Network Working Group Zhang Internet-Draft Rekhter Updates: 6514 (if approved) Juniper Networks Intended status: Standards Track Dolganow Expires: April 24, 2014 Alcatel-Lucent October 21, 2013 Simulating "Partial Mesh of MP2MP P-Tunnels" with Ingress Replication draft-zzhang-l3vpn-mvpn-bidir-ingress-replication-01.txt Abstract RFC 6513 described a method to support bidirectional C-flow using "Partial Mesh of MP2MP P-Tunnels". This document describes how partial mesh of MP2MP P-Tunnels can be simulated with Ingress Replication, instead of a real MP2MP tunnel. This enables a Service Provider to use Ingress Replication to offer transparent BIDIR-PIM service to its VPN customers. 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 April 24, 2014. Copyright Notice Copyright (c) 2013 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 Zhang, et al. Expires April 24, 2014 [Page 1] Internet-Draft C-Bidir support with IR October 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Control State . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Forwarding State . . . . . . . . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 7. Normative References . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Zhang, et al. Expires April 24, 2014 [Page 2] Internet-Draft C-Bidir support with IR October 2013 1. Introduction Section 11.2 of RFC 6513, "Partitioned Sets of PEs", describes two methods of carrying bidirectional C-flow traffic over a provider core without using the core as RPL or requiring Designated Forwarder election. With these two methods, all PEs of a particular VPN are separated into partitions, with each partition being all the PEs that elect the same PE as the Upstream PE wrt the C-RPA. A PE must discard bidirectional C-flow traffic from PEs that are not in the same partition as the PE itself. In particular, Section 11.2.3 of RFC 6513, "Partial Mesh of MP2MP P-Tunnels", guarantees the above discard behavior without using an extra PE Distinguisher label by having all PEs in the same partition join a single MP2MP tunnel dedicated to that partition and use it to transmit traffic. All traffic arriving on the tunnel will be from PEs in the same partition, so it will be always accepted. RFC 6514 specifies BGP encodings and procedures used to implement MVPN as specified in RFC 6513, while the details related to MP2MP tunnels are specified in [draft-ietf-l3vpn-mvpn-bidir-05]. [draft-ietf-l3vpn-mvpn-bidir-05] assumes that an MP2MP P-tunnel is realized either via PIM-Bidir, or via MP2MP mLDP. Each of them would require signaling and state not just on PEs, but on the P routers as well. This document describes how the MP2MP tunnel can be simulated with a mesh of P2MP tunnels, each of which is instantiated by Ingress Replication. This does not require each PE on the MP2MP tunnel to send an S-PMSI A-D route for the P2MP tunnel that the PE is the root for, nor does it require each PE to send a Leaf A-D route to the root of each P2MP tunnel in the mesh. With the use of Ingress Replication,this scheme has both the advantages and the disadvantages of Ingress Replication in general. 1.1. Terminology This document uses terminology from [RFC6513], [RFC6514], and [draft-ietf-l3vpn-mvpn-bidir-05]. In particular, the following new term is defined: o C-G-BIDIR: A C-G where G is a Bidir-PIM group. Zhang, et al. Expires April 24, 2014 [Page 3] Internet-Draft C-Bidir support with IR October 2013 2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Zhang, et al. Expires April 24, 2014 [Page 4] Internet-Draft C-Bidir support with IR October 2013 3. Operation In following sections, the originator of an S-PMSI A-D route or Leaf A-D route is determined from the "originating router's IP address" field of the corresponding route. 3.1. Control State If a PE, say PEx, is connected to a site of a given VPN, and PEx's next hop interface to some C-RPA is a VRF interface, then PEx MUST advertises a (C-*,C-BIDIR) S-PMSI A-D route, regardless of whether it has any local Bidir-PIM join states corresponding to the C-RPA learned from its CEs. It MAY also advertise one or more (C-*,C-G- BIDIR) S-PMSI A-D route, just like how any other S-PMSI A-D routes are triggered. Here the C-G-BIDIR refers to a C-G where G is a Bidir-PIM group, and the corresponding C-RPA is in the site that the PEx connects to. For example, the (C-*,C-G-BIDIR) S-PMSI A-D routes could be triggered when the (C-*, C-G-BIDIR) traffic rate goes above a threshold, and fan-out could also be taken into account. Note that this requires measuring the traffic in both directions, due to the nature of Bidir-PIM. The S-PMSI A-D routes include a PMSI Tunnel Attribute (PTA) with tunnel type set to Ingress Replication, with Leaf Information Required flag set, with a downstream allocated MPLS label that other PEs in the same partition MUST use when sending relevant C-bidir flows to this PE, and with the Tunnel Identifier field in the PTA set to a routable address of the originator. The label may be shared with other P-tunnels, subject to the anti-ambiguity rules for extranet. For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI A-D routes originated by a given PE can optionally share a label. If some other PE, PEy, receives and imports into one of its VRFs any (C-*, C-BIDIR) S-PMSI A-D route whose PTA specifies an IR P-tunnel, and the VRF has any local Bidir-PIM join state that PEy has received from its CEs, and if PEy chooses PEx as its Upstream PE wrt the C-RPA for those states, PEy MUST advertise a Leaf A-D route in response. Or, if PEy has received and imported into one of its VRFs a (C-*,C- BIDIR) S-PMSI A-D route from PEx before, then upon receiving in the VRF any local Bidir-PIM join state from its CEs with PEx being the Upstream PE for those states' C-RPA, PEy MUST advertise a Leaf A-D route. The encoding of the Leaf A-D route is as specified in RFC 6514, except that the Route Targets are set to the same value as in the corresponding S-PMSI A-D route so that the Leaf A-D route will be imported by all VRFs that import the corresponding S-PMSI A-D route. This is irrespective of whether from a receiving PE, PEz's Zhang, et al. Expires April 24, 2014 [Page 5] Internet-Draft C-Bidir support with IR October 2013 perspective PEx (originator of the S-PMSI A-D route) is the Upstream PE or not. The label in the PTA of the Leaf A-D route originated by PEy MUST be allocated specifically for PEx, so that when traffic arrives with that label, the traffic can associated with the partition (represented by the PEx). The label may be shared with other P-tunnels, subject to the anti-ambiguity rules for extranet. For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI A-D routes originated by a given PE can optionally share a label. Note that RFC 6514 requires a PE/ASBR take no action with regard to a Leaf A-D route unless that Leaf A-D route carries an IP Address Specific RT identifying the PE/ASBR. This document removes that requirement when the route key of a Leaf A-D route identifies a (C-*,C-BIDIR) or a (C-*,C-G-BIDIR) S-PMSI. To speed up convergence (so that PEy starts receiving traffic from its new Upstream PE immediately instead of waiting until the new Leaf A-D route corresponding to the new Upstream PE is received by sending PEs), PEy MAY advertise a Leaf A-D route even if does not choose PEx as its Upstream PE wrt the C-RPA. With that, it will receive traffic from all PEs, but some will arrive with the label corresponding to its choice of Upstream PE while some will arrive with a different label, and the traffic in the latter case will be discarded. Similar to the (C-*,C-BIDIR) case, if PEy receives and imports into one of its VRFs any (C-*,C-G-BIDIR) S-PMSI A-D route whose PTA specifies an IR P-tunnel, and PEy chooses PEx as its Upstream PE wrt the C-RPA, and it has corresponding local (C-*,C-G-BIDIR) join state that it has received from its CEs in the VRF, PEy MUST advertise a Leaf A-D route in response. Or, if PEy has received and imported into one of its VRFs a (C-*,C-G-BIDIR) S-PMSI A-D route before, then upon receiving its local (C-*,C-G-BIDIR) join state from its CEs in the VRF, it MUST advertise a Leaf A-D route. The encoding of the Leaf A-D route is as specified in RFC 6514, except that the Route Targets are set to the same as in the corresponding S-PMSI A-D route so that the Leaf A-D route will be imported by all VRFs that import the corresponding S-PMSI A-D route. This is irrespective of whether from the receiving PE, PEz's perspective PEx (originator of the S-PMSI A-D route) is the Upstream PE or not. The label in the PTA of the Leaf A-D route originated by PEy MUST be allocated specifically for PEx, so that when traffic arrives with that label, the traffic can associated with the partition (represented by the PEx). The label may be shared with other P-tunnels, subject to the anti-ambiguity rules for extranet. For example, the (C-*,C-BIDIR) and (C-*,C-G-BIDIR) S-PMSI A-D routes originated by a given PE can optionally share a label. Zhang, et al. Expires April 24, 2014 [Page 6] Internet-Draft C-Bidir support with IR October 2013 Whenever the (C-*,C-BIDIR) or (C-*,C-G-BIDIR) S-PMSI A-D route is withdrawn, or if PEy no longer chooses the originator PEx as its Upstream PE wrt C-RPA and PEy only advertises Leaf A-D routes in response to its Upstream PE's S-PMSI A-D route, or if relevant local join state is pruned, PEy MUST withdraw the corresponding Leaf A-D route. 3.2. Forwarding State The following specification regarding forwarding state matches the "When an S-PMSI is a 'Match for Transmission'" and "When an S-PMSI is a 'Match for Reception'" rules for "Flat Partitioning" method in [draft-ietf-l3vpn-mvpn-bidir-05], except that the rules about (C-*,C-*) are not applicable, because this document requires that (C-*,C-BIDIR) S-PMSI A-D routes are always originated for a VPN that supports C-Bidir flows. For the (C-*,C-G-BIDIR) S-PMSI A-D route that a PEy receives and imports into one of its VRFs from its Upstream PE wrt the C-RPA, or if PEy itself advertises the S-PMSI A-D route in the VRF, PEy maintains a (C-*,C-G-BIDR) forwarding state in the VRF, with the Ingress Replication provider tunnel leaves being the originators of the S-PMSI A-D route and all relevant Leaf-A-D routes. The relevant Leaf A-D routes are the routes whose Route Key field contains the same information as the MCAST-VPN NLRI of the (C-*, C-G-BIDIR) S-PMSI A-D route advertised by the Upstream PE. For the (C-*,C-BIDIR) S-PMSI A-D route that a PEy receives and imports into one of its VRFs from its Upstream PE wrt a C-RPA, or if PEy itself advertises the S-PMSI A-D route in the VRF, it maintains appropriate forwarding states in the VRF for the ranges of bidirectional groups for which the C-RPA is responsible. The provider tunnel leaves are the originators of the S-PMSI A-D route and all relevant Leaf-A-D routes. The relevant Leaf A-D routes are the routes whose Route Key field contains the same information as the MCAST-VPN NLRI of the (C-*, C-BIDIR) S-PMSI A-D route advertised by the Upstream PE. This is for the so-called "Sender Only Branches" where a router only has data to send upstream towards C-RPA but no explicit join state for a particular bidirectional group. Note that the traffic must be sent to all PEs (not just the Upstream PE) in the partition, because they may have specific (C-*,C-G-BIDIR) join states that this PEy is not aware of, while there is no corresponding (C-*,C-G-BIDIR) S-PMSI A-D and Leaf A-D routes. For a (C-*,C-G-BIDIR) join state that a PEy has received from its CEs in a VRF, if there is no corresponding (C-*,C-G-BIDIR) S-PMSI A-D route from its Upstream PE in the VRF, PEy maintains a corresponding forwarding state in the VRF, with the provider tunnel leaves being Zhang, et al. Expires April 24, 2014 [Page 7] Internet-Draft C-Bidir support with IR October 2013 the originators of the (C-*,C-BIDIR) S-PMSI A-D route and all relevant Leaf-A-D routes (same as the above Sender Only Branch case). The relevant Leaf A-D routes are the routes whose Route Key field contains the same information as the MCAST-VPN NLRI of the (C-*, C-BIDIR) S-PMSI A-D route originated by the Upstream PE. If there is no (C-*,C-BIDIR) S-PMSI A-D route from its Upstream PE either, then the provider tunnel has an empty set of leaves and PEy does not forward relevant traffic across the provider network. Zhang, et al. Expires April 24, 2014 [Page 8] Internet-Draft C-Bidir support with IR October 2013 4. Security Considerations This document raises no new security issues. Security considerations for the base protocol are covered in [RFC6514]. Zhang, et al. Expires April 24, 2014 [Page 9] Internet-Draft C-Bidir support with IR October 2013 5. IANA Considerations This document has no IANA considerations. This section should be removed by the RFC Editor prior to final publication. Zhang, et al. Expires April 24, 2014 [Page 10] Internet-Draft C-Bidir support with IR October 2013 6. Acknowledgements We would like to thank Eric Rosen for his comments, and suggestions of some texts used in the document. Zhang, et al. Expires April 24, 2014 [Page 11] Internet-Draft C-Bidir support with IR October 2013 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP VPNs", RFC 6513, February 2012. [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP Encodings and Procedures for Multicast in MPLS/BGP IP VPNs", RFC 6514, February 2012. [RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, "Bidirectional Protocol Independent Multicast (BIDIR- PIM)", RFC 5015, October 2007. [I-D.ietf-l3vpn-mvpn-bidir] Rosen, E., Wijnands, I., Cai, Y., and A. Boers, "MVPN: Using Bidirectional P-Tunnels", draft-ietf-l3vpn-mvpn-bidir-06 (work in progress), October 2013. Zhang, et al. Expires April 24, 2014 [Page 12] Internet-Draft C-Bidir support with IR October 2013 Authors' Addresses Jeffrey Zhang Juniper Networks 10 Technology Park Dr. Westford, MA 01886 US Email: zzhang@juniper.net Yakov Rekhter Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 US Email: yakov@juniper.net Andrew Dolganow Alcatel-Lucent 600 March Rd. Ottawa, ON K2K 2E6 CANADA Email: andrew.dolganow@alcatel-lucent.com Zhang, et al. Expires April 24, 2014 [Page 13]