as [RFC7761] Section 4.9.6 Number of Group Records The number of packed group records. A record consists of a group address and a source address list. The format of each group record is: 0 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Group Address (Encoded-Group format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Number of Sources (P) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address 1 (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address 2 (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address P (Encoded-Unicast format) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Group Address and Reserved Same as [RFC7761] Section 4.9.6 Number of Sources Liu, et al. Expires December, 2019 [Page 10] Internet-Draft PIM Assert Packing June 2019 The number of source addresses corresponding to the group address field in the group record. Source Address Same as [RFC7761] Section 4.9.6, but there are multiple source addresses in the group record. 5. IANA Considerations This document requests IANA to assign a registry for PIM assert packing Hello Option in the PIM-Hello Options and new PIM assert packet type and subtype. The assignment is requested permanent for IANA when this document is published as an RFC. The string TBD should be replaced by the assigned values accordingly. 6. Security Considerations For general PIM-SM protocol Security Considerations, see [RFC7761]. TBD 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,Parekh, R., Zhang, Z., and L. Zheng, "Protocol IndependentMulticast - Sparse Mode (PIM-SM): Protocol Specification(Revised)", RFC 7761, March 2016 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017 7.2. Informative References TBD Liu, et al. Expires December, 2019 [Page 11] Internet-Draft PIM Assert Packing June 2019 8. Acknowledgments The authors would like to thank the following for their valuable contributions of this document: TBD Liu, et al. Expires December, 2019 [Page 12] Internet-Draft PIM Assert Packing June 2019 Authors' Addresses Yisong Liu Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China Email: liuyisong@huawei.com Mike McBride Futurewei 2330 Central Expressway Santa Clara, CA 95055 USA Email: michael.mcbride@futurewei.com Toerless Eckert Futurewei 2330 Central Expy Santa Clara 95050 USA Email: tte+ietf@cs.fau.de Liu, et al. Expires December, 2019 [Page 13]