Internet DRAFT - draft-fedyk-gmpls-ethernet-pbb-te

draft-fedyk-gmpls-ethernet-pbb-te




 
Network Working Group                     Don Fedyk, David Allan, Nortel 
Internet Draft                                      Himanshu Shah, Ciena 
Category: Standards Track                           Nabil Bitar, Verizon 
                                 Attila Takacs, Diego Caviglia, Ericsson 
                                                        Alan McGuire, BT 
                                  Nurit Sprecher, Nokia Siemens Networks 
                                                        Lou Berger, LabN 
                                                       November 19, 2007 
                                                                         
                      GMPLS control of Ethernet PBB-TE 
                 draft-fedyk-gmpls-ethernet-pbb-te-02.txt 
   
Status of this Memo 
    
   By submitting this Internet-Draft, each author represents that any 
   applicable patent or other IPR claims of which he or she is aware 
   have been or will be disclosed, and any of which he or she becomes 
   aware will be disclosed, in accordance with Section 6 of BCP 79. 
    
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   This Internet-Draft will expire in May 2008. 
 
Copyright Notice 
    
   Copyright (C) The IETF Trust (2007). 
 
Abstract 
 
   This memo is complementary to [ARCH] and describes how a GMPLS 
   control plane may be applied to the Provider Backbone Bridges Traffic 
   Engineering (PBB-TE) [IEEE 802.1Qay] amendment to 802.1Q and how 
   GMPLS can be used to configure VLAN-aware Ethernet switches in order 
   to establish Ethernet point to point (P2P) and P2MP MAC switched 


    
    
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   paths and P2P/P2MP VID based trees.  This document supports, but does 
   not modify, the standard IEEE data.  
    
Conventions used in this document  
 
   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]. 
    
Document History 
 
   This document has under gone name changes to follow the 
   standardization of Provider Backbone Bridges and the Traffic 
   engineering capability.  
    
   draft-fedyk-gmpls-ethernet-ivl-00.txt. 
    
   This was the original draft. 
    
   draft-fedyk-gmpls-ethernet-pbt-00.txt  
   draft-fedyk-gmpls-ethernet-pbt-01.txt  
    
   This draft was renamed to reflect the Provider Backbone Transport 
   (PBT) nomenclature. Several co-authors joined the draft.  
    
   draft-fedyk-gmpls-ethernet-pbb-te-00.txt 
    
   The standardization of PBT is called Provider Backbone Bridges 
   Traffic Engineering (PBB-TE). The draft was aligned the PBB-TE 
   Technology.  
    
   draft-fedyk-gmpls-ethernet-pbb-te-01.txt 
    
   This is the second revision of the PBB-TE draft with editing to 
   clarify the document and the addition of co-authors. 
    
   draft-fedyk-gmpls-ethernet-pbb-te-02.txt 
    
   This is a third revision with the general aspects of Ethernet being 
   move to the architecture and framework [ARCH] and the specifics for 
   PBB-TE becoming more clear.  
    
    
    
    








 
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Table of Contents 
 
   1. Introduction..................................................4 
   2. Terminology...................................................4 
   2.1  PBB-TE Terminology..........................................5 
   3. GMPLS creation and maintenance of PBB-TE Service Instances....5 
   3.1  Ethernet Service............................................6 
   3.2  Addresses, Interfaces, and Labels...........................7 
   4. Specific Procedures...........................................9 
   4.1  P2P connections.............................................9 
   4.1.1 Shared Forwarding........................................ 10 
   4.1.2 P2P connections with shared forwarding................... 11 
   4.1.3 Dynamic P2P symmetry with shared forwarding.............. 12 
   4.1.4 Planned P2P symmetry..................................... 12 
   4.1.5 P2P Path Maintenance..................................... 12 
   4.2  P2MP Signaling............................................ 13 
   4.3  P2MP VID/ESP-MAC DA Connections........................... 13 
   4.3.1 Setup procedures......................................... 13 
   4.3.2 Maintenance Procedures................................... 13 
   4.4  Ethernet Label............................................ 14 
   4.5  OAM MEP ID and MA ID synchronization...................... 15 
   4.6  Protection Paths.......................................... 15 
   5. Error conditions............................................ 16 
   5.1  Invalid ESP-VID value for PBB-TE MSTI range............... 16 
   5.2  Invalid MAC Address....................................... 16 
   5.3  Invalid ERO for UPSTREAM_LABEL Object..................... 16 
   5.4  Invalid ERO for LABEL_SET Object ......................... 16 
   5.5  Switch is not ESP P2MP capable............................ 16 
   5.6  Invalid ESP-VID in UPSTREAM_LABEL object ................. 16 
   6. Deployment Scenarios........................................ 16 
   7. Security Considerations .................................... 16 
   8. IANA Considerations......................................... 17 
   9. References.................................................. 17 
   9.1  Normative References...................................... 17 
   9.2  Informative References.................................... 17 
   10.  Author's Address.......................................... 18 
   11.  Intellectual Property Statement........................... 19 
   12.  Disclaimer of Validity.................................... 20 
   13.  Copyright Statement....................................... 20 
   14.  Acknowledgments........................................... 20 
   Appendix A..................................................... 21 
   Rational and mechanism for PBB_TE Ethernet Forwarding.......... 21 
   A 1.  Overview of configuration of VID/DMAC tuples............. 23 
   A 2.  Overview of configuration of VID port membership......... 26 
   A 3.  OAM Aspects ............................................. 26 
   A 4.  QOS Aspects ............................................. 27 
   A 5.  Resiliency Aspects ...................................... 27 
   A 5.1.  E2E Path protection.................................... 27 





 
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1. Introduction 
    
   IEEE 802.1 is specifying Traffic Engineered Ethernet paths in the 
   Provider Backbone Bridged network (PBB-TE) [IEEE 802.1Qay] based on 
   managed objects that can be separated from the Spanning Tree Control 
   Plane and statically configured or managed by a another control 
   plane. These paths have minor changes to Ethernet data plane 
   specified in the IEEE. IEEE 802 termed these paths "PBB-TE service 
   instances".  
      
   The purpose of this document is to specify extensions for a GMPLS 
   based control plane to manage PBB-TE service instances. This draft 
   is aligned with GMPLS Ethernet Label Switching Architecture and 
   Framework [ARCH].  
    
   It should be noted that due to the changes in the separation of the 
   Spanning Tree Control plane and the PBB-TE forwarding, the behavior 
   of PBB-TE for the specified VLAN range is a new behavior. (It does 
   not default to conventional Ethernet forwarding with learning at any 
   time). Appendix A summarized the rational for this data plane 
   technology until the IEEE specification is more mature.  
    
2. Terminology 
    
   In addition to well understood GMPLS terms, this memo uses 
   terminology from IEEE 802.1 and introduces a few new terms: 
    
   B-MAC        Backbone MAC 
   B-VID        Backbone VLAN ID 
   B-VLAN       Backbone VLAN 
   CBP          Customer Backbone Port 
   CCM          Continuity Check Message 
   COS          Class of Service 
   CLI          Command Line Interface 
   CIP          Customer Instance Port 
   C-MAC        Customer MAC 
   C-VID        Customer VLAN ID 
   C-VLAN       Customer VLAN 
   DMAC         Destination MAC Address 
   ESP          Ethernet Switched Path 
   Eth-LSP      Ethernet Label switched Path 
   I-SID        Ethernet Service Instance Identifier 
   LBM          Loopback Message 
   LBR          Loopback Reply 
   LLDP         Link Layer Discovery Protocol 
   LMM          Loss Measurement Message 
   LMR          Loss Measurement Reply 
   MAC          Media Access Control 
   MMAC         Multicast MAC 
   MSTI         Multiple Spanning Tree Instance  
   MP2MP        Multipoint to multipoint 
   PBB          Provider Backbone Bridges 
   PBB-TE       Provider Backbone Bridges Traffic Engineering 
 
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   PIP          Provider Instance Port 
   PNP          Provider Network Port 
   P2P          Point to Point 
   P2MP         Point to Multipoint 
   QOS          Quality of Service 
   ESP-MAC SA           Source MAC Address 
   S-VID        Service VLAN ID 
   SVL          Shared VLAN Learning 
   VID          VLAN ID 
   VLAN         Virtual LAN 
    
    
    
2.1 PBB-TE Terminology   
    
   The PBB-TE specification has defiend some additional termminology to 
   clarify the PBB-TE functions. We repeat these here in expanded 
   context to translate from IEEE to GMPLS terminology.  
    
   - Ethernet Switched Path (ESP): A provisioned traffic engineered 
     unidirectional connectivity path between two or more Customer 
     Backbone Ports(CBPs) which extends over a Provider Backbone Bridge 
     Network (PBBN). The path is identified by the 3-tuple <ESP-MAC DA, 
     ESP-MAC SA, ESP-VID> where the ESP-VID value is allocated to the 
     PBB-TE Multiple Spanning Tree Instance (MSTI)(A set of VIDs for 
     PBB-TE is allocated as a set of MSTIs). An ESP is analogous to an 
     GMPLS LSP. 
    
   - PBB-TE Region: A set of PBB switches and PB switches by a set of 
     Service-VLANs allocated to provisioned Ethernet Switched Paths 
     (ESPs). 
    
   - PBB-TE service instance: A Point-to-Point or a Point-to-Multipoint 
     PBB-TE service instance. 
    
   - PBB-TE Trunk: A Point-to-Point PBB-TE service instance.  
    
   - Point-to-Point PBB-TE service instance: An instance of the MAC 
     service provided by two unidirectional co-routed ESPs forming a 
     bidirectional service. A GMPLS bidirectional path is analogous to 
     a P2P PBB-TE Service instance.  
    
   - Point-to-Multipoint PBB-TE service instance: An instance of the 
     MAC service provided by a set of ESPs which comprises one 
     multipoint ESP plus n unidirectional point-to-point ESPs, routed 
     along the leaves of the multicast ESP. A P2MP GMPLS bidirectional 
     tree is analogous to a P2MP PBB-TE service instance.  
    
3. GMPLS creation and maintenance of PBB-TE Service Instances 
    
   PBB-TE is an Ethernet connection oriented technology, being 
   specified in the IEEE, which can be controlled by configuration of 
   static filtering entries [see Appendix A] for some details on the 
 
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   rational for the data plane. PBB-TE ESPs are created switch by 
   switch by simple configuration of Ethernet logical ports and 
   assignment of PBB-TE labels or by a control plane. This document 
   describes GMPLS as a valid control plane for Eth-LSPs that are based 
   on PBB-TE ESPs. A Point-to-Point PBB-TE service instance is a form 
   of Ethernet LSP (Eth-LSP) which is more broadly defined in [ARCH].  
   This memo describes GMPLS as a mechanism to automate set-up 
   teardown, protection and recovery of PBB-TE ESPs and specifies the 
   specific TLVs for control of PBB-TE service instances.  
    
   When configuring a PBB-TE ESP with GMPLS, the ESP-MAC DA and ESP-VID 
   are carried in a generalized label object and are assigned hop by 
   hop but are invariant within a domain. This invariance is similar to 
   GMPLS operation in transparent optical networks. As is typical with 
   other technologies controlled by GMPLS, the data plane receiver must 
   accept, and usually assigns, labels from its available label pool. 
   This, together with the label invariance requirement mentioned 
   above, result in each PBB-TE label being a domain wide unique label, 
   with a unique ESP-VID + ESP-MAC DA, for each direction.    
    
   The following illustrates the identifiers for Labels and ESPs.  
     
   GMPLS Upstream Label          <ESP:MAC1(DA), VID1> (60 bits) 
   GMPLS Downstream Label        <ESP:MAC2(DA), VID2> (60 bits) 
   Upstream PBB-TE ESP 3-tuple   <ESP:MAC1, MAC2, VID1> (108 bits) 
   Downstream PBB-TE ESP 3-tuple <ESP:MAC2, MAC1, VID2> (108 bits) 
    
                         Table 1 Labels and ESPs 
    
   The MAC is domain wide unique in the network. PBB-TE defines the 
   tuple of <ESP-MAC DA, ESP-MAC SA, ESP-VID> as a unique connection 
   identifier in the data plane but the forwarding operation only uses 
   the ESP-MAC DA (DMAC) and the ESP-VID in each direction. Note that 
   the MAC addresses for PBB-TE are part of the Backbone Component 
   Relay (B-Component) and are associated with Provider addresses 
   corresponding to the Backbone Customer ports as described in section 
   3.2. The ESP-VID (VID) typically comes from a small number of VIDs 
   dedicated to PBB-TE MSTI. The ESP-VID (VID) can be reused across 
   ESPs. There is no requirement the ESP-VID for two ESPs that for a 
   PBB-TE Service instance be the same. 
    
   Several attributes may be associated with an Eth-LSP.  These are 
   reviewed in Section 3 of [ARCH]. Several other aspects of GMPLS 
   covered by [ARCH] also apply equally to PBB-TE.  This includes the 
   GMPLS routing and addressing model, link management, path 
   computation and selection, and multiple domains. 
    
 
3.1 Ethernet Service 
    
   Ethernet Switched Paths that are setup either by configuration or 
   signaling can be used to provide an Ethernet service to customers of 
   the Ethernet network.  The Metro Ethernet Forum has defined some 
 
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   services in [MEF.6] (e.g., Ethernet Private Line), and these are also 
   aligned with ITU-T G.8011-x Recommendations.  Of particular interest 
   are the bandwidth profile parameters in [MEF.10] and whose associated 
   bandwidth profile algorithm are based on [RFC4115] [RFC3270].  
   Consideration should be given to supporting these in any signaling 
   extensions for Ethernet LSPs. This will be addressed in a future 
   version of this specification. 
    
    
3.2 Addresses, Interfaces, and Labels 
    
   This specification uses an addressing scheme and a label space for 
   the ingress/egress connection; the hierarchical TE Router 
   ID/Interface ID and the Ethernet ESP-VID/ESP-MAC DA tuple or ESP-
   VID/Multicast MAC as a label space. This draft is intended to be 
   consistent with GMPLS addressing and Routing [ARCH]. 
    
    
   PBB-TE is defined for a PBB IB-Bridge. This is illustrated in Figure 
   1.  The Ethernet service is attached to a Customer Instance Port 
   (CIP) of the Backbone Service Instance (I-component) Relay. The CIP 
   is interfaced to a Virtual instance port (VIP) which is identified 
   with a configured service instance (I-SID) and attached to a Provider 
   Instance Port (PIP). The PIP is configured to be attached to a 
   customer Backbone port (CBP). (A point to point service instance is 
   illustrated. A point to multipoint service could allow more than one 
   CBP to be attached to a single PIP.) The CBP has a BMAC that defines 
   the MAC for the PBB-TE Service Instance. The B-Component relay adds 
   the ESP Header the ESP-MAC DA, ESP-MAC SA and the ESP-VID.  GMPLS is 
   being defined here to connect CPB MACs to signal the PBB-TE service 
   Instance before the association of ESP-MAC DA and ESP-MAC SA is 
   defined.   
    
   The diagram also shows the addition of a TE Router ID to the PBB 
   switch and the TE Link identifier to enable GMPLS. TE Links are not 
   associated with CPBs. TE Links are associated with PNPs. TE links are 
   associated with node identifiers of backbone edge bridges (BEB) and 
   backbone core bridges (BCB). CBPs are also associated with these node 
   ids.  For GMPLS the node IDs are expressed as IP addresses as TE-
   Router IDs. [ADDRESS] 
    
    
    
     









 
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                      Backbone Edge Bridge (BEB) 
     +------------------------------------------------------+ 
     |                    <TE - Router ID >                 | 
     |                                                      |    
     |  I-Component Relay             B-Component Relay     | 
     | +-----------------------+    +---------------------+ | 
     | |          +---+        |    |         B-VID       | | 
     | |          |VIP|        |    | +---+         +---+ | | <TE Link> 
     | |          +---+        |  +---|CBP|         |PNP|------ 
     | |                       |  | | +---+         +---+ | | 
     | |  +---+          +---+ |  | |                     | | 
    ------|CIP|          |PIP|----+ |                     | | 
     | |  +---+          +---+ |    |                     | | 
     | +-----------------------+    +---------------------+ | 
     |                                                      | 
     |                   PBB Edge Bridge                    | 
     +------------------------------------------------------+ 
     
     ^--------Configured--------------^  
                                      ^-GMPLS or Configured-.  
    
             Figure 2 Ethernet/GMPLS Addressing & Label Space 
    
    
    
    
    
        
       TE Router ID                     TE Router ID 
          |  (TE Link)                       | 
          V     |                            V          N=named port 
        +----+  |                         +-----+         <port index> 
        |    |  |    label=ESP:VID/MAC DA |     |         <MAC> 
        | PB |  V    label=ESP:VID/MMAC   |     |         <string> 
   -----N    N----------------------------N PBB N---------- 
        |    |                            |(MAC)|   \     
        |    |                            /     |     Customer   
        +----+                           /+-----+     Facing      
         BCB                       ESP:MAC  BEB       Ports 
    
             Figure 3 Ethernet/GMPLS Addressing & Label Space 
    
    
    
    
   For a GMPLS based system, the TE Router ID/logical port is the 
   logical signaling identifier for the control plane via which Ethernet 
   layer label bindings are solicited. In order to create a P2P path an 
   association must be made between the ingress and egress node.  The 
   actual label distributed via signaling and instantiated in the switch 
   forwarding tables identifies the upstream and downstream egress ESP-
   VID/ESP-MAC DA of the PBB-TE ESP (see Figure 4).  
    
 
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   GMPLS uses identifiers in the form of 32 bit numbers which are in the 
   IP address notation which may or may not be IP addresses.  The 
   provider MAC port addresses are exchanged by the LLDP [IEEE 802.1AB] 
   and by LMP [RFC4204] if supported. However these identifiers are 
   merely for link control and legacy Ethernet support and have local 
   link scope. Actual label assignment is performed by the ingress and 
   egress nodes using CPB MAC addresses. 
    
   A particular PNP would have:  
   - A VID/MAC 
   - An IP address, which is typically the TE router ID, plus a 32 bit 
   interface Identifier also call an unnumbered link.  
   - One (or more) Mnemonic String Identifiers 
    
   This multiple naming convention leaves the issue of resolving the set 
   given one of the port identifiers. On a particular node, mapping is 
   relatively straightforward.  Per [ARCH], standard GMPLS mechanisms 
   are used for signaling resolution. In so doing, the problem of 
   setting up a path is reduced to figuring out what switch supports an 
   egress CBP MAC address and then finding the corresponding egress IP 
   address and performing all signaling and routing with respect to the 
   egress.  
    
   There are several options to achieve this:  
   - Provisioning 
   - Auto discovery protocols that carry MAC address 
   - Augmenting Routing TE with MAC Addresses 
   - Name Servers with identifier/address registration 
   The specific procedures will be clarified in a subsequent version of 
   this document. 
    
    
4.  Specific Procedures 
    
4.1 P2P connections  
    
   The PBB-TE Service Instance is defined by the ESP 3-tuples for each 
   of the unidirectional ESPs. From a GMPLS control plane point of view 
   an Ethernet LSP MAY also be identified as any other LSP using the 5-
   tuple [Ip_Source_Sddr, Ip_Dest_Addr, LSP_Id, Tunnel_ID, 
   Extended_Tunnel_ID]. The ESP-VID and ESP-MAC DA tuple identifies the 
   forwarding multiplex at transit switches and a simple degenerate form 
   of the multiplex is a single P2P connection.  
    
   This results in unique labels end to end. The data streams MAY merge, 
   the forwarding entries MAY be shared but the headers are still unique 
   allowing the connection to be de-multiplexed downstream.     
    
   On the initiating and terminating nodes, a function administers the 
   ESP-VIDs associated with the ESP-MAC SA and ESP-MAC DA respectively.  
   PBB-TE is designed to be bidirectional and symmetrically routed just 
   like Ethernet. Therefore in PBB-TE, the packet ESP-MAC SA and ESP-

 
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   MAC DA pair is same in the forwarding path and the associated 
   reverse path except they are flipped in the reverse direction.  
    
   To initiate a bidirectional ESP-VID/ESP-MAC DA P2P or P2MP path, the 
   initiator of the PATH message uses procedures outlined in [RFC3473] 
   possibly augmented with [RFC4875], it: 
    
   1) Sets the LSP encoding type to Ethernet. 
         
   2) Sets the LSP switching type to 802_1 PBB-TE [IANA to define].  
         
   3) Sets the GPID to service type [IANA to define]. 
         
   4) Sets the UPSTREAM_LABEL to the ESP-VID/ESP-MAC SA tuple where the 
   ESP-VID is administered from the configured ESP-VID/ESP-MAC DA 
   range.  
    
   5) Optionally sets the LABEL_SET or SUGGESTED_LABEL if it chooses to 
   influence the choice of ESP-VID/ESP-MAC DA. 
    
   6) Optionally look at Call / Connection ID for Carrying I-SID.  
    
    
   Intermediate and egress node processing is not modified by this 
   document, i.e., is per [RFC3473] and, in the case of P2MP, as 
   extended in [RFC4875]. Note, as previously stated intermediate nodes 
   supporting the 802_1 switching type may not modify LABEL values. 
    
   The ESP-VID/ESP-MAC SA tuple contained in the UPSTREAM_LABEL is used 
   to create a static forwarding entry in the Filtering Database of 
   bridges at each hop for the upstream direction. This behavior is 
   inferred from the switching type which is 802_1 [IANA to define]. 
   The port derived from the RSVP_HOP object and the ESP-VID and ESP-
   MAC DA included in the label constitute the static entry.  
    
   At the destination, a ESP-VID is allocated in the local MAC range 
   for the ESP-MAC DA and the ESP-VID/ESP-MAC DA tuple is passed in a 
   LABEL object in the RESV message.  As with the Path message, 
   intermediate node processing is per [RFC3473] and [RFC4875], and the 
   LABEL object is passed on unchanged, upstream.  The ESP-VID/ESP-MAC 
   DA tuple contained in the LABEL Object is installed in the 
   forwarding table as a static forwarding entry at each hop. This 
   creates a bidirectional path as the PATH and RESV messages follow 
   the same path. 
    
4.1.1   Shared Forwarding 
    
   One capability of a connectionless Ethernet data plane is to reuse 
   destination forwarding entries for packets from any source within a 
   VLAN to a destination. When setting up P2P PBB-TE connections for 
   multiple sources sharing a common destination this capability MAY be 
   preserved provided certain requirements are met. We refer to this 
   capability as Shared Forwarding.  Shared forwarding is invoked based 
 
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   on policy when conditions are met.  It is a local decision by label 
   allocation at each end. Shared forwarding has no impact on the 
   actual paths setup, but it allows the reduction of forwarding 
   entries. Shared forwarding paths are identical to independently 
   routed paths with the exception that they share the same labels and 
   same path from the merge point.  
    
   To achieve shared forwarding, a Path computation engine [PATHCOMP] 
   should ensure the ERO is consistent with an existing path for the 
   shared segments. If a path satisfies the consistency check, the 
   upstream end of the signaling may chose to share an existing ESP-
   VID/ESP-MAC DA for the upstream traffic with an existing Eth-LSP.  
   The criteria for shared forwarding is the Eth-LSPs must share the 
   same destination port and the paths of the Eth-LSP share one or more 
   hops consecutively. Once the paths converge they must remain 
   converged. If no existing path has this behavior when a new path is 
   being created, the new path will be created without sharing either 
   by using another ESP-VID or another ESP-MAC DA or both.   
    
   In other words, shared forwarding is possible when paths share 
   segments either from the source or the destination. There is no 
   requirement that the paths share reservations or other attributes. 
   For the source, the UPSTREAM_LABEL is chosen to be the same as an 
   existing path that shares the ERO for some number of hops.  
   Similarly for the destination, shared forwarding is possible when an 
   existing path that shares segments with the new paths ERO, viewed 
   from the destination switch.  The downstream label in this case is 
   chosen to be the same as the existing path. In this manner shared 
   forwarding is a function that is controlled primarily by policy and 
   in combination with the local label allocation at the end points of 
   the path. 
    
4.1.2   P2P connections with shared forwarding 
    
   The ESP-VID/ESP-MAC DA MAY be considered to be a shared forwarding 
   identifier or label for a multiplex consisting of some number of P2P 
   connections distinctly identified by the MAC ESP-VID/ESP-MAC DA/ESP-
   MAC SA tuple. In some ways this is analogous to an LDP label merge 
   but in the shared forwarding case only the forwarding entry is 
   reused. Resources can continue to be allocated per LSP. 
    
   VLAN tagged Ethernet packets include priority marking. Priority bits 
   MAY be used to indicate class of Service (COS) and drop priority. 
   Thus, traffic from multiple COSs could be multiplexed on the same 
   Eth-LSP (i.e., similar to E-LSPs) and queuing and drop decisions are 
   made based on the p-bits. This means that the queue selection can be 
   done based on a per flow (i.e., Eth-LSP + priority) basis and is 
   decoupled from the actual steering of the packet at any given node.  
    
   A switch terminating an Eth-LSP will frequently have more than one 
   suitable candidate path and it may choose to share a forwarding entry 
   (common ESP-VID/ESP-MAC DA, unique ESP-MAC SA). It is a local 

 
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   decision of how this is performed but the best choice is a path that 
   maximizes the shared forwarding.  
    
   The concept of bandwidth management still applies equally well with 
   shared forwarding. As an example consider a PBB-TE edge switch that 
   terminates an Ethernet LSP with the following attributes: bandwidth 
   B1, ESP-MAC DA D, ESP-MAC SA S1, ESP-VID V. A request to establish an 
   additional Ethernet LSP with attributes (bandwidth B2, ESP-MAC DA D, 
   ESP-MAC SA S2, ESP-VID V) can be accepted provided there is 
   sufficient link capacity remaining. 
    
    
4.1.3  Dynamic P2P symmetry with shared forwarding 
    
   Similar to how a destination switch MAY select a ESP-VID/ESP-MAC DA 
   from the set of existing shared forwarding multiplexes rooted at the 
   destination node, the originating switch MAY also do so for the 
   reverse path. Once the initial ERO has been computed and the set of 
   existing Ethernet LSPs that include the target ESP-MAC DA have been 
   pruned, the originating switch may select the optimal (by whatever 
   criteria) existing shared forwarding multiplex for the new 
   destination to merge with and offer its own ESP-VID/ESP-MAC DA tuple 
   for itself as a destination.  
    
4.1.4   Planned P2P symmetry 
    
   Normally the originating switch will not have knowledge of the set of 
   shared forwarding paths rooted on the destination node. 
    
   Use of a Path Computation Server [PATHCOMP] or other planning style 
   of tool with more complete knowledge of the network configuration may 
   wish to impose pre-selection of shared forwarding multiplexes to use 
   for both directions. In this scenario the originating switch uses the 
   LABEL_SET and UPSTREAM_LABEL objects to indicate complete selection 
   of the shared forwarding multiplexes at both ends. This may also 
   result in the establishment of a new ESP-VID/ESP-MAC DA path as the 
   LABEL_SET object may legitimately refer to a path that does not yet 
   exist.  
    
4.1.5   P2P Path Maintenance 
    
   Make before break procedures can be employed to modify the 
   characteristics of a P2P Ethernet LSP. As described in [RFC3209], 
   the LSP ID in the sender template is updated as the new path is 
   signaled. The procedures (including those for shared forwarding) are 
   identical to those employed in establishing a new LSP, with the 
   extended tunnel ID in the signaling exchange ensuring that double 
   booking of the associated resources does not occur. 
    
   Where individual paths in a protection group are modified, signaling 
   procedures may be combined with Protection Switching (PS) 
   coordination to administratively force PS switching operations such 
   that modifications are only ever performed on the protection path. 
 
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4.2 P2MP Signaling 
    
   Note specifics for P2MP paths are being defined. This section will 
   be updated to align with the PBB-TE specification [IEEE 802.1Qay]. 
    
   To initiate a P2MP VID/Multicast MAC (MMAC) path the initiator of 
   the PATH message uses procedures outlined in [RFC3473] and 
   [RFC4875]. A P2MP tree consists of a VID tree or MMAC tree in the 
   forward direction (from root to leaves) and a set of P2P paths 
   running on identical paths from Tree to root in the reverse 
   direction. The result is a composite path with Multicast VID/ESP-
   MMAC DA labels with a single ESP-MMAC DA in the forward direction 
   and a symmetric unidirectional ESP-VID/ESP-MAC DA label in the 
   reverse direction: 
    
   1-4) Same points as P2P paths previously specified.  
    
   5) Sets the downstream label as the Multicast VID/ESP-MMAC DA.  
    
   6) VID translation may optionally be permitted on a local basis 
   between two switches by a downstream switch replying with a 
   Multicast VID/ESP-MMAC DA other than the LABEL_SET. The upstream 
   switch then sets a VID translation on the port associated with the 
   label to allow VID translation. This flexibility allows the tree to 
   be constructed with out having to worry about colliding with another 
   tree using the same VID. (Inclusion of this point is TBD by [IEEE 
   802.1Qay]) 
    
4.3 P2MP VID/ESP-MAC DA Connections 
    
4.3.1 Setup procedures 
    
   The group ESP-MMAC DA is administered from a central pool of 
   multicast addresses and the VLAN selected from the PBB-TE MSTI range. 
   The P2MP tree is constructed via incremental addition of leaves to 
   the tree in signaling exchange where the root is the originating 
   switch (as per (RFC4875). The multicast VID/ESP-MAC DA is encoded in 
   the LABEL_SET (as a member of one) object using the Ethernet label 
   encoding. 
    
   Where a return path is required the unicast MAC corresponding to the 
   originating interface and a VID selected from the configured VID/ESP-
   MAC DA range is encoded as an Ethernet label in the UPSTREAM_LABEL 
   object. 
    
4.3.2   Maintenance Procedures 
 
   Maintenance and modification to a P2MP tree can be achieved by a 
   number of means. The preferred technique is to modify existing VLAN 
   configuration vs. assignment of a new label and completely 
   constructing a new tree.  
    
 
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   Make before break on a live tree reusing existing label assignments 
   requires a 1:1 or 1+1 construct. The protection switch state of the 
   traffic is forced on the working tree and locked (PS not allowed) 
   while the backup tree is modified. Explicit path tear of leaves to 
   be modified is required to ensure no loops are left behind as 
   artifacts of tree modification. Once modifications are complete, a 
   forced switch to the backup tree occurs and the original tree may be 
   similarly modified. This also suggests that 1+1 or 1:1 resilience 
   can be achieved for P2MP trees for any single failure (switch on any 
   failure and use restoration techniques to repair the failed tree). 
    
    
4.4 Ethernet Label 
    
   The Ethernet label is a new generalized label with a suggested 
   format of: 
    
    
       0                   1                   2                   3 
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0 0 0 0|      ESP VID          |    ESP MAC (highest 2 bytes)  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                            ESP MAC                            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   This format can be used to carry P2P and P2MP labels. For P2P labels 
   the fields specify ESP <VID, MAC DA>. The semantics for P2MP label o 
   using a MMAC DA is that that the label is passed unchanged. This 
   label is also a domain wide label.  This has similarity to the way 
   in which a wavelength label is handled at an intermediate switch 
   that cannot perform wavelength conversion, and is described in 
   [RFC3473]. The option to allow just a Multicast VID to be signaled 
   without a MAC (A zero MAC) is for cases where a single VID is 
   desired to be signaled for P2MP trees in cases where a multicast MAC 
   is not desired. 
    
   These domain wide labels are allocated to switches that control the 
   assignment of labels. There are two options for Ethernet MAC based 
   domain wide unique labels. One option is to allocate the ESP-MAC DAs 
   from globally unique addresses assigned to the either the switch 
   manufacturer or the owner. The other option is to use ESP-MAC DAs 
   out of the local admin space and ensue these labels are unique 
   within the domain. This local ESP-MAC DA space does not have to be 
   globally unique because the labels are only valid within a single 
   provider domain. 
    
   In the case of local label allocation there is less administrative 
   overhead to allocate labels. However when using configuration, a 
   tool would have to perform a consistency check to make sure that 
   labels were unique. When using GMPLS signaling it is assumed a 
   unique pool of labels would be assigned to each switch. The ESP-MAC 
   DA addresses are domain wide unique and so is the combination of ESP 
 
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   <VID, MAC DA>. It is intended that the ESP <VID, MAC DA> be only 
   used by one destination. However, should an error occur and a 
   somehow a duplicate label be assigned to one or more destination 
   switches GMPLS signaling procedures would allow the first assignment 
   of the label and prevent any duplicate label from colliding. If a 
   collision occurs an alarm would be generated. In fact some of these 
   procedures have been defined in GMPLS control of photonic networks 
   where a lambda may exist as a form of domain wide label. 
    
    
4.5 OAM MEP ID and MA ID synchronization  
    
   This section is aligned with [IEEE 802.1Qay]. At present it Ethernet 
   OAM is signaled in Ethernet packet data units.   
    
   The Maintenance end point IDs (MEP IDs) and maintenance association 
   IDs for the switched path endpoints can be synchronized using the 
   ETH-MCC (maintenance communication channel) transaction set once the 
   switched path has been established. 
    
   MEPs are located at the endpoints of the Ethernet LSP. Typical 
   configuration associated with a MEP is Maintenance Domain Name, 
   Short Maintenance Association Name, and MA Level, MEP ID, and CCM 
   transmission rate (when ETH-CC functionality is desired). As part of 
   the synchronization, it is verified that the Maintenance Domain 
   Name, Short Maintenance Association Name, MA Level, and CCM 
   transmission rate are the same. It is also determined that MEP IDs 
   are unique for each MEP. 
    
   Besides the unicast CCM functionality, the PBB-TE MEPs can also 
   offer the LBM/LBR and LMM/LMR functionalities for on-demand 
   connectivity verification and loss measurement purposes. 
    
4.6 Protection Paths 
    
   The IEEE is currently defining protection procedures for PBB-TE 
   [IEEE 802.1Qay]. This section will be updated when these procedures 
   are documented.  
    
   When protection is used for path recovery it is required to 
   associate the working and protection paths into a protection group. 
   This is achieved as defined in [RFC4872] and [RFC4873] using the 
   ASSOCIATION and PROTECTION objects. Protection may be used for P2P 
   VID/ESP-MAC DA, P2MP VID/ESP-MAC DA and P2MP VID configured modes of 
   operation. The 'P' bit in the protection object indicates the role 
   (working or protection) of the LSP currently being signaled. 
    
   If the initiating switch wishes to use G.8031 [G-8031] data plane 
   protection switching coordination (vs. control plane notifications), 
   it sets the N bit to 1 in the protection object. This must be 
   consistently applied for all paths associated as a protection group. 
    

 
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   If the terminating switch does not support G.8031, the error 
   "Admission Control Failure/Unsupported Notification Type" is used.  
 
5. Error conditions 
    
   The following errors have been identified as being unique to these 
   procedures and in addition to those already defined. This will be 
   addressed in a proper IANA considerations section in a future 
   version of the document: 
    
5.1 Invalid ESP-VID value for PBB-TE MSTI range 
    
   The originator of the error is not configured to use the ESP-VID 
   value in conjunction with GMPLS signaling of <ESP: VID, MAC DA > 
   tuples. This may be any switch along the path. 
    
5.2 Invalid MAC Address 
    
   The MAC address is out of a reserved range that cannot be used by 
   then node which is processing the address. While almost all MAC 
   addresses are valid there are a small number of reserved MAC 
   addresses.   
     
5.3 Invalid ERO for UPSTREAM_LABEL Object 
     
    The ERO offered has discontinuities with the identified ESP-
    VID/ESP-MAC DA path in the UPSTREAM_LABEL object. 
     
5.4 Invalid ERO for LABEL_SET Object 
    
   The ERO offered has discontinuities with the identified ESP-VID/ESP-
   MAC DA path in the LABEL_SET object.  
    
5.5 Switch is not ESP P2MP capable 
     
    This error may arise only in P2MP VID Tree allocation. 
    
5.6 Invalid ESP-VID in UPSTREAM_LABEL object 
     
    The ESP-VID in the UPSTREAM_LABEL object for the "asymmetrical ESP-
    VID" P2MP tree did not correspond to the ESP-VID used in previous 
    transactions. 
     
6. Deployment Scenarios  
    
   This technique of GMPLS controlled Ethernet switching is applicable 
   to all deployment scenarios considered by the design team [CCAMP-
   ETHERNET]. 
     
     
7. Security Considerations 
    

 
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   The architecture assumes that the GMPLS controlled Ethernet subnet 
   consists of trusted devices and that the UNI ports to the domain are 
   untrusted. Care is required to ensure untrusted access to the trusted 
   domain does not occur. Where GMPLS is applied to the control of VLAN 
   only, the commonly known techniques for mitigation of Ethernet DOS 
   attacks may be required on UNI ports. 
    
8. IANA Considerations 
    
   New values are required for signaling and error codes as indicated. 
   This section will be completed in a later version. 
    
9. References 
    
9.1  Normative References 
 
   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate  
      Requirement Levels", BCP 14, RFC 2119, March 1997.  
    
   [ARCH] Fedyk, D. Berger, L., Andersson L., "GMPLS Ethernet Label 
      Switching Architecture and Framework", work in progress.   
    
   [RFC3473] Berger, L. et.al., "Generalized Multi-Protocol Label  
      Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic  
      Engineering (RSVP-TE) Extensions", IETF RFC 3473, January 2003. 
    
    
9.2  Informative References 
    
   [IEEE 802.1Qay] "IEEE standard for Provider Backbone Bridges Traffic 
      Engineering", work in progress. 
    
   [RFC4115] Aboul-Magd, O. et.al. "A Differentiated Service Two-Rate,  
      Three-Color Marker with Efficient Handling of in-Profile Traffic",  
      IETF RFC 4115, July 2005 
    
   [G-8031] ITU-T Draft Recommendation G.8031, Ethernet Protection 
      Switching. 
     
   [IEEE 802.1AB] "IEEE Standard for Local and Metropolitan Area  
      Networks, Station and Media Access Control Connectivity  
      Discovery". 
                          
   [IEEE 802.1ag] "IEEE Draft Standard for Connectivity Fault 
      Management", work in progress. 
    
   [IEEE 802.1ah] "IEEE standard for Provider Backbone Bridges", work in 
      progress. 
    
   [RFC4204] Lang. J. Editor, "Link Management Protocol (LMP)" RFC4204, 
      October 2005 
    

 
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   [MEF.6] The Metro Ethernet Forum MEF 6 (2004), "Ethernet Services 
      Definitions - Phase I". 
 
   [MEF.10] The Metro Ethernet Forum MEF 10 (2004), "Ethernet Services 
      Attributes Phase 1". 
    
   [RFC3270] Le Faucheur, F. et.al., "Multi-Protocol Label Switching 
      (MPLS) Support of Differentiated Services" IETF RFC 3270, May 
      2002. 
    
   [RFC4875] Aggarwal, R. Ed., "Extensions to RSVP-TE for Point to 
      Multipoint TE LSPs", IETF RFC 4875, May 2007 
    
   [PATHCOMP] Farrel, A. et.al., "Path Computation Element (PCE) 
      Architecture", work in progress. 
    
   [RFC3985] Bryant, S., Pate, P. et al., "Pseudo Wire Emulation Edge-
      to Edge (PWE3) Architecture", IETF RFC 3985, March 2005. 
    
   [RFC4872] Lang et.al., "RSVP-TE Extensions in support of End-to-End 
      Generalized Multi-Protocol Label Switching (GMPLS)-based Recovery 
      ", RFC 4872, May 2007. 
    
   [RFC4873] Berger, L. et.al.,"MPLS Segment Recovery", RFC 4873, May 
      2007. 
    
   [RFC3209] Awduche et.al., "RSVP-TE: Extensions to RSVP for LSP  
      Tunnels, IETF RFC 3209, December 2001. 
    
   [Y.1731] ITU-T Draft Recommendation Y.1731(ethoam), " OAM Functions 
      and Mechanisms for Ethernet based Networks ", work in progress. 
    
   [ADDRESS] Shimoto, K., Papneja, R., Rabbat, R., "Use of Addresses in 
      Generalized Multi-Protocol Label Switching (GMPLS) Networks", 
      work in progress.  
    
   [CCAMP-ETHERNET] Papadimitriou, D. et.al, "A Framework for 
      Generalized MPLS (GMPLS) Ethernet", internet draft, draft-
      papadimitriou-ccamp-gmpls-ethernet-framework-00.txt, June 2005  
    
    
10.  Author's Address 
 
   Don Fedyk                     
   Nortel Networks               
   600 Technology Park Drive     
   Billerica, MA, 01821    
   Email: dwfedyk@nortel.com 
    
   David Allan                   
   Nortel Networks                
   3500 Carling Ave.             
   Ottawa, Ontario, CANADA 
 
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   Email: dallan@nortel.com 
    
   Himanshu Shah                 
   Ciena                         
   35 Nagog Park,                
   Acton, MA 01720  
   Email: hshah@ciena.com                
    
   Nabil Bitar                   
   Verizon,                      
   40 Sylvan Rd.,  
   Waltham, MA 02451 
   Email: nabil.n.bitar@verizon.com 
    
   Attila Takacs                 
   Ericsson  
   1. Laborc u.  
   Budapest, HUNGARY 1037 
   Email: attila.takacs@ericsson.com     
    
   Diego Caviglia                
   Ericsson 
   Via Negrone 1/A 
   Genoa, Italy 16153 
   Email: diego.caviglia@ericsson.com 
                                 
   Alan McGuire                  
   BT Group PLC                  
   OP6 Polaris House,            
   Adastral Park, Martlesham Heath,  
   Ipswich, Suffolk, IP5 3RE, UK 
   Email: alan.mcguire@bt.com 
    
   Nurit Sprecher                
   Nokia Siemens Networks,       
   GmbH & Co. KG 
   COO RTP IE Fixed  
   3 Hanagar St. Neve Ne'eman B, 
   45241 Hod Hasharon, Israel 
   Email: nurit.sprecher@nsn.com 
    
   Lou Berger                    
   LabN Consulting, L.L.C.       
   Phone: +1-301-468-9228  
   Email: lberger@labn.net 
    
11. Intellectual Property Statement 
    
   The IETF takes no position regarding the validity or scope of any 
   Intellectual Property Rights or other rights that might be claimed to 
   pertain to the implementation or use of the technology described in 
   this document or the extent to which any license under such rights 
   might or might not be available; nor does it represent that it has 
 
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   made any independent effort to identify any such rights.  Information 
   on the procedures with respect to rights in RFC documents can be 
   found in BCP 78 and BCP 79. 
    
   Copies of IPR disclosures made to the IETF Secretariat and any 
   assurances of licenses to be made available, or the result of an 
   attempt made to obtain a general license or permission for the use of 
   such proprietary rights by implementers or users of this 
   specification can be obtained from the IETF on-line IPR repository at 
   http://www.ietf.org/ipr. 
    
   The IETF invites any interested party to bring to its attention any 
   copyrights, patents or patent applications, or other proprietary 
   rights that may cover technology that may be required to implement 
   this standard.  Please address the information to the IETF at 
   ietf-ipr@ietf.org. 
    
12. Disclaimer of Validity 
    
   "This document and the information contained herein are provided on 
   an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE 
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE 
   IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL 
   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY 
   WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY 
   RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A 
   PARTICULAR PURPOSE. 
    
    
13. Copyright Statement 
    
   Copyright (C) The IETF Trust (2007).  
    
   This document is subject to the rights, licenses and restrictions 
   contained in BCP 78, and except as set forth therein, the authors 
   retain all their rights.  
    
    
14. Acknowledgments 
    
   The authors would like to thank Dinesh Mohan, Nigel Bragg, Stephen 
   Shew and Sandra Ballarte for their contributions to this document. 











 
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Appendix A      
    
Rational and mechanism for PBB_TE Ethernet Forwarding  
    
   This appendix describes work currently being undertaken in the 801.1 
   PBB-TE [IEEE 802.1Qay] project. This information is for reference 
   only and will be removed when 802.1Qay becomes mature. This text 
   captures some of the original rational for changing Ethernet 
   forwarding. The PBB-TE [IEEE 802.1Qay] document simply documents the 
   PBB-TE data plane.    
    
   Ethernet as specified today is a complete system consisting of a 
   data plane and a number of control plane functions. Spanning tree, 
   data plane flooding and MAC learning combine to populate forwarding 
   tables and produce resilient any-to-any behavior in a bridged 
   network.  
    
   Ethernet consists of a very simple and reliable data plane that has 
   been optimized and mass produced. By simply disabling some Ethernet 
   control plane functionality, it is possible to employ alternative 
   control planes and obtain different forwarding behaviors. 
    
   Customer     Provider        Provider         
   Bridge/      Bridge          Backbone                                         
                                Bridge 
        
   C-MAC/C-VID------------------802.1Q -------------------C-MAC-CVID 
                S-VID-----------802.1ad------------S-VID 
                        B-MAC---802.1ah---B-MAC 
                        B-VID---802.1ah---B-VID 
    
                     Figure 1 802.1 MAC/VLAN Hierarchy 
    
   Recent works in IETF Pseudo Wire Emulation [RFC3985] and IEEE 802 
   are defining a separation of Ethernet functions permitting an 
   increasing degree of provider control. The result is that the 
   Ethernet service to the customer appears the same, yet the provider 
   components and behaviors have become decoupled from the customer 
   presentation and the provider has gained control of all VID/DMAC 
   endpoints. 
     
   One example of this is the 802.1ah work in hierarchical bridging 
   whereby customer Ethernet frames are fully encapsulated into a 
   provider Ethernet frame, isolating the customer VID/DMAC space from 
   the provider VID/DMAC space. In this case, the forwarding behavior 
   of the of the Backbone MAC in the provider's network is as per 
   802.1Q. 
    
   The Ethernet data plane provides protocol multiplexing via the ether 
   type field which allows encapsulation of different protocols 
   supporting various applications. More recently, the Carrier Ethernet 
   effort has created provider and customer separation that enables 
    
    
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   another level of multiplexing. This in effect creates provider MAC 
   endpoints in the Ethernet sub-network controlled by the provider. In 
   this appendix we concentrate on the provider solutions and therefore 
   subsequent references to VLAN, VID and MAC refer to those under 
   provider control, be it in the backbone layer of 802.1ah. The 
   Customer Ethernet service is the same native Ethernet service with 
   functions such as bridging, learning and spanning trees all 
   functioning over the provider infrastructure. 
    
   Bridging offers a simple solution for any-to-any connectivity within 
   a VLAN partition via the Spanning tree, flooding and MAC learning. 
   Spanning tree provides some unnecessary capabilities for P2P 
   services and since the Spanning tree must interconnect all MACs with 
   the same VLAN IDs (VIDs) it consumes a scarce resource (VIDs). In 
   this document we present that it is easier to modify Ethernet to 
   scale engineered P2P services and this is the approach we take with 
   PBB-TE. (The number of usable VLANs IDs in conventional Ethernet 
   bridging is constrained to 4094, therefore the use of VLAN only 
   configuration for all forwarding could be limited for some 
   applications where large number of P2P connections are required.) 
   This is because in Ethernet, each Spanning tree is associated with 
   one or more VLAN IDs. Also Port membership in a VLAN is configured 
   which controls the connectivity of all MAC interfaces participating 
   in the VLAN.  
    
   The roots for PBB-TE capability exist in the Ethernet management 
   plane. The management of Ethernet switches provides for static 
   configuration of Ethernet forwarding. The Ethernet Control plane 
   allows for forwarding entries that are statically provisioned or 
   configured. In this document we are expanding the meaning of 
   "configured" from an Ethernet Control plane sense to mean either 
   provisioned, or controlled by GMPLS. The connectivity aspects of 
   Ethernet forwarding is based upon VLANs and MAC addresses. In other 
   words the VLAN + DMAC are an Ethernet Label that can be looked up at 
   each switch to determine the egress link (or links in the case of 
   link aggregation).  
                      
   This is a finer granularity than traditional VLAN networks since 
   each P2P connection is independent. By provisioning MAC addresses 
   independently of Spanning tree in a domain, both the VLAN and the 
   VLAN/DMAC configured forwarding can be exploited. This greatly 
   extends the scalability of what can be achieved in a pure Ethernet 
   bridged sub network. 
    
   The global/domain wide uniqueness and semantics of MAC addresses as 
   interface names or multicast group addresses has been preserved. (In 
   Ethernet overlap of MAC addresses across VLANs is allowed. However 
   for PBB-TE MAC addresses should be unique for all VLANs assigned to 
   PBB-TE. With PBB-TE it is an operational choice if the operator uses 
   PBT-TE labels out of the global MAC address space or the local admin 
   space.) We then redefine the semantics associated with 
   administration and uses of VLAN values for the case of explicit 
   forwarding such as you get with statically configured Ethernet. 
 
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   The PBB_TE is Ethernet Forwarding where configured VID + DMAC 
   provide a forwarding table that is consistent with existing PBB and 
   Ethernet switching. At the same time it provides domain wide labels 
   that can be controlled by a common GMPLS control plane. This makes 
   GMPLS control and resource management procedures ideal to create 
   paths. The outcome is that the GMPLS control plane can be utilized 
   to set up the following atomic modes of connectivity: 
    
          1) P2P connectivity and MP2P multiplexed connectivity based 
             on configuration of unicast MAC addresses in conjunction 
             with a VID from a set of pre-configured VIDs. 
          2) P2MP connectivity based on configuration of multicast MAC 
             address in conjunction with a VID from a set of pre-
             configured VIDs. This corresponds to (Source, Group) or 
             (S,G) multicast. 
          3) P2MP connectivity based on configuration of VID port 
             membership. This corresponds to (S,*) or (*,*) multicast 
             (where * represents the extent of the VLAN Tree). 
          4) MP2MP connectivity based on configuration of VID port 
             membership (P2MP trees in which leaves are permitted to 
             communicate). Although, we caution that this approach 
             poses resilience issues (discussed in section 5) and hence 
             is not recommended. 
    
    
   The modes above are not completely distinct. Some modes involve 
   combinations of P2P connections in one direction and MP connectivity 
   in the other direction.  Also, more than one mode may be combined in 
   a single GMPLS transaction. One example is the incremental addition 
   of a leaf to a P2MP tree with a corresponding MP2P return path 
   (analogous to a root initiated join).  
    
   In order to realize the above connectivity modes, a partition of the 
   VLAN IDs from traditional Ethernet needs to be established. The 
   partition allows for a pool of Ethernet labels for manual 
   configuration and/or for GMPLS control plane usage. The VID 
   partition actually consists of a "configured VID/DMAC range" and 
   "configured VID range" since in some instances the label is a VID/ 
   DMAC and sometimes the label is a VID/Multicast DMAC. 
     
A 1. Overview of configuration of VID/DMAC tuples 
    
   Statically configured MAC and VID entries are a complete 60 bit 
   lookup. The basic operation of an Ethernet switch is filtering on 
   VID and forwarding on DMAC. The resulting operation is the same as 
   performing a full 60 bit lookup (VID (12) + DMAC(48)) for P2P 
   operations, only requiring uniqueness of the full 60 bits for 
   forwarding to resolve correctly. This is an Ethernet domain wide 
   label.  
    
   Complete route freedom is available for each domain wide label (60 
   bit VLAN/DMAC tuple) and the ability to define multiple connectivity 
 
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   instances or paths per DMAC for each of the VIDs in the "configured 
   VID/DMAC range".  
    
   The semantics of MAC addresses are preserved, and simply broaden the 
   potential interpretations of VLAN ID from spanning tree identifier 
   to topology instance identifier. Therefore, operation of both 
   standard bridging and configured unicast/multicast operation is 
   available side by side. The VID space is partitioned and a range of 
   VIDs is allocated(say 'n' VIDs) as only significant when combined 
   with a configured DMAC address (the aforementioned "configured 
   VID/DMAC range" of VIDs). A VID in that range is considered as an 
   individual connectivity instance identifier for a configured P2P 
   path terminating at the associated DMAC address. Or in the case of 
   P2MP, a P2MP multicast tree corresponding to the destination 
   multicast group address. Note that this is destination based 
   forwarding consistent with how Ethernet works today. The only thing 
   changed is the mechanism of populating the forwarding tables.  
    
   Ethernet MAC addresses are typically globally unique since the 48 
   bits consists of 24 bit Organizational Unique Identifier and a 24 
   bit serial number. There is also a bit set aside for Multicast and 
   for local addresses out of the OUI field. We define domain wide as 
   within a single organization, or more strictly within a single 
   network within an organization. For provider MAC addresses that will 
   only be used in a domain wide sense we can define MAC addresses out 
   of a either the local space or the global space since they both have 
   the domain wide unique property. When used in the context of GMPLS, 
   it is useful to think of a domain wide pool of labels where switches 
   are assigned a set of MAC addresses. These labels are assigned 
   traffic that terminates on the respective switches.  
    
   It is also worth noting that unique identification of source in the 
   form of the ESP-MAC SA is carried e2e in the MAC header. So although 
   we have a 60 bit domain wide unique label, it may be shared by 
   multiple sources and the full connection identifier for an 
   individual P2P instance is 108 bits (ESP-MAC SA, VID and DMAC). The 
   ESP-MAC SA is not referenced in forwarding operations but it would 
   allow additional context for tracing or other operations at the end 
   of the path.   
    
   For multicast group addresses, the VID/DMAC concatenated label can 
   be distributed by the source but label assignment (as it encodes 
   global multicast group information) requires coordination within the 
   GMPLS controlled domain. 
    
   As mentioned earlier, this technique results in a single unique and 
   invariant identifier, in our case a VID/DMAC label associated with 
   the path termination or the multicast group.  There can be up to 
   4094 labels to any one MAC address.  However, practically, from 
   Ethernet network wide aspect; there would be only a handful of VLANs 
   allocated for PBB-TE. In addition, all 48 bits are not completely 
   available for the MAC addresses.  One way to maximize the space is 
   to use the locally administered space. This is a large number for 
 
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   P2P applications and even larger when shared or multiplexed 
   forwarding is leveraged. In practice, most network scaling 
   requirements may be met via allocation of only a small portion of 
   the VID space, to the configured VID/DMAC range. The result is 
   minimal impact on the number of remaining bridging VLANs that can be 
   concurrently supported.  
    
   In order to use this unique 60 bit label, we disable the normal 
   mechanisms by which Ethernet populates the forwarding table for the 
   allocated range of VIDs. When a path is setup, for a specific label 
   across a contiguous sequence of Ethernet switches, a unidirectional 
   connection is the functional building block for an Ethernet Label 
   Switched path (Eth-LSP).  
    
   In P2P mode a bidirectional path is composed of two unidirectional 
   paths that are created with a single RSVP-TE session. The technique 
   does not require the VID to be common in both directions. However, 
   keeping in line with regular Ethernet these paths are symmetrical 
   such that a single bidirectional connection is composed of two 
   unidirectional paths that have common routing (i.e. traverse the 
   same switches and links) in the network and hence share the same 
   fate.  
    
   In P2MP mode a bidirectional path is composed of a unidirectional 
   multicast tree and a number of P2P paths from the leaves of the tree 
   to the root. Similarly these paths may have bandwidth and must have 
   common routing as in the P2P case.  
    
   There are a few modifications required to standard Ethernet to make 
   this approach robust: 
    
   1. In Standard Ethernet, discontinuities in forwarding table 
   configuration in the path of a connection will normally result in 
   packets being flooded as "unknown". For configured operation (e.g. 
   PBB-TE), unknown addresses are indicative of a fault or 
   configuration error and the flooding of these is undesirable in 
   meshed topologies. Therefore flooding of "unknown" unicast/multicast 
   MAC addresses must be disabled for the "configured VID/DMAC range".  
    
   2. MAC learning is not required, and although it will not interfere 
   with management/control population of the forwarding tables, since 
   static entries are not overridden, it appears prudent to explicitly 
   disable MAC learning for the configured VID/DMAC and VID range. 
    
   3. Spanning tree is disabled for the allocated VID/DMAC and VID 
   range and port blocking must be disabled to achieve complete 
   configured route freedom. As noted earlier, it is a control plane 
   requirement to ensure configured paths are loop free.  
    
   All three modifications described above are within the scope of 
   acceptable configuration options defined in IEEE802.1Q 
   specification. 
    
 
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A 2.    Overview of configuration of VID port membership 
    
   Procedures almost identical to that for configuration of P2P 
   VID/DMAC tuples can also be used for the incremental configuration 
   of P2MP VID trees. For the replication of forwarding in this case 
   the label is common for the multipoint destinations. The MAC field 
   is set to multicast address and is common to the multicast 
   community. The VID is a distinguisher common to the multicast 
   community. The signaling procedures are as per that for [RFC4875]. 
    
   Since VID translation is relatively new and is not a ubiquitously 
   deployed capability, we consider a VID to be a domain global value. 
   Therefore, the VID value to be used by the originating switch may be 
   assigned by management and nominally is required to be invariant 
   across the network. The ability to indicate permissibility of 
   translation will be addressed in a future version of the document. 
    
   A procedure known as "asymmetrical VID" may be employed to constrain 
   connectivity (root to leaves, and leaves to root only) when switches 
   also support shared VLAN learning (or SVL). This would be consistent 
   with the root as a point of failure.  
    
A 3. OAM Aspects 
    
   Robustness is enhanced with the addition of data plane OAM to 
   provide both fault and performance management.  
    
   For the configured VID/DMAC unicast mode of behavior, the hardware 
   performs unicast packet forwarding of known MAC addresses exactly as 
   Ethernet currently operates. The OAM currently defined, [802.1ag and 
   Y.1731] can also be reused without modification of the protocols. 
   However currently if the VID for PBB-TE is different in each 
   direction some modification of the OAM may be required.   
    
   An additional benefit of domain wide path identifiers, for data 
   plane forwarding, is the tight coupling of the 60 bit unique 
   connection ID (VID/DMAC) and the associated OAM packets. It is a 
   simple matter to determine a broken path or misdirected packet since 
   the unique connection ID cannot be altered on the Eth-LSP. This is 
   in fact one of the most powerful and unique aspects of the domain 
   wide label for any type of rapid diagnosis of the data plane faults. 
   It is also independent of the control plane so it works equally well 
   for provisioned or GMPLS controlled paths.  
    
   Bidirectional transactions (e.g. ETH-LB) and reverse direction 
   transactions MAY have a different VID for each direction. PBB-TE is 
   specifying this aspect of CFM. 
    
   For configured multicast VID/DMAC mode, the current versions of 
   802.1ag and Y.1731] make no representation as to how PDUs which are 
   not using unicast addresses or which use OAM reserved multicast 

 
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   addresses are handled. Therefore this specification makes no 
   representation as to whether such trees can be instrumented. 
    
   When configured VID mode of operation is used PBB-TE can be forced 
   to use the same VID in both directions, emulating the current 
   Ethernet data plane and the OAM functions as defined in the current 
   versions of 802.1ag and Y.1731 can be used with no restriction. 
    
A 4. QOS Aspects 
    
   Ethernet VLAN tags include priority tagging in the form of the 
   802.1p priority bits. When combined with configuration of the paths 
   via management or control plane, priority tagging produces the 
   Ethernet equivalent of an MPLS-TE E-LSPs [RFC3270]. Priority tagged 
   Ethernet PDUs self-identify the required queuing discipline 
   independent of the configured connectivity.  
    
   It should be noted that the consequence of this is that there is a 
   common COS model across the different modes of configured operation 
   specified in this document. 
    
   The actual QOS objects required for signaling will be in a future 
   version of this memo. 
    
A 5.  Resiliency Aspects 
    
A 5.1. E2E Path protection 
 
   One plus One(1+1) protection is a primary LSP with a disjoint 
   dedicated back up LSP. One for one (1:1) protection is a primary LSP 
   with a disjoint backup LSP that may share resources with other LSPs. 
   One plus One and One for One Automatic Protection Switching 
   strategies are supported. Such schemes offer: 
          1) Engineered disjoint protection paths that can protect both 
             directions of traffic. 
          2) Fast switchover due to tunable OAM mechanisms.  
          3) Revertive path capability when primary paths are restored. 
          4) Option for redialing paths under failure.  
    
   Specific procedures for establishment of protection paths and 
   associating paths into "protection groups" are TBD. 
    
   Note that E2E path protection is able to respond to failures with a 
   number of configurable intervals. The loss of CCM OAM frames in the 
   data plane can trigger paths to switch. In the case of CCM OAM 
   frames, the detection time is typically 3.5 times the CCM interval 
   plus the propagation delay from the fault.   
    
    




 
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