TRILL Weiguo Hao Yizhou Li Donald Eastlake Liang Xia Internet Draft Huawei Intended status: Informational June 9, 2014 Expires: December 2014 TRILL Distributed Layer 3 Gateway Framework draft-hao-trill-irb-04.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. 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It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." Hao & Li Expires December 9, 2014 [Page 1] Internet-Draft TRILL Distributed Gateway Solution June 2014 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 9, 2014. Copyright 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. 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. Abstract Currently TRILL protocol can only provide optimal pair-wise data frame forwarding for layer 2 intra-subnet traffic, not for layer 3 inter-subnet traffic. Normally centralized gateway solution is used for layer 3 inter-subnet traffic forwarding. Centralized gateway solution has following issues: 1. Sub-optimum forwarding path for inter-subnet traffic. 2. Huge number of gateway interfaces, 16M in extreme case, needs to be supported on the centralized gateway. 3. Traffic bottleneck on the gateways. TRILL distributed gateway solution is proposed in this document, this solution can resolve the above centralized gateway issues. Hao & Li Expires December 9, 2014 [Page 2] Internet-Draft TRILL Distributed Gateway Solution June 2014 TRILL LSP extension can be used for synchronizing routing information in each routing domain among edge RBridges. Table of Contents 1. Introduction ................................................ 3 2. Conventions used in this document............................ 4 3. Problem Statement ........................................... 4 4. Layer 3 traffic forwarding model............................. 6 5. Distributed gateway solution overview........................ 6 5.1. Local routing information............................... 7 5.2. Local routing information synchronization............... 8 5.3. Data traffic forwarding process......................... 9 6. Distributed layer 3 gateway process example................. 10 6.1. Control plane process.................................. 11 6.2. Data plane process..................................... 12 7. TRILL protocol extension.................................... 13 7.1. The tenant gateway MAC sub-TLV......................... 13 7.2. The tenant VLAN sub-TLV................................ 14 7.3. The IPv4 Prefix sub-TLV................................ 15 8. Security Considerations..................................... 15 9. IANA Considerations ........................................ 15 10. Normative References....................................... 15 11. Informative References..................................... 16 12. Acknowledgments ........................................... 16 1. Introduction The IETF has standardized the TRILL (Transparent Interconnection of Lots of Links) protocol [RFC6325] that provides a solution for least cost transparent routing in multi-hop networks with arbitrary topologies and link technologies, using [IS-IS] [RFC6165] [RFC6326bis] link-state routing and a hop count. TRILL switches are sometimes called RBridges (Routing Bridges). Currently, TRILL only provides the optimal unicast forwarding for Layer 2 intra-subnet traffic, not for Layer 3 inter-subnet traffic. In this document, a TRILL-based distributed layer 3 gateway solution is introduced to provide the optimal unicast forwarding for Layer 3 inter-subnet traffic. The edge RBridge supports bridging among end stations(ESs) that belong to same subnet and routing among end stations that belong to different subnets of same routing domain at same time. The edge RBridge needs to provide routing instances and layer 3 gateway interfaces for local connected ESs. The routing instances are for IP address isolation for each tenant. In TRILL distributed layer 3 gateway solution, inter-subnet traffic can be Hao & Li Expires December 9, 2014 [Page 3] Internet-Draft TRILL Distributed Gateway Solution June 2014 fully dispersed among edge RBridges, so there is no single bottleneck. This document is organized as follows: Section 3 describes why a distributed gateway solution is required. Section 4 gives layer 3 traffic forwarding model. Section 5 gives distributed gateway solution overview. Section 6 gives a distributed gateway example. Section 7 describes TRILL protocol extensions to support TRILL distributed gateway solution. 2. Conventions used in this document End Station: ES. VM or physical server, whose address is either a destination or the source of a data frame. ND: IPv6's Neighbor Discovery [RFC4861]. VN: Virtual Network. Each virtual network is identified by a unique 12-bit VLAN ID or 24-bit Fine Grained Label [FGL] in TRILL network. VRF: Virtual Routing and Forwarding. In IP-based computer networks, Virtual Routing and Forwarding (VRF) is a technology that allows multiple instances of a routing table to co-exist within the same router at the same time. 3. Problem Statement -------- --------- | GW1 | | GW2 | | | | | --------- --------- | | | | --------- --------- | AGG1 | | AGG2 | | | | | --------- --------- | | __________|_________________________________|_______________________ | | | | | __|_________|___________|___________________ |____________________ | | | | | | | | | | | | | | | | | --------- --------- --------- --------- | TOR1 | | TOR2 | | TOR3 | | TOR4 | Hao & Li Expires December 9, 2014 [Page 4] Internet-Draft TRILL Distributed Gateway Solution June 2014 | | | | | | | | --------- --------- --------- --------- | | | | | | | | | | | | | | | | __|_ _|___ ____ ____ ____ ____ ____ ____ |E | |E | |E | |E | |E | |E | |E | |E | |S1| |S2| |S3| |S4| |S5| |S6| |S7| |S8| ---- ---- ---- ---- ---- ---- ---- ---- Figure 1 A typical DC network Figure 1 depicts a Data Center Network (DCN) using TRILL where edge RBs are Top of Rack (ToR) switches. Centralized gateway GW1 and GW2 in figure 1 provide the layer 3 packet forwarding for both north-south traffic and east-west inter subnet traffic between ESs. If two end stations of same tenant are on two different subnets and need to communicate with each other, their packets need to be forwarded all the way to a centralized layer 3 GW to perform L3 forwarding. This is generally sub-optimal because the two end stations may be connected to the same TOR where L3 switching could have been performed locally. If an edge RB has distributed gateway capability, then it can perform optimum L2 forwarding for intra- subnet traffic and optimum L3 forwarding for inter-subnet traffic, delivering optimum forwarding for unicast packets in all important cases. For example, in above figure1, assuming ES1(10.1.1.2 ) and ES2(20.1.1.2) belongs to different subnet of same tenant, the unicast IP traffic between them should go through centralized gateway, it can't be locally forwarded on TOR1. When Fine Grained Label [RFC7172] is introduced, theoretically 16M layer 2 VN can be supported in a TRILL campus. To support inter- subnet traffic, up to 16M layer 3 gateway interface should be created on a centralized gateway if each VN corresponds to a subnet. It is a huge burden for the centralized gateway to support so many interfaces.In addition all inter-subnet traffic will go through the centralized gateway which may become the traffic bottleneck. In summary, the centralized gateway has the following issues: 1. Sub-optimum forwarding path for inter-subnet traffic. 2. Huge number of gateway interfaces, 16M in extreme case, needs to be supported on the centralized gateway. Hao & Li Expires December 9, 2014 [Page 5] Internet-Draft TRILL Distributed Gateway Solution June 2014 3. Traffic bottleneck on the gateways. Distributed gateway on edge RBridges can be used to address these issues. 4. Layer 3 traffic forwarding model +---------------------------------------------+ | | | +-----------+ +-----------+ | | | Tenant n |---------| VRF n | | | +------------+ | +------------+ | | | | +-----+ | | | | | | | | | VN1 | | | | | | | | | +-----+ | | | VRF 1 | | | | | .. +-------+ | | | | | +-----+ | | | | | | | | | VNm | | | | | | | | | +-----+ | | | | | | | | Tenant 1 |-+ | | | | | +------------+ | | | | | +------------+ +------------+ | | | | Edge RB | +---------------------------------------------+ Figure 2 Edge RB Model as distributed GW In a data center network (DCN), each tenant may include one or more layer 2 virtual network and in normal cases each tenant corresponds to one routing domain (RD). Normally each layer 2 virtual network corresponds to one or more subnets. Each layer 2 virtual network in a TRILL campus is identified by a unique 12-bit VLAN ID or 24-bit Fine Grained Label [FGL]. Different routing domains may have overlapping address space but need distinct and separate routes. The end systems that belongs to the same subnet communicate through L2 forwarding, end systems of same tenant that belongs to different subnet communicate through L3 forwarding. The above figure 2 depicts the model where there are N VRFs corresponding to N tenants with each tenant having up to M segments/subnets (virtual network). 5. Distributed gateway solution overview In the TRILL distributed gateway scenario, an edge RBridge must perform Layer 2 routing for the ESs that are on the same subnet and Hao & Li Expires December 9, 2014 [Page 6] Internet-Draft TRILL Distributed Gateway Solution June 2014 IP routing for the ESs that are on the different subnets of same tenant. As IP address space in different routing domain can be overlapped, so VRF should be created on each edge RBridge to isolate IP forwarding process among different routing domain. Each routing domain is identified by a globally unique tenant ID. The operators should ensure the consistency of the tenant ID on each edge RBridge for each routing domain. If a routing domain spreads over multiple edge RBridges, routing information of the routing domain should be synchronized among these edge RBridges to ensure the reachability to all ESs in that routing domain. Tenant ID should be carried with the routing information synchronization to differentiate the routing domain. From data plane perspective, all edge RBridges are connected to each other via one or multiple TRILL hops, however they are always a single IP hop away. When an ingress RBridge receives inter-subnet traffic from local ES whose destination MAC is gateway MAC, the RBridge will perform Ethernet header termination and look up IP forwarding table to forward the traffic to IP next hop. If destination ES is connected to a remote edge RBridge, the remote RBridge will be the IP next hop for traffic forwarding. Ingress RBridge will perform TRILL encapsulation for such inter-subnet traffic and forward it to the remote RBridge through TRILL campus. When the remote RBridge receives the traffic, the RBridge will decapsulate TRILL header and then looks up IP forwarding table to forward it to the destination ES. Through this solution, TRILL can provide pair-wise data frame routing for inter-subnet traffic. 5.1. Local routing information An ES can be locally connected to an edge RBridges through layer 2 network or through external layer 3 IP network. If the ES is connected to an edge RBridge through layer 2 network, then the edge RBridge must act as layer 3 GW for the ES. Gateway interface should be established on the edge RBridge for the connecting ES. Because the ESs of same subnet may spread over multiple edge RBridges, each of these edge RBridges should establish it's gateway interface for the subnet, these gateway interfaces on different edge RBridges share same gateway MAC and gateway IP address. Before an ES starts to send inter-subnet traffic data, it should acquire it's gateway's MAC through ARP/ND process. Local connecting edge RBridge always respond with the gateway MAC address when Hao & Li Expires December 9, 2014 [Page 7] Internet-Draft TRILL Distributed Gateway Solution June 2014 receiving ARP/ND request for the gateway IP. Through the ARP/ND process, the edge RBridge can learn IP and MAC correspondence of local layer 2 connecting ES and then generates local IP routing entries for the ES in corresponding routing domain. If an ES is located in an external IP network, the ES also can be connected to TRILL campus through a TRILL edge RBridge. The TRILL edge RBridge runs unified routing protocol with external IP network for each routing domain. The edge RBridge learns the IP prefix corresponding to the ES through the IP routing protocol, then the RBridge generates local IP routing entries in corresponding routing domain. 5.2. Local routing information synchronization Each edge RBridge should announce its own tenant gateway MAC to TRILL campus. Tenant gateway MAC is to differentiate inter-subnet layer 3 traffic or intra-subnet layer 2 traffic on egress RB, ingress RB will use the tenant gateway MAC announced by egress RB as inner destination MAC for inter-subnet traffic TRILL encapsulation. All tenants on a RB can share same tenant gateway MAC for inter- subnet traffic purpose, the MAC normally is the RB's system MAC. When a routing instance is created on an edge RBridge, globally tenant ID, tenant VLAN or FGL should be specified. The correspondence between tenant ID and tenant VLAN or FGL should be synchronized to other edge RBridges. Ingress RB uses the VLAN or FGL of egress RB as inner VLAN(or FGL) when it performs inter-subnet traffic TRILL encapsulation. The egress RBridge relies on tenant VLAN or FGL to find local VRF for IP forwarding process when receiving inter-subnet traffic from TRILL campus, the role of tenant VLAN is akin to MPLS VPN Label in MPLS IP/MPLS VPN network. Tenant VLANs are independently allocated on each edge RBridge for each routing domain, an edge RBridge can pick up an access VLAN in a routing domain to act as inter-subnet VLAN, or the edge RBridge can use a different VLAN from any access VLANs to act as tenant VLAN, it's implementation dependant and there is no restriction on this. When a local prefix is learned in a routing instance on an edge RBridge, the edge RBridge should synchronize the prefix information of the routing instance to other edge RBridges to generate IP routing entries, global unique tenant ID also should be carried to differentiate IP prefix between different tenant, because IP address space among different tenant can be overlapped. TRILL LSP extension can be used for IP routing information synchronization in each routing domain among edge RBridges. Based on Hao & Li Expires December 9, 2014 [Page 8] Internet-Draft TRILL Distributed Gateway Solution June 2014 the synchronized information from other edge RBridges, each edge RBridge generate remote IP routing entries in each routing domain. Through this solution, intra-subnet bridging function and inter- subnet IP routing function are integrated in only one protocol, network management and deployment will be greatly simplified. 5.3. Data traffic forwarding process After a layer 2 connected ES1 of VLAN-x acquires its gateway's MAC, it can start inter-subnet data traffic process to ES2 of VLAN-y. When the local connecting edge RBridge receives inter-subnet traffic from ES1, the RBridge performs layer 2 header termination, then it gets local VRF corresponding to VLAN-x and performs IP forwarding process in the VRF. If destination ES2 is also attached to the ingress RBridge, the traffic will be locally forwarded to ES2 on the ingress RB. Comparing to the centralized gateway solution, forwarding path is optimal and traffic detour is avoided. If ES2 is attached to a remote edge RBridge, the remote edge RBridge is IP next hop, inter-subnet traffic is forwarded to the IP next hop through TRILL encapsulation. If there are multiple equal cost shortest path between ingress RBridge and egress RBridge, all these path can be used for inter-subnet traffic forwarding, so pair-wise forwarding can be achieved for inter-subnet traffic. When the remote RBridge receives the inter-subnet TRILL encapsulation traffic, the RBridge decapsulates the TRILL encapsulation and checks inner destination MAC, if the MAC equals to local gateway MAC corresponding to inner VLAN or FGL, inner VLAN or FGL will be used to find corresponding local VRF, then IP forwarding process in the VRF will be performed, the traffic will be locally forwarded to the destination ES2. In summary, through this solution, traffic detour is avoided, both inter-subnet and intra-subnet traffic can be forwarded along pair- wise shortest path, network bandwidth can be greatly saved. Hao & Li Expires December 9, 2014 [Page 9] Internet-Draft TRILL Distributed Gateway Solution June 2014 6. Distributed layer 3 gateway process example ----------- ----------- | RB3 | | RB4 | ----------- ----------- # # * * # # ************************** ########################### * # * # * # * # * # * # * ------------ ------------- | RB1 | | RB2 | ------------ ------------- | | | | ____ ____ |E | |E | |S1| |S2| ---- ---- Figure 3 Distributed gateway scenario In figure 3 above, RB1 and RB2 support distribution gateway function, ES1 connects to RB1, ES2 connects to RB2. ES1 and ES2 belongs to Tenant1, but in different subnet. The IP address, VLAN and subnet information of ES1 and ES2 are as follows. +-----+---------+----------------------+-----------------+--------------+ | ES | Tenant | IP Address | Subnet | VLAN | +-----+---------+----------------------+-----------------+--------------+ | ES1 | Tenant1 | 10.1.1.2 | 10.1.1.1/32 | 10 | +-----+---------+----------------------+-----------------+--------------+ | ES2 | Tenant2 | 20.1.1.2 | 20.1.1.1/32 | 20 | +-----+---------+----------------------+-----------------+--------------+ Figure 4 ES information The nickname, VRF, tenant VLAN, tenant gateway MAC for tenant1 on RB1 and RB2 are as follows: Hao & Li Expires December 9, 2014 [Page 10] Internet-Draft TRILL Distributed Gateway Solution June 2014 +-----+---------+-----------+-----------+----------------+-----------------+ | RB | Nickname| Tenant | VRF | Tenant VLAN | Gateway MAC | +-----+---------+-----------+-----------+----------------+-----------------+ | RB1 | nick1 | Tenant1 | VRF1 | 100 | MAC1 | +-----+---------+-----------+-----------+----------------+-----------------+ | RB2 | nick2 | Tenant1 | VRF2 | 100 | MAC2 | +-----+---------+-----------+-----------+----------------+-----------------+ Figure 5 RB information 6.1. Control plane process RB1 announces the following local routing information to TRILL campus: Tenant gateway MAC: MAC1. Tenant VLAN for Tenant1: VLAN 100. IP prefix in Tenant1: 10.1.1.2/32. RB2 announces the following local routing information to TRILL campus: Tenant gateway MAC: MAC2. Tenant VLAN for Tenant1: VLAN 100. IP prefix in Tenant1: 20.1.1.2/32. Relying on the routing information from RB2, remote routing entries on RB1 are generated as follows: +----------------------+------------------------+-----------------------+----------------------------+ | Prefix/Mask | inner dest MAC | inner VLAN | egress nickname | +----------------------+------------------------+-----------------------+----------------------------+ | 20.1.1.2/32 | MAC2 | 100 | nick2 | +----------------------+------------------------+-----------------------+----------------------------+ Figure 6 Tenant 1 remote routing table on RB1 Similarly, relying on the routing information from RB1, remote routing entries on RB2 are generated as follows: Hao & Li Expires December 9, 2014 [Page 11] Internet-Draft TRILL Distributed Gateway Solution June 2014 +----------------------+------------------------+-----------------------+----------------------------+ | Prefix/Mask | inner dest MAC | inner VLAN | egress nickname | +----------------------+------------------------+-----------------------+----------------------------+ | 10.1.1.2/32 | MAC1 | 100 | nick1 | +----------------------+------------------------+-----------------------+----------------------------+ Figure 7 Tenant 1 remote routing table on RB1 6.2. Data plane process Assuming ES1 sends unicast inter-subnet traffic to ES4, the traffic forwarding process is as follows: 1. ES1 sends unicast inter-subnet traffic to RB1, the destination MAC is gateway's MAC. 2. Ingress RB(RB1) forwarding process: RB1 checks the destination MAC, if the destination MAC equals to local gateway MAC, the GW will terminate layer 2 header and perform L3 forwarding process. RB1 looks up IP forwarding table by destination IP to get IP next hop information, which includes egress RBridge's gateway MAC(MAC2), tenant VLAN(VLAN 100) and egress nickname(nick2). Relying on these information, RB1 will perform inner Ethernet header encapsulation and TRILL encapsulation. RB1 will use MAC2 as inner destination MAC, MAC1(RB1's own gateway MAC) as inner source MAC, VLAN 100 as inner VLAN, nick2 as egress nickname and nick1 as ingress nickname. RB1 looks up TRILL forwarding table by egress nickname and forwards the traffic to TRILL next hop as per RFC 6325. The traffic will be forwarded to RB3 or RB4 as result of load balancing. Assuming the traffic is forwarded to RB3. 3. Transit RB(RB3) forwarding process: Hao & Li Expires December 9, 2014 [Page 12] Internet-Draft TRILL Distributed Gateway Solution June 2014 RB3 looks up TRILL forwarding table by egress nickname and forwards the traffic to RB2 as per RFC 6325. 4. Egress RB forwarding process: As the egress nickname is RB2's own nickname, so RB2 performs TRILL decapsulation. Then it checks inner destination MAC, because the MAC is equal to local gateway MAC, inner Ethernet header termination is performed. Relying on inner VLAN, RB2 find local corresponding VRF and looks up the VRF's IP forwarding table. The traffic will be locally forwarded to ES2. 7. TRILL protocol extension If a edge RBridge RB1 participates distributed gateway function, it should announce its tenant gateway MAC, tenant VLAN and IPv4/IPv6 prefix to TRILL campus through the tenant gateway MAC sub-TLV, tenant VLAN sub-TLV and IPv4/IPv6 prefix sub-TLV. Other edge RBridges belonging to same routing domain leverage these information to generate IP routing entries in corresponding routing domain. Ingress RB use the tenant gateway MAC and tenant VLAN of egress RB to perform inter-subnet traffic TRILL encapsulation when it receives inter-subnet traffic from local ES, tenant gateway MAC is used as inner destination MAC, tenant VLAN is used as inner destination VLAN. 7.1. The tenant gateway MAC sub-TLV +-+-+-+-+-+-+-+-+ | Type | (1 byte) +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tenant gateway MAC | (6 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o Type: Router Capability sub-TLV type, TBD (Inter-Subnet MAC sub-TLV). o Length:6. o Tenant gateway MAC: This identifies local tenant gateway MAC for inter-subnet traffic forwarding. Hao & Li Expires December 9, 2014 [Page 13] Internet-Draft TRILL Distributed Gateway Solution June 2014 7.2. The tenant VLAN sub-TLV +-+-+-+-+-+-+-+-+ | Type | (1 byte) +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tenant ID | (4 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L|Resv| Label1 | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+ | Resv2| Label2 | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+ o Type: Router Capability sub-TLV type, TBD (Next Hop sub-TLV). o Length: If Label1 field is used to represent VLAN, the value of the length field is 12. If Label1 and Label2 field are used to represent FGL, the value of the length field is 14. o Tenant ID: This identifies a global tenant ID. o L: 1 bit. When Label1 and Label2 field are used to identify FGL, it is set to 1. When Label1 field is used to identify VLAN, it is set to 0. o Resv: 3 bits that MUST be sent as zero and ignored on receipt. o Resv2: 4 bits that MUST be sent as zero and ignored on receipt. o Label1: If the value of length field is 12, the field is to identify tenant VLAN ID. If the value of length field is 14, the field is to identify higher 12 bits of tenant FGL. o Label2: Only when the value of length field is 14, the field has significance. It is to identify lower 12 bits of tenant FGL. Hao & Li Expires December 9, 2014 [Page 14] Internet-Draft TRILL Distributed Gateway Solution June 2014 7.3. The IPv4 Prefix sub-TLV +-+-+-+-+-+-+-+-+ | Type | (1 byte) +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | Tenant ID |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | Prefix(1) |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | Mask(1) |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | ..... |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | ..... |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | Prefix(N) |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ | Mask(N) |(4 bytes) +-+-+-+-+-+-+-+-+-+-+-+--+--+-+-+-+-+-+-+-+-+-+-+--+ o Type: Router Capability sub-TLV type, TBD (IPv4 Prefix sub-TLV). o Length: 4+8*n bytes, where there are n prefix and mask . o Tenant ID: This identifies a global tenant ID. o Prefix: This identifies a IPv4 prefix. o Mask: This identifies a IPv4 mask. 8. Security Considerations For general TRILL Security Considerations, see [RFC6325]. 9. IANA Considerations This document requires no IANA actions. RFC Editor: Please remove this section before publication. 10. Normative References [1] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Hao & Li Expires December 9, 2014 [Page 15] Internet-Draft TRILL Distributed Gateway Solution June 2014 Requirement Levels", BCP 14, RFC 2119, March 1997. 11. Informative References [1] [RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A. Ghanwani, "Routing Bridges (RBridges): Base Protocol Specification", RFC 6325, July 2011. [2] [rfc6326bis] - Eastlake, D., Banerjee, A., Dutt, D., Perlman, R., and A. Ghanwani, "TRILL Use of IS-IS", draft-ietf- isisrfc6326bis-00.txt, work in progress. [3] [RFC6165] Banerjee,A., Ward, D., Dutt, D., , "Extensions to IS-IS for Layer-2 Systems", RFC 6165, April 2011. [4] [RFC7172] Eastlake, D., M. Zhang, P. Agarwal, R. Perlman, D. Dutt, "TRILL (Transparent Interconnection of Lots of Links): Fine-Grained Labeling", RFC7172, May 2014. 12. Acknowledgments The authors wish to acknowledge the important contributions of Guangrui Wu, Zhenbin Li. Hao & Li Expires December 9, 2014 [Page 16] Internet-Draft TRILL Distributed Gateway Solution June 2014 Authors' Addresses Weiguo Hao Huawei Technologies 101 Software Avenue, Nanjing 210012 China Phone: +86-25-56623144 Email: haoweiguo@huawei.com Yizhou Li Huawei Technologies 101 Software Avenue, Nanjing 210012 China Phone: +86-25-56625375 Email: liyizhou@huawei.com Donald E. Eastlake Huawei Technologies 155 Beaver Street Milford, MA 01757 USA Phone: +1-508-333-2270 EMail: d3e3e3@gmail.com Liang Xia(Frank) Huawei Technologies 101 Software Avenue, Nanjing 210012 China Phone: +86-25-56624539 Email: frank.xialiang@huawei.com Hao & Li Expires December 9, 2014 [Page 17]