BIER WG Z. Zhang Internet-Draft B. Wu Intended status: Standards Track C. Wang Expires: June 23, 2016 ZTE Corporation December 21, 2015 Path Autogeneration in BIER draft-zhang-bier-path-autogeneration-00 Abstract [I-D.ietf-bier-architecture] BIER introduces a method for multicast flow forwarding, without storing states in every node along the multicast path. This document introduces a method of establishing multicast path automatically. 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). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on June 23, 2016. Copyright Notice Copyright (c) 2015 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. Zhang, et al. Expires June 23, 2016 [Page 1] Internet-Draft Path Autogeneration in BIER December 2015 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. BFIR procedure . . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. Sending the path packets . . . . . . . . . . . . . . . 6 3.1.2. Withdraw Nodes . . . . . . . . . . . . . . . . . . . . 6 3.2. BFR and BFER . . . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Normative References . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Zhang, et al. Expires June 23, 2016 [Page 2] Internet-Draft Path Autogeneration in BIER December 2015 1. Introduction [I-D.ietf-bier-architecture] BIER is a technology of multicast flow forwarding. [I-D.ietf-bier-mpls-encapsulation] introduces a way to use mpls in BIER forwarding. This document introduces a method of establishing multicast path automatically. Upstream-assigned label is used in this document. Associate with the label indicated the BFIR, the two labels compose the keywords for multicast flow forwarding. Every node along the multicast path used the two labels to forward multicast flow without label changing. Obviously, the nodes along the path establish the mpls forwarding table, when they receive the packet which include the label combination and the path specification. BFIR sends the first packet with label combination and path specification, every node along the path build the mpls forwarding table, and forward the packet to next node according to the path specification. If there is already a mpls forwarding item which has the same label combination, the node combines the next-hop in the packet to the existed forwarding item. Zhang, et al. Expires June 23, 2016 [Page 3] Internet-Draft Path Autogeneration in BIER December 2015 2. Packet Formats This document introduces a new TLV that is carried by the BIER packet, and this TLV is composed by the nodes in the multicast path. There is a flag in the BIER header indicates that a path TLV is be carried. One of the reserved flag may be used to signal this. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 0 1| Ver | Len | Entropy | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitString (first 32 bits) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ BitString (last 32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |OAM| Reserved 1| Proto | BFIR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 BIER Header The path list is composed by nodes along the multicast path. The multicast path is decided by BFIR in advance through PCE or other calculations or configurations. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFIR label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Upstream-assigned label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Id | Id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Id | BFER-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Path Specification o Type TBD, indicate that there is a path TLV. o Length The length of the TLV. Zhang, et al. Expires June 23, 2016 [Page 4] Internet-Draft Path Autogeneration in BIER December 2015 o BFIR label The label of BFIR. o Upstream-assigned label The label that is assigned by BFIR for the specific multicast flow. o Id The node BFR-id or the link id along the multicast path. They are carried by the packets in order. o BFER-id The BFR-id of BFER. Like the ingress replication, BFIR repeats BIER packets several times according to every BFER of the multicast flow. And then BFIR sends the BIER packets with the two labels. The withdraw packet is the same format with the path packet. But the type should be another type, and the last node that is carried by the withdraw packet is the canceled node. Zhang, et al. Expires June 23, 2016 [Page 5] Internet-Draft Path Autogeneration in BIER December 2015 3. Procedures 3.1. BFIR procedure 3.1.1. Sending the path packets When BFIR gains the BFER information of a specific multicast flow, BFIR encapsulates the receiving flow with the path list, and sends to every BFER individually.Particularly, the encapsulated packet that is sent by BFIR includes the label combination. B-------- C ------ D -------- | | | | A ------- F ------ G ------ H | | | | --------- K ------ L -------M Figure 3 An Example For example, in figure 3, A is BFIR for a specific multicast flow. And D, H, M are BFER. According the PCE calculation, the multicast flow should be sent along these paths: A-F-G-D/H, A-K-L-M. So A encapsulates the flow with the two label combination and makes three copies, and then sends to D/H/M separately. In node A, there is one mpls label forwarding item which the ingress label is the two labels combination, and the next-hops are F and K with the same two label out. A encapsulates the formal multicast flow with the two labels and forwards to next hops. For the stability consideration, BFIR sends the path packets every once in a while. The interval may be 30 minutes. And when new BFER joined, BFIR sends the path packets to the new BFER immediately. 3.1.2. Withdraw Nodes According to the PCE calculation, some existed nodes in the path may be canceled. BFIR sends the withdraw path packet which the last node is the canceled node. For example in figure 1, if the bandwidth in the network is changed, the multicast flow should be forwarded along these ways: A-B-C-D-H, A-K-L-M. The specific multicast flow will not pass by the node F and G anymore. Except A sending a new path packet along the path A-B-C-D-H, A also sends two withdraw path packets to node F and G. 3.2. BFR and BFER When BFR and BFER receive the path packets, they build an item in the mpls forwarding table according to the label combination that is Zhang, et al. Expires June 23, 2016 [Page 6] Internet-Draft Path Autogeneration in BIER December 2015 carried by the packets. If there is an item already in the forwarding table, the nodes should add the next-hop which is the next node in the path packet. When BFR and BFER receive the withdraw path packets which indicate that they should be canceled, the BFR and BFER delete the mpls forwarding item which line with the label combination. If the middle node finds that the next node that along the path is the canceled node, the middle node deletes the next-hop in the mpls forwarding item. If there is no next-hop in the mpls forwarding item, the node deletes the mpls item in the mpls forwarding table. Zhang, et al. Expires June 23, 2016 [Page 7] Internet-Draft Path Autogeneration in BIER December 2015 4. Security Considerations There should be some common security methods to guarantee the validation of path packets. Zhang, et al. Expires June 23, 2016 [Page 8] Internet-Draft Path Autogeneration in BIER December 2015 5. IANA considerations IANA is requested to allocate types in TLVs of BIER path packets. Zhang, et al. Expires June 23, 2016 [Page 9] Internet-Draft Path Autogeneration in BIER December 2015 6. Normative References [I-D.ietf-bier-architecture] Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast using Bit Index Explicit Replication", draft-ietf-bier-architecture-02 (work in progress), July 2015. [I-D.ietf-bier-mpls-encapsulation] Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and S. Aldrin, "Encapsulation for Bit Index Explicit Replication in MPLS Networks", draft-ietf-bier-mpls-encapsulation-02 (work in progress), August 2015. Zhang, et al. Expires June 23, 2016 [Page 10] Internet-Draft Path Autogeneration in BIER December 2015 Authors' Addresses Zheng(Sandy) Zhang ZTE Corporation No. 50 Software Ave, Yuhuatai Distinct Nanjing, China Email: zhang.zheng@zte.com.cn Bo Wu ZTE Corporation No. 50 Software Ave, Yuhuatai Distinct Nanjing, China Email: wu.bo@zte.com.cn Cui(Linda) Wang ZTE Corporation No. 50 Software Ave, Yuhuatai Distinct Nanjing, China Email: wang.cui1@zte.com.cn Zhang, et al. Expires June 23, 2016 [Page 11]