Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) extension for recording TE Metric of a Label Switched Path
draft-ietf-teas-te-metric-recording-08

Document Type Active Internet-Draft (teas WG)
Last updated 2018-12-20
Replaces draft-ietf-ccamp-te-metric-recording
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TEAS Working Group                                             Zafar Ali                     
     Internet Draft                                    Clarence Filsfils
     Intended status: Standard Track                       Cisco Systems
     Expires: May 15, 2019                                 Julien Meuric
                                                          France telecom
                                                            Kenji Kumaki 
                                                        KDDI Corporation 
                                                          Ruediger Kunze 
                                                     Deutsche Telekom AG 
                                                            Nov 16, 2018  
      
                                         
         Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) 
          extension for recording TE Metric of a Label Switched Path 
                    draft-ietf-teas-te-metric-recording-08 
                                        
     Status of this Memo 

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     This document may contain material from IETF Documents or IETF 
     Contributions published or made publicly available before November 
     10, 2008.  The person(s) controlling the copyright in some of this 
     material may not have granted the IETF Trust the right to allow 
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     Without obtaining an adequate license from the person(s) 
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     Abstract 

     There are many scenarios in which Traffic Engineering (TE) metrics 
     such as cost, delay and delay variation associated with the TE link 
     formed by Label Switched Path (LSP) are not available to the 
     ingress and egress nodes. This draft provides extensions for the 
     Resource ReserVation Protocol- Traffic Engineering (RSVP-TE) to 
     support automatic collection of cost, delay and delay variation 
     information for the TE link formed by a LSP.  

     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. Use Cases  ......................................... 4 
              1.1.1. Inter-domain TE LSPs ....................... 4 
              1.1.2. Inter-area tunnels with loose-hops ......... 4 
        2. RSVP-TE Requirement .................................. 4 
        2.1. Cost, Delay and Delay Variation Collection 
             Indication ......................................... 4 
        2.2. Cost, Delay and Delay Variation Collection ......... 5 
        2.3. Cost, Delay and Delay Variation Update ............. 5 
        2.4. Cost Definition .................................... 5 
        3. Encoding ............................................. 5 
        3.1. Cost, Delay and Delay Variation Collection Flags ... 5 
        3.2. RRO Cost Subobject ................................. 6 
        3.3. RRO Delay Subobject ................................ 7 
        3.4. RRO Delay Variation Subobject ...................... 7 
        4. Signaling Procedures ................................. 8 
        4.1. Cost, Delay and Delay Variation Collection ......... 9 
        4.2. Metric Update ......................................12 
        4.3. Domain Boundaries ..................................12 
        4.4. Endpoint processing ................................12 
        4.5. Compatibility ......................................13 

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        5. Manageability Considerations .........................13 
        5.1. Policy Configuration ...............................13 
        6. Security Considerations ..............................14 
        7. IANA Considerations ..................................14 
        7.1. RSVP Attribute Bit Flags ...........................14 
        7.2. ROUTE_RECORD subobject .............................15 
        7.3. Policy Control Failure Error subcodes ..............15 
 
        8. References ...........................................16 
        8.1. Normative References ...............................16 
        8.2. Informative References .............................16
        Acknowledgements .........................................16 
        Contributors .............................................17 
        Authors' Addresses .......................................17 

     1. Introduction 

        In certain networks, such as financial information networks, 
        network performance information (e.g. delay, delay variation) is 
        becoming as critical to data path selection as other metrics 
        [RFC7471], [RFC7810]. If cost, delay or delay 
        variation associated with a Forwarding Adjacency (FA) or a 
        Routing Adjacency (RA) LSP is not available to the ingress or 
        egress node, it cannot be advertised as an attribute of the TE 
        link (FA or RA). There are scenarios in packet and optical 
        networks where the route information of an LSP may not be 
        provided to the ingress node for confidentiality reasons and/or 
        the ingress node may not run the same routing instance as the 
        intermediate nodes traversed by the path. Similarly, there are 
        scenarios in which measuring delay and/ or delay variation on a 
        TE link formed by a LSP is not supported. In such scenarios, the 
        ingress node cannot determine the cost, delay and delay 
        variation properties of the LSP's route.  

        One possible way to address this issue is to configure cost, 
        delay and delay variation values manually. However, in the event 
        of an LSP being rerouted (e.g. due to re-optimization), such 
        configuration information may become invalid. Consequently, in 
        cases where an LSP is advertised as a TE-Link, the ingress 
        and/or egress nodes cannot provide the correct delay, delay 
        variation and cost information associated with the TE-Link 
        automatically.  

        In summary, there is a requirement for the ingress and egress 
        nodes to learn the cost, delay and delay variation information 
        of the TE link formed by a LSP. This document provides a 
        mechanism to collect the cost, delay and delay variation 
        information of a LSP, which can then be advertised as properties 
        of the TE-link formed by that LSP. 

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     1.1. Use Cases 

        This section describes some of the use cases for the TE metric 
        recording.  

     1.1.1. Inter-domain TE LSPs 

        The cost, delay, delay-variation information of a LSP collected
        by procedures defined in this document can be advertised as
        properties of TE-link formed by that LSP. This information is
        very helpful in multi-domain or multi-layer network. A GMPLS
        User-Network Interface (UNI) [RFC4208] is also an example of
        such networks. 

     1.1.2. Inter-area tunnels with loose-hops 

        When a LSP is established over multiple IGP-areas using loose 
        hops in the ERO, the ingress node may only have knowledge of the 
        first IGP-area traversed by the LSP. In this case, it cannot 
        determine the cost, delay and delay variation properties of the 
        LSP path. 

     2. RSVP-TE Requirement  

        This section outlines RSVP-TE requirements for the support of 
        the automatic collection of cost, delay and delay variation 
        information of an LSP.  

        As RSVP-TE requirements for cost, delay and delay variation 
        collection are similar, many parts of this section are written 
        such that they apply equally to cost, delay and delay variation 
        collection. There is also very strong similarity of these RSVP- 
        requirements with SRLG recording [RFC8001].

        The Cost, Delay, Delay variation collection process takes place
         in three stages:

        o  The LSP's ingress node requests that Cost, Delay, Delay
           Variation collection should take place;

        o  Cost, Delay, Delay Variation data is added to the Path and
           Resv ROUTE_RECORD Objects(RROs) by all nodes during signaling;

        o  Changes to previously signaled Cost, Delay, Delay variation
           data are made by sending updated Path and Resv messages as
           required.
  

     2.1. Cost, Delay and Delay Variation Collection Indication 

        The ingress node of the LSP needs be capable of indicating 
        whether the cost and/or delay and/ or delay variation 
        information of the LSP is to be collected during the signaling 
        procedure of setting up an LSP. A separate collection indication 
        flag for each of these attributes is required. There is no need 
        for cost and/or delay and/ or delay variation to be collected 
        without an explicit request for it being made by the ingress 
        node.  

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        It may be preferable for the cost and/ or delay and/ or delay 
        variation collection request to be understood by all nodes along 
        the LSP's path, or it may be more important for the LSP to be 
        established successfully even if it traverses nodes that cannot 
        supply the requested information or have not implemented the 
        procedures specified in this document. It is desirable for the 
        ingress node to make the cost, delay and delay variation 
        collection request in a manner that best suits its own policy. 

     2.2. Cost, Delay and Delay Variation Collection 

        If requested, the cost and/or delay and/ or delay variation 
        information is collected during the setup of an LSP. Each of the 
        cost, delay or delay variation can be collected independently. 
        Cost and/ or delay and/ or delay variation information is added
        by each hop to the Path RRO during Path message processing. The
        corresponding information is also added to the Resv RRO during
        Resv processing at each hop.

     2.3. Cost, Delay and Delay Variation Update 

        When the cost and/or delay and/ or delay variation information 
        of an existing LSP for which corresponding information was 
        collected during signaling changes, the relevant nodes of the 
        LSP need to be capable of updating the associated information of 
        the LSP.  This means that the signaling procedure needs to be 
        capable of updating the new cost and/or delay and/ or delay 
        variation information. 

     2.4. Cost Definition 

        Although the terms delay and delay variation are well 
        understood, "cost" may be ambiguous; in particular, in the 
        context of a LSP that traverse nodes and links operated by 
        different entities, there may be no common definition of cost. 
        However, there are situations in which the entire LSP may be 
        within a single AS (e.g. inter-area LSPs) in which cost 
        discovery is useful. 

        The precise meaning and interpretation of numerical costs is a 
        matter for the network operator. For the purposes of this 
        document, two constraints are assumed: 

          . A higher cost represents an inferior path.  

          . Simple addition of costs for different sections of a path 
             must make sense. 

     3. Encoding 

     3.1. Cost, Delay and Delay Variation Collection Flags 

        In order to indicate nodes that cost and/or Delay and/or Delay 
        variation collection is desired, this document defines the 
        following new flags in the Attribute Flags TLV (see RFC 5420 

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        [RFC5420]). A node that wishes to indicate Cost and/or Delay
        and/or Delay Variation collection is desired MUST set 
        corresponding flag in Attribute Flags TLV in an
        LSP_REQUIRED_ATTRIBUTES object (if collection is mandatory)
        or LSP_ATTRIBUTES Object(if collection is desired but not mandatory): 

        - Cost Collection flag (Bit number to be assigned by IANA) 

        - Delay Collection flag (Bit number to be assigned by IANA) 

        - Delay Variation Collection flag (Bit number to be assigned by 
        IANA) 

        The Cost, Delay and Delay Variation Collection flags are 
        meaningful on a Path message.  If the Cost Collection flag is 
        set to 1, it means that the cost information SHOULD be reported 
        to the ingress and egress node along the setup of the LSP. 
        Similarly, if the Delay Collection flag is set to 1, it means 
        that the Delay information SHOULD be reported to the ingress and 
        egress node along the setup of the LSP. Likewise, if the Delay 
        Variation Collection flag is set to 1, it means that the Delay 
        Variation information SHOULD be reported to the ingress and 
        egress node along the setup of the LSP. 

        The rules of the processing of the Attribute Flags TLV are not 
        changed.  

     3.2. RRO Cost Subobject  

        This document defines a new RRO sub-object (ROUTE_RECORD sub-
        object) to record the cost information of the LSP.  Its format 
        is modeled on the RRO sub-objects defined in RFC 3209 [RFC3209]. 

         
        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 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |     Type      |    Length     |D|  Reserved (must be zero)    | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                              Cost                             | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
         
           Type: The type of the sub-object (value to be assigned by 
           IANA). 

           Length: The Length field contains the total length of the 
           sub-object in bytes, including the Type and Length fields. 
           The Length value is set to 8.  

           Direction bit (D-bit) 

           If not set, the cost contained in this sub-object applies to 
           the downstream direction. If set, it applies to the upstream 
           direction.  
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           Reserved: This field is reserved for future use. It MUST be 
           set to 0 on transmission and MUST be ignored when received.  

           Cost: Cost of the local TE link along the route of the LSP.  

     3.3. RRO Delay Subobject 

        This document defines a new RRO sub-object (ROUTE_RECORD sub-
        object) to record the delay information of the LSP.  Its format 
        is modeled on the RRO sub-objects defined in RFC 3209 [RFC3209].  

        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 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |   Type        |   Length      |D|  Reserved (must be zero)    | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |A|  Reserved   |                      Delay                    |              
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         

           Type: The type of the sub-object (value to be assigned by 
           IANA). 

           Length: The Length field contains the total length of the 
           sub-object in bytes, including the Type and Length fields. 
           The Length value is set to 8. 

           Direction bit (D-bit) 

           If not set, the Delay contained in this sub-object applies to 
           the downstream direction. If set, it applies to the upstream 
           direction.  

           A-bit: These fields represent the Anomalous (A) bit 
           associated with the Downstream and Upstream Delay 
           respectively, as defined in RFC 7471 [RFC7471]. 

           Reserved: These fields are reserved for future use. They MUST 
           be set to 0 when sent and MUST be ignored when received. 

           Delay: Delay of the local TE link along the route of the LSP, 
           encoded as 24-bit integer, as defined in RFC 7471 [RFC7471]. 
           When set to the maximum value 16,777,215 (16.777215 sec), the 
           delay is at least that value and may be larger.  

     3.4. RRO Delay Variation Subobject 

        This document defines a new RRO sub-object (ROUTE_RECORD sub-
        object) to record the delay variation information of the LSP.  

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        Its format is modeled on the RRO sub-objects defined in RFC 3209 
        [RFC3209].  
         
        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 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |   Type        |   Length      |D|  Reserved (must be zero)    | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |A|  Reserved   |                 Delay Variation               |              
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         

           Type: The type of the sub-object (value to be assigned by 
           IANA). 

           Length: The Length field contains the total length of the 
           sub-object in bytes, including the Type and Length fields. 
           The Length value is set to 8. 

           Direction bit (D-bit) 

           If not set, the Delay Variation contained in this sub-object 
           applies to the downstream direction. If set, it applies to 
           the upstream direction.  

           A-bit: These fields represent the Anomalous (A) bit 
           associated with the Downstream and Upstream Delay Variation 
           respectively, as defined in RFC 7471 [RFC7471]. 

           Reserved: These fields are reserved for future use. It SHOULD 
           be set to 0 when sent and MUST be ignored when received. 

           Delay Variation: Delay Variation of the local TE link along 
           the route of the LSP, encoded as 24-bit integer, as defined 
           in RFC 7471 [RFC7471]. When set to the maximum value 
           16,777,215 (16.777215 sec), the delay variation is at least 
           that value and may be larger.  

     4. Signaling Procedures 

        As signaling procedure for cost, delay and delay variation 
        collection is similar, many parts of this section are written 
        such that they apply equally to cost, delay and delay variation 
        collection. There is also very strong similarity of these 
        procedures with SRLG recording [RFC8001].  

        The ingress node of the LSP MUST be capable of indicating 
        whether the Cost and/ or Delay and/ or Delay Variation 
        information of the LSP is to be collected during the signaling 
        procedure of setting up an LSP.   

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        A node MUST NOT push Cost and/ or Delay and/ or Delay Variation 
        sub-object(s) in the RECORD_ROUTE without also pushing either an 
        IPv4 sub-object, an IPv6 sub-object, an Unnumbered Interface ID 
        sub-object or a Path Key sub-object or an SRLG sub-object.  

        As described in RFC 3209 [RFC3209], the RECORD_ROUTE object is 
        managed as a stack.  The Cost and/ or Delay and/ or Delay 
        Variation sub-object(s) SHOULD be pushed by the node before the 
        node IP address or link identifier. These sub-object(s) SHOULD 
        be pushed after the Attribute sub-object, if present, and after 
        the LABEL sub-object, if requested, and after the SRLG sub-
        object, if requested. These sub-object(s) MUST be pushed within 
        the hop to which it applies.  

        RFC 5553 [RFC5553] describes mechanisms to carry a PKS (Path Key 
        Sub-object) in the RRO so as to facilitate confidentiality in 
        the signaling of inter-domain TE LSPs, and allows the path 
        segment that needs to be hidden (that is, a Confidential Path 
        Segment (CPS)) to be replaced in the RRO with a PKS. If the CPS 
        contains Cost and/ or Delay and/ or Delay Variation Sub-objects, 
        these MAY be retained in the RRO by adding them again after the 
        PKS Sub-object in the RRO.  The CPS is defined in RFC 5520 
        [RFC5520].  

        The rules of the processing of the LSP_REQUIRED_ATTRIBUTES, 
        LSP_ATTRIBUTE and ROUTE_RECORD Objects are not changed. 

     4.1. Cost, Delay and Delay Variation Collection  

        Per RFC 3209 [RFC3209], an ingress node initiates the recording 
        of the route information of an LSP by adding a RRO to a Path 
        message. If an ingress node also desires Cost and/or Delay 
        and/or Delay Variation recording, it MUST set the appropriate 
        flag(s) in the Attribute Flags TLV which MAY be carried either 
        in an LSP_REQUIRED_ATTRIBUTES Object when the collection is 
        mandatory, or in an LSP_ATTRIBUTES Object when the collection is 
        desired, but not mandatory. 

        When a node receives a Path message which carries an 
        LSP_REQUIRED_ATTRIBUTES Object with the Cost Collection Flag 
        set, if local policy determines that the Cost information is not 
        to be provided to the endpoints, it MUST return a PathErr 
        message with: 

           o  Error Code 2 (policy) and  

           o  Error subcode "Cost Recording Rejected" (value to be 
        assigned by IANA) 

        to reject the Path message. Similarly, when a node receives a 
        Path message which carries an LSP_REQUIRED_ATTRIBUTES Object 
        with the Delay Collection Flag set, if local policy determines 
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        that the Delay information is not to be provided to the 
        endpoints, it MUST return a PathErr message with: 

           o  Error Code 2 (policy) and  

           o  Error subcode "Delay Recording Rejected" (value to be 
        assigned by IANA) 

        to reject the Path message. Likewise, when a node receives a 
        Path message which carries an LSP_REQUIRED_ATTRIBUTES Object 
        with the Delay Variation Collection Flag set, if local policy 
        determines that the Delay Variation information is not to be 
        provided to the endpoints, it MUST return a PathErr message 
        with: 

           o  Error Code 2 (policy) and  

           o  Error subcode "Delay Variation Recording Rejected" (value 
        to be assigned by IANA) 

        to reject the Path message. 

        When a node receives a Path message which carries an 
        LSP_ATTRIBUTES Object and the Cost and/or Delay and/or Delay 
        Variation Collection Flag set, if local policy determines that 
        the corresponding information is not to be provided to the 
        endpoints, or the information is not known, the Path message 
        SHOULD NOT be rejected due to the recording restriction and the 
        Path message SHOULD be forwarded without any Cost and/or Delay 
        and/or Delay Variation sub-object(s) in the RRO of the 
        corresponding outgoing Path message. 

        If local policy permits the recording of the Cost and/or Delay 
        and/or Delay Variation information, the processing node SHOULD 
        add corresponding information for the local TE link, as defined 
        below, to the RRO of the corresponding outgoing Path message. 
        The A-bit for the Delay MUST be set as described in RFC 7471 
        [RFC7471]. Similarly, the A-bit for the Delay Variation MUST be 
        set as described in RFC 7471 [RFC7471]. It then forwards the 
        Path message to the next node in the downstream direction. The 
        processing node MUST retain a record of the Cost and/ or Delay 
        and/ or Delay Variation Collection request for reference during 
        Resv processing described below. 

        If the addition of Cost and/or Delay and/or Delay Variation 
        information to the RRO would result in the RRO exceeding its 
        maximum possible size or becoming too large for the Path message 
        to contain it, the requested information MUST NOT be added. If 
        the Cost and/or Delay and/or Delay Variation collection request 
        was contained in an LSP_REQUIRED_ATTRIBUTES Object, the 
        processing node MUST behave as specified by RFC 3209 [RFC3209] 
        and drop the RRO from the Path message entirely.  If the Cost 
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        and/or Delay and/or Delay Variation collection request was 
        contained in an LSP_ATTRIBUTES Object, the processing node MAY 
        omit some or all of the corresponding information from the RRO; 
        otherwise it MUST behave as specified by RFC 3209 [RFC3209] and 
        drop the RRO from the Path message entirely. 

        Following the steps described above, the intermediate nodes of 
        the LSP can collect the Cost and/or Delay and/or Delay Variation 
        information in the RRO during the processing of the Path message 
        hop by hop.  When the Path message arrives at the egress node, 
        the egress node receives the corresponding information in the 
        RRO. 

        Per RFC 3209 [RFC3209], when issuing a Resv message for a Path 
        message, which contains an RRO, an egress node initiates the RRO 
        process by adding an RRO to the outgoing Resv message.  The 
        processing for RROs contained in Resv messages then mirrors that 
        of the Path messages. 

        When a node receives a Resv message for an LSP for which Cost 
        and/or Delay and/or Delay Variation Collection was specified, 
        then when local policy allows recording of the requested 
        information, the node SHOULD add corresponding information, to 
        the RRO of the outgoing Resv message, as specified below.  The 
        A-bit for the Delay MUST be set as described in RFC 7471 
        [RFC7471]. Similarly, the A-bit for the Delay Variation MUST be 
        set as described in RFC 7471 [RFC7471]. When the Resv message 
        arrives at the ingress node, the ingress node can extract the 
        requested information from the RRO in the same way as the egress 
        node. 

        Note that a link's Cost and/ or Delay and/ or Delay Variation 
        information for the upstream direction cannot be assumed to be 
        the same as that in the downstream. 

          o For Path and Resv messages for a unidirectional LSP, a node 
             SHOULD include Cost and/ or Delay and/ or Delay Variation 
             sub-objects in the RRO for the downstream data link only. 

          o For Path and Resv messages for a bidirectional LSP, a node 
             SHOULD include Cost and/ or Delay and/ or Delay Variation 
             sub-objects in the RRO for both the upstream data link and 
             the downstream data link from the local node.  In this 
             case, the node MUST include the metric information in the 
             same order for both Path messages and Resv messages.  That 
             is, the Cost and/ or Delay and/ or Delay Variation sub-
             object(s) for the upstream link is added to the RRO before 
             the corresponding sub-object for the downstream link.  

             If Cost and/ or Delay and/ or Delay Variation data is added 
             for both the upstream and downstream links, the two sets of 
             the data MUST be added in separate corresponding sub-
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             object(s). A single Cost or Delay or Delay Variation sub-
             object MUST NOT contain a mixture of the applicable data 
             for upstream and downstream directions. When adding a Cost 
             or Delay or Delay Variation sub-object to an RRO, the D-bit 
             MUST be set appropriately to indicate the direction of the 
             TE Link. If the same value applies in both directions, it 
             SHOULD be added to both the corresponding upstream and 
             downstream sub-objects. 

        Based on the local policy, a transit node may edit a Path or 
        Resv RRO to remove route information (e.g. node or interface 
        identifier information) before forwarding it. A node that does 
        this SHOULD summarize the cost, Delay and Delay Variation data. 
        How a node that performs the RRO edit operation calculates the 
        Cost and/ or Delay and/or Delay variation metric is beyond the 
        scope of this document. 

        A node SHOULD NOT add Cost or Delay or Delay Variation 
        information without an explicit request for the corresponding 
        information being made by the ingress node in the Path message. 

     4.2. Metric Update 

        When the Cost and/or Delay and/or Delay Variation information of 
        a link is changed, the endpoints of LSPs using that link need to 
        be aware of the changes.  When a change to Cost or Delay or 
        Delay Variation information associated with a link occurs, the 
        procedures defined in Section 4.4.3 of RFC 3209 [RFC3209] MUST 
        be used to refresh the corresponding metric information if the 
        change is to be communicated to other nodes according to the 
        local node's policy.  If local policy is that the Cost and/or 
        Delay and/or Delay Variation change SHOULD be suppressed or 
        would result in no change to the previously signaled 
        information, the node SHOULD NOT send an update. 

     4.3. Domain Boundaries 

        If mandated by local policy, a node MAY remove Cost and/or Delay 
        and/or Delay Variation information from any RRO in a Path or 
        Resv message being processed. A node that does this SHOULD 
        summarize the Cost, Delay and Delay Variation data. How a node 
        that performs the RRO edit operation calculates the Cost, Delay 
        and/or Delay variation metric is beyond the scope of this 
        document.  

     4.4. Endpoint processing 

        Based on the procedures described above, the endpoints can get 
        the Cost and/or Delay and/or Delay Variation information 
        automatically.  Then the endpoints can for instance advertise it 
        as a TE link to the routing instance based on the procedure 
        described in [RFC6107] and configure the corresponding TE metric 
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        information of the Forwarding Adjacency (FA) or Routing 
        Adjacency (RA) automatically. How the end point uses the 
        collected information is outside the scope of this document.  

        The ingress and egress nodes of a LSP may calculate the end-to- 
        end Cost, Delay and/or Delay variation properties of the LSP 
        from the supplied values in the Resv or Path RRO, respectively. 

        Typically, Cost and Delay are additive metrics, but Delay 
        variation is not an additive metric. The means by which the 
        ingress and egress nodes compute the end-to-end Cost, Delay and 
        Delay variation metric from information recorded in the RRO is a 
        local decision and is beyond the scope of this document. 

        Based on the local policy, the ingress and egress nodes can 
        advertise the calculated end-to-end Cost, Delay and/or Delay 
        variation properties of the FA or RA LSP in TE link 
        advertisement to the routing instance based on the procedure 
        described in RFC 7471 [RFC7471], [DRAFT-ISIS-TE-METRIC]. 

     4.5. Compatibility 

        A node that does not recognize the Cost and/or Delay and/or 
        Delay Variation Collection Flag in the Attribute Flags TLV is 
        expected to proceed as specified in RFC 5420 [RFC5420]. 
        Specifically, the node is expected to pass the TLV on unaltered 
        if it appears in a LSP_ATTRIBUTES object. On the other hand, if 
        the TLV appears in a LSP_REQUIRED_ATTRIBUTES object, the node is 
        expected to reject the Path message with the Error Code and 
        Value defined in RFC 5420 [RFC5420]. 

        A node that does not recognize the Cost and/or Delay and/or 
        Delay Variation RRO sub-object is expected to behave as 
        specified in RFC 3209 [RFC3209]: unrecognized sub-objects are to 
        be ignored and passed on unchanged. 

     5. Manageability Considerations 

     5.1. Policy Configuration 

        In a border node of inter-domain or inter-layer network, the 
        following Cost and/or Delay and/or Delay Variation processing 
        policy SHOULD be capable of being configured: 

          o Whether the node is allowed to participate in Cost or Delay 
             or Delay Variation collection.  

          o Whether the node should notify changes to collected Cost 
             and/ or Delay and/ or Delay Variation information to 
             endpoint nodes as described in section 4.2.  

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          o Whether the Cost and/or Delay and/or Delay Variation of the 
             domain or specific layer network can be exposed to the 
             nodes outside the domain or layer network, or whether they 
             SHOULD be summarized, mapped to values that are 
             comprehensible to nodes outside the domain or layer 
             network, or removed entirely. 

        A node using RFC 5553 [RFC5553] and PKS MAY apply the same 
        policy. 

     6. Security Considerations 

        This document builds on the mechanisms defined in [RFC3473], 
        which also discusses related security measures.  In addition, 
        [RFC5920] provides an overview of security vulnerabilities and 
        protection mechanisms for the GMPLS control plane.  The 
        procedures defined in this document permit the transfer of Cost 
        and/or Delay and/or Delay Variation data between layers or 
        domains during the signaling of LSPs, subject to policy at the 
        layer or domain boundary. It is recommended that domain/layer 
        boundary policies take the implications of releasing Cost and/or 
        Delay and/or Delay Variation information into consideration and 
        behave accordingly during LSP signaling. 

     7. IANA Considerations 

     7.1. RSVP Attribute Bit Flags 

        IANA has created a registry and manages the space of the 
        Attribute bit flags of the Attribute Flags TLV, as described in 
        section 11.3 of RFC 5420 [RFC5420], in the "Attribute Flags" 
        section of the "Resource Reservation Protocol-Traffic 
        Engineering (RSVP-TE) Parameters" registry located in 
        http://www.iana.org/assignments/rsvp-te- parameters".   

        This document introduces the following three new Attribute Bit 
        Flags: 

        Bit No      Name       Attribute    Attribute   RRO  Reference 

                               Flags Path   Flags Resv 

        ----------- ----------  ----------  ----------- ---  ------- 

        TBA by      Cost        Yes         No         Yes  This I-D 
        IANA        Collection 
                    Flag 
         

        TBA by      Delay       Yes         No         Yes  This I-D 
        IANA        Collection 
                    Flag 
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        TBA by      Delay       Yes         No         Yes  This I-D 
        IANA        Variation 
                    Collection             
                    Flag 
         

     7.2. ROUTE_RECORD sub-object 

        IANA manages the "RSVP PARAMETERS" registry located at 
        http://www.iana.org/assignments/rsvp-parameters. This document 
        introduces the following three new RRO sub-object: 

             Type         Name                        Reference 

             ---------    ----------------------      --------- 

             TBA by IANA  Cost sub-object             This I-D 

             TBA by IANA  Delay sub-object            This I-D 

             TBA by IANA  Delay Variation sub-object  This I-D 

     7.3. Policy Control Failure Error subcodes  

        IANA manages the assignments in the "Error Codes and Globally-
        Defined Error Value Sub-Codes" section of the "RSVP PARAMETERS" 
        registry located at http://www.iana.org/assignments/rsvp-
        parameters. This document introduces the following three new 
        Policy Control Failure Error sub-code: 
          
        Value           Description                          Reference 
        -----           -----------                          --------- 
      
        TBA by IANA     Cost Recoding Rejected               This I-D 
      
        TBA by IANA     Delay Recoding Rejected              This I-D 
      
        TBA by IANA     Delay Variation Recoding Rejected    This I-D 
                                                  

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     8. References 

     8.1. 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 Lab Switching 
                  (GMPLS) Signaling Resource ReserVation Protocol-
                  Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 
                  January 2003. 

        [RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and 
                  A. Ayyangarps, "Encoding of Attributes for MPLS LSP 
                  Establishment Using Resource Reservation Protocol 
                  Traffic Engineering (RSVP-TE)", RFC 5420, February 
                  2009. 

        [RFC7471] S. Giacalone, D. Ward, J. Drake, A. Atlas, S. 
                  Previdi., "OSPF Traffic Engineering (TE) Metric 
                  Extensions", RFC 7471, March 2015.  

        [RFC7810] S. Previdi, S. Giacalone, D. Ward, J. 
                  Drake, A. Atlas, C. Filsfils, "IS-IS Traffic 
                  Engineering (TE) Metric Extensions", draft-ietf-isis-
                  te-metric-extensions, work in progress. 

     8.2. 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. 

        [RFC2209] Braden, R. and L. Zhang, "Resource ReSerVation 
                  Protocol (RSVP) -- Version 1 Message Processing 
                  Rules", RFC 2209, September 1997. 

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

        [RFC8001] F. Zhang, O. Gonzalez de Dios, M. 
                  Hartley, Z. Ali, C. Margaria,, "RSVP-TE Extensions for 
                  Collecting SRLG Information", draft-ietf-teas-rsvp-te-
                  srlg-collect.txt, work in progress.  

    Acknowledgements

        Authors would like to thank Ori Gerstel, Gabriele Maria 
        Galimberti, Luyuan Fang and Walid Wakim for their review 
        comments.

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     Contributors

        Sajal Agarwal
        Cisco Systems
        Email: sajaagar@cisco.com

        George Swallow
        Individual

        Matt Hartley
        Individual
 
      Authors' Addresses 
 
        Zafar Ali 
        Cisco Systems, Inc. 
        Email: zali@cisco.com 
      
        George Swallow 
        Cisco Systems, Inc. 
        swallow@cisco.com 
         
        Clarence Filsfils  
        Cisco Systems, Inc. 
        cfilsfil@cisco.com 
         
        Matt Hartley 
        Cisco Systems 
        Email: mhartley@cisco.com  
         
        Kenji Kumaki 
        KDDI Corporation 
        Email: ke-kumaki@kddi.com  
         
        Rudiger Kunze 
        Deutsche Telekom AG 
        Ruediger.Kunze@telekom.de  
        
        Julien Meuric
        France Telecom
        Email: julien.meuric@orange.com 

         

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