L2VPNs K. Patel Internet-Draft A. Sajassi Intended status: Standards Track Cisco Systems Expires: January 3, 2016 J. Drake Juniper Networks, Inc. W. Henderickx Alcatel-Lucent July 2, 2015 Virtual Hub-and-Spoke in BGP EVPNs draft-keyupate-evpn-virtual-hub-00 Abstract Ethernet Virtual Private Network (EVPN) solution is becoming pervasive for Network Virtualization Overlay (NVO) services in data center (DC) applications and as the next generation virtual private LAN services in service provider (SP) applications. The use of host IP default route and host unknown MAC route within a DC is well understood in order to ensure that leaf nodes within a DC only learn and store host MAC and IP addresses for that DC. All other host MAC and IP addresses from remote DCs are learned and stored in DC GW nodes thus alleviating leaf nodes from learning host MAC and IP addresses from the remote DCs. This draft further optimizes the MAC and IP address learning at the leaf nodes such that a leaf node within a DC only needs to learn and store MAC and IP addresses associated with the sites directly connected to it. A leaf node does not need to learn and store MAC and IP addresses from any other leaf nodes thus reducing the number of learned MACs and IP addresses per EVI substantially. The modifications provided by this draft updates and extends RFC7024 for BGP EVPN Address Family. 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/. Patel, et al. Expires January 3, 2016 [Page 1] Internet-Draft July 2015 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 January 3, 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Routing Information Exchange for EVPN routes . . . . . . . . 4 5. EVPN unknown MAC Route . . . . . . . . . . . . . . . . . . . 5 5.1. Originating EVPN Unknown MAC Route by a V-Hub . . . . . . 5 5.2. Processing VPN-MAC EVPN unknown Route by a V-SPOKE . . . 5 5.3. Aliasing . . . . . . . . . . . . . . . . . . . . . . . . 5 5.4. Split-Horizon And Mass Withdraw . . . . . . . . . . . . . 6 6. Forwarding Considerations . . . . . . . . . . . . . . . . . . 7 6.1. IP-only Forwarding . . . . . . . . . . . . . . . . . . . 7 6.2. MAC-only Forwarding - Bridging . . . . . . . . . . . . . 7 6.3. MAC and IP Forwarding - IRB . . . . . . . . . . . . . . . 7 7. Handling of the Broadcast and Multicast traffic . . . . . . . 8 8. ARP/ND Suppression . . . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 10. Security Considerations . . . . . . . . . . . . . . . . . . . 9 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 12. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 9 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 13.1. Normative References . . . . . . . . . . . . . . . . . . 9 13.2. Informative References . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Patel, et al. Expires January 3, 2016 [Page 2] Internet-Draft July 2015 1. Introduction Ethernet Virtual Private Network (EVPN) solution is becoming pervasive for Network Virtualization Overlay (NVO) services in data center (DC) applications and as the next generation virtual private LAN services in service provider (SP) applications. With EVPN, providing any-to-any connectivity among sites of a given EVPN Instance (EVI) would require each Provider Edge (PE) router connected to one or more of these sites to hold all the host MAC and IP addresses for that EVI. The use of host IP default route and host unknown MAC route within a DC is well understood in order to alleviate the learning of host MAC and IP addresses to only leaf nodes (PEs) within that DC. All other host MAC and IP addresses from remote DCs are learned and stored in DC GW nodes thus alleviating leaf nodes from learning host MAC and IP addresses from the remote DCs. This draft further optimizes the MAC and IP address learning at the leaf nodes such that a leaf node within a DC only needs to learn and store MAC and IP addresses associated with the sites directly connected to it. A leaf node does not need to learn and store MAC and IP addresses from any other leaf nodes thus reducing the number of learned MACs and IP addresses per EVI substantially. [RFC7024] provides rules for Hub and Spoke VPNs for BGP L3VPNs. This draft updates and extends [RFC7024] for BGP EVPN Address Family. This draft provides rules for Originating and Processing of the EVPN host unknown MAC route and host default IP route by EVPN Virtual Hub (V-HUB). This draft also provides rules for the handling of the BUM traffic in Hub and Spoke EVPNs and handling of ARP suppression. The leaf nodes and DC GW nodes in a data center are referred to as Virtual Spokes (V-spokes) and Virtual Hubs (V-hubs) respectively. A set of V-spoke can be associated with one or more V-hubs. If a V- spokes is associated with more than one V-hubs, then it can load balanced traffic among these V-hubs. Different V-spokes can be associated with different sets of V-hubs such that at one extreme each V-spoke can have a different V-hub set although this may not be desirable and a more typical scenario may be to associate a set of V- spokes to a set of V-hubs - e.g., topology for a DC POD where a set of V-spokes are associated with a set of spine nodes or DC GW nodes. In order to avoid repeating many of the materials covered in [RFC7024], this draft is written as a delta document with its sections organized to follow those of that RFC with only delta description pertinent to EVPN operation in each section. Therefore, Patel, et al. Expires January 3, 2016 [Page 3] Internet-Draft July 2015 it is assumed that the readers are very familiar with [RFC7024] and EVPN. 2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119] only when they appear in all upper case. They may also appear in lower or mixed case as English words, without any normative meaning. 3. Terminology ARP: Address Resolution Protocol BEB: Backbone Edge Bridge B-MAC: Backbone MAC Address CE: Customer Edge C-MAC: Customer/Client MAC Address ES: Ethernet Segment ESI: Ethernet Segment Identifier IRB: Integrated Routing and Bridging LSP: Label Switched Path MP2MP: Multipoint to Multipoint MP2P: Multipoint to Point ND: Neighbor Discovery NA: Neighbor Advertisement P2MP: Point to Multipoint P2P: Point to Point PE: Provider Edge EVPN: Ethernet VPN EVI: EVPN Instance RT: Route Target Single-Active Redundancy Mode: When only a single PE, among a group of PEs attached to an Ethernet segment, is allowed to forward traffic to/from that Ethernet Segment, 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 traffic to/from that Ethernet Segment, then the Ethernet segment is defined to be operating in All-Active redundancy mode. 4. Routing Information Exchange for EVPN routes [RFC7024] defines multiple Route Types NLRI along with procedures for advertisements and processing of these routes. Some of these procedures are impacted as the result of hub-and-spoke architecture. Patel, et al. Expires January 3, 2016 [Page 4] Internet-Draft July 2015 The routing information exchange among the hub, spoke, and vanilla PEs are subject to the same rules as described in section 3 of [RFC7024]. Furthermore, if there are any changes to the EVPN route advisements and processing from advertisements and processing from [RFC7024], they are described below. 5. EVPN unknown MAC Route Section 3 of [RFC7024] talks about how a V-hub of a given VPN must export a VPN-IP default route for that VPN and this route must be exported to only the V-spokes of that VPN associated with that V-hub. [I-D.EVPN-overlay] defines the notion of the unknown MAC route for an EVI which is analogous to a VPN-IP default route for a VPN. This unknown MAC route is exported by a V-hub to its associated V-spokes. If multiple V-hubs are associated with a set of V-spokes, then each V- hub advertises it with a distinct RD when originating this route. If a V-spoke imports several of these unknown MAC routes and they all have the same preference, then traffic from the V-spoke to other sites of that EVI would be load balanced among the V-hubs. 5.1. Originating EVPN Unknown MAC Route by a V-Hub Section 7.3 of the [RFC7024] defines procedures for originating a VPN-IP default route for a VPN. The same procuedures apply when a V-hub wants to originate EVPN unknown MAC route for a given EVI. The V-hub MUST announce unknown MAC route using the MAC/IP advertisement route along with the Default Gateway extended community as defined in section 10.1 of the [RFC7432]. 5.2. Processing VPN-MAC EVPN unknown Route by a V-SPOKE Within a given EVPN, a V-spoke MUST import all the unknown MAC routes unless the route-target mismatch happens. The processing of the received VPN-MAC EVPN default route follows the rules explained in the section 3 of the [RFC7024]. The unknown MAC route MUST be installed according to the rules of MAC/IP Advertisement route installation rules in section 9.2.2 of [RFC7024]. In absense of any more specific VPN-MAC EVPN routes, V-spokes installing the unknown MAC route MUST use the route when performing ARP proxy. This behavior would allow V-Spokes to forward the traffic towards V-Hub. 5.3. Aliasing [RFC7432] describes the concept and procedures for Aliasing where a station is multi-homed to multiple PEs operating in an All-Active redundancy mode, it is possible that only a single PE learns a set of Patel, et al. Expires January 3, 2016 [Page 5] Internet-Draft July 2015 MAC addresses associated with traffic transmitted by the station. [RFC7432] describes the concepts and procedures for Aliasing, which occurs when a CE is multi-homed to multiple PE nodes, operating in all-active redundancy mode, but not all of the PEs learn the CE's set of MAC addresses. This leads to a situation where remote PEs receive MAC advertisement routes, for these addresses, from a single NVE even though multiple NVEs are connected to the multi-homed station. As a result, the remote NVEs are not able to effectively load-balance traffic among the NVEs connected to the multi-homed Ethernet segment. To alleviate this issue, EVPN introduces the concept of Aliasing. This refers to the ability of a PE to signal that it has reachability to a given locally attached Ethernet segment, even when it has learnt no MAC addresses from that segment. The Ethernet A-D per-EVI route is used to that end. Remote PEs which receive MAC advertisement routes with non-zero ESI SHOULD consider the MAC address as reachable via all NVEs that advertise reachability to the relevant Segment using Ethernet A-D routes with the same ESI and with the Single- Active flag reset. This procedure is impacted for virtual hub-and-spoke topology because a given V-spoke does not receive any MAC/IP advertisements from remote V-spokes; therefore, there is no point in propagating Ethernet A-D per-EVI route to the remote V-spokes. In this solution, the V- hubs terminate the Ethernet A-D per-EVI route (used for Aliasing) and follows the procedures described in [RFC7432] for handling this route. There are scenarios for which it is desirable to establish direct communication path between a pair of V-spokes for a given host MAC address. In such scenario, the advertising V-spoke advertises both the MAC/IP route and Ethernet A-D per-EVI route with the RT of V-hub (RT-VH) per section 3 of [RFC7024]. The use of RT-VH, ensures that these routes are received by the V-spokes associated with that V-hub set and thus enables the V-spokes to perform the Aliasing procedure. In summary, PE devices (V-hubs in general and V-spokes occasionally) that receive EVPN MAC/IP route advertisements (associated with a multi-homed site) need to also receive the associated Ethernet A-D per-EVI route advertisement(s) in order for them to perform Aliasing procedure. 5.4. Split-Horizon And Mass Withdraw [RFC7432] uses Ethernet A-D per-ES route to a) signal to remote PEs the multi-homing redundancy type (Single-Active versus All-Active), b) advertise ESI label for split-horizon filtering when MPLS encapsulation is used, and c) advertise mass-withdraw when a failure Patel, et al. Expires January 3, 2016 [Page 6] Internet-Draft July 2015 of an access interface impacts many MAC addresses. This route does not need to be advertise from a V-spoke to any remote V-spoke unless a direct communication path between a pair of spoke is needed for a given flow. Even if communication between a pair of V-spoke is needed for just a single flow, the Ethernet A-D per ES route needs to be advertised from the originating V-spoke for that ES which may handle tens or hundreds of thousands of flows. This is because in order to perform Aliasing function for a given flow, the Ethernet A-D per-EVI route is needed and this route itself is dependent on the Ethernet A-D per-ES route. In such scenario, the advertising V-spoke advertises the Ethernet A-D per-ES route with the RT of V-hub (RT-VH) per section 3 of [RFC7024]. In summary, PE devices (V-hubs in general and V-spokes occasionally) that receive EVPN MAC/IP route advertisements (associated with a multi-homed site) need to also receive the associated Ethernet A-D per-ES route advertisement(s). 6. Forwarding Considerations 6.1. IP-only Forwarding When EVPN operates in IP-only forwarding mode using EVPN Route Type 5, then all forwarding considerations in section 4 of [RFC7024] are directly applicable here. 6.2. MAC-only Forwarding - Bridging When EVPN operates in MAC-only forwarding mode (i.e., bridging mode), then for a given EVI, the MPLS label that a V-hub advertises with an Unknown MAC address MUST be the label that identifies the MAC-VRF of the V-hub in absense of a more specific MAC route. When the V-hub receives a packet with such label, the V- hub pops the label and determines further disposition of the packet based on the lookup in the MAC-VRF. Otherwise, the MPLS label of the matching more specific route is used and packet is is forwarded towards the associated NEXTHOP of the more specific route. 6.3. MAC and IP Forwarding - IRB When a EVPN speaker operates in IRB mode, it implements both the "IP and MAC forwarding Modes" (aka Integrated Routing and Bridging - IRB). On a packet by packet basis, the V-spoke decides whether to do forwarding based on a MAC address lookup (bridge) or based on a IP address lookup (route). If the host destination MAC address is that of the IRB interface (i.e., if the traffic is inter-subnet), then the Patel, et al. Expires January 3, 2016 [Page 7] Internet-Draft July 2015 V-spoke performs an additional IP lookup in the IP-VRF. However, if the host destination MAC address is that of an actual host MAC address (i.e., the traffic is intra-subnet) , then the V-spoke only performs a MAC lookup in the MAC-VRF. The procedure specified in Section 6.1 and Section 6.2 are applicable to inter-subnet and intra- subnet forwarding respectively. For intra-subnet traffic, if the MAC address is not found in the MAC-VRF, then the V-spoke forwards the traffic to the V-hub with the MPLS label received from the V-hub for the unknown MAC address. For the Inter-subnet traffic, if the IP prefix is not found in the IP-VRF, then the V-spoke forwards the traffic to the V-hub with the MPLS label received from the V-hub for the default IP address. 7. Handling of the Broadcast and Multicast traffic The handling of the Broadcast and Multicast traffic should be done according to the EVPN rules described in [RFC7432]. 8. ARP/ND Suppression [RFC7432] defines the procedures for ARP/ND suppression where a PE can terminate gratuitous ARP/ND request message from directly connected site and advertises the associated MAC and IP addresses in an EVPN MAC/IP advertisement route to all other remote PEs. The remote PEs that receive this EVPN route advertisement, install the MAC/IP pair in their ARP/ND cache table thus enabling them to terminate ARP/ND requests and generate ARP/ND responses locally thus suppressing the flooding of ARP/ND requests over the EVPN network. In this hub-and-spoke approach, the ARP suppression needs to be performed by both the EVPN V-hubs as well V-spokes as follow. When a V-Spoke receives a gratuitous ARP/ND request, it terminates it and stores the source MAC/IP pair in its ARP/ND cache table. Then, it advertises the source MAC/IP pair to its associated V-Hubs using EVPN MAC/IP advertisement route. The V-Hubs upon receiving this EVPN route advertisement, create an entry in their ARP/ND cache table for this MAC/IP pair. Now when a V-Spoke receives an ARP/ND request, it first looks up its ARP cache table, if an entry for that MAC/IP pair is found, then an ARP/ND response is generated locally and sent to the CE. However, if an entry is not found, then the ARP/ND request is unicasted to one of the V-hub associated with this V-spoke. Since, the associated V-hub keeps all the MAC/IP ARP entries in its cache table, it can formulate and ARP/ND response and forward it to that CE via the corresponding V-spoke. Patel, et al. Expires January 3, 2016 [Page 8] Internet-Draft July 2015 9. IANA Considerations This document does NOT make any new requests for IANA allocations. 10. Security Considerations All the security considerations in [RFC7432] apply directly to this document because this document leverages [RFC7432] control plane and their associated procedures - although not the complete set but rather a subset. This draft does not introduce any new security considerations beyond that of [RFC7432] and [RFC4761] because advertisements and processing of B-MAC addresses follow that of [RFC7432] and processing of C-MAC addresses follow that of [RFC4761] - i.e, B-MAC addresses are learned in control plane and C-MAC addresses are learned in data plane. 11. Acknowledgements The authors would like to thank Yakov Rekhter for initial idea discussions. 12. Change Log Initial Version: Sep 21 2014 13. References 13.1. Normative References [I-D.ietf-l2vpn-evpn] Sajassi, A., Aggarwal, R., Bitar, N., Isaac, A., and J. Uttaro, "BGP MPLS Based Ethernet VPN", draft-ietf-l2vpn- evpn-11 (work in progress), October 2014. [RFC1771] Rekhter, Y. and T. Li, "A Border Gateway Protocol 4 (BGP- 4)", RFC 1771, March 1995. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. Patel, et al. Expires January 3, 2016 [Page 9] Internet-Draft July 2015 [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms for IPv6 Hosts and Routers", RFC 4213, October 2005. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC4374] McCobb, G., "The application/xv+xml Media Type", RFC 4374, January 2006. [RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS)", RFC 6459, January 2012. [RFC7024] Jeng, H., Uttaro, J., Jalil, L., Decraene, B., Rekhter, Y., and R. Aggarwal, "Virtual Hub-and-Spoke in BGP/MPLS VPNs", RFC 7024, October 2013. [RFC7432] Sajassi, A., Aggarwal, R., Bitar, N., Isaac, A., Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet VPN", RFC 7432, February 2015. 13.2. Informative References [I-D.drao-bgp-l3vpn-virtual-network-overlays] Rao, D., Mullooly, J., and R. Fernando, "Layer-3 virtual network overlays based on BGP Layer-3 VPNs", draft-drao- bgp-l3vpn-virtual-network-overlays-03 (work in progress), July 2014. [I-D.ietf-bess-evpn-overlay] Sajassi, A., Drake, J., Bitar, N., Isaac, A., Uttaro, J., and W. Henderickx, "A Network Virtualization Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-01 (work in progress), February 2015. [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery Proxies (ND Proxy)", RFC 4389, April 2006. [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, January 2007. Patel, et al. Expires January 3, 2016 [Page 10] Internet-Draft July 2015 [RFC7080] Sajassi, A., Salam, S., Bitar, N., and F. Balus, "Virtual Private LAN Service (VPLS) Interoperability with Provider Backbone Bridges", RFC 7080, December 2013. [RFC7209] Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N., Henderickx, W., and A. Isaac, "Requirements for Ethernet VPN (EVPN)", RFC 7209, May 2014. Authors' Addresses Keyur Patel Cisco Systems 170 W. Tasman Drive San Jose, CA 95124 95134 USA Email: keyupate@cisco.com Ali Sajassi Cisco Systems 170 W. Tasman Drive San Jose, CA 95124 95134 USA Email: sajassi@cisco.com John E. Drake Juniper Networks, Inc. Email: jdrake@juniper.net Wim Henderickx Alcatel-Lucent Email: wim.henderickx@alcatel-lucent.com Patel, et al. Expires January 3, 2016 [Page 11]