GMPLS Ethernet UNI: Generalized MPLS (GMPLS) Support for Metro Ethernet Forum and G.8011 User Network Interface (UNI)

Internet Engineering Task Force (IETF)                         L. Berger
Request for Comments: 6005                                          LabN
Category: Standards Track                                       D. Fedyk
ISSN: 2070-1721                                           Alcatel-Lucent
                                                            October 2010


       Generalized MPLS (GMPLS) Support for Metro Ethernet Forum
                and G.8011 User Network Interface (UNI)

Abstract

   This document describes a method for controlling two specific types
   of Ethernet switching via a GMPLS-based User Network Interface (UNI).
   This document supports the types of switching required by the
   Ethernet services that have been defined in the context of the Metro
   Ethernet Forum (MEF) and International Telecommunication Union (ITU)
   G.8011.  This document is the UNI companion to "Generalized MPLS
   (GMPLS) Support for Metro Ethernet Forum and G.8011 Ethernet Service
   Switching".  This document does not define or limit the underlying
   intra-domain or Internal NNI (I-NNI) technology used to support the
   UNI.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6005.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Overview ...................................................4
      1.2. Conventions Used in This Document ..........................5
   2. Common Signaling Support ........................................5
      2.1. UNI Addressing .............................................5
      2.2. Ethernet Endpoint (UNI) Identification .....................6
           2.2.1. Address Resolution ..................................6
      2.3. Connection Identification ..................................7
   3. EPL Service .....................................................7
   4. EVPL Service ....................................................7
      4.1. Egress VLAN ID Control and VLAN ID Preservation ............7
   5. IANA Considerations .............................................8
      5.1. Error Value: Routing Problem/Unknown Endpoint ..............8
   6. Security Considerations .........................................8
   7. References ......................................................8
      7.1. Normative References .......................................8
      7.2. Informative References .....................................9
   Acknowledgments ....................................................9

1.  Introduction

   [MEF6] and [G.8011] provide parallel frameworks for defining network-
   oriented characteristics of Ethernet services in transport networks.
   The framework discusses general Ethernet connection characteristics,
   Ethernet User Network Interfaces (UNIs), and Ethernet Network-Network
   Interfaces (NNIs).  Within this framework, [G.8011.1] defines the
   Ethernet Private Line (EPL) service and [G.8011.2] defines the
   Ethernet Virtual Private Line (EVPL) service. [MEF6] covers both
   service types.  [MEF10.1] defines service parameters and [MEF11]
   provides UNI requirements and framework.

   This document provides a method for GMPLS-based control of Label
   Switched Paths (LSPs) that support the transport services defined in
   the above documents at the UNI network reference points.  This
   document does not define or limit the underlying intra-domain or
   Internal NNI (I-NNI) technology used to support the UNI.  This
   document makes use of the GMPLS extensions defined in [RFC6004] and
   [RFC6002].

   The scope of this document covers Ethernet UNI applications, and it
   is intended to be consistent with the GMPLS overlay model presented
   in [RFC4208] and aligned with GMPLS Core Network signaling.  The
   scope and reference model used in this document are represented in
   Figure 1, which is based on Figure 1 of [RFC4208].

   Figure 1 shows two core networks, each containing two core nodes.
   The core nodes are labeled 'CN'.  Connected to each CN is an edge
   node.  The edge nodes are labeled 'EN'.  Each EN supports Ethernet
   Networks and use Ethernet services provided by the core nodes via a
   UNI.  Two services are represented: one EPL and one EVPL type
   service.  Signaling within the core network is out of scope of this
   document and may include any technology that supports overlay UNI
   services.  The UNI function in the edge node can be referred to as
   the UNI client, or UNI-C, and in the CN as UNI network, or UNI-N.

        Ethernet                                          Ethernet
        Network       +----------+    +-----------+       Network
      +---------+     |          |    |           |     +---------+
      |  +----+ |     |  +-----+ |    |  +-----+  |     | +----+  |
   ------+    | | EPL |  |     | |    |  |     |  | EPL | |    +------
   ------+ EN +-+-----+--+ CN  +---------+  CN +--+-----+-+ EN +------
      |  |    | |  +--+--|     +---+  |  |     +--+-----+-+    |  |
      |  +----+ |  |  |  +--+--+ | |  |  +--+--+  |     | +----+  |
      |         |  |  |     |    | |  |     |     |     |         |
      +---------+  |  |     |    | |  |     |     |     +---------+
                   |  |     |    | |  |     |     |
      +---------+  |  |     |    | |  |     |     |     +---------+
      |         |  |  |  +--+--+ | |  |  +--+--+  |     |         |
      |  +----+ |  |  |  |     | | +-----+     |  |     | +----+  |
   ------+    +-+--+  |  | CN  +---------+ CN  |  |     | |    +------
   ------+ EN +-+-----+--+     | |    |  |     +--+-----+-+ EN +------
      |  |    | |EVPL |  +-----+ |    |  +-----+  |EVPL | |    |  |
      |  +----+ |     |          |    |           |     | +----+  |
      |         |     +----------+    |-----------+     |         |
      +---------+            Core Network(s)            +---------+
        Ethernet  UNI                               UNI   Ethernet
        Network <----->                           <-----> Network
                          Scope of This Document

                        Legend:   EN  -  Edge Node
                                  CN  -  Core Node

                  Figure 1: Ethernet UNI Reference Model

1.1.  Overview

   This document uses a common approach to supporting the switching
   implied by the Ethernet services defined in [MEF6], [G.8011.1], and
   [G.8011.2].  The approach builds on standard GMPLS mechanisms to
   deliver the required control capabilities.  This document reuses the
   GMPLS mechanisms specified in [RFC6004], [RFC4208], and [RFC4974].

   Support for Point-to-Point (P2P) and Multipoint-to-Multipoint (MP2MP)
   service is required by [G.8011] and [MEF11].  P2P service delivery
   support is based on the GMPLS support for Ethernet services covered
   in [RFC6004].  As with [RFC6004], the definition of support for MP2MP
   service is left for future study and is not addressed in this
   document.

   [MEF11] defines multiple types of control for UNI Ethernet services.
   In MEF UNI Type 1, services are configured manually.  In MEF UNI Type
   2, services may be configured manually or via a link management
   interface.  In MEF UNI Type 3, services may be established and
   managed via a signaling interface.  As with [RFC6004], this document
   is aimed at supporting the MEF UNI Type 3 mode of operation (and not
   MEF UNI Types 1 and 2).  As mentioned above, this document is limited
   to covering UNI-specific topics.

   Common procedures used to signal Ethernet connections are described
   in Section 2 of this document.  Procedures related to signaling
   switching in support of EPL services are described in Section 3.
   Procedures related to signaling switching in support of EVPL services
   are described in Section 4.

1.2.  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].

2.  Common Signaling Support

   This section describes the common mechanisms for supporting a UNI
   reference point for LSPs that provide the Ethernet Services described
   in [RFC6004].

   Except as specifically modified in this document, the procedures
   related to the processing of Resource ReSerVation Protocol (RSVP)
   objects is not modified by this document.  The relevant procedures in
   existing documents, notably [RFC6002], [RFC6004], [RFC4208], and
   [RFC4974], MUST be followed in all cases not explicitly described in
   this document.

2.1.  UNI Addressing

   LSPs providing Ethernet connections controlled via the mechanisms
   defined in this document MUST use the addressing and other procedures
   defined in [RFC4208].  Of note, this includes the use of the egress
   edge node's IP address in the endpoint address field in the SESSION
   object.

   One issue that presents itself with the addressing approach taken in
   [RFC4208] is that an ingress edge node may not receive the egress
   edge node's IP address as part of the management, or other, request
   that results in the initiation of a new Ethernet connection.  This
   case is covered as described in Section 7.2 of [RFC4974] and modified
   below in Section 2.2.1.

2.2.  Ethernet Endpoint (UNI) Identification

   UNI identification, except as noted below, MUST follow Ethernet
   endpoint (UNI) identification as defined in [RFC6004].  There is one
   additional case that is covered in this document where the scope of
   the Ethernet endpoint identifier is relevant beyond the typical case
   of just ingress and egress nodes.

2.2.1.  Address Resolution

   At the UNI reference point, it is possible for the ingress edge node
   to not have the egress edge node's IP address when initiating an LSP.
   This presents an issue as the egress edge node's IP address is
   carried in the SESSION object.  This case is handled leveraging the
   approach described in Section 7.2 of [RFC4974] to address call ID
   assignment by the first core node.

   When an edge node (the UNI-C) initiates an LSP and it has the egress
   Ethernet endpoint identifier, but does not have its IP address, the
   edge node MUST create a Notify message as described in [RFC4974].
   The Notify message MUST include the CALL_ATTRIBUTES object with the
   Endpoint ID TLV defined [RFC6004].  The tunnel endpoint address field
   of the SESSION object in the Notify message MUST be set to zero (0).
   The message MUST be addressed and sent to an address associated with
   the first core node.

   When a core node, i.e., the node providing the network side of the
   UNI (the UNI-N), receives a Notify message with the tunnel endpoint
   address field of the SESSION object set to zero, it MUST locate the
   Endpoint ID TLV in the CALL_ATTRIBUTES object.  If the object or TLV
   are not present, the node MUST discard the message.  In this case, a
   Message ID Acknowledgment MUST NOT be sent for the Notify message.

   When the Endpoint ID TLV is located, the node MUST map the Endpoint
   ID into an IP address associated with the egress edge node.  If the
   node is unable to obtain an egress address, it MUST issue an error
   response Notify messages according to Section 6.2.2. of [RFC4974].
   The Error code and value SHOULD be "Routing Problem/Unknown Endpoint"
   (Error code 24, Error value 35).

   When the node is able to obtain an egress address, the endpoint
   address field of the SESSION object MUST be set to the obtained
   address, and the Notify message should be sent according to the
   standard processing defined in [RFC4974].  The downstream nodes will
   then process the Notify according to standard processing rules.

   When the ingress receives the response Notify message, it SHOULD
   identify the call based on the Endpoint ID TLV and, when not set to
   zero on the corresponding setup Notify message, the short and long
   Call IDs.  The endpoint address field of the SESSION object carried
   in the response Notify message will include the egress's IP address.
   This returned address MUST be used in all subsequent messages
   associated with the Ethernet connection.

   Note that the procedure described in this section MAY be used when
   the Call IDs are generated by the initiating UNI or generated by the
   first core node.

2.3.  Connection Identification

   With one exception, UNI signaling for Ethernet connections MUST
   follow the Connection Identification procedures defined in [RFC6004].
   The exception is that the procedures defined in Section 7.2 of
   [RFC4974] MAY be used to provide support for allocation of Call IDs
   by the first core node rather than by the initiating edge node.

3.  EPL Service

   There are no additional UNI-specific requirements for signaling LSPs
   supporting Ethernet Private Line (EPL) services.  The procedures
   defined in [RFC6004], as modified above, MUST be followed when
   signaling an LSPs supporting an EPL Service.

4.  EVPL Service

   There is one additional UNI-specific requirement for signaling LSPs
   supporting an EVPL type service as described in Section 4.1.  Except
   as modified above and by this section, the procedures defined in
   [RFC6004] MUST be followed when signaling an EVPL Service.

4.1.  Egress VLAN ID Control and VLAN ID Preservation

   Per [MEF6], the mapping of the single VLAN ID used at the ingress UNI
   to a different VLAN ID at the egress UNI is allowed for EVPL services
   that do not support both bundling and VLAN ID preservation.  Such a
   mapping MUST be requested and signaled based on the explicit label
   control mechanism defined in [RFC4208], and not the mechanisms
   defined in [RFC6004].

   As is the case in [RFC6004], when the explicit label control
   mechanism is not used VLAN IDs MUST be preserved, i.e., not modified,
   across the LSP.

5.  IANA Considerations

   IANA has assigned new values for namespaces defined in this document
   and summarized in this section.

5.1.  Error Value: Routing Problem/Unknown Endpoint

   IANA has made the following assignment in the "Error Codes and
   Globally-Defined Error Value Sub-Codes" section of the "RSVP
   Parameters" registry located at http://www.iana.org:

   Error Code      Meaning
     24  Routing Problem                             [RFC3209]

   Under "This Error Code has the following globally-defined Error
          Value sub-codes:"

         35 =  Unknown Endpoint                      [RFC6005]

6.  Security Considerations

   This document makes use of the mechanisms defined in [RFC6004] and
   [RFC4974].  It does not in itself change the security models offered
   in each.  (Note that the address resolution discussed in Section 2.2
   above, parallels the replacement of information that occurs per
   Section 7.2 of [RFC4974].)  See [RFC6004] and [RFC4974] for the
   security considerations that are relevant to and introduced by the
   base mechanisms used by this document.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC4208]  Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
              "Generalized Multiprotocol Label Switching (GMPLS) User-
              Network Interface (UNI): Resource ReserVation Protocol-
              Traffic Engineering (RSVP-TE) Support for the Overlay
              Model", RFC 4208, October 2005.

   [RFC4974]  Papadimitriou, D. and A. Farrel, "Generalized MPLS (GMPLS)
              RSVP-TE Signaling Extensions in Support of Calls", RFC
              4974, August 2007.

   [RFC6002]  Berger, L. and D. Fedyk, "Generalized MPLS (GMPLS) Data
              Channel Switching Capable (DCSC) and Channel Set Label
              Extensions", RFC 6002, October 2010.

   [RFC6004]  Berger, L. and D. Fedyk, "Generalized MPLS (GMPLS) Support
              for Metro Ethernet Forum and G.8011 Ethernet Service
              Switching", RFC 6004, October 2010.

7.2.  Informative References

   [G.8011]   ITU-T G.8011/Y.1307, "Ethernet over Transport Ethernet
              services framework", August 2004.

   [G.8011.1] ITU-T G.G.8011.1/Y.1307.1, "Ethernet private line
              service", August 2004.

   [G.8011.2] ITU-T G.8011.2/Y.1307.2, "Ethernet virtual private line
              service", September 2005.

   [MEF6]     The Metro Ethernet Forum, "Ethernet Services Definitions -
              Phase I", MEF 6, June 2004.

   [MEF10.1]  The Metro Ethernet Forum, "Ethernet Services Attributes
              Phase 2", MEF 10.1, November 2006.

   [MEF11]    The Metro Ethernet Forum , "User Network Interface (UNI)
              Requirements and Framework", MEF 11, November 2004.

Acknowledgments

   Dimitri Papadimitriou provided substantial textual contributions to
   this document and coauthored earlier versions of this document.

   The authors would like to thank Evelyne Roch and Stephen Shew for
   their valuable comments.

Authors' Addresses

   Lou Berger
   LabN Consulting, L.L.C.
   Phone: +1-301-468-9228
   EMail: lberger@labn.net

   Don Fedyk
   Alcatel-Lucent
   Groton, MA 01450
   Phone: +1-978-467-5645
   EMail: donald.fedyk@alcatel-lucent.com