Internet DRAFT - draft-fedyk-ccamp-l1vpn-extnd-overlay

draft-fedyk-ccamp-l1vpn-extnd-overlay



 



Network Working Group                                           D. Fedyk
Internet Draft                                                 D. Beller
Intended status: Standards Track                           Lieven Levrau
                                                          Alcatel-Lucent
                                                           D. Ceccarelli
                                                                Ericsson
                                                                F. Zhang
                                                     Huawei Technologies
                                                               Y. Tochio
                                                                 Fujitsu




Expires: April 2013                                     October 22, 2012



                    Overlay Extension Service Model
              draft-fedyk-ccamp-l1vpn-extnd-overlay-01.txt


Status of this Memo

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   This Internet-Draft will expire on April 25, 2013.




 


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Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Abstract

   This document builds on the GMPLS overlay model [RFC4208] and defines
   extensions to the GMPLS User-Network Interface (UNI) to support route
   diversity within the core network for sets of LSPs initiated by edge
   nodes. A particular example where route diversity within the core
   network is desired, are dual-homed edge nodes. The document also
   defines GMPLS UNI extensions to deal with latency requirements for
   edge node initiated LSPs.

   This document is also applicable to the L1VPN framework [RFC4847] to
   extend the L1VPN from the basic mode to the enhanced mode by
   including additional constraints, focusing upon the overlay extension
   service model. Route Diversity for customer LSPs are common
   requirement applicable to L1VPNs. This document describes L1VPN
   compatible mechanisms to achieve diversity for sets of customer LSPs.
   The extended overlay service model can support other extensions for
   L1VPN signaling, for example, those related to latency requirements.


Table of Contents

   1. Introduction...................................................3
   2. Conventions used in this document..............................3
   3. Contributors...................................................3
   4. LSP Diversity in the Overlay Extension Service Model...........4
      4.1. LSP diversity for dual-homed customer edge (CE) devices...5
         4.1.1. Exchanging SRLG information between the PEs via the CE
         device......................................................7
            4.1.1.1. Operational Procedures..........................8
            4.1.1.2. Error handling procedures.......................8
         4.1.2. Using Path Affinity Set extension....................9
            4.1.2.1. Operational Procedures.........................12
 


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            4.1.2.2. Error handling procedures......................13
            4.1.2.3. Distribution of the Path Affinity Set information
            ........................................................13
   5. Latency signaling.............................................14
   6. Security Considerations.......................................14
   7. IANA Considerations...........................................15
   8. References....................................................15
      8.1. Normative References.....................................15
      8.2. Informative References...................................15
   9. Acknowledgments...............................................16






































 


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1. Introduction

   This document builds on the GMPLS overlay model [RFC4208] and defines
   extensions to the GMPLS User-Network Interface (UNI) to support route
   diversity within the core network for sets of LSPs initiated by edge
   nodes. In the following, the term customer edge (CE) device node is
   used synonymously for the term edge node (EN) as in [RFC4208].
   Moreover, the L1VPN terminology is used below when the core network
   as in [RFC4208] is described.

   The document is also applicable to the L1VPN framework [RFC4847] to
   extend the L1VPN from the basic mode to the enhanced mode by
   including additional constraints, focusing upon the overlay extension
   service model.

   The overlay model assumes a UNI interface between the edge nodes of
   the respective transport domains. Route diversity for LSPs from
   single homed CE and dual-home CEs is a common requirement in optical
   transport networks. This document describes two signaling variations
   that may be used for supporting LSP diversity within the overlay
   extension service model considering dual-homing. Dual-homing is
   typically used to avoid a single point of failure (UNI link, PE) or
   if two disjoint connections are forming a protection group.  While
   both methods are similar in that they utilize common mechanisms in
   the PE network to achieve diversity, they are distinguished according
   to whether the CE is permitted to retrieve provider SRLG diversity
   information for an LSP from a PE1 and pass it on to a PE2 (SRLG
   information is shared with the CE), or whether a new attribute is
   used that allows the PE2 that receives this attribute to derive the
   SRLG information for an LSP based on this attribute value.

   The extended overlay service model can support other extensions for
   L1VPN signaling, for example, those related to latency. When
   requesting diverse LSPs latency may also be an additional
   requirement.


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 RFC-2119 [RFC2119].

   In this document, these words will appear with that interpretation
   only when in ALL CAPS. Lower case uses of these words are not to be
   interpreted as carrying RFC-2119 significance.


 


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3. Contributors

   The Authors would like to thank Eve Varma and Sergio Belotti for
   their review and contributions to this document.


4. LSP Diversity in the Overlay Extension Service Model

   The L1VPN Framework [RFC4847] (Enhanced Mode) describes the overlay
   extension service model, which builds upon the UNI Overlay [RFC4208]
   serving as the interface between the CE edge node and the PE edge
   node. In this service model, a CE receives a list of CE-PE TE link
   addresses to which it can request a L1VPN connection (i.e.,
   membership information) and may include additional information
   concerning these TE links.  This document further builds on the
   overlay extension service model by adding shared constraint
   information for path diversity in the optical transport network.

   This document describes two signaling variations that may be used for
   supporting LSP diversity within the overlay extension service model
   considering dual-homing.  While both methods are similar in that they
   utilize common mechanisms in the PE network to achieve diversity,
   they are distinguished according to whether the CE is permitted to
   retrieve provider SRLG diversity information for an LSP from a PE1
   and pass it on to a PE2 (SRLG information is shared with the CE or
   whether a new attribute is used that allows the PE2 that receives
   this attribute to derive the SRLG information for an LSP based on
   this attribute value. The selection between these methods is governed
   by both PE-network specific policies and approaches taken (i.e., in
   terms of how the provider chooses to perform routing internal to
   their network).

   The first method (see 3.1.1) assumes that provider Shared Resource
   Link Group (SRLG) Identifier information is both available and
   shareable (policy decision) with the CE.  Since SRLG IDs can then be
   used (passed transparently between PEs via the dual-homed CE) as
   signaled information on a UNI message, a mechanism supporting LSP
   diversity for the overlay extension service model can be provided via
   straightforward signaling extensions.

   The second method (see 3.1.2) assumes that provider SRLG IDs are
   either not available or not shareable (based on provider network
   operator policy) with the CE.  For this case, a mechanism is provided
   where information signaled to the PE on UNI messages does not require
   shared knowledge of provider SRLG IDs to support LSP diversity for
   the overlay extension model.

   Both approaches follow the L1VPN framework.
 


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   While both methods could be implemented in the same PE network, it is
   likely that an L1VPN CE network would use only one mechanism at a
   time.


4.1. LSP diversity for dual-homed customer edge (CE) devices

   Single-homed CE devices are connected to a single PE device via a
   single UNI link (could be a bundle of parallel links which are
   typically using the same fiber cable). This single UNI link may
   constitute a single point of failure. Such a single point of failure
   can be avoided when the CE device is connected to two PE devices via
   two UNI interfaces as depicted for CE1 in Figure 1 below.

   For the dual-homing case, it is possible to establish two connections
   from the source CE device to the same destination CE device where one
   connection is using one UNI link to, for example, PE1 and the other
   connection is using the UNI link to PE2. In order to avoid single
   points of failure within the provider network, it is necessary to
   also ensure path (LSP) diversity within the provider network in order
   to achieve end-to-end diversity for the two LSPs between the two CE
   devices. This document describes how it is possible to enable such
   path diversity to be achieved within the provider network (which is
   subject to additional routing constraints). [RFC4202] defines SRLG
   information that can be used to allow GMPLS to provide path diversity
   in a GMPLS controlled transport network. As the two connections are
   entering the provider network at different PE devices, the PE device
   that receives the connection request for the second connection needs
   to be capable of determining the additional path computation
   constraints such that the path of the second LSP is disjoint with
   respect to the already established first connection entering the
   network at a different PE device. The methods described in this
   document allow a PE device to determine the SRLG information for a
   connection in the provider network that is entering the network on a
   different PE device.

   PE SRLG information can be used directly by a CE if the CE
   understands the context, and the CE view is limited to its L1VPN
   context. In this case, there is a dependency on the provider
   information and there is a need to be able to query the SRLG in the
   provider network.

   It may, on the other hand, be preferable to avoid this dependency and
   to decouple the SRLG identifier space used in the provider network
   from the SRLG space used in the client network. This is possible with
   both methods detailed below. Even for the method where provider SRLG
   information is passing through the CE device (note the CE device does
   not need to process and decode this information) the two SRLG
 


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   identifier spaces can remain fully decoupled and the operator of the
   client network is free to assign SRLG identifiers from the client
   SRLG identifier space to the CE to CE connection that is passing
   through the provider network.

   Referring to Figure 1, the UNI signaling mechanism must support at
   least one of the two mechanisms described in this document for CE
   dual homing to achieve LSP diversity in the provider network.

   The described mechanisms can also be applied to a scenario where two
   CE devices are connected to two different PE devices. In this case,
   the additional information that is exchanged across the UNI
   interfaces also needs to be exchanged between the two CE devices in
   order to achieve the desired diversity in the provider network.

   This information may be configured or exchanged by some automated
   mechanism not described in this document.

   In the dual-homing example, CE1 can locally correlate the LSP
   requests. For the slightly more complicated example involving CE2 and
   CE3, both requiring a path that shall be diverse to a connection
   initiated by the other CE device, CE2 and CE3 need to have a common
   view of the SRLG information to be signaled.  In this document, we
   detail the required diversity information and the signaling of this
   diversity information; however, the means for distributing this
   information within the PE domain or the CE domain is out of scope.






                         +---+    +---+
                         | P |....| P |
                         +---+    +---+
                        /              \
                   +-----+               +-----+    +---+
          +---+    | PE1 |               |     |----|   |
          |CE1|----|     |               |     |    |CE2|
          +---+\   +-----+               |     |----|   |
                \     |                  | PE3 |    +---+
                 \ +-----+               |     |
                  \| PE2 |               |     |    +---+
                   |     |               |     |----|CE3|
                   +-----+               +-----+    +---+
                         \              /
                         +---+    +---+
                         | P |....| P |
 


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                         +---+    +---+

               Figure 1: Generalized Layer 1 VPN Reference Model

                     Figure 1 Overlay Reference Diagram

   In an overlay model, the information exchanged between the CE and the
   PE is kept to a minimum.

   How diversity is achieved, in terms of configuration, distribution
   and usage in each part of the transport networks should be kept
   independent and separate from how diversity is signaled at the UNI
   between the two transport networks.

   Signaling parameters discussed in this document are:

   o  SRLG information (see [RFC4202])

   o  Path Affinity Set


4.1.1. Exchanging SRLG information between the PEs via the CE device

   SRLG information is defined in [RFC4202] and if the SRLG information
   of an LSP is known, it can be used to calculate a path for another
   LSP that is SRLG diverse with respect to an existing LSP. SRLG
   information is an unordered list of SRLGs. SRLG information is
   normally not shared between the transport network and the client
   network; i.e., not shared with the CEs of a L1VPN in the L1VPN
   context. However, this becomes more challenging when a CE is dual-
   homed.   For example, CE1 in Figure 1 may have requested an LSP1 from
   CE1 to CE2 via PE1 and PE3.  CE1 could subsequently request an LSP2
   to CE2 via PE2 and PE3 with the requirement that it should be
   maximally SRLG disjoint with respect to LSP1. Since PE2 does not have
   any information about LSP1, PE2 would need to know the SRLG
   information associated with LSP1. If CE1 could request the SRLG
   information of LSP1 from PE1, it could then transparently pass this
   information to PE2 as part of the LSP2 setup request, and PE2 would
   now be capable of calculating a path for LSP2 that is SRLG disjoint
   with respect to LSP1.

   The exchange of SRLG information is achieved on a per L1VPN LSP basis
   using the existing RSVP-TE signaling procedures. It can be exchanged
   in the PATH (exclusion information) or RESV message in the original
   request or it can be requested by the CE at any time the path is
   active.

   It shall be noted that SRLG information is an unordered list of SRLG
 


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   identifiers and the encoding of SRLG information for RSVP signaling
   is already defined in [SRLG_info]. Even if SRLG information is known
   for several LSPs it is not possible for the CEs to derive the
   provider network topology from this information.



4.1.1.1. Operational Procedures

   Retrieving SRLG information from a PE for an existing LSP:

   When a dual-homed UNI-C intends to establish an LSP to the same
   destination UNI-C via another PE node, it can request the SRLG
   information for an already established LSP by setting the SRLG
   information flag in the LSP attributes sub-object of the RSVP PATH
   message (IANA to assign the new SRLG flag). As long as the SRLG
   information flag is set in the PATH message, the PE node inserts the
   SRLG sub-object as defined in [SRLG_info] into the RSVP RESV message
   that contains the current SRLG information for the LSP. If the
   provider network's policy has been configured so as not to share SRLG
   information with the client network, the SRLG sub-object is not
   inserted in the PATH message even if the SRLG information flag is
   set. The PE passes on the SRLG information for the LSP.  Note the
   SRLG information is expected to be up-to-date.

   Establishment of a new LSP with SRLG diversity constraints:

   When a dual-homed CE device sends an LSP setup requests to a PE
   device for a new LSP that is required to be SRLG diverse with respect
   to an existing LSP that is entering the network via another PE
   device, the UNI-C sets the SRLG diversity flag (note: IANA to assign
   the new SRLG diversity flag) in the LSP attributes sub-object of the
   PATH message that initiates the setup of this new LSP. When the PE
   device receives this request it calculates a path to the given
   destination and uses the received SRLG information as path
   computation constraints.


4.1.1.2. Error handling procedures

   To be added in the next version of the document.







 


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4.1.2. Using Path Affinity Set extension

   The Path Affinity Set (PAS) is used to signal diversity in a pure CE
   context by abstracting SRLG information. There are two types of
   diversity information in the PAS. The first type of information is a
   single PAS identifier. Optionally, more detailed PATH information of
   an exclude path or set of paths can be specified. The motive behind
   the PAS information is to have as little exchange of diversity
   information as possible between the L1VPN CE and PE elements.

   Rather than a detailed CE or PE SRLG list, the Path Affinity Set
   contains an abstract SRLG identifier that associates the given path
   as diverse. Logically the identifier is in an L1VPN context and
   therefore only unique with respect to a particular L1VPN.

   How the CE determines the PAS identifier is a local matter for the CE
   administrator. A CE may signal PAS as a diversity object in the PATH
   message. This identifier is a suggested identifier and may be
   overridden by a PE under some conditions.

   For example, PAS can be used with no prior exchange of PAS
   information between the CE and the PE. Upon reception of the PAS
   information the PE can infer the CEs requirements.  The actual PAS
   identifier used will be returned in the RESV message. Optionally an
   empty PAS identifier allows the PE to pick the PAS identifier.
   Similar to the section 4.1.1 on SRLG information, a PE can return PAS
   identifier as the response to a Query allowing flexibility.

   A PE interprets the specific PAS identifier, for example, "123" as
   meaning to exclude that identifier and by association any PE related
   SRLG information, for any LSPs associated with the resources assigned
   to the L1VPN. For example, if a Path exists for the LSP with the
   identifier "123", the PE would use local knowledge of the PE SRLGs
   associated with the "123" LSPs and exclude those SRLGs in the path
   request.  In other words, two LSPs that need to be diverse both
   signal "123" and the PEs interpret this as meaning not to use shared
   resources.  Alternatively, a PE could use the PAS identifier to
   select from already established LSPs. Once the path is established it
   becomes associated with the "123" identifier or optionally another
   PAS identifier for that L1VPN.

   The PAS Source and Destination Address tuple represents one or more
   source addresses and destination addresses associated with the CE
   Path Affinity Set identifier. These associated address tuples
   represent paths that use resources that should be excluded for the
   establishment of the current LSP.  The address tuple information
   gives both finer grain details on the path diversity request and
   serves as an alternative identifier in the case when the PAS
 


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   identifier is not known by the PE.  The address tuples used in
   signaling is within a CE context and its interpretation is local to a
   PE that receives a Path request from a CE. The PE can use the address
   information to relate to PE Addresses and PE SRLG information.  When
   a PE satisfies a connection setup for a (SRLG) diverse signaled path,
   the PE may optionally record the PE SRLG information for that
   connection in terms of PE based parameters and associate that with
   the CE addresses in the Path message.

   The L1VPN Port Information table (PIT) [RFC5251] can be leveraged to
   translate between CE based addresses and PE based addresses. The Path
   Affinity Set and associated PE addresses with PE SRLG information can
   be distributed via the IGP in the provider transport network (or by
   other means such as configuration); they can be utilized by other PEs
   when other CE Paths are setup that would require path/connection
   diversity. This information is distributed on a L1VPN basis and
   contains a PAS identifier, PE addresses and SRLG information.

   The CE Path Affinity Set may be used to signal paths without CE
   Source and Destination addresses; however, the PE will always
   associate the CE SRLG Group with a list of PE SRLG plus the PE
   addresses associated with this LSP.

   If diversity is not signaled, the assumption is that no diversity is
   required and the Provider network is free to route the LSP to
   optimize traffic. No Path affinity set information needs to be
   recorded for these LSPs.  If a diversity object is included in the
   connection request, the PE in the Provider Network should be able to
   look-up the existing Provider SRLG information from the provider
   network and choose an LSP that is maximally diverse from other LSPs.
   The mechanisms to achieve this are outside the scope of this
   document.
















 


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   A new L1VPN Diverse LSP LABEL object is specified:

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       Length                  |    Type (TBA) |0| C-type (TBA)|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         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

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | ADDR Length   |Number of PAS  |D|           reserved          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 Path Affinity Set identifier                  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 Source Address (variable)                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                 Destination Address (variable)                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 2 Diverse LSP information


   1. The Address Length field (8 bits) is the number of bytes for both
      the source address and destination address. The address may be in
      any format from 1 to 32 bytes but the key point is the customers
      can maintain their existing addresses.  A value of zero indicates
      there are no addresses included.

   2. The Number of Path Affinity (8 bits)sets is included in the
      object. This is typically 1. Addition of other sets is for further
      study.

   3. The Path affinity Set identifier (4 bytes) is a single number that
      represents a summarized SRLG for this path. Paths with that same
      Path Affinity set should be set up with diverse paths and
      associated with the path affinity set.  A value of all zeros
      allows the PE to pick a PAS identifier to return.  A PAS
      identifier of an established path may be different than the
      requested path identifier.

   4. The diversity Bit (D) (one Bit) indicates if the diversity must be
      satisfied when set as a one. If a PE finds an established path
      with a Path Affinity set matching the signaled Path Affinity Set
      or the signaled Address tuple it should attempt find a diverse
      path.

 


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   5. The Diverse Path Source address/destination address tuple is that
      of an established LSP in the PE network that belongs to the same
      Path Affinity Set identifier. If the path for these addresses is
      not setup or cannot be determined by the PE edge processing the
      UNI then the path is only with the Path Affinity set constraint.
      If the path(s) for these address tuples are known by the PE the PE
      uses the SRLG information associated with these addresses. If in
      any case a diverse path cannot be setup then the Diverse bit
      controls whether a path is established anyway. The PE must use a
      mechanism to translate CE Addresses into provider addresses when
      correlating with provider SRLG information. How SRLG information
      and network address tuples are distributed is for future study.




































 


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4.1.2.1. Operational Procedures

   When a UNI-C constructs a PATH message it may optionally specify and
   insert a Path Affinity Set in the PATH message. This Path Affinity
   Set may optionally include the address of an LSP that that could
   belong to the same Path Affinity Set. The Path Affinity Set
   identifier is a value (0 through 2**32-255) that is independent of
   the mechanism the CE or the PE use for diversity. The Path Affinity
   Set is a single identifier that can be used to request diversity and
   associate diversity.

   When processing a CE PATH message in a L1VPN Overlay, the PE first
   looks up the PE based addresses in the Provider Index Table (PIT). If
   the Path Affinity Set is included in the PATH message, the PE must
   look up the SRLG information (or equivalent) in the PE network that
   has been allocated by LSPs associated with a Path Affinity Set and
   exclude those resources from the path computation for this LSP if it
   is a new path.  The PE may alternatively choose from an existing path
   with a disjoint set of resources. If a path that is disjoint cannot
   be found, the value of the PAS diversity bit determines whether a
   path should be setup anyway. If the PAS diversity bit is clear, one
   can still attempt to setup the LSP.  A PE should still attempt to
   minimize shared resources but that is an implementation issue, and is
   outside the scope of this document.

   Optionally the CE may use a value of all zeros in the PAS identifier
   allowing the PE to select an appropriate PAS identifier. Also the PE
   may to override the PAS identifier allowing the PE to re-assign the
   identifier if required. A CE should not assume that the PAS
   identifier used for setup is the actual PAS identifier.


4.1.2.2. Error handling procedures

   The PAS object must be understood by the PE device. Otherwise, the CE
   should not use the PAS object. Path Message processing of the PAS
   object SHOULD follow CTYPE 0. An Error code of IANA (TBD) indicates
   that the PAS object is not understood.

   When a PAS identifier is not recognized by a PE it must assume this
   LSP defines that PAS identifier however the PE may override PAS
   identifier under certain conditions.

   If the identifier is recognized but the Source Address-Destination
   address pair(s) are not recognized, this LSP must be set up using the
   PAS identifier only.

   If the identifier is recognized and the Source Address-Destination
 


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   address pair(s) are also recognized, then the PE SHOULD use the PE
   SRLG information associated with the LSPs identified by the address
   pairs to select a disjoint path.

   The Following are the additional error codes:

   1) Route Blocked by Exclude Route Value IANA (TBA).


4.1.2.3. Distribution of the Path Affinity Set information

   Information about SRLG is already available in the IGP TE database. A
   PE network can be designed to have additional opaque records for
   Provider paths that distribute PE paths and SRLG on a L1VPN basis.
   When a PE path is setup, the following information allows a PE to
   lookup the PE diversity information:

   -  L1 VPN Identifier 8 bytes
   -  Path Affinity Set Identifier
   -  Source PE Address
   -  Destination PE Address
   -  List of PE SRLG (variable)

   The source PE address and destination PE address are the same
   addresses in the L1VPN PIT and correspond to the respective CE
   address identifiers.


   Note that all of the information is local to the PE context and is
   not shared with the CE. The L1VPN Identifier is associated with a CE.
   The only value that is signaled from the CE is the Path Affinity Set
   and optionally the addresses of an existing LSP. The PE stores source
   and destination PE addresses of the LSP in their native format along
   with the SRLG information. This information is internal to the PE
   network and is always known.

   PE paths may be setup on demand or they may be pre-established. When
   paths are pre-established, the Path Affinity Set is set to unassigned
   0x0000 and is ignored. When a CE uses a pre-established path the PE
   may set the Path SRLG Path Affinity Set value if the CE signals one
   otherwise the Path Affinity Set remains unassigned 0x0000.


5. Latency signaling

   A latency requirement can be added to signaling in the form of a
   constraint [DRAFT OBJECTIVE FUNCTION]. The constraint can take the
   form of:
 


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   -  Minimize latency

   -  Maximum acceptable

   While some systems may be able to compute routes based on delay
   metrics it is usual that minimizing hops subject to bandwidth
   reservation are satisfied as the object function and delay is not
   considered. When considering diversity latency falls after diversity
   constraints have been satisfied.

   Recording the latency of existing paths [DRAFT_TE_METRIC RECORD] to
   ensure they meet a maximum acceptable latency can be utilized to
   ensure latency constraint is met.

   When a low latency path is required, the minimize latency subject to
   other constraints criteria should be signaled.  A CE device can use
   the record latency to ensure that the maximum acceptable latency has
   been met.

   More detail to be added in a future revision.


6. Security Considerations

   Security for L1VPNs is covered in [RFC4847], [RFC5251] and [RFC5253].
   In this document, the model follows the L1VPN control plane model
   where CE addresses are completely distinct from the PE addresses.

   The use of a private network assumes that entities outside the
   network cannot spoof or modify control plane communications between
   CE and PE.  Furthermore, all entities in the private network are
   assumed to be trusted.  Thus, no security mechanisms are required by
   the protocol exchanges described in this document.

   However, an operator that is concerned about the security of their
   private control plane network may use the authentication and
   integrity functions available in RSVP-TE [RFC3473] or utilize IPsec
   ([RFC4301], [RFC4302], [RFC4835], [RFC5996], and [RFC6071]) for the
   point-to-point signaling between PE and CE.  See [RFC5920] for a full
   discussion of the security options available for the GMPLS control
   plane.


7. IANA Considerations

   TBD


 


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8. References

 Normative References

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

   [RFC4202] Kompella, K., Rekhter, Y., "Routing Extensions in Support
             of Generalized Multi-Protocol Label Switching (GMPLS)", RFC
             4202, October 2005.

   [RFC4208] G. Swallow, J. Drake, H. Ishimatsu, 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.

   [RFC5251] Fedyk, D., Rekhter, Y., Editors "Layer 1 VPN Basic Mode",
             RFC 5251, July 2008.

   [SRLG_info] Zhang, F., Li, D., Gonzalez de Dios, O., Margaria, C.,
             "RSVP-TE Extensions for Collecting SRLG Information",
             draft-ietf-ccamp-rsvp-te-srlg-collect-00.txt, June 2012.

8.2. Informative References

   [RFC6071] S. Frankel, S. Krishnan, " IP Security (IPsec) and Internet
             Key Exchange (IKE) Document Roadmap", RFC 6071, February
             2011.

   [RFC3473] Berger, L. (editor), "Generalized MPLS Signaling - RSVP-TE
             Extensions", RFC 3473, January 2003.

   [RFC4301] S. Kent, K. Seo, "Security Architecture for the Internet
             Protocol," December 2005.

   [RFC4302] S. Kent, "IP Authentication Header," December 2005.

   [RFC5996] C. Kaufman, P. Hoffman, Y. Nir, P. Eronen " Internet Key
             Exchange Protocol Version 2 (IKEv2)", September 2010.

   [RFC4835] V. Manral, "Cryptographic Algorithm Implementation
             Requirements for Encapsulating Security Payload (ESP) and
             Authentication Header (AH)", April 2007.

   [RFC4847] Takeda, T., Editor "Framework and Requirements for Layer 1
             Virtual Private Networks", RFC 4847, April 2007.

 


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   [RFC5253] Takeda, T., Editor "Applicability Statement for Layer 1
             Virtual Private Network (L1VPN) Basic Mode", RFC 5253, July
             2008.

   [RFC5920] L. Fang, Ed., "Security Framework for MPLS and GMPLS
             Networks", RFC 5920, July 2010.

   [DRAFT OBJECTIVE FUNCTION] Ali, Z., Swallow, G., Filsfils, C., Fang,
             L., Kumaki, K., Kunze, R.,"Resource ReserVation Protocol-
             Traffic Engineering (RSVP-TE) extension for signaling
             Objective Function and Metric Bound", draft-ali-ccamp-rc-
             objective-function-metric-bound-02.txt, July 2012.

   [DRAFT_TE_METRIC RECORD] Ali, Z., Swallow, G., Filsfils, C., Kumaki,
             K., Kunze, R., "Resource ReserVation Protocol-Traffic
             Engineering (RSVP-TE) extension for recording TE Metric of
             a Label Switched Path", draft-ali-ccamp-te-metric-
             recording-02.txt, July 2012.



9. Acknowledgments


   Copyright (c) 2012 IETF Trust and the persons identified as authors
   of the code. All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, is permitted pursuant to, and subject to the license
   terms contained in, the Simplified BSD License set forth in Section
   4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info).
















 


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Authors' Addresses

   Don Fedyk
   Alcatel-Lucent
   Groton, MA, 01450
   Email: donald.fedyk@alcatel-lucent.com


   Dieter Beller
   Alcatel-Lucent
   Email: Dieter.Beller@alcatel-lucent.com

   Lieven Levrau
   Alcatel-Lucent
   Email: Lieven.Levrau@alcatel-lucent.com

   Daniele Ceccarelli
   Ericsson
   Email: Daniele.Ceccarelli@ericsson.com

   Fatai Zhang
   Huawei Technologies
   Email: zhangfatai@huawei.com

   Yuji Tochio
   Fujitsu
   Email: tochio@jp.fujitsu.com
























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