INTERNET-DRAFT Mingui Zhang Intended Status: Proposed Standard Huawei Radia Perlman Intel Hongjun Zhai ZTE Mukhtiar Shaikh Muhammad Durrani Brocade Expires: October 6, 2014 April 4, 2014 TRILL Active-Active Edge Using Multiple MAC Attachments draft-zhang-trill-aa-multi-attach-02.txt Abstract TRILL active-active service is to provide end stations with flow level load balance and resilience against link failures at the edge of TRILL campuses. This draft proposes that member RBridges in an active-active edge RBridge group use their own nicknames as ingress RBridge nicknames to encapsulate frames from attached end systems. Thus, remote edge RBridges are required to learn multiple locations of one MAC address in one Data Label. Design goals of this proposal are discussed in the document. 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 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Mingui Zhang, et al Expires October 6, 2014 [Page 1] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 Copyright and License Notice Copyright (c) 2014 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. Acronyms and Terminology . . . . . . . . . . . . . . . . . . . 3 2.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 5 4.1. Detail of Option C . . . . . . . . . . . . . . . . . . . . 6 4.2. Capability Flags TLV . . . . . . . . . . . . . . . . . . . 7 5. Design Goals . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. No MAC Flip-Floping (Normal Unicast Egress) . . . . . . . . 8 5.2. Regular Unicast/Multicast Ingress . . . . . . . . . . . . . 8 5.3. Right Multicast Egress . . . . . . . . . . . . . . . . . . 9 5.3.1. No Duplication (Single Exit Point) . . . . . . . . . . 9 5.3.2. No Echo (Split Horizon) . . . . . . . . . . . . . . . . 9 5.4. No Black-hole & No Triangular Forwarding . . . . . . . . . 10 5.5. Load Balance Towards the AAE . . . . . . . . . . . . . . . 10 5.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11 7.1. TRILL APPsub-TLVs . . . . . . . . . . . . . . . . . . . . . 11 7.2. Active Active Flags . . . . . . . . . . . . . . . . . . . . 11 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . . 13 Appendix A. Scenarios on Split Horizon . . . . . . . . . . . . . . 13 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Mingui Zhang, et al Expires October 6, 2014 [Page 2] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 1. Introduction In the TRILL Active-Active Edge (AAE) topology, a Multi-Chassis Link Aggregation Group (MC-LAG) is used to connect multiple RBridges to a switch or a vSwitch. An endnode clump is attached to this switch or vSwitch. It's required that data traffic within a specific Data Label (VLAN or Fine Grained Label (FGL)) from this endnode clump can be ingressed and egressed by any of these RBridges simultaneously. End systems in the clump can spread their traffic among these edge RBridges at the flow level. When a link fails, end systems can keep using the rest of links in the MC-LAG without waiting for the convergence of TRILL, which provides the resilience towards link failures. Since a packet from each endnode can be ingressed by any RBridge in the AAE group, a remote edge RBridge may observe multiple attachment points (i.e., egress RBridges) for this endnode identified by its MAC address. This issue is known as the "MAC flip-flopping". Three potential solutions arise to address this issue: 1) AAE member RBridges use a pseudonode nickname, instead of their own, as the ingress nickname for end systems attached to the MC- LAG. [CMT] falls within this category. 2) AAE member RBridges split work among themselves for which one will be responsible for which MAC addresses. A member RBridge will encapsulate the packet using its own nickname if it is responsible for the source MAC address. Otherwise, if the frame is known unicast, it encapsulates the packet using the nickname of the responsible RBridge; if the frame is multicast, it needs to redirect the packet to its responsible RBridge for encapsulation. 3) AAE member RBridges keep using their own nicknames. Remote edge RBridges are required to keep multiple points of attachment per VLAN for a MAC address attached to the AAE. The purpose of this ID is to develop an approach based on solution 3. Although it focuses on exploring solution 3, the major design goals discussed here are common for AAE. Through mirroring the scenarios studied in this draft, other potential solutions may benefit as well. The main body of the document is organized as follows. Section 2 lists the acronyms and terminologies. Section 3 gives the overview model. Section 4 provides three options for incremental deployment. Section 5 describes how this approach meets the design goals. 2. Acronyms and Terminology Mingui Zhang, et al Expires October 6, 2014 [Page 3] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 2.1. Acronyms TRILL: TRansparent Interconnection of Lots of Links AAE: Active-Active Edge MC-LAG: Multi-Chassis Link Aggregation Group IS-IS: Intermediate System to Intermediate System FGL: Fine Grained Label Data Label: VLAN or FGL ESADI: End Station Address Distribution Information 2.2. Terminology 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 RFC 2119 [RFC2119]. Familiarity with [RFC6325], [RFC6327], [RFC6327bis] and [RFC6439] is assumed in this document. 3. Overview +-----+ | RB4 | +----------+-----+----------+ | | | | | Rest of campus | | | | | +-+-----+--+-----+--+-----+-+ | RB1 | | RB2 | | RB3 | +-----\ +-----+ /-----+ \ | / \ | / |||MC-LAG1 ||| +---+ | B | +---+ H1 H2 H3 H4: VLAN 10 Figure 3.1: An example topology of TRILL Active-Active Edge Figure 3.1 shows an example network of TRILL Active-Active Edge. In this figure, endnodes (H1, H2, H3 and H4) are attached to a bridge (B) which communicates with multiple RBridges (RB1, RB2 and RB3) via the MC-LAG. Suppose RB4 is a 'remote' RBridge out of the AAE group in the TRILL campus. This connection model is also applicable to the Mingui Zhang, et al Expires October 6, 2014 [Page 4] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 virtualized environment where the physical bridge can be replaced with a vSwitch while those bare metal hosts are replaced with virtual machines (VM). For a packet received from their attached endnode clumps, member RBridges of the AAE group always encapsulate it using their own nickname no matter it's unicast or multicast. The remote RBridge RB4 will see multiple attachments of one MAC from the end nodes. 4. Backward Compatibility Three options are listed below to cope with incremental deployment scenarios. Among them, Option C can be hardware independent. -- Option A A new capability announcement would appear in LSPs. "I can cope with multiple endnode attachments". Only if all edge RBridges announce this capability can the AAE group use this approach. For those legacy RBridges who are not capable to cope with multiple endnode attachments, new type TRILL switches will not establish connectivity with them so that they are isolated from these new type TRILL switches. Note only edge RBridges (those that are Appointed Forwarders [RFC6439]) need to be able to support this. It does not affect totally transit RBridges. -- Option B Each edge RBridge in the AAE group ingress data frames from any MC-LAG into a specific TRILL topology. In this way, the topology ID is used as the discriminator of different locations of a specific MAC address at the remote RBridge. TRILL MAY reserve a list of topology IDs to be dedicated to AAE. RBridges which do not support this reserved list MUST NOT establish connectivity with edge RBridges in the AAE group. -- Option C As pointed out in Section 4.2.6 of [RFC6325] and Section 5.3 of [ESADI], one MAC address may be persistently claimed to be attached to multiple RBridges within the same Data Label in the TRILL ESADI PDUs. For this option, AAE member RBridges make use of TRILL ESADI protocol to distribute multiple attachments of MAC addresses. Remote RBridges disable the data plane learning for such multi-attached MAC addresses. Mingui Zhang, et al Expires October 6, 2014 [Page 5] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 4.1. Detail of Option C An RBridge in an AAE MUST advertise all Data Labels enabled for all its attached MC-LAG. This causes remote RBridges to disable the MAC learning via the TRILL Data packet decapsulation within these data labels for this RBridge. The advertisement of such Data Labels can be realized by taking one reserved flag from the Interested VLANs and Spanning Tree Roots Sub-TLV (Section 2.3.6 of [RFC6326bis]) or one reserved flag from the Interested Labels and Spanning Tree Roots Sub- TLV (Section 2.3.8 of [RFC6326bis]). When this flag is set to 1, the originating IS is advertising Data Labels for MC-LAGs rather than a plain LAN link. (See Section 7.2) Whenever a MAC from the MC-LAG of this AAE is learned, it need advertise it via ESADI. In the TRILL ESADI PDUs, the originating IS need includes all other RBridges' nicknames in the same AAE. It requires each AAE member to be aware of other RBridges in the same AAE (See Section 5.3.2). MAC Reachability TLVs [RFC6165] are composed in a way that each TLV only contains MAC addresses for a single MC- LAG. Each such TLV or TLVs MUST be enclosed by a pair of boundary TRILL APPsub-TLVs defined as follows. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = NICKNAME-GROUP-START | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Nickname (1) | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Nickname (2) | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ............. | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Nickname (n) | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: Nickname Group Start (TRILL APPsub-TLV type #TBD) o Length: 2*n, where n is the number of RBridges in the AAE. o Nickname: The nickname of an RBridge in the same AAE group as the originating IS. The nickname of the originating IS is also included. Mingui Zhang, et al Expires October 6, 2014 [Page 6] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = NICKNAME-GROUP-END | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: Nickname Group End (TRILL APPsub-TLV type #TBD) o Length: 0 This pair of TRILL APPsub-TLVs SHOULD be included respectively in a pair of GENINFO TLVs [RFC6823] in the ESADI-LSP. There may be more than one occurrences of such pair of APPsub-TLVs in one ESADI-LSP fragment. For those MAC Reachability TLVs not enclosed by the boundary TLVs, [EASDI] applies. Otherwise, this document applies. When the remote RBridge learns MAC addresses via ESADI, it always regards that the packets destined to these MAC addresses are to be egressed by the closest one (the one to which the remote RBridge has the least cost forwarding path) of those RBridges identified by the nicknames in the Nickname Group Start TLV. If there are multiple such member RBridges, the one with the lowest System ID will be recorded as the egress RBridge. When another RBridge in the same AAE group receives the ESADI-LSP with above pair of boundary TRILL APPsub-TLVs, it also learns MAC addresses served by the corresponding MC-LAG. This RBridge should regard as if these MAC addresses are attached to itself. This point can also be understood as that, the RBridge itself is always the closest one out of all the AAE member RBridges. An AAE member RBridge also need to advertise in ESADI the MAC addresses learned from a plain link (non MC-LAG link) with data labels happen to be covered by the Data Labels of any attached MC- LAG. The reason is that data plane learning within these Data Labels at the remote RBridge has been disabled for this RBridge. 4.2. Capability Flags TLV The following Capability Flags TLV will be included in LSP as TRILL APPsub-TLV of GENINFO-TLV. Mingui Zhang, et al Expires October 6, 2014 [Page 7] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = MULTI-MAC-ATTACH-CAP | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E|H| Reserved | +-+-+-+-+-+-+-+-+ o Type: Multi-MAC-Attach Capability (TRILL APPsub-TLV type #TBD) o Length: 1 o E: When this bit is set, it indicates the originating IS keeps multiple MAC attachments in the ESADI-LSDB while disables the MAC learning from the remote TRILL Data decapsulation as specified in Option C. o H: When this bit is set, it indicates that the originating IS keeps multiple MAC attachments with new hardware at the data plane. o Reserved: Reserved flags for future use. Capability specification for Option B is out the scope of this document. It may be specified in documents for TRILL multi-topology. 5. Design Goals Proposals to meet the major design goals of AAE are explored in this section. 5.1. No MAC Flip-Floping (Normal Unicast Egress) Since all RBridges talking with the AAE RBridges in the campus are able to keep multiple locations for one MAC address, a MAC address learned from one AAE member will not be overwritten by the same MAC address learned from another AAE member. Although multiple entries for this MAC address will be created, the remote RBridge can adhere to one of the locations (e.g., the closest one) for each MAC address rather than keep flip-floping among them. 5.2. Regular Unicast/Multicast Ingress MC-LAG guarantees that each frame will be sent upward to the AAE via exactly one uplink. RBridges in the AAE can simply follow the process per [RFC6325] to ingress the frame. For example, each RBridge uses its own nickname as the ingress nickname to encapsulate the packet. In such scenario, each RBridge takes for granted that it is the Mingui Zhang, et al Expires October 6, 2014 [Page 8] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 Appointed Forwarder for the Data Labels enabled on the uplink of the MC-LAG. 5.3. Right Multicast Egress A fundamental design goal of AAE is that there is no duplication and forwarding loop. 5.3.1. No Duplication (Single Exit Point) When multi-destination packets for a specific Data Label are received from the campus, it's important that exactly one RBridge out of the AAE group let through each multicast packet, therefore no duplication happens. Since AAE member RBridges support MC-LAG, they are able to utilize the hashing function of MC-LAG to determine the single exit point. 5.3.2. No Echo (Split Horizon) When a multicast frame originated from an MC-LAG is ingressed by an RBridge of an AAE group, forwarded across the TRILL network and then received by another RBridge in the same AAE group, it is important that this RBridge does not egress this frame back to this MC-LAG. Otherwise, it will cause a forwarding loop (echo). The well known 'split horizon' technique can be used to eliminate the echo issue. RBridges in the AAE group need split horizon based on the ingress RBridge nickname plus the Data Label (VLAN or FGL) of the TRILL Data packet. They need set up per port filtering lists consists of the tuple of . Packets with information matching with any entry of the filtering list MUST NOT be egressed out of that port. The information of such filters is obtained by listening to the following "MC-LAG Group RBridges" TRILL APPsub-TLV included in the GENINFO TLV in LSPs. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = MC-LAG-GROUP-RBRIDGES | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Nickname | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+ | MC-LAG System ID | (8 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+ o Type: MC-LAG Group RBridges (TRILL APPsub-TLV type #TBD) o Length: 10 Mingui Zhang, et al Expires October 6, 2014 [Page 9] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 o Sender Nickname: The nickname of the originating IS. o MC-LAG System ID: The System ID of the MC-LAG as specified in Section 6.3.2 in [802.1ax-rev]. All enabled VLANs/FGLs MUST be consistent on all ports connected to an MC-LAG [802.1ax-rev]. So that the enabled Data Labels need not be included in the MC-LAG Group RBridges TRILL APPsub-TLV. They can be locally obtained from the port attached to that MC-LAG. Through parsing an MC-LAG Group RBridges TRILL APPsub-TLV, the receiver RBridge discovers all other RBridges connected to the same MC-LAG. The Sender Nickname of the originating IS will be added into the filtering list of the port attached to the MC-LAG. For example, RB3 in Figure 3.1 will set up a filtering list looks like {, } on its port attached to MC-LAG1. According to split horizon, TRILL Data packets within VLAN10 ingressed by RB1 or RB2 will not be egressed out of this port. When there are multiple MC-LAGs connected to the same RBridge, these MC-LAGs may have overlap Data Labels. Customer may need hosts within these overlap Data Labels communicate with each other. In Appendix A, several scenarios are given to explain how hosts communicate within the overlap Data Labels and how split horizon happens. 5.4. No Black-hole & No Triangular Forwarding If a sub-link of the MC-LAG fails while remote RBridges continue to send packets to those MAC addresses they have learned via the failed port, black-hole happens. The AAE member attached to the failed sub-link can make use of ESADI protocol to flush those failure affected MAC addresses as defined in Section 5.2 of [ESADI]. After doing that, no traffic will be sent to the failed port, hence no black-hole happens. 5.5. Load Balance Towards the AAE Since a remote RBridge can record multiple attachments of one MAC address, this remote RBridge can choose to spread the traffic to this MAC towards any of the AAE members. Each of them is able to egress the traffic. With Option A and Option B, flow-level load balance mechanisms can be implemented to optimize the distribution of the traffic load from the remote RBridge towards the AAE group. 5.6. Scalability In order to record the multiple attachments of MAC addresses learned Mingui Zhang, et al Expires October 6, 2014 [Page 10] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 from AAE RBridges, more entries may be consumed in the table of learned MAC addresses. However, MAC addresses attached to MC-LAG is probably only a small part of all MAC addresses in the whole TRILL campus. As a result, the extra space required by the multi-attached MAC addresses may be much less than the RBridge's current unused MAC table space. Also, with option C, remote RBridges will keep the multiple attachments of a MAC address in the ESADI link state databases. In the MAC table, an RBridge still establishes only one entry for each MAC address. 6. Security Considerations Authenticity for contents transported in IS-IS PDUs is enforced using regular IS-IS security mechanism [ISIS][RFC5310]. For security considerations pertain to extensions hosted by TRILL ESADI, Security Considerations in [ESADI] should be referred. 7. IANA Considerations 7.1. TRILL APPsub-TLVs IANA is requested to create several new sub-registries under the Generic Information TLV (#251) [RFC6823] for TRILL APPsub-TLVs defined in Section 4.1, 4.2 and 5.3.2 of this document. Reference: [ESADI] and [This document] Type Name Reference ---------- -------- ----------- 0 Reserved 1 ESADI-PARAM [ESADI] 2-254 Unassigned 255 Reserved 256 NICKNAME-GROUP-START This document 257 NICKNAME-GROUP-END This document 258 MULTI-MAC-ATTACH-CAP This document 259 MC-LAG-GROUP-RBRIDGES This document 260-65534 Available 65535 Unassigned 7.2. Active Active Flags Similar as Section 7.1 of [ESADI], this document requires IANA to create two sub-registries for TRILL Active-Active as follows. Mingui Zhang, et al Expires October 6, 2014 [Page 11] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 One flag bit appears in the "Interested VLANs and Spanning Tree Roots Sub-TLV". References: [RFC6326bis], [ESADI] and [This document] Bit Mnemonic Description Reference --- -------- ----------- --------- 0 M4 IPv4 Multicast Router Attached [RFC6326bis] 1 M6 IPv6 Multicast Router Attached [RFC6326bis] 2 - Unassigned 3 ES ESADI Participation [ESADI] 4-15 - (used for a VLAN ID) [RFC6326bis] 16 AA Enabled VLANs for Active-Active This document 17-19 - Unassigned 20-31 - (used for a VLAN ID) [RFC6326bis] One flag bit appears in the "Interested Labels and Spanning Tree Roots Sub-TLV". References: [RFC6326bis], [ESADI] and [This document] Bit Mnemonic Description Reference --- -------- ----------- --------- 0 M4 IPv4 Multicast Router Attached [RFC6326bis] 1 M6 IPv6 Multicast Router Attached [RFC6326bis] 2 BM Bit Map [RFC6326bis] 3 ES ESADI Participation [ESADI] 4 AA FGLs Enabled for Active-Active This document 5-7 - Unassigned Acknowledgements Authors would like to thank the comments and suggestions from Donald Eastlake, Erik Nordmark, Fangwei Hu and Liang Xia. 8. References 8.1. Normative References [RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A. Ghanwani, "Routing Bridges (RBridges): Base Protocol Specification", RFC 6325, July 2011. [RFC6327] Eastlake 3rd, D., Perlman, R., Ghanwani, A., Dutt, D., and V. Manral, "Routing Bridges (RBridges): Adjacency", RFC 6327, July 2011. [RFC6327bis] D. Eastlake, R. Perlman, et al, "TRILL: Adjacency", Mingui Zhang, et al Expires October 6, 2014 [Page 12] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 draft-ietf-trill-rfc6327bis-04.txt, January 2014, in RFC Ed Queue. [RFC6439] Perlman, R., Eastlake, D., Li, Y., Banerjee, A., and F. Hu, "Routing Bridges (RBridges): Appointed Forwarders", RFC 6439, November 2011. [ESADI] H. Zhai, F. Hu, et al, "TRILL (Transparent Interconnection of Lots of Links): ESADI (End Station Address Distribution Information) Protocol", draft-ietf-trill-esadi-05.txt, February 2014, working in progress. [RFC6326bis] D. Eastlake, R. Perlman, et al, "Routing Bridges (RBridges): Adjacency", draft-ietf-trill-rfc6327bis-03.txt, January 2014, work in progress. [RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising Generic Information in IS-IS", RFC 6823, December 20165 [RFC6165] Banerjee, A. and D. Ward, "Extensions to IS-IS for Layer-2 Systems", RFC 6165, April 2011. 8.2. Informative References [CMT] T. Senevirathne, J. Pathangi, et al, "Coordinated Multicast Trees (CMT)for TRILL", draft-ietf-trill-cmt-02.txt, November 2012, working in progress. [802.1ax-rev] IEEE, "Local and Metropolitan Area Networks - Link Aggregation", IEEE P802.1AX-REV/D3.2, February 2014. [ISIS] ISO, "Intermediate system to Intermediate system routeing information exchange protocol for use in conjunction with the Protocol for providing the Connectionless-mode Network Service (ISO 8473)", ISO/IEC 10589:2002. [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC 5310, February 2009. Appendix A. Scenarios on Split Horizon Mingui Zhang, et al Expires October 6, 2014 [Page 13] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 +------------------+ +------------------+ +------------------+ | RB1 | | RB2 | | RB3 | +------------------+ +------------------+ +------------------+ L1 L2 L3 L1 L2 L3 L1 L2 L3 VL10~20 VL15~25 VL15 VL10~20 VL15~25 VL15 VL10~20 VL15~25 VL15 MC-LAG1 MC-LAG2 LAN MC-LAG1 MC-LAG2 LAN MC-LAG1 MC-LAG2 LAN B1 B2 B10 B1 B2 B20 B1 B2 B30 Figure A.1: An example topology to explain split horizon Suppose RB1, RB2 and RB3 are the Active-Active group connecting MC- LAG1 and MC-LAG2. MC-LAG1 and MC-LAG2 are connected to B1 and B2 at their other ends. Suppose all these RBridges use port L1 to connect MC-LAG1 while they use port L2 to connect MC-LAG2. Assume all three L1 enable VLAN 10~20 while all three L2 enable VLAN 15~25. So that there is a overlap of VLAN 15~20. Customer needs hosts in these overlap VLANs communicate with each other. That is, hosts attached to B1 in VLAN 15~20 need communicate with hosts attached to B2 in VLAN 15~20. Assume the remote plain RBridge RB4 also has hosts attached in VLAN 15~20 which need communicate with those hosts in these VLANs attached to B1 and B2. Two major requirements: 1. Frames ingressed from RB1-L1-VLAN 15~20 MUST NOT be egressed out of ports RB2-L1 and RB3-L1. At the same time, 2. frames coming from B1-VLAN 15~20 should reach B2-VLAN 15~20. RB3 stores the information for split horizon on its ports L1&L2. On L1: {, } and on L2: {, }. Five clarification scenarios: a. Suppose RB2/RB3 receives a TRILL multicast data packet with data label VLAN 15 and ingress nickname RB1. RB3 is the single exit point (selected out according to the hashing function of MC-LAG) for this packet. On ports L1&L2, RB3 has covered , so that RB3 will not egress this packet out of either L1 or L2. Here, _split horizon_ happens. Beforehand, RB1 obtains a native frame on port L1 from B1 in VLAN 15. RB1 judges it should be forwarded as a multicast frame across the TRILL campus. Also, RB1 replicates this frame without TRILL encapsulation and sends it out of port L2, so that B2 will get this frame. Mingui Zhang, et al Expires October 6, 2014 [Page 14] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 b. Suppose RB2/RB3 receives a TRILL multicast data packet with data label VLAN 15 and ingress nickname RB4. RB3 is the single exit point. On ports L1&L2, since RB3 has not stored any tuple with ingress_ nickname_RB4, RB3 will decapsulate the packet and egress it out of both ports L1 and L2. So both B1 and B2 will receive the frame. c. Suppose there is a plain LAN link port L3 on RB1, RB2 and RB3, connecting to B10, B20 and B30 respectively. These L3 ports happen to be configured with VLAN 15. On port L3, RB1 and RB3 stores no information of split horizon for AAE (since this port has not been configured to be in any MC-LAG). They will egress the packet ingressed out of RB1-L1 in VLAN 15. d. If a packet is ingressed from RB1-L1 or RB1-L2 with data label VLAN 15, port RB1-L3 will not egress packets with ingress- nickname-RB1. RB1 need replicates this frame without encapsulation and sends it out of port L3. e. If a packet is ingressed from RB1-L3, since RB1-L1 and RB1-L2 cannot egress packets with data label VLAN 15 and ingress- nickname-RB1, RB1 need replicates this frame without encapsulation and sends it out of port L1 and L2. Mingui Zhang, et al Expires October 6, 2014 [Page 15] INTERNET-DRAFT MAC Multi-Attach for Active/Active April 4, 2014 Author's Addresses Mingui Zhang Huawei Technologies No.156 Beiqing Rd. Haidian District, Beijing 100095 P.R. China Email: zhangmingui@huawei.com Radia Perlman Intel Email: radiaperlman@gmail.com Hongjun Zhai ZTE Corporation 68 Zijinghua Road Nanjing 200012 China Phone: +86-25-52877345 Email: zhai.hongjun@zte.com.cn Mukhtiar Shaikh Brocade Email: mshaikh@brocade.com Muhammad Durrani Brocade Email: mdurrani@brocade.com Mingui Zhang, et al Expires October 6, 2014 [Page 16]