【正文】 the core of a data center IEEE 20 BVLAN ISID SVLAN CVLAN ISID BDA BSA BVID Ethertype Payload CVID Ethertype CDA CSA SVID Ethertype Ethertype Ethertype IP Sub BVLAN ISID ISID BDA BSA BVID Ethertype Payload Ethertype CDA CSA Ethertype PBB Customer Network Customer Network PB PB PBB Itag It Is All About Mapping of Virtual Networks to Each Other at Edges ? An External Entity needs to perform the mapping on the edges ? All the rest can be done automatically by the distributed control plane, unless the External Entity maintains full control, see next section ? ?Intelligence? is at the edges, Core Bridges are relatively ?dumb? IEEE 21 PBBN BEB1 BEB3 BEB2 BEB4 CB BVID2 ISID6 SVID15 SVID: Service VLAN ID ISID: Backbone Service Instance Identifier BVID: Backbone VLAN ID BEB: Backbone Edge Bridge CB: Core Bridge SVID ? ISID ? BVID manytoone mappings BEB BVID SVID SVID SVID ISID ISID Edge Virtual Bridging [] IEEE 22 ? Edge Virtual Bridge a bridge incorporated into an end node (often in the work interface hardware, hypervisor or both). ? Virtual Edge Bridge (VEB), or ? Relays traffic between VMs like an external Bridge ? Not required to support learning since VM addresses may be configured ? Not required to support any spanning tree protocol as it is always at the bridged work edge ? Virtual Edge Port Aggregator (VEPA) ? Sends all traffic from VMs to the adjacent bridge ? Reflective relay in external Bridge returns any frames destined to local VMs ? Makes VM to VM traffic visible to adjacent bridge ? Policies do not have to be distributed to the VEPA VEB Bridge VM VM VM VEPA SChannels [also ] IEEE 23 ? SChannels are virtual links between the end system and the adjacent Bridge ? Traffic carries an SVLANTag (from Provider Bridging) to identify it with an SChannel ? Each SChannel can have a single VM, a VEB or VEPA attached ? Normally, even with a single VM there will be a 2port VEB to handle VLAN Tag insertion, removal and tagging SChannels Bridge VM VM VM Sponent IETF 86 – Tutorial CONTROL PLANE March 10, 2023 IEEE 24 Topology Layers (Contexts) IEEE 25 Physical Network Topology Active Topology Station Location (MAC address topology) VLAN Topology Subset (real or nonreal) see Figure 71 – “VLAN Bridging overview” of for more details The Distributed Protocols for Control of the Active Topology IEEE 26 ? RSTP: a single spanning tree shared by all traffic ? MSTP: different VLANs may share different spanning trees ? SPB: each node has its own Shortest Path Tree (SPT) ? We are not limited to shared spanning trees any more gle spannin ee shared by all RSTP Rapid Spanning Tree Protocol MSTP Multiple Spanning Tree Protocol SPB Shortest Path Bridging BR A BR C BR B BR D BR E BR B BR D BR A BR E BR C BR A BR C BR B BR D BR E Note: the Spanning Tree Protocol (STP) is historical, it has been replaced by RSTP Control Plane Overview IEEE 28 Data Plane Frame out Frame in Control Plane Relay Ingress Port Egress Port External Agent MAC Bridge Higher Layer Entities ? A VLAN is assigned to a control mode ? Multiple control modes may coexist in the same work ? Hybrid control by distributed protocols and an External Agent, . and SDN controller for TE paths ? External control can be a protocol: PCE, GMPLS ? Summary of control options software defined VLANs shortest path VLANs External Agent Shortest Path Bridging VLAN space: Control: spanning tree VLANs Multiple Spanning Tree Protocol Management controls (enable/disable port) Physical Network Topology SPB, MSTP, RSTP Active Topology (shortest path, spanning tree, TE path) SPB, MMRP, SRP source address learning Station Location (MAC address topology) External Agent SPB, MVRP, SRP VLAN Topology Software Defined Networking Aspects ? Software Defined Networking (SDN) principles are supported by ? Separation of the control plane from the data plane ? The bridge architecture separates the control plane from the data plane (see page 13) ? The External Agent is geographically separated ? Separate topologies per VLAN ? Any given VLAN can be assigned to MSTP, SPB, External Agent, or any other standard or userdefined control methodology ? Centralized controller having a view of the work ? The External Agent can be a centralized SDN Controller ? The bridges may run the Link Layer Discovery Protocol (LLDP) [] for retrieval by controller ? The bridges can run ISIS to distribute topology, whether any VLANs are assigned to control by SPB or not ? Programmability of the work ? Well defined objects and functionality for programming the bridges IEEE 29 Shortest Path Bridging (SPB) ? SPB applies a link state control protocol to MAC Bridging ? Based on the ISO Intermediate System to Intermediate System (ISIS) intradomain routing information exchange protocol ? ISISSPB ? Leverages the automation features of link state, . autodiscovery ? Preserves the MAC Service model, . delivery inorder ? ISISSPB operation ? Link state data base ? Identical replica at each bridge ? Topology information ? Properties of the bridges ? Service information ? Computation instead of signaling or registration protocols ? Leverage Moore?s law and technology trends ? ISISSPB specifications ? IEEE specifies operation and backwards patibility provisions ? ISIS extensions for SPB (new TLVs) also documented in IETF RFC 6329 IEEE 30 SPB Operation Modes IEEE 31 ? A bridge only uses its own SPT for frame forwarding ? Destination