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Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Path Diversity using Exclude Route
draft-ietf-teas-lsp-diversity-09

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Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8390.
Authors Zafar Ali , George Swallow , Fatai Zhang , Dieter Beller
Last updated 2017-11-12
Replaces draft-ietf-ccamp-lsp-diversity
RFC stream Internet Engineering Task Force (IETF)
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Stream WG state Submitted to IESG for Publication
Document shepherd Lou Berger
Shepherd write-up Show Last changed 2017-04-28
IESG IESG state Became RFC 8390 (Proposed Standard)
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Responsible AD Deborah Brungard
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IANA IANA review state Version Changed - Review Needed
draft-ietf-teas-lsp-diversity-09
TEAS Working Group                                    Zafar Ali, Ed. 
   Internet Draft                                   George Swallow, Ed. 
   Intended status: Standard Track                        Cisco Systems 
   Updates RFC4874                                        F. Zhang, Ed. 
   Expires: May 17, 2018                                         Huawei 
                                                         D. Beller, Ed. 
                                                                  Nokia 
                                                      November 13, 2017 
    
      Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Path 
                       Diversity using Exclude Route 

                    draft-ietf-teas-lsp-diversity-09.txt 

   Status of this Memo 

   This Internet-Draft is submitted in full conformance with the 
   provisions of BCP 78 and BCP 79. 

   Internet-Drafts are working documents of the Internet Engineering 
   Task Force (IETF).  Note that other groups may also distribute 
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/. 

   Internet-Drafts are draft documents valid for a maximum of six 
   months and may be updated, replaced, or obsoleted by other documents 
   at any time.  It is inappropriate to use Internet-Drafts as 
   reference material or to cite them other than as "work in progress." 

   This Internet-Draft will expire on September 28, 2017. 
       
   Copyright Notice 

   Copyright (c) 2017 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. 

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   Internet Draft      draft-ietf-teas-lsp-diversity-09.txt 

   Abstract 

   Resource ReSerVation Protocol-Traffic Engineering provides support 
   for the communication of exclusion information during label switched 
   path (LSP) setup. This document specifies two new diversity 
   subobjects for the RSVP eXclude Route Object (XRO) and the Explicit 
   Exclusion Route Subobject (EXRS). Three different mechanisms are 
   defined to accomplish LSP diversity in the provider or core network: 
   the signaled diversity type indicates whether diversity is based on 
   client, path computation engine (PCE), or network assigned 
   identifiers. 
   The solution described in this document is based on the assumption 
   that LSPs are requested sequentially, i.e., the time period between 
   the LSP setup requests for the two LSPs may be relatively long (in 
   the order of days, weeks, months). Re-routing the LSP that was 
   established first and may have existed for some time is not 
   considered. 
    
   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]. 

   Table of Contents 

   1. Introduction..................................................3 
      1.1. Client-Initiated Identifier..............................5 
      1.2. PCE-allocated Identifier.................................6 
      1.3. Network-Assigned Identifier..............................7 
   2. RSVP-TE signaling extensions..................................9 
      2.1. Diversity XRO Subobject..................................9 
      2.2. Diversity EXRS Subobject................................16 
      2.3. Processing rules for the Diversity XRO and EXRS 
           subobjects..............................................16 
   3. Security Considerations......................................20 
   4. IANA Considerations..........................................20 
      4.1. New XRO subobject types.................................20 
      4.2. New EXRS subobject types................................21 
      4.3. New RSVP error sub-codes................................21 
   5. Acknowledgements.............................................22 
   6. References...................................................22 
      6.1. Normative References....................................22 
      6.2. Informative References..................................23 
    

    
    
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   1. Introduction 

      Path diversity for multiple connections is a well-known Service 
      Provider requirement. Diversity constraints ensure that Label-
      Switched Paths (LSPs) can be established without sharing network 
      resources, thus greatly reducing the probability of simultaneous 
      connection failures. 

      The source node can compute diverse paths for LSPs when it has 
      full knowledge of the network topology and is permitted to signal 
      an Explicit Route Object. However, there are scenarios where 
      different nodes perform path computations, and therefore there is 
      a need for relevant diversity constraints to be signaled to those 
      nodes. These include (but are not limited to): 

      .  LSPs with loose hops in the Explicit Route Object (ERO), e.g. 
        inter-domain LSPs. 

      .  Generalized Multi-Protocol Label Switching (GMPLS) User-
        Network Interface (UNI), where the core node may perform path 
        computation [RFC4208]. 

      [RFC4874] introduced a means of specifying nodes and resources to 
      be excluded from a route, using the eXclude Route Object (XRO) and 
      Explicit Exclusion Route Subobject (EXRS). It facilitates the 
      calculation of diverse paths for LSPs based on known properties of 
      those paths including addresses of links and nodes traversed, and 
      Shared Risk Link Groups (SRLGs) of traversed links. Employing 
      these mechanisms requires that the source node that initiates 
      signaling knows the relevant properties of the path(s) from which 
      diversity is desired. However, there are circumstances under which 
      this may not be possible or desirable, including (but not limited 
      to): 

      .  Exclusion of a path which does not originate, terminate or 
         traverse the source node of the diverse LSP, in which case the 
         addresses of links and SRLGs of the path from which diversity 
         is required are unknown to the source node. 

      .  Exclusion of a path which is known to the source node of the 
         diverse LSP for which the node has incomplete or no path 
         information, e.g. due to operator policy. In this case, the 
         source node is aware of the existence of the reference path but 
         the information required to construct an XRO object to 
         guarantee diversity from the reference path is not fully known. 
         Inter-domain and GMPLS overlay networks can impose such 
         restrictions. 
    
    
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      This is exemplified in the Figure 1, where the overlay reference 
      model from [RFC4208] is shown. 

     
      Overlay                                                  Overlay 
      Network       +----------------------------------+       Network 
    +---------+     |                                  |     +---------+ 
    |  +----+ |     |  +-----+    +-----+    +-----+   |     | +----+  | 
    |  |    | | UNI |  |     |    |     |    |     |   | UNI | |    |  | 
    | -+ EN1+-+-----+--+ CN1 +----+ CN2 +----+ CN3 +---+-----+-+ EN3+- | 
    |  |    | |  +--+--+     |    |     |    |     |   | +---+-|    |  | 
    |  +----+ |  |  |  +--+--+    +--+--+    +--+--+   | |   | +----+  | 
    +---------+  |  |     |          |          |      | |   +---------+ 
                 |  |     |          |          |      | | 
    +---------+  |  |  +--+--+       |       +--+--+   | |   +---------+ 
    |  +----+ |  |  |  |     |       +-------+     +-----+   | +----+  | 
    |  |    +-+--+  |  | CN4 +---------------+ CN5 |   |     | |    |  | 
    | -+ EN2+-+-----+--+     |               |     +---+-----+-+ EN4+- | 
    |  |    | | UNI |  +-----+               +-----+   | UNI | |    |  | 
    |  +----+ |     |                                  |     | +----+  | 
    +---------+     +----------------------------------+     +---------+ 
      Overlay                 Core Network                     Overlay 
      Network                                                  Network 
     
                        Legend:   EN  -  Edge Node 
                                  CN  -  Core Node 
     
               Figure 1:  Overlay Reference Model [RFC4208] 
       

      Figure 1 depicts two types of UNI connectivity: single-homed and 
      dual-homed ENs (which also applies to higher order multi-homed 
      connectivity.). Single-homed EN devices are connected to a single 
      CN device via a single UNI link. This single UNI link may 
      constitute a single point of failure. UNI connection between EN1 
      and CN1 is an example of singled-homed UNI connectivity. 

      A single point of failure caused by a single-homed UNI can be 
      avoided when the EN device is connected to two different CN 
      devices, as depicted for EN2 in Figure 1. For the dual-homing 
      case, it is possible to establish two different UNI connections 
      from the same source EN device to the same destination EN device. 
      For example, two connections from EN2 to EN3 may use the two UNI 
    
    
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      links EN2-CN1 and EN2-CN4. To avoid single points of failure 
      within the provider network, it is necessary to also ensure path 
      (LSP) diversity within the core network. 

      In a UNI network such as that shown in Figure 1, the CNs 
      typically perform path computation. Information sharing across 
      the UNI boundary is restricted based on the policy rules imposed 
      by the core network. Typically, the core network topology 
      information is not exposed to the ENs. In the network shown in 
      Figure 1, consider a use case where an LSP from EN2 to EN4 needs 
      to be SRLG diverse from an LSP from EN1 to EN3. In this case, EN2 
      may not know SRLG attributes of the EN1- EN3 LSP and hence cannot 
      construct an XRO to exclude these SRLGs. In this example EN2 
      cannot use the procedures described in [RFC4874]. Similarly, an 
      LSP from EN2 to EN3 traversing CN1 needs to be diverse from an 
      LSP from EN2 to EN3 going via CN4. Again in this case, exclusions 
      based on [RFC4874] cannot be used. 

      This document addresses these diversity requirements by 
      introducing the notion of excluding the path taken by particular 
      LSP(s). The reference LSP(s) or route(s) from which diversity is 
      required is/are identified by an "identifier". The type of 
      identifier to use is highly dependent on the networking 
      deployment scenario; it could be client-initiated, allocated by 
      the (core) network or managed by a PCE. This document defines 
      three different types of identifiers corresponding to these three 
      cases: a client initiated identifier, a PCE allocated Identifier 
      and CN ingress node (UNI-N) allocated Identifier. 

   1.1. Client-Initiated Identifier 

         The following fields MUST be used to represent the client-
         controlled identifier: IPv4/IPv6 tunnel sender address, 
         IPv4/IPv6 tunnel endpoint address, Tunnel ID, and Extended 
         Tunnel ID. The client MAY also include LSP ID to identify a 
         specific LSP within the tunnel. These fields are defined in 
         [RFC3209], sections 4.6.1.1 and 4.6.2.1.  

      The usage of the client-initiated identifier is illustrated by 
      Figure 1. Suppose a LSP from EN2 to EN4 needs to be diverse with 
      respect to a LSP from EN1 to EN3. The LSP identifier of the EN1-
      EN3 LSP is LSP-IDENTIFIER1, where LSP-IDENTIFIER1 is defined by 
      the tuple (tunnel-id = T1, LSP ID = L1, source address = 
      EN1.ROUTE Identifier (RID), destination address = EN3.RID, 
      extended tunnel-id = EN1.RID). Similarly, LSP identifier of the 
      EN2-EN3 LSP is LSP-IDENTIFIER2, where LSP-IDENTIFIER12 is defined 
      by the tuple (tunnel-id = T2, LSP IS = L1, source address = 
    
    
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      EN2.RID, destination address = EN4.RID, extended tunnel-id = 
      EN2.RID). The EN1-EN3 LSP is signaled with an exclusion 
      requirement from LSP-IDENTIFIER2, and the EN2-EN3 LSP is signaled 
      with an exclusion requirement from LSP-IDENTIFIER1. In order to 
      maintain diversity between these two connections within the core 
      network, the core network SHOULD implement Crankback Signaling 
      [RFC4920]. Note that crankback signaling is known to lead to 
      slower setup times and sub-optimal paths under some circumstances 
      as described by [RFC4920]. 

   1.2. PCE-allocated Identifier 

      In scenarios where a PCE is deployed and used to perform path 
      computation, the core edge node (e.g., node CN1 in Figure 1) 
      could consult a PCE to allocate identifiers, which are used to 
      signal path diversity constraints. In other scenarios, a PCE is 
      deployed at network node(s) or a PCE is part of a Network 
      Management System (NMS). In all these cases, the Path Key as 
      defined in [RFC5520] can be used in RSVP signaling as the 
      identifier to ensure diversity. 

      An example of specifying LSP diversity using a Path Key is shown 
      in Figure 2, where a simple network with two domains is shown. It 
      is desired to set up a pair of path-disjoint LSPs from the source 
      in Domain 1 to the destination in Domain 2, but the domains keep 
      strict confidentiality about all path and topology information. 

      The first LSP is signaled by the source with ERO {A, B, loose Dst} 
      and is set up with the path {Src, A, B, U, V, W, Dst}. However, 
      when sending the RRO out of Domain 2, node U would normally strip 
      the path and replace it with a loose hop to the destination. With 
      this limited information, the source is unable to include enough 
      detail in the ERO of the second LSP to avoid it taking, for 
      example, the path {Src, C, D, X, V, W, Dst} for path-disjointness. 

    
    
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          ---------------------    ----------------------------- 
         | Domain 1            |  |                    Domain 2 | 
         |                     |  |                             | 
         |        ---    ---   |  |   ---    ---     ---        | 
         |       | A |--| B |--+--+--| U |--| V |---| W |       | 
         |      / ---    ---   |  |   ---    ---     --- \      | 
         |  ---/               |  |          /       /    \---  | 
         | |Src|               |  |         /       /     |Dst| | 
         |  ---\               |  |        /       /      /---  | 
         |      \ ---    ---   |  |   --- /   --- /  --- /      | 
         |       | C |--| D |--+--+--| X |---| Y |--| Z |       | 
         |        ---    ---   |  |   ---     ---    ---        | 
         |                     |  |                             | 
          ---------------------    ----------------------------- 
       
                Figure 2: A Simple Multi-Domain Network 
       
      In order to improve the situation, node U performs the PCE 
      function and replaces the path segment {U, V, W} in the RRO with 
      a Path Key subobject. The Path Key subobject assigns an 
      "identifier" to the key. The PCE ID in the message indicates that 
      it was node U that made the replacement. 
       
      With this additional information, the source is able to signal 
      the subsequent LSPs with the ERO set to {C, D, exclude Path 
      Key(EXRS), loose Dst}. When the signaling message reaches node X, 
      it can consult node U to expand the Path Key and know how to 
      avoid the path of the first LSP. Alternatively, the source could 
      use an ERO of {C, D, loose Dst} and include an XRO containing the 
      Path Key. 
       
      This mechanism can work with all the Path-Key resolution 
      mechanisms, as detailed in [RFC5553] section 3.1. A PCE, co-
      located or not, may be used to resolve the Path-Key, but the node 
      (i.e., a Label Switching Router (LSR)) can also use the Path Key 
      information to index a Path Segment previously supplied to it by 
      the entity that originated the Path-Key, for example the LSR that 
      inserted the Path-Key in the RRO or a management system. 
    

   1.3. Network-Assigned Identifier 

      There are scenarios in which the network provides diversity-
      related information for a service that allows the client device 
      to include this information in the signaling message. If the 
      Shared Resource Link Group (SRLG) identifier information is both 
      available and shareable (by policy) with the ENs, the procedure 
    
    
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      defined in [RFC8001] can be used to collect SRLG identifiers 
      associated with an LSP (LSP1). When a second LSP (LSP2) needs to 
      be diverse with respect to LSP1, the EN constructing the RSVP 
      signaling message for setting up LSP2 can insert the SRLG 
      identifiers associated with LSP1 as diversity constraints into 
      the XRO using the procedure described in [RFC4874]. However, if 
      the core network SRLG identifiers are either not available or not 
      shareable with the ENs based on policies enforced by core 
      network, existing mechanisms cannot be used. 

      In this draft, a signaling mechanism is defined where information 
      signaled to the CN via the UNI does not require shared knowledge 
      of core network SRLG information. For this purpose, the concept 
      of a Path Affinity Set (PAS) is defined for abstracting SRLG 
      information. The motive behind the introduction of the PAS is to 
      minimize the exchange of diversity information between the core 
      network (CNs) and the client devices (ENs). The PAS contains an 
      abstract SRLG identifier associated with a given path rather than 
      a detailed SRLG list. The PAS is a single identifier that can be 
      used to request diversity and associate diversity. The means by 
      which the processing node determines the path corresponding to 
      the PAS is beyond the scope of this document. 

      A CN on the core network boundary interprets the specific PAS 
      identifier (e.g. "123") as meaning to exclude the core network 
      SRLG information (or equivalent) that has been allocated by LSPs 
      associated with this PAS identifier value. For example, if a Path 
      exists for the LSP with the identifier "123", the CN would use 
      local knowledge of the core network SRLGs associated with the 
      "123" LSPs and use those SRLGs as constraints for path 
      computation. If a PAS identifier is included for exclusion in the 
      connection request, the CN (UNI-N) in the core network is assumed 
      to be able to determine the existing core network SRLG 
      information and calculate a path that meets the determined 
      diversity constraints.  

      When a CN satisfies a connection setup for a (SRLG) diverse 
      signaled path, the CN may optionally record the core network SRLG 
      information for that connection in terms of CN based parameters 
      and associates that with the EN addresses in the Path message. 
      Specifically, for Layer-1 Virtual Private Networks (L1VPNs), Port 
      Information Tables (PIT) [RFC5251] can be leveraged to translate 
      between client (EN) addresses and core network addresses. 

      The means to distribute the PAS information within the core 
      network is beyond the scope of this document. For example, the 
      PAS and the associated SRLG information can be distributed within 
    
    
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      the core network by an Interior Gateway Protocol (IGP) or by 
      other means such as configuration. Regardless of means used to 
      distribute the PAS information, the information is kept inside 
      core network and is not shared with the overlay network (see 
      Figure 1). 

       

   2. RSVP-TE signaling extensions 

      This section describes the signaling extensions required to 
      address the aforementioned requirements and use cases. 

   2.1. Diversity XRO Subobject 

      New Diversity XRO subobjects are defined below for the IPv4 and 
      IPv6 address families. Most of the fields in the IPv4 and IPv6 
      Diversity XRO subobjects are common and are described following 
      the definition of the two subobjects. 

       

      IPv4 Diversity XRO subobject is defined as follows: 

       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  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |L|  XRO Type   |     Length    |DI Type|A-Flags|E-Flags| Resvd | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |           IPv4 Diversity Identifier Source Address            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                  Diversity Identifier Value                   | 
      //                            ...                              // 
      |                                                               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
    

    
    
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      Similarly, the IPv6 Diversity XRO subobject is defined as 
      follows: 

       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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |L|  XRO Type   |     Length    |DI Type|A-Flags|E-Flags| Resvd | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |           IPv6 Diversity Identifier source address            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         IPv6 Diversity Identifier source address (cont.)      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         IPv6 Diversity Identifier source address (cont.)      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         IPv6 Diversity Identifier source address (cont.)      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                  Diversity Identifier Value                   | 
      //                            ...                              // 
      |                                                               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
    
        L: 
             The L-flag is used as for the XRO subobjects defined in 
             [RFC4874], i.e., 
              
             0 indicates that the attribute specified MUST be excluded. 
              
             1 indicates that the attribute specified SHOULD be avoided. 
              
        XRO Type 
         
             The value is set to TBA1 for the IPv4 diversity XRO 
             subobject (value to be assigned by IANA). Similarly, the 
             value is set to TBA2 for the IPv6 diversity XRO subobject 
             (value to be assigned by IANA). 

              
        Length 

             Per [RFC4874], the Length contains the total length of the 
             IPv4/IPv6 subobject in bytes, including the Type and 

    
    
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             Length fields. The Length is variable, depending on the 
             diversity identifier value. 

        Diversity Identifier Type (DI Type) 
         
             Diversity Identifier Type (DI Type) indicates the way the 
             reference LSP(s) or route(s) with which diversity is 
             required is identified in the IPv4/IPv6 Diversity 
             subobjects. The following three DI type values are defined 
             in this document: 
              
                DI Type value   Definition 
                -------------   -------------------------------- 
                      1         Client Initiated Identifier 
                      2         PCE Allocated Identifier 
                      3         Network Assigned Identifier 
              
        Attribute Flags (A-Flags): 

            The Attribute Flags (A-Flags) are used to communicate 
            desirable attributes of the LSP being signaled in the IPv4/ 
            IPv6 Diversity subobjects. The following flags are defined. 
            Each flag acts independently.  Any combination of flags is 
            permitted.  

            0x01 = Destination node exception 

               Indicates that the exclusion does not apply to the 
               destination node of the LSP being signaled. 

            0x02 = Processing node exception 

               Indicates that the exclusion does not apply to the 
               node(s) performing ERO expansion for the LSP being 
               signaled. An ingress UNI-N node is an example of such a 
               node. 

            0x04 = Penultimate node exception 

               Indicates that the penultimate node of the LSP being 
               signaled MAY be shared with the excluded path even when 
               this violates the exclusion flags. 

               The penultimate node exception flag is typically set 
               when the destination node is single homed (e.g. EN1 or 
    
    
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               EN4 in Figure 1). In such a case, LSP diversity can only 
               be accomplished inside the core network up to the egress 
               node and the penultimate hop must be the same for the 
               LSPs. 

            0x08 = LSP ID to be ignored  

               This flag is used to indicate tunnel level exclusion. 
               Specifically, this flag is used to indicate that if 
               diversity identifier contains lsp-id field, the lsp-id 
               is to be ignored and the exclusion applies to any LSP 
               matching the rest of the diversity identifier.  

        Exclusion Flags (E-Flags): 
         
             The Exclusion-Flags are used to communicate the desired 
             type(s) of exclusion requested in the IPv4/IPv6 diversity 
             subobjects. The following flags are defined. Any 
             combination of these flags is permitted. Please note that 
             the exclusion specified by these flags may be modified by 
             the value of the Attribute-flags. For example, node 
             exclusion flag is ignored for the "Penultimate node" if 
             the "Penultimate node exception" flag of the Attribute-
             flags is set. 
    
             0x01 = SRLG exclusion 
               
                  Indicates that the path of the LSP being signaled is 
                  requested to be SRLG-diverse from the excluded path 
                  specified by the IPv4/IPv6 Diversity XRO subobject. 
                   
             0x02 = Node exclusion 
              
                  Indicates that the path of the LSP being signaled is 
                  requested to be node-diverse from the excluded path 
                  specified by the IPv4/IPv6 Diversity XRO subobject. 

             0x04 = Link exclusion 
              
                  Indicates that the path of the LSP being signaled is 
                  requested to be link-diverse from the path specified 
                  by the IPv4/IPv6 Diversity XRO subobject. 
       
    
    
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             0x08 = reserved 
              
                  This flag is reserved. It MUST be set to zero on 
                  transmission, and MUST be ignored on receipt for both 
                  IPv4/IPv6 Diversity XRO subobjects. 
                   
        Resvd 
              
             This field is reserved. It MUST be set to zero on 
             transmission, and MUST be ignored on receipt for both 
             IPv4/IPv6 Diversity XRO subobjects. 
              
              
        IPv4 / IPv6 Diversity Identifier source address: 
         
            This field MUST be set to the IPv4/IPv6 address of the node 
            that assigns the diversity identifier. Depending on the 
            diversity identifier type, the diversity identifier source 
            may be a client node, PCE entity or network node. 
            Specifically: 

           o  When the diversity identifier type is set to "IPv4/IPv6 
              Client Initiated Identifier", the value MUST be set to 
              IPv4/IPv6 tunnel sender address of the reference LSP 
              against which diversity is desired. IPv4/IPv6 tunnel 
              sender address is as defined in [RFC3209]. 

           o  When the diversity identifier type is set to "IPv4/IPv6 
              PCE Allocated Identifier", the value MUST be set to the 
              IPv4/IPv6 address of the node that assigned the Path Key 
              identifier and that can return an expansion of the Path 
              Key or use the Path Key as exclusion in a path 
              computation. The Path Key is defined in [RFC5553]. The 
              PCE-ID is carried in the Identifier Source Address field 
              of the subobject. 

           o  When the diversity identifier type is set to "IPv4/IPv6 
              Network Assigned Identifier", the value MUST be set to the 
              IPv4/IPv6 address of the node allocating the Path Affinity 
              Set (PAS). 

        Diversity Identifier Value: 
         

    
    
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            Encoding for this field depends on the diversity identifier 
            type, as defined in the following. 

            When the diversity identifier type is set to "Client 
            Initiated Identifier" in the IPv4 Diversity XRO subobject, 
            the diversity identifier value MUST be encoded as follows: 
    
             
       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  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 IPv4 tunnel end point address                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          Must Be Zero         |     Tunnel ID                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                       Extended Tunnel ID                      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          Must Be Zero         |            LSP ID             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       

            The IPv4 tunnel end point address, Tunnel ID, Extended 
            Tunnel ID and LSP ID are as defined in [RFC3209]. 

            When the diversity identifier type is set to "Client 
            Initiated Identifier" in the IPv6 Diversity XRO subobject, 
            the diversity identifier value MUST be encoded as follows: 
             
       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  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 IPv6 tunnel end point address                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             IPv6 tunnel end point address (cont.)             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             IPv6 tunnel end point address (cont.)             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             IPv6 tunnel end point address (cont.)             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          Must Be Zero         |     Tunnel ID                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                       Extended Tunnel ID                      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Extended Tunnel ID (cont.)                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
    
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      |                   Extended Tunnel ID (cont.)                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Extended Tunnel ID (cont.)                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          Must Be Zero         |            LSP ID             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

            The IPv6 tunnel end point address, Tunnel ID, IPv6 Extended 
            Tunnel ID and LSP ID are as defined in [RFC3209].  

            When the diversity identifier type is set to "PCE Allocated 
            Identifier" in IPv4 or IPv6 Diversity XRO subobject, the 
            diversity identifier value MUST be encoded as follows: 

       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  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Must Be Zero          |           Path Key            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       

            The Path Key is defined in [RFC5553]. 

            When the diversity identifier type is set to "Network 
            Assigned Identifier" in IPv4 or IPv6 Diversity XRO 
            subobject, the diversity identifier value MUST be encoded 
            as follows: 

       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  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             Path Affinity Set (PAS) identifier                | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

             The Path Affinity Set (PAS) identifier field is a 32-bit 
             value that is scoped by, i.e., is only meaningful when 
             used in combination with, the Diversity Identifier source 
             address field. There are no restrictions on how a node 
             selects a PAS identifier value. Section 1.3 defines the 
             PAS term and provides context on how values may be 
             selected. 
    

    
    
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   2.2. Diversity EXRS Subobject 

      [RFC4874] defines the EXRS ERO subobject. An EXRS is used to 
      identify abstract nodes or resources that must not or should not 
      be used on the path between two inclusive abstract nodes or 
      resources in the explicit route. An EXRS contains one or more 
      subobjects of its own, called EXRS subobjects [RFC4874]. 

      An EXRS MAY include Diversity subobject as specified in this 
      document. The same type values TBA1 and TBA2 SHALL be used. 

   2.3. Processing rules for the Diversity XRO and EXRS subobjects 

      The procedure defined in [RFC4874] for processing the XRO and 
      EXRS is not changed by this document. The processing rules for 
      the Diversity XRO and EXRS subobjects are similar unless the 
      differences are explicitly described. Similarly, IPv4 and IPv6 
      Diversity XRO subobjects and IPv4 and IPv6 Diversity EXRS 
      subobjects follow the same processing rules.  

      If the processing node cannot recognize the Diversity XRO/ EXRS 
      subobject, the node is expected to follow the procedure defined 
      in [RFC4874]. 

      An XRO/ EXRS object MAY contain multiple Diversity subobjects of 
      the same DI Type. E.g., in order to exclude multiple Path Keys, a 
      node MAY include multiple Diversity XRO subobjects each with a 
      different Path Key. Similarly, in order to exclude the routes 
      taken by multiple LSPs, a node MAY include multiple Diversity 
      XRO/ EXRS subobjects each with a different LSP identifier. 
      Likewise, to exclude multiple PAS identifiers, a node MAY include 
      multiple Diversity XRO/ EXRS subobjects each with a different PAS 
      identifier. However, all Diversity subobjects in an XRO/ EXRS 
      MUST contain the same Diversity Identifier Type. If a Path 
      message contains an XRO/ EXRS with multiple Diversity subobjects 
      of different DI Types, the processing node MUST return a PathErr 
      with the error code "Routing Problem" (24) and error sub-code 
      "XRO/ EXRS Too Complex" (68/ 69). 

      If the processing node recognize the Diversity XRO/ EXRS 
      subobject but does not support the DI type, it MUST return a 
      PathErr with the error code "Routing Problem" (24) and error sub-
      code "Unsupported Diversity Identifier Type" (TBA3). 

      In case of DI type "Client Initiated Identifier", all nodes along 
      the path SHOULD process the diversity information signaled in the 
      XRO/ EXRS Diversity subobjects to verify that the signaled 
    
    
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      diversity constraint is satisfied. If a diversity violation is 
      detected, crankback signaling MAY be initiated. 

      In case of DI type "PCE Allocated Identifier" and "Network 
      Assigned Identifier", the nodes in the domain that perform path 
      computation SHOULD process the diversity information signaled in 
      the XRO/ EXRS Diversity subobjects. Typically, the ingress node 
      of a domain sends a path computation request from ingress node to 
      egress node including diversity constraints to a PCE or the 
      ingress node is capable to calculate the path for a new LSP from 
      ingress node to the egress node taking the diversity constraints 
      into account. The calculated path is then carried in the explicit 
      route object (ERO). Hence, the transit nodes in a domain and the 
      domain egress node SHOULD NOT process the signaled diversity 
      information unless path computation is performed. 

      While processing EXRS object, if a loose-hop expansion results in 
      the creation of another loose-hop in the outgoing ERO, the 
      processing node MAY include the EXRS in the newly created loose 
      hop for further processing by downstream nodes.  

      The attribute-flags affect the processing of the Diversity XRO/ 
      EXRS subobject as follows:  

           o When the "processing node exception" flag is set, the 
             exclusion MUST be ignored for the node processing the XRO 
             or EXRS subobject.  

           o When the "destination node exception" flag is set, the 
             exclusion MUST be ignored for the destination node in 
             processing the XRO subobject. The destination node 
             exception for the EXRS subobject applies to the explicit 
             node identified by the ERO subobject that identifies the 
             next abstract node. When the "destination node exception" 
             flag is set in the EXRS subobject, exclusion MUST be 
             ignored for the said node (i.e., the next abstract node). 

           o  When the "penultimate node exception" flag is set in the 
             XRO subobject, the exclusion MUST be ignored for the 
             penultimate node on the path of the LSP being established. 
             The penultimate node exception for the EXRS subobject 
             applies to the node before the explicit node identified by 
             the ERO subobject that identifies the next abstract node. 
             When the "penultimate node exception" flag is set in the 
             EXRS subobject, the exclusion MUST be ignored for the said 
             node (i.e., the node before the next abstract node).  

    
    
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      If the L-flag of the diversity XRO subobject or diversity EXRS 
      subobject is not set, the processing node proceeds as follows.  

      -  If the Diversity Identifier Type is set to "IPv4/IPv6 Client 
         Initiated Identifiers", the processing node MUST ensure that 
         the path calculated/ expended for the signaled LSP is diverse 
         from the route taken by the LSP identified in the Diversity 
         Identifier Value field. 

      -  If the Diversity Identifier Type is set to "IPv4/IPv6 PCE 
         Allocated Identifiers", the processing node MUST ensure that 
         any path calculated for the signaled LSP is diverse from the 
         route identified by the Path-Key. The processing node MAY use 
         the PCE identified by the IPv4/IPv6 Diversity Identifier Source 
         Address in the subobject for route computation. The processing 
         node MAY use the Path-Key resolution mechanisms described in 
         [RFC5553]. 

      -  If the Diversity Identifier Type is set to "IPv4/IPv6 Network 
         Assigned Identifiers", the processing node MUST ensure that the 
         path calculated for the signaled LSP is diverse with respect to 
         the values associated with the PAS identifier and Diversity 
         Identifier source address fields.  

      -  Regardless of whether the path computation is performed 
         locally or at a remote node (e.g., PCE), the processing node 
         MUST ensure that any path calculated for the signaled LSP is 
         diverse from the requested Exclusion Flags. 

      -  If the excluded path referenced in the XRO subobject is 
         unknown to the processing node, the processing node SHOULD 
         ignore the diversity XRO subobject and SHOULD proceed with the 
         signaling request. After sending the Resv for the signaled LSP, 
         the processing node MUST return a PathErr with the error code 
         "Notify Error" (25) and error sub-code TBA4 "Route of XRO LSP 
         identifier unknown" (value to be assigned by IANA) for the 
         signaled LSP. 

      -  If the processing node fails to find a path that meets the 
         requested constraint, the processing node MUST return a PathErr 
         with the error code "Routing Problem" (24) and error sub-code 
         "Route blocked by Exclude Route" (67). 

      If the L-flag of the XRO diversity subobject or EXRS diversity 
      subobject is set, the processing node proceeds as follows: 

    
    
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      -  If the Diversity Identifier Type is set to "IPv4/IPv6 Client 
         Initiated Identifiers", the processing node SHOULD ensure that 
         the path calculated/ expended for the signaled LSP is diverse 
         from the route taken by the LSP identified in the Diversity 
         Identifier Value field. 

      -  If the Diversity Identifier Type is set to "IPv4/IPv6 PCE 
         Allocated Identifiers", the processing node SHOULD ensure that 
         the path calculated for the signaled LSP is diverse from the 
         route identified by the Path-Key. 

      -  If the Diversity Identifier Type is set to "IPv4/IPv6 Network 
         Assigned Identifiers", the processing node SHOULD ensure that 
         the path calculated for the signaled LSP is diverse with 
         respect to the values associated with the PAS identifier and 
         Diversity Identifier source address fields. 

      -  If the processing node fails to find a path that meets the 
         requested constraint, it SHOULD proceed with signaling using a 
         suitable path that meets the constraint as far as possible. 
         After sending the Resv for the signaled LSP, it MUST return a 
         PathErr message with error code "Notify Error" (25) and error 
         sub-code TBA5 "Failed to satisfy Exclude Route" (value: to be 
         assigned by IANA) to the source node. 

      If, subsequent to the initial signaling of a diverse LSP, an 
      excluded path referenced in the XRO subobject becomes known to 
      the processing node, or a change in the excluded path becomes 
      known to the processing node, the processing node MUST re-
      evaluate the exclusion and diversity constraints requested by the 
      diverse LSP to determine whether they are still satisfied. 

      -  In case the L-flag was not set in the initial setup message, 
         the exclusion and diversity constraints were satisfied at the 
         time of the initial setup. If the processing node re-evaluating 
         the exclusion and diversity constraints for a diverse LSP 
         detects that the exclusion and diversity constraints are no 
         longer met, it MUST send a PathErr message for the diverse LSP 
         with the error code "Routing Problem" (24) and error sub-code 
         "Route blocked by Exclude Route" (67). The Path_State_Removed 
         flag (PSR) [RFC3473] MUST NOT be set. A source node receiving a 
         PathErr message with this error code and sub-code combination 
         SHOULD take appropriate actions and move the diverse LSP to a 
         new path that meets the original constraints. 

      -  In case the L-flag was set in the initial setup message, the 
         exclusion and diversity constraints may or may not be satisfied 
    
    
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         at any given time. If the exclusion constraints for a diverse 
         LSP were satisfied before and if the processing node re-
         evaluating the exclusion and diversity constraints for a 
         diverse LSP detects that exclusion and diversity constraints 
         are no longer met, it MUST send a PathErr message for the 
         diverse LSP with the error code error code "Notify Error" (25) 
         and error sub-code TBA5 "Failed to satisfy Exclude Route" 
         (value: to be assigned by IANA). The PSR flag MUST NOT be set. 
         The source node MAY take no consequent action and keep the LSP 
         along the path that does not meet the original constraints. 
         Similarly, if the exclusion constraints for a diverse LSP were 
         not satisfied before and if the processing node re-evaluating 
         the exclusion and diversity constraints for a diverse LSP 
         detects that the exclusion constraints are met, it MUST send a 
         PathErr message for the diverse LSP with the error code "Notify 
         Error" (25) and a new error sub- code TBA6 "Compliant path 
         exists" (value: to be assigned by IANA). The PSR flag MUST NOT 
         be set. A source node receiving a PathErr message with this 
         error code and sub-code combination MAY move the diverse LSP to 
         a new path that meets the original constraints. 

       
       
   3. Security Considerations 

      This document does not introduce any additional security issues 
      above those identified in [RFC5920], [RFC2205], [RFC3209], 
      [RFC3473] and [RFC4874].  

      The diversity mechanism defined in this document, relies on the 
      new diversity subobject that is carried in the XRO or EXRS, 
      respectively. In section 7 of [RFC4874], it is stated that the 
      XRO could be considered for removal from the Path message due to 
      security concerns for example at administrative boundaries. In 
      this case, the diversity subobject would also be removed. Hence, 
      the diversity subobject MUST be kept while other subobjects may 
      be removed. 

   4. IANA Considerations 

      IANA is requested to administer the assignment of new values 
      defined in this document and summarized in this section. 

   4.1. New XRO subobject types 

      IANA registry: RSVP PARAMETERS 
      Subsection: Class Names, Class Numbers, and Class Types 
    
    
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      This document defines two new subobjects for the EXCLUDE_ROUTE 
      object [RFC4874], C-Type 1. (see: 
      http://www.iana.org/assignments/rsvp-parameters/rsvp-
      parameters.xhtml#rsvp-parameters-94) 
       
      Subobject Description         Subobject Type 
      ------------------------      -------------- 
      IPv4 Diversity subobject         TBA1 
      IPv6 Diversity subobject         TBA2 
       
       
   4.2. New EXRS subobject types 

      The diversity XRO subobjects are also defined as new EXRS 
      subobjects. (EXPLICIT_ROUTE see: 
      http://www.iana.org/assignments/rsvp-parameters/rsvp-
      parameters.xhtml#rsvp-parameters-24). The same numeric subobject 
      type values TBA1 and TBA2 are being requested for the two new 
      EXRS subobjects. 
       
       
   4.3. New RSVP error sub-codes 

      IANA registry: RSVP PARAMETERS 
      Subsection: Error Codes and Globally Defined Error Value Sub-
      Codes.  
      For Error Code "Routing Problem" (24) (see [RFC3209]) the 
      following sub-codes are defined. (see: 
      http://www.iana.org/assignments/rsvp-parameters/rsvp-
      parameters.xhtml#rsvp-parameters-105) 

       
       +-------------+----------------------------+---------------+ 
       | Error Value | Description                | Reference     | 
       | Sub-codes   |                            |               | 
       +-------------+----------------------------+---------------+ 
       | TBA3        | Unsupported Diversity      | This document | 
       |             | Identifier Type            |               | 
       +-------------+----------------------------+---------------+ 
       
      For Error Code "Notify Error" (25) (see [RFC3209]) the following 
      sub-codes are defined. (see: 
    
    
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      http://www.iana.org/assignments/rsvp-parameters/rsvp-
      parameters.xhtml#rsvp-parameters-105) 

       
       +-------------+----------------------------+---------------+ 
       | Error Value | Description                | Reference     | 
       | Sub-codes   |                            |               | 
       +-------------+----------------------------+---------------+ 
       | TBA4        | Route of XRO LSP           | This document | 
       |             | identifier unknown         |               | 
       | TBA5        | Failed to satisfy          | This document | 
       |             | Exclude Route              |               | 
       | TBA6        | Compliant path exists      | This document | 
       +-------------+----------------------------+---------------+ 
       
       
   5. Acknowledgements 

      The authors would like to thank Xihua Fu for his contributions. 
      The authors also would like to thank Luyuan Fang and Walid Wakim 
      for their review comments.  
       
   6. References 

   6.1. 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. 

      [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching 
                (GMPLS) Signaling Resource ReserVation Protocol-Traffic 
                Engineering (RSVP-TE) Extensions", RFC 3473, January 
                2003.  

      [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude 
                Routes - Extension to Resource ReserVation Protocol-
                Traffic Engineering (RSVP-TE)", RFC 4874, April 2007. 

      [RFC4920] Farrel, A., Ed., Satyanarayana, A., Iwata, A., Fujita, 
                N., and G. Ash, "Crankback Signaling Extensions for 
                MPLS and GMPLS RSVP-TE", RFC 4920, July 2007. 

    
    
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      [RFC5553] Farrel, A., Ed., Bradford, R., and JP. Vasseur, 
                "Resource Reservation Protocol (RSVP) Extensions for 
                Path Key Support", RFC 5553, May 2009. 

       

   6.2. Informative References 

      [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. 

      [RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, 
                "Preserving Topology Confidentiality in Inter-Domain 
                Path Computation Using a Path-Key-Based Mechanism", RFC 
                5520, April 2009. 

      [RFC8001] F. Zhang, D. Li, O. Gonzalez de Dios, C. Margaria, 
                "RSVP-TE Extensions for Collecting SRLG Information", 
                RFC 8001, January 2017. 

      [RFC2205] Braden, R. (Ed.), Zhang, L., Berson, S., Herzog, S. and 
                S. Jamin, "Resource ReserVation Protocol -- Version 1 
                Functional Specification", RFC 2205, September 1997. 

      [RFC5251] Fedyk, D. (Ed.), Rekhter, Y. (Ed.), Papadimitriou, D., 
                Rabbat, R., and Berger, L., "Layer 1 VPN Basic Mode", 
                RFC 5251, July 2008. 

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

       

   Contributors' Addresses 

      Igor Bryskin 
      Huawei Technologies 
      Email: Igor.Bryskin@huawei.com 
    
      Daniele Ceccarelli 
      Ericsson 
      Email: Daniele.Ceccarelli@ericsson.com 
    

    
    
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      Dhruv Dhody 
      Huawei Technologies 
      Email: dhruv.ietf@gmail.com 
    
      Oscar Gonzalez de Dios 
      Telefonica I+D 
      Email: ogondio@tid.es 
    
      Don Fedyk 
      Hewlett-Packard Enterprise 
      Email: don.fedyk@hpe.com 
    
      Clarence Filsfils  
      Cisco Systems, Inc. 
      Email: cfilsfil@cisco.com 
    
      Gabriele Maria Galimberti 
      Cisco Systems 
      Email: ggalimbe@cisco.com 
       
      Ori Gerstel 
      SDN Solutions Ltd. 
      Email: origerstel@gmail.com 
    
      Matt Hartley 
      Cisco Systems 
      Email: mhartley@cisco.com  
          
      Kenji Kumaki 
      KDDI Corporation 
      Email: ke-kumaki@kddi.com  
       
      Ruediger Kunze 
      Deutsche Telekom AG 
      Email: Ruediger.Kunze@telekom.de  
       
      Lieven Levrau 
      Nokia 
      Email: Lieven.Levrau@nokia.com 
       
      Cyril Margaria 
      cyril.margaria@gmail.com 
    
      Julien Meuric 
      France Telecom Orange 
      Email: julien.meuric@orange.com 
    
    
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      Yuji Tochio 
      Fujitsu 
      Email: tochio@jp.fujitsu.com 
    
      Xian Zhang 
      Huawei Technologies 
      Email: zhang.xian@huawei.com 
    
   Authors' Addresses 

      Zafar Ali 
      Cisco Systems. 
      Email: zali@cisco.com 
       
      Dieter Beller 
      Nokia 
      Email: Dieter.Beller@nokia.com 
    
      George Swallow 
      Cisco Systems 
      Email: swallow@cisco.com 
       
      Fatai Zhang 
      Huawei Technologies 
      Email: zhangfatai@huawei.com 
       
    

    
    
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