Network Working Group S. Previdi
Internet-Draft
Intended status: Standards Track K. Talaulikar, Ed.
Expires: April 25, 2022 Cisco Systems, Inc.
J. Dong, Ed.
M. Chen
Huawei Technologies
H. Gredler
RtBrick Inc.
J. Tantsura
Apstra
October 22, 2021
Distribution of Traffic Engineering (TE) Policies and State using BGP-LS
draft-ietf-idr-te-lsp-distribution-16
Abstract
This document describes a mechanism to collect the Traffic
Engineering and Policy information that is locally available in a
node and advertise it into BGP Link State (BGP-LS) updates. Such
information can be used by external components for path computation,
re-optimization, service placement, network visualization, etc.
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
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This Internet-Draft will expire on April 25, 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Carrying TE Policy Information in BGP . . . . . . . . . . . . 5
3. TE Policy NLRI . . . . . . . . . . . . . . . . . . . . . . . 6
4. TE Policy Descriptors . . . . . . . . . . . . . . . . . . . . 7
4.1. Tunnel Identifier (Tunnel ID) . . . . . . . . . . . . . . 8
4.2. LSP Identifier (LSP ID) . . . . . . . . . . . . . . . . . 8
4.3. IPv4/IPv6 Tunnel Head-End Address . . . . . . . . . . . . 9
4.4. IPv4/IPv6 Tunnel Tail-End Address . . . . . . . . . . . . 9
4.5. SR Policy Candidate Path Descriptor . . . . . . . . . . . 10
4.6. Local MPLS Cross Connect . . . . . . . . . . . . . . . . 11
4.6.1. MPLS Cross Connect Interface . . . . . . . . . . . . 13
4.6.2. MPLS Cross Connect FEC . . . . . . . . . . . . . . . 14
5. MPLS-TE Policy State TLV . . . . . . . . . . . . . . . . . . 15
5.1. RSVP Objects . . . . . . . . . . . . . . . . . . . . . . 16
5.2. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 17
6. SR Policy State TLVs . . . . . . . . . . . . . . . . . . . . 18
6.1. SR Binding SID . . . . . . . . . . . . . . . . . . . . . 18
6.2. SRv6 Binding SID . . . . . . . . . . . . . . . . . . . . 20
6.3. SR Candidate Path State . . . . . . . . . . . . . . . . . 22
6.4. SR Policy Name . . . . . . . . . . . . . . . . . . . . . 24
6.5. SR Candidate Path Name . . . . . . . . . . . . . . . . . 24
6.6. SR Candidate Path Constraints . . . . . . . . . . . . . . 25
6.6.1. SR Affinity Constraint . . . . . . . . . . . . . . . 27
6.6.2. SR SRLG Constraint . . . . . . . . . . . . . . . . . 28
6.6.3. SR Bandwidth Constraint . . . . . . . . . . . . . . . 28
6.6.4. SR Disjoint Group Constraint . . . . . . . . . . . . 29
6.7. SR Segment List . . . . . . . . . . . . . . . . . . . . . 31
6.8. SR Segment . . . . . . . . . . . . . . . . . . . . . . . 33
6.8.1. Segment Descriptors . . . . . . . . . . . . . . . . . 35
6.9. SR Segment List Metric . . . . . . . . . . . . . . . . . 42
7. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 44
8. Manageability Considerations . . . . . . . . . . . . . . . . 44
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45
9.1. BGP-LS NLRI-Types . . . . . . . . . . . . . . . . . . . . 45
9.2. BGP-LS Protocol-IDs . . . . . . . . . . . . . . . . . . . 45
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9.3. BGP-LS TLVs . . . . . . . . . . . . . . . . . . . . . . . 45
9.4. BGP-LS SR Policy Protocol Origin . . . . . . . . . . . . 46
9.5. BGP-LS TE State Object Origin . . . . . . . . . . . . . . 47
9.6. BGP-LS TE State Address Family . . . . . . . . . . . . . 47
9.7. BGP-LS SR Segment Descriptors . . . . . . . . . . . . . . 47
9.8. BGP-LS Metric Type . . . . . . . . . . . . . . . . . . . 48
10. Security Considerations . . . . . . . . . . . . . . . . . . . 48
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 49
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 49
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 49
13.1. Normative References . . . . . . . . . . . . . . . . . . 49
13.2. Informative References . . . . . . . . . . . . . . . . . 51
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction
In many network environments, traffic engineering (TE) policies are
instantiated into various forms:
o MPLS Traffic Engineering Label Switched Paths (TE-LSPs).
o IP based tunnels (IP in IP, GRE, etc).
o Segment Routing (SR) Policies as defined in
[I-D.ietf-spring-segment-routing-policy]
o Local MPLS cross-connect configuration
All this information can be grouped into the same term: TE Policies.
In the rest of this document we refer to TE Policies as the set of
information related to the various instantiation of polices: MPLS TE
LSPs, IP tunnels (IPv4 or IPv6), SR Policies, etc.
TE Polices are generally instantiated at the head-end and are based
on either local configuration or controller based programming of the
node using various APIs and protocols, e.g., PCEP or BGP.
In many network environments, the configuration and state of each TE
Policy that is available in the network is required by a controller
which allows the network operator to optimize several functions and
operations through the use of a controller aware of both topology and
state information.
One example of a controller is the stateful Path Computation Element
(PCE) [RFC8231], which could provide benefits in path reoptimization.
While some extensions are proposed in Path Computation Element
Communication Protocol (PCEP) for the Path Computation Clients (PCCs)
to report the LSP states to the PCE, this mechanism may not be
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applicable in a management-based PCE architecture as specified in
section 5.5 of [RFC4655]. As illustrated in the figure below, the
PCC is not an LSR in the routing domain, thus the head-end nodes of
the TE-LSPs may not implement the PCEP protocol. In this case a
general mechanism to collect the TE-LSP states from the ingress LERs
is needed. This document proposes an TE Policy state collection
mechanism complementary to the mechanism defined in [RFC8231].
-----------
| ----- |
Service | | TED |<-+----------->
Request | ----- | TED synchronization
| | | | mechanism (for example,
v | | | routing protocol)
------------- Request/ | v |
| | Response| ----- |
| NMS |<--------+> | PCE | |
| | | ----- |
------------- -----------
Service |
Request |
v
---------- Signaling ----------
| Head-End | Protocol | Adjacent |
| Node |<---------->| Node |
---------- ----------
Figure 1. Management-Based PCE Usage
In networks with composite PCE nodes as specified in section 5.1 of
[RFC4655], PCE is implemented on several routers in the network, and
the PCCs in the network can use the mechanism described in [RFC8231]
to report the TE Policy information to the PCE nodes. An external
component may also need to collect the TE Policy information from all
the PCEs in the network to obtain a global view of the LSP state in
the network.
In multi-area or multi-AS scenarios, each area or AS can have a child
PCE to collect the TE Policies in its own domain, in addition, a
parent PCE needs to collect TE Policy information from multiple child
PCEs to obtain a global view of LSPs inside and across the domains
involved.
In another network scenario, a centralized controller is used for
service placement. Obtaining the TE Policy state information is
quite important for making appropriate service placement decisions
with the purpose to both meet the application's requirements and
utilize network resources efficiently.
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The Network Management System (NMS) may need to provide global
visibility of the TE Policies in the network as part of the network
visualization function.
BGP has been extended to distribute link-state and traffic
engineering information to external components [RFC7752]. Using the
same protocol to collect Traffic Engineering Policy and state
information is desirable for these external components since this
avoids introducing multiple protocols for network information
collection. This document describes a mechanism to distribute
traffic engineering policy information (MPLS, SR, IPv4 and IPv6) to
external components using BGP-LS.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Carrying TE Policy Information in BGP
TE Policy information is advertised in BGP UPDATE messages using the
MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760]. The "Link-
State NLRI" defined in [RFC7752] is extended to carry the TE Policy
information. BGP speakers that wish to exchange TE Policy
information MUST use the BGP Multiprotocol Extensions Capability Code
(1) to advertise the corresponding (AFI, SAFI) pair, as specified in
[RFC4760]. New TLVs carried in the Link_State Attribute defined in
[RFC7752] are also defined in order to carry the attributes of a TE
Policy in the subsequent sections.
The format of "Link-State NLRI" is defined in [RFC7752] 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link-State NLRI (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A new "NLRI Type" is defined for TE Policy Information as following:
o NLRI Type: TE Policy NLRI value 5.
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The format of this new NLRI type is defined in Section 3 below.
3. TE Policy NLRI
This document defines the new TE Policy NLRI-Type and its format as
shown in the following figure:
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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Headend (Node Descriptors) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TE Policy Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Protocol-ID field specifies the component that owns the TE Policy
state in the advertising node. The following new Protocol-IDs are
defined and apply to the TE Policy NLRI:
+-------------+----------------------------------+
| Protocol-ID | NLRI information source protocol |
+-------------+----------------------------------+
| 8 | RSVP-TE |
| 9 | Segment Routing |
+-------------+----------------------------------+
o "Identifier" is an 8 octet value as defined in [RFC7752].
o "Headend" consists of a Local Node Descriptor (TLV 256) as defined
in [RFC7752].
o "TE Policy Descriptors" consists of one or more of the TLVs listed
as below:
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+-----------+----------------------------------+
| Codepoint | Descriptor TLVs |
+-----------+----------------------------------+
| 550 | Tunnel ID |
| 551 | LSP ID |
| 552 | IPv4/6 Tunnel Head-end address |
| 553 | IPv4/6 Tunnel Tail-end address |
| 554 | SR Policy Candidate Path |
| 555 | Local MPLS Cross Connect |
+-----------+----------------------------------+
The Local Node Descriptor TLV MUST include the following Node
Descriptor TLVs:
o BGP Router-ID (TLV 516) [RFC9086], which contains a valid BGP
Identifier of the local node.
o Autonomous System Number (TLV 512) [RFC7752], which contains the
ASN or AS Confederation Identifier (ASN) [RFC5065], if
confederations are used, of the local node.
The Local Node Descriptor TLV SHOULD include the following Node
Descriptor TLVs:
o IPv4 Router-ID of Local Node (TLV 1028) [RFC7752], which contains
the IPv4 TE Router-ID of the local node when one is provisioned.
o IPv6 Router-ID of Local Node (TLV 1029) [RFC7752], which contains
the IPv6 TE Router-ID of the local node when one is provisioned.
The Local Node Descriptor TLV MAY include the following Node
Descriptor TLVs:
o Member-ASN (TLV 517) [RFC9086], which contains the ASN of the
confederation member (i.e. Member-AS Number), if BGP
confederations are used, of the local node.
o Node Descriptors as defined in [RFC7752].
4. TE Policy Descriptors
This sections defines the TE Policy Descriptors TLVs which are used
to describe the TE Policy being advertised by using the new BGP-LS TE
Policy NLRI type defined in Section 3.
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4.1. Tunnel Identifier (Tunnel ID)
The Tunnel Identifier TLV contains the Tunnel ID defined in [RFC3209]
and is used for RSVP-TE protocol TE Policies. It has the following
format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 550
o Length: 2 octets.
o Tunnel ID: 2 octets as defined in [RFC3209].
4.2. LSP Identifier (LSP ID)
The LSP Identifier TLV contains the LSP ID defined in [RFC3209] and
is used for RSVP-TE protocol TE Policies. It has the following
format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 551
o Length: 2 octets.
o LSP ID: 2 octets as defined in [RFC3209].
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4.3. IPv4/IPv6 Tunnel Head-End Address
The IPv4/IPv6 Tunnel Head-End Address TLV contains the Tunnel Head-
End Address defined in [RFC3209] and is used for RSVP-TE protocol TE
Policies. It has following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IPv4/IPv6 Tunnel Head-End Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 552
o Length: 4 or 16 octets.
When the IPv4/IPv6 Tunnel Head-end Address TLV contains an IPv4
address, its length is 4 (octets).
When the IPv4/IPv6 Tunnel Head-end Address TLV contains an IPv6
address, its length is 16 (octets).
4.4. IPv4/IPv6 Tunnel Tail-End Address
The IPv4/IPv6 Tunnel Tail-End Address TLV contains the Tunnel Tail-
End Address defined in [RFC3209] and is used for RSVP-TE protocol TE
Policies. It has following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IPv4/IPv6 Tunnel Tail-End Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 553
o Length: 4 or 16 octets.
When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv4
address, its length is 4 (octets).
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When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv6
address, its length is 16 (octets).
4.5. SR Policy Candidate Path Descriptor
The SR Policy Candidate Path Descriptor TLV identifies a Segment
Routing Policy candidate path (CP) as defined in
[I-D.ietf-spring-segment-routing-policy] and has the following
format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Protocol-origin| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy Color (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator AS Number (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator Address (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 554
o Length: variable (valid values are 24, 36 or 48 octets)
o Protocol-Origin : 1 octet field which identifies the protocol or
component which is responsible for the instantiation of this path.
Following protocol-origin codepoints are defined in this document.
+------------+---------------------------------------------------------+
| Code Point | Protocol Origin |
+------------+---------------------------------------------------------+
| 1 | PCEP |
| 2 | BGP SR Policy |
| 3 | Local (via CLI, Yang model through NETCONF, gRPC, etc.) |
+------------+---------------------------------------------------------+
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o Flags: 1 octet field with following bit positions defined. Other
bits SHOULD be cleared by originator and MUST be ignored by
receiver.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|E|O| |
+-+-+-+-+-+-+-+-+
where:
* E-Flag : Indicates the encoding of endpoint as IPv6 address
when set and IPv4 address when clear
* O-Flag : Indicates the encoding of originator address as IPv6
address when set and IPv4 address when clear
o Reserved : 2 octets which SHOULD be set to 0 by originator and
MUST be ignored by receiver.
o Endpoint : 4 or 16 octets (as indicated by the flags) containing
the address of the endpoint of the SR Policy
o Color : 4 octets that indicates the color of the SR Policy
o Originator ASN : 4 octets to carry the 4 byte encoding of the ASN
of the originator. Refer [I-D.ietf-spring-segment-routing-policy]
Sec 2.4 for details.
o Originator Address : 4 or 16 octets (as indicated by the flags) to
carry the address of the originator. Refer
[I-D.ietf-spring-segment-routing-policy] Sec 2.4 for details.
o Discriminator : 4 octets to carry the discrimator of the path.
Refer [I-D.ietf-spring-segment-routing-policy] Sec 2.5 for
details.
4.6. Local MPLS Cross Connect
The Local MPLS Cross Connect TLV identifies a local MPLS state in the
form of incoming label and interface followed by an outgoing label
and interface. Outgoing interface may appear multiple times (for
multicast states). It is used with Protocol ID set to "Static
Configuration" value 5 as defined in [RFC7752].
The Local MPLS Cross Connect TLV has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Incoming label (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing label (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 555
o Length: variable.
o Incoming and Outgoing labels: 4 octets each.
o Sub-TLVs: following Sub-TLVs are defined:
* Interface Sub-TLV
* Forwarding Equivalent Class (FEC)
The Local MPLS Cross Connect TLV:
MUST have an incoming label.
MUST have an outgoing label.
MAY contain an Interface Sub-TLV having the I-flag set.
MUST contain at least one Interface Sub-TLV having the I-flag
unset.
MAY contain multiple Interface Sub-TLV having the I-flag unset.
This is the case of a multicast MPLS cross connect.
MAY contain a FEC Sub-TLV.
The following sub-TLVs are defined for the Local MPLS Cross Connect
TLV:
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+-----------+----------------------------------+
| Codepoint | Descriptor TLV |
+-----------+----------------------------------+
| 556 | MPLS Cross Connect Interface |
| 557 | MPLS Cross Connect FEC |
+-----------+----------------------------------+
These are defined in the following sub-sections.
4.6.1. MPLS Cross Connect Interface
The MPLS Cross Connect Interface sub-TLV is optional and contains the
identifier of the interface (incoming or outgoing) in the form of an
IPv4/IPv6 address and/or a local interface identifier.
The MPLS Cross Connect Interface sub-TLV has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+
| Flags |
+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface Identifier (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Interface Address (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 556
o Length: 9 or 21.
o Flags: 1 octet of flags defined as follows:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|I| |
+-+-+-+-+-+-+-+-+
where:
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* I-Flag is the Interface flag. When set, the Interface Sub-TLV
describes an incoming interface. If the I-flag is not set,
then the Interface Sub-TLV describes an outgoing interface.
o Local Interface Identifier: a 4 octet identifier.
o Interface address: a 4 octet IPv4 address or a 16 octet IPv6
address.
4.6.2. MPLS Cross Connect FEC
The MPLS Cross Connect FEC sub-TLV is optional and contains the FEC
associated to the incoming label.
The MPLS Cross Connect FEC sub-TLV has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Masklength | Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Prefix (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 557
o Length: variable.
o Flags: 1 octet of flags defined as follows:
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|4| |
+-+-+-+-+-+-+-+-+
where:
* 4-Flag is the IPv4 flag. When set, the FEC Sub-TLV describes
an IPv4 FEC. If the 4-flag is not set, then the FEC Sub-TLV
describes an IPv6 FEC.
o Mask Length: 1 octet of prefix length.
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o Prefix: an IPv4 or IPv6 prefix whose mask length is given by the "
Mask Length" field padded to an octet boundary.
5. MPLS-TE Policy State TLV
A new TLV called "MPLS-TE Policy State TLV", is used to describe the
characteristics of the MPLS-TE Policy and it is carried in the
optional non-transitive BGP Attribute "LINK_STATE Attribute" defined
in [RFC7752]. These MPLS-TE Policy characteristics include the
characteristics and attributes of the policy, its dataplane, explicit
path, Quality of Service (QoS) parameters, route information, the
protection mechanisms, etc.
The MPLS-TE Policy State TLV has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Object-origin | Address Family| RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// MPLS-TE Policy State Objects (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
MPLS-TE Policy State TLV
o Type: 1200
o Length: the total length of the MPLS-TE Policy State TLV not
including Type and Length fields.
o Object-origin: identifies the component (or protocol) from which
the contained object originated. This allows for objects defined
in different components to be collected while avoiding the
possible codepoint collisions among these components. Following
object-origin codepoints are defined in this document.
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+----------+------------------+
| Code | Object |
| Point | Origin |
+----------+------------------+
| 1 | RSVP-TE |
| 2 | PCEP |
| 3 | Local/Static |
+----------+------------------+
o Address Family: describes the address family used to setup the
MPLS-TE policy. The following address family values are defined
in this document:
+----------+------------------+
| Code | Dataplane |
| Point | |
+----------+------------------+
| 1 | MPLS-IPv4 |
| 2 | MPLS-IPv6 |
+----------+------------------+
o RESERVED: 16-bit field. SHOULD be set to 0 on transmission and
MUST be ignored on receipt.
o TE Policy State Objects: Rather than replicating all these objects
in this document, the semantics and encodings of the objects as
defined in RSVP-TE and PCEP are reused.
The state information is carried in the "MPLS-TE Policy State
Objects" with the following format as described in the sub-sections
below.
5.1. RSVP Objects
RSVP-TE objects are encoded in the "MPLS-TE Policy State Objects"
field of the MPLS-TE Policy State TLV and consists of MPLS TE LSP
objects defined in RSVP-TE [RFC3209] [RFC3473]. Rather than
replicating all MPLS TE LSP related objects in this document, the
semantics and encodings of the MPLS TE LSP objects are re-used.
These MPLS TE LSP objects are carried in the MPLS-TE Policy State
TLV.
When carrying RSVP-TE objects, the "Object-Origin" field is set to
"RSVP-TE".
The following RSVP-TE Objects are defined:
o SENDER_TSPEC and FLOW_SPEC [RFC2205]
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o SESSION_ATTRIBUTE [RFC3209]
o EXPLICIT_ROUTE Object (ERO) [RFC3209]
o ROUTE_RECORD Object (RRO) [RFC3209]
o FAST_REROUTE Object [RFC4090]
o DETOUR Object [RFC4090]
o EXCLUDE_ROUTE Object (XRO) [RFC4874]
o SECONDARY_EXPLICIT_ROUTE Object (SERO) [RFC4873]
o SECONDARY_RECORD_ROUTE (SRRO) [RFC4873]
o LSP_ATTRIBUTES Object [RFC5420]
o LSP_REQUIRED_ATTRIBUTES Object [RFC5420]
o PROTECTION Object [RFC3473][RFC4872][RFC4873]
o ASSOCIATION Object [RFC4872]
o PRIMARY_PATH_ROUTE Object [RFC4872]
o ADMIN_STATUS Object [RFC3473]
o LABEL_REQUEST Object [RFC3209][RFC3473]
For the MPLS TE LSP Objects listed above, the corresponding sub-
objects are also applicable to this mechanism. Note that this list
is not exhaustive, other MPLS TE LSP objects which reflect specific
characteristics of the MPLS TE LSP can also be carried in the LSP
state TLV.
5.2. PCEP Objects
PCEP objects are encoded in the "MPLS-TE Policy State Objects" field
of the MPLS-TE Policy State TLV and consists of PCEP objects defined
in [RFC5440]. Rather than replicating all MPLS TE LSP related
objects in this document, the semantics and encodings of the MPLS TE
LSP objects are re-used. These MPLS TE LSP objects are carried in
the MPLS-TE Policy State TLV.
When carrying PCEP objects, the "Object-Origin" field is set to
"PCEP".
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The following PCEP Objects are defined:
o METRIC Object [RFC5440]
o BANDWIDTH Object [RFC5440]
For the MPLS TE LSP Objects listed above, the corresponding sub-
objects are also applicable to this mechanism. Note that this list
is not exhaustive, other MPLS TE LSP objects which reflect specific
characteristics of the MPLS TE LSP can also be carried in the TE
Policy State TLV.
6. SR Policy State TLVs
Segment Routing Policy (SR Policy) architecture is specified in
[I-D.ietf-spring-segment-routing-policy]. A SR Policy can comprise
of one or more candidate paths (CP) of which at a given time one and
only one may be active (i.e. installed in forwarding and usable for
steering of traffic). Each CP in turn may have one or more SID-List
of which one or more may be active; when multiple are active then
traffic is load balanced over them.
This section defines the various TLVs which enable the headend to
report the state of an SR Policy, its CP(s), SID-List(s) and their
status. These TLVs are carried in the optional non-transitive BGP
Attribute "LINK_STATE Attribute" defined in [RFC7752] and enable the
same consistent form of reporting for SR Policy state irrespective of
the Protocol-Origin used to provision the policy. Detailed procedure
is described in Section 7 .
6.1. SR Binding SID
The SR Binding SID (BSID) is an optional TLV that provides the BSID
and its attributes for the SR Policy CP. The TLV MAY also optionally
contain the Specified BSID value for reporting as described in
section 6.2.3 of [I-D.ietf-spring-segment-routing-policy].
The TLV has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BSID Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Binding SID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Specified Binding SID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1201
o Length: variable (valid values are 12 or 36 octets)
o BSID Flags: 2 octet field that indicates attribute and status of
the Binding SID (BSID) associated with this CP. The following bit
positions are defined and the semantics are described in detail in
[I-D.ietf-spring-segment-routing-policy]. Other bits SHOULD be
cleared by originator and MUST be ignored by receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|B|U|L|F| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* D-Flag : Indicates the dataplane for the BSIDs and if they are
16 octet SRv6 SID when set and are 4 octet SR/MPLS label value
when clear.
* B-Flag : Indicates the allocation of the value in the BSID
field when set and indicates that BSID is not allocated when
clear.
* U-Flag : Indicates the specified BSID value is unavailable when
set.
* L-Flag : Indicates the BSID value is from the Segment Routing
Local Block (SRLB) of the headend node when set and is from the
local dynamic label pool when clear
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* F-Flag : Indicates the BSID value is one allocated from dynamic
label pool due to fallback (e.g. when specified BSID is
unavailable) when set.
o RESERVED: 2 octets. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Binding SID: It indicates the operational or allocated BSID value
for the CP based on the status flags.
o Specified BSID: It is used to report the explicitly specified BSID
value regardless of whether it is successfully allocated or not.
The field is set to value 0 when BSID has not been specified for
the CP.
The BSID fields above are 4 octet carrying the MPLS Label or 16
octets carrying the SRv6 SID based on the BSID D-flag. When carrying
the MPLS Label, as shown in the figure below, the TC, S and TTL
(total of 12 bits) are RESERVED and SHOULD be set to 0 by originator
and MUST be ignored by the receiver.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In the case of an SRv6, the Binding SID sub-TLV does not have the
ability to signal the SRv6 Endpoint Behavior [RFC8986] or the
structure of the SID. It is RECOMMENDED that the SRv6 Binding SID
TLV defined in Section 6.2, that enables the specification of the
SRv6 Endpoint Behavior, be used for signaling of an SRv6 Binding SID
for an SR Policy candidate path.
6.2. SRv6 Binding SID
The SRv6 Binding SID (BSID) is an optional TLV that provides the SRv6
BSID and its attributes for the SR Policy CP. The TLV MAY also
optionally contain the Specified SRv6 BSID value for reporting as
described in section 6.2.3 of
[I-D.ietf-spring-segment-routing-policy].
The TLV has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BSID Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Binding SID (16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Specified Binding SID (16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable
o BSID Flags: 2 octet field that indicates attribute and status of
the Binding SID (BSID) associated with this CP. The following bit
positions are defined and the semantics are described in detail in
[I-D.ietf-spring-segment-routing-policy]. Other bits SHOULD be
cleared by originator and MUST be ignored by receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|B|U|F| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* B-Flag : Indicates the allocation of the value in the BSID
field when set and indicates that BSID is not allocated when
clear.
* U-Flag : Indicates the specified BSID value is unavailable when
set.
* F-Flag : Indicates the BSID value is one allocated dynamically
due to fallback (e.g. when specified BSID is unavailable) when
set.
o RESERVED: 2 octets. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
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o Binding SID: It indicates the operational or allocated BSID value
for the CP based on the status flags.
o Specified BSID: It is used to report the explicitly specified BSID
value regardless of whether it is successfully allocated or not.
The field is set to value 0 when BSID has not been specified for
the CP.
o Sub-TLVs : variable and contains any other optional attributes
associated with the SRv6 BSID.
The SRv6 Endpoint Behavior TLV (1250) and the SRv6 SID Structure TLV
(1252) defined in [I-D.ietf-idr-bgpls-srv6-ext] are used as sub-TLVs
of the SRv6 Binding SID TLV to optionally indicate the SRv6 Endpoint
behavior and SID structure for the Binding SID value in the TLV.
6.3. SR Candidate Path State
The SR Candidate Path (CP) State TLV provides the operational status
and attributes of the SR Policy at the CP level. The TLV has the
following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority | RESERVED | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1202
o Length: 8 octets
o Priority : 1 octet value which indicates the priority of the CP.
Refer Section 2.12 of [I-D.ietf-spring-segment-routing-policy].
o RESERVED: 1 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Flags: 2 octet field that indicates attribute and status of the
CP. The following bit positions are defined and the semantics are
described in detail in [I-D.ietf-spring-segment-routing-policy].
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Other bits SHOULD be cleared by originator and MUST be ignored by
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|A|B|E|V|O|D|C|I|T| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* S-Flag : Indicates the CP is in administrative shut state when
set
* A-Flag : Indicates the CP is the active path (i.e. one
provisioned in the forwarding plane) for the SR Policy when set
* B-Flag : Indicates the CP is the backup path (i.e. one
identified for path protection of the active path) for the SR
Policy when set
* E-Flag : Indicates that the CP has been evaluated for validity
(e.g. headend may evaluate CPs based on their preferences) when
set
* V-Flag : Indicates the CP has at least one valid SID-List when
set. When the E-Flag is clear (i.e. the CP has not been
evaluated), then this flag MUST be set to 0 by the originator
and ignored by the receiver.
* O-Flag : Indicates the CP was instantiated by the headend due
to an on-demand-nexthop trigger based on local template when
set. Refer Section 8.5 of
[I-D.ietf-spring-segment-routing-policy].
* D-Flag : Indicates the CP was delegated for computation to a
PCE/controller when set
* C-Flag : Indicates the CP was provisioned by a PCE/controller
when set
* I-Flag : Indicates the CP will perform the "drop upon invalid"
behavior when no other active path is available for this SR
Policy and this path is the one with best preference amongst
the available CPs. Refer Section 8.2 of
[I-D.ietf-spring-segment-routing-policy].
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* T-Flag : Indicates the CP has been marked as eligible for use
as Transit Policy on the headend when set. Refer Section 8.3
of [I-D.ietf-spring-segment-routing-policy].
o Preference : 4 octet value which indicates the preference of the
CP. Refer Section 2.7 of
[I-D.ietf-spring-segment-routing-policy].
6.4. SR Policy Name
The SR Policy Name TLV is an optional TLV that is used to carry the
symbolic name associated with the SR Policy. The TLV has the
following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SR Policy Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable
o SR Policy Name : Symbolic name for the SR Policy without a NULL
terminator as specified in section 2.6 of
[I-D.ietf-spring-segment-routing-policy]. It is RECOMMENDED that
the size of the symbolic name be limited to 255 bytes.
Implementations MAY choose to truncate long names to 255 bytes
when signaling via BGP-LS.
6.5. SR Candidate Path Name
The SR Candidate Path Name TLV is an optional TLV that is used to
carry the symbolic name associated with the candidate path. The TLV
has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Candidate Path Name (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1203
o Length: variable
o Candidate Path Name : Symbolic name for the SR Policy candidate
path without a NULL terminator as specified in section 2.6 of
[I-D.ietf-spring-segment-routing-policy]. It is RECOMMENDED that
the size of the symbolic name be limited to 255 bytes.
Implementations MAY choose to truncate long names to 255 bytes
when signaling via BGP-LS.
6.6. SR Candidate Path Constraints
The SR Candidate Path Constraints TLV is an optional TLV that is used
to report the constraints associated with the candidate path. The
constraints are generally applied to a dynamic candidate path which
is computed by the headend. The constraints may also be applied to
an explicit path where the headend is expected to validate that the
path expresses satisfies the specified constraints and the path is to
be invalidated by the headend when the constraints are no longer met
(e.g. due to topology changes).
The TLV has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTID | Algorithm | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
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o Type: 1204
o Length: variable
o Flags: 2 octet field that indicates the constraints that are being
applied to the CP. The following bit positions are defined and
the other bits SHOULD be cleared by originator and MUST be ignored
by receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|P|U|A|T| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* D-Flag : Indicates that the CP needs to use SRv6 dataplane when
set and SR/MPLS dataplane when clear
* P-Flag : Indicates that the CP needs to use only protected SIDs
when set
* U-Flag : Indicates that the CP needs to use only unprotected
SIDs when set
* A-Flag : Indicates that the CP needs to use the SIDs belonging
to the specified SR Algorithm only when set
* T-Flag: Indicates that the CP needs to use the SIDs belonging
to the specified topology only when set
o RESERVED: 2 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o MTID : Indicates the multi-topology identifier of the IGP topology
that is preferred to be used when the path is setup. When the
T-flag is set then the path is strictly useing the specified
topology SIDs only.
o Algorithm : Indicates the algorithm that is preferred to be used
when the path is setup. When the A-flag is set then the path is
strictly using the specified algorithm SIDs only.
o RESERVED: 1 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
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o sub-TLVs: optional sub-TLVs MAY be included in this TLV to
describe other constraints.
The following constraint sub-TLVs are defined for the SR CP
Constraints TLV.
6.6.1. SR Affinity Constraint
The SR Affinity Constraint sub-TLV is an optional sub-TLV that is
used to carry the affinity constraints [RFC2702] associated with the
candidate path. The affinity is expressed in terms of Extended Admin
Group (EAG) as defined in [RFC7308]. The TLV has the following
format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excl-Any-Size | Incl-Any-Size | Incl-All-Size | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Exclude-Any EAG (optional, variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-Any EAG (optional, variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-All EAG (optional, variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1208
o Length: variable, dependent on the size of the Extended Admin
Group. MUST be a multiple of 4 octets.
o Exclude-Any-Size : one octet to indicate the size of Exclude-Any
EAG bitmask size in multiples of 4 octets. (e.g. value 0
indicates the Exclude-Any EAG field is skipped, value 1 indicates
that 4 octets of Exclude-Any EAG is included)
o Include-Any-Size : one octet to indicate the size of Include-Any
EAG bitmask size in multiples of 4 octets. (e.g. value 0
indicates the Include-Any EAG field is skipped, value 1 indicates
that 4 octets of Include-Any EAG is included)
o Include-All-Size : one octet to indicate the size of Include-All
EAG bitmask size in multiples of 4 octets. (e.g. value 0
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indicates the Include-All EAG field is skipped, value 1 indicates
that 4 octets of Include-All EAG is included)
o RESERVED: 1 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Exclude-Any EAG : the bitmask used to represent the affinities to
be excluded from the path.
o Include-Any EAG : the bitmask used to represent the affinities to
be included in the path.
o Include-All EAG : the bitmask used to represent the all affinities
to be included in the path.
6.6.2. SR SRLG Constraint
The SR SRLG Constraint sub-TLV is an optional sub-TLV that is used to
carry the Shared Risk Link Group (SRLG) values [RFC4202] that are to
be excluded from the candidate path. The TLV has the following
format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG Values (variable, multiples of 4 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1209
o Length: variable, dependent on the number of SRLGs encoded. MUST
be a multiple of 4 octets.
o SRLG Values : One or more SRLG values (each of 4 octets).
6.6.3. SR Bandwidth Constraint
The SR Bandwidth Constraint sub-TLV is an optional sub-TLV that is
used to indicate the desired bandwidth availability that needs to be
ensured for the candidate path. The TLV has the following format:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1210
o Length: 4 octects
o Bandwidth : 4 octets which specify the desired bandwidth in unit
of bytes per second in IEEE floating point format.
6.6.4. SR Disjoint Group Constraint
The SR Disjoint Group Constraint sub-TLV is an optional sub-TLV that
is used to carry the disjointness constraint associated with the
candidate path. The disjointness between two SR Policy Candidate
Paths is expressed by associating them with the same disjoint group
identifier and then specifying the type of disjointness required
between their paths. The computation is expected to achieve the
highest level of disjointness requested and when that is not possible
then fallback to a lesser level progressively based on the levels
indicated.
The TLV has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request-Flags | Status-Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Disjoint Group Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1211
o Length: 8 octets
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o Request Flags : one octet to indicate the level of disjointness
requested as specified in the form of flags. The following flags
are defined and the other bits SHOULD be cleared by originator and
MUST be ignored by receiver.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|S|N|L|F|I| |
+-+-+-+-+-+-+-+-+
where:
* S-Flag : Indicates that SRLG disjointness is requested
* N-Flag : Indicates that node disjointness is requested when
* L-Flag : Indicates that link disjointness is requested when
* F-Flag : Indicates that the computation may fallback to a lower
level of disjointness amongst the ones requested when all
cannot be achieved
* I-Flag : Indicates that the computation may fallback to the
default best path (e.g. IGP path) in case of none of the
desired disjointness can be achieved.
o Status Flags : one octet to indicate the level of disjointness
that has been achieved by the computation as specified in the form
of flags. The following flags are defined and the other bits
SHOULD be cleared by originator and MUST be ignored by receiver.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|S|N|L|F|I|X| |
+-+-+-+-+-+-+-+-+
where:
* S-Flag : Indicates that SRLG disjointness is achieved
* N-Flag : Indicates that node disjointness is achieved
* L-Flag : Indicates that link disjointness is achieved
* F-Flag : Indicates that the computation has fallen back to a
lower level of disjointness that requested.
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* I-Flag : Indicates that the computation has fallen back to the
best path (e.g. IGP path) and disjointness has not been
achieved
* X-Flag : Indicates that the disjointness constraint could not
be achieved and hence path has been invalidated
o RESERVED: 2 octets. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Disjointness Group Identifier : 4 octet value that is the group
identifier for a set of disjoint paths
6.7. SR Segment List
The SR Segment List TLV is used to report the SID-List(s) of a
candidate path. The TLV has following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTID | Algorithm | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1205
o Length: variable
o Flags: 2 octet field that indicates attribute and status of the
SID-List.The following bit positions are defined and the semantics
are described in detail in
[I-D.ietf-spring-segment-routing-policy]. Other bits SHOULD be
cleared by originator and MUST be ignored by receiver.
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0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|E|C|V|R|F|A|T|M| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* D-Flag : Indicates the SID-List is comprised of SRv6 SIDs when
set and indicates it is comprised of SR/MPLS labels when clear.
* E-Flag : Indicates that SID-List is an explicit path when set
and indicates dynamic path when clear.
* C-Flag : Indicates that SID-List has been computed for a
dynamic path when set. It is always reported as set for
explicit paths.
* V-Flag : Indicates the SID-List has passed verification or its
verification was not required when set and failed verification
when clear.
* R-Flag : Indicates that the first Segment has been resolved
when set and failed resolution when clear.
* F-Flag : Indicates that the computation for the dynamic path
failed when set and succeeded (or not required in case of
explicit path) when clear
* A-Flag : Indicates that all the SIDs in the SID-List belong to
the specified algorithm when set.
* T-Flag : Indicates that all the SIDs in the SID-List belong to
the specified topology (identified by the multi-topology ID)
when set.
* M-Flag : Indicates that the SID-list has been removed from the
forwarding plane due to fault detection by a monitoring
mechanism (e.g. BFD) when set and indicates no fault detected
or monitoring is not being done when clear.
o RESERVED: 2 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o MTID : 2 octet that indicates the multi-topology identifier of the
IGP topology to be used when the T-flag is set.
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o Algorithm: 1 octet that indicates the algorithm of the SIDs used
in the SID-List when the A-flag is set.
o RESERVED: 1 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Weight: 4 octet field that indicates the weight associated with
the SID-List for weighted load-balancing. Refer Section 2.2 and
2.11 of [I-D.ietf-spring-segment-routing-policy].
o Sub-TLVs : variable and contains the ordered set of Segments and
any other optional attributes associated with the specific SID-
List.
The SR Segment sub-TLV (defined in Section 6.8) MUST be included as
an ordered set of sub-TLVs within the SR Segment List TLV when the
SID-List is not empty. A SID-List may be empty in certain cases
(e.g. for a dynamic path) where the headend has not yet performed the
computation and hence not derived the segments required for the path;
in such cases, the SR Segment List TLV SHOULD NOT include any SR
Segment sub-TLVs.
6.8. SR Segment
The SR Segment sub-TLV describes a single segment in a SID-List. One
or more instances of this sub-TLV in an ordered manner constitute a
SID-List for a SR Policy candidate path. It is a sub-TLV of the SR
Segment List TLV and has following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment Type | RESERVED | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Segment Descriptor (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1206
o Length: variable
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o Segment Type : 1 octet which indicates the type of segment (refer
Section 6.8.1 for details)
o RESERVED: 1 octet. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Flags: 2 octet field that indicates attribute and status of the
Segment and its SID. The following bit positions are defined and
the semantics are described in detail in
[I-D.ietf-spring-segment-routing-policy]. Other bits SHOULD be
cleared by originator and MUST be ignored by receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|E|V|R|A| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* S-Flag : Indicates the presence of SID value in the SID field
when set and that no value is indicated when clear.
* E-Flag : Indicates the SID value is explicitly provisioned
value (locally on headend or via controller/PCE) when set and
is a dynamically resolved value by headend when clear
* V-Flag : Indicates the SID has passed verification or did not
require verification when set and failed verification when
clear.
* R-Flag : Indicates the SID has been resolved or did not require
resolution (e.g. because it is not the first SID) when set and
failed resolution when clear.
* A-Flag : Indicates that the Algorithm indicated in the Segment
descriptor is valid when set. When clear, it indicates that
the headend is unable to determine the algorithm of the SID.
o SID : 4 octet carrying the MPLS Label or 16 octets carrying the
SRv6 SID based on the Segment Type. When carrying the MPLS Label,
as shown in the figure below, the TC, S and TTL (total of 12 bits)
are RESERVED and SHOULD be set to 0 by originator and MUST be
ignored by the receiver.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Segment Descriptor : variable size Segment descriptor based on the
type of segment (refer Section 6.8.1 for details)
o Sub-Sub-TLVs : variable and contains any other optional attributes
associated with the specific segment.
The SRv6 Endpoint Behavior TLV (1250) and the SRv6 SID Structure TLV
(1252) defined in [I-D.ietf-idr-bgpls-srv6-ext] are used as sub-sub-
TLVs of the SR Segment sub-TLV to optionally indicate the SRv6
Endpoint behavior and SID structure when advertising the SRv6
specific segment types.
6.8.1. Segment Descriptors
[I-D.ietf-spring-segment-routing-policy] section 4 defines multiple
types of segments and their description. This section defines the
encoding of the Segment Descriptors for each of those Segment types
to be used in the Segment sub-TLV describes previously in
Section 6.8.
The following types are currently defined:
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+-------+--------------------------------------------------------------+
| Type | Segment Description |
+-------+--------------------------------------------------------------+
| 0 | Invalid |
| 1 | SR-MPLS Label |
| 2 | SRv6 SID as IPv6 address |
| 3 | SR-MPLS Prefix SID as IPv4 Node Address |
| 4 | SR-MPLS Prefix SID as IPv6 Node Global Address |
| 5 | SR-MPLS Adjacency SID as IPv4 Node Address & Local |
| | Interface ID |
| 6 | SR-MPLS Adjacency SID as IPv4 Local & Remote Interface |
| | Addresses |
| 7 | SR-MPLS Adjacency SID as pair of IPv6 Global Address & |
| | Interface ID for Local & Remote nodes |
| 8 | SR-MPLS Adjacency SID as pair of IPv6 Global Addresses for |
| | the Local & Remote Interface |
| 9 | SRv6 END SID as IPv6 Node Global Address |
| 10 | SRv6 END.X SID as pair of IPv6 Global Address & Interface ID |
| | for Local & Remote nodes |
| 11 | SRv6 END.X SID as pair of IPv6 Global Addresses for the |
| | Local & Remote Interface |
+-------+--------------------------------------------------------------+
6.8.1.1. Type 1: SR-MPLS Label
The Segment is SR-MPLS type and is specified simply as the label.
The format of its Segment Descriptor is 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
+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+
Where:
o Algorithm: 1 octet value that indicates the algorithm used for
picking the SID. This is valid only when the A-flag has been set
in the Segment TLV.
6.8.1.2. Type 2: SRv6 SID
The Segment is SRv6 type and is specified simply as the SRv6 SID
address. The format of its Segment Descriptor is as follows:
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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
+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+
Where:
o Algorithm: 1 octet value that indicates the algorithm used for
picking the SID. This is valid only when the A-flag has been set
in the Segment TLV.
6.8.1.3. Type 3: SR-MPLS Prefix SID for IPv4
The Segment is SR-MPLS Prefix SID type and is specified as an IPv4
node address. The format of its Segment Descriptor is 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
+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Node Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o Algorithm: 1 octet value that indicates the algorithm used for
picking the SID
o IPv4 Node Address: 4 octet value which carries the IPv4 address
associated with the node
6.8.1.4. Type 4: SR-MPLS Prefix SID for IPv6
The Segment is SR-MPLS Prefix SID type and is specified as an IPv6
global address. The format of its Segment Descriptor is 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
+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
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o Algorithm: 1 octet value that indicates the algorithm used for
picking the SID
o IPv6 Node Global Address: 16 octet value which carries the IPv6
global address associated with the node
6.8.1.5. Type 5: SR-MPLS Adjacency SID for IPv4 with Interface ID
The Segment is SR-MPLS Adjacency SID type and is specified as an IPv4
node address along with the local interface ID on that node. The
format of its Segment Descriptor is 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 Node Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPv4 Node Address: 4 octet value which carries the IPv4 address
associated with the node
o Local Interface ID : 4 octet value which carries the local
interface ID of the node identified by the Node Address
6.8.1.6. Type 6: SR-MPLS Adjacency SID for IPv4 with Interface Address
The Segment is SR-MPLS Adjacency SID type and is specified as a pair
of IPv4 local and remote addresses. The format of its Segment
Descriptor is 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 Local Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Remote Address (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPv4 Local Address: 4 octet value which carries the local IPv4
address associated with the node
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o IPv4 Remote Address: 4 octet value which carries the remote IPv4
address associated with the node's neighbor. This is optional and
MAY be set to 0 when not used (e.g. when identifying point-to-
point links).
6.8.1.7. Type 7: SR-MPLS Adjacency SID for IPv6 with interface ID
The Segment is SR-MPLS Adjacency SID type and is specified as a pair
of IPv6 global address and interface ID for local and remote nodes.
The format of its Segment Descriptor is 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 Local Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Remote Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Node Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPv6 Local Node Global Address: 16 octet value which carries the
IPv6 global address associated with the local node
o Local Node Interface ID : 4 octet value which carries the
interface ID of the local node identified by the Local Node
Address
o IPv6 Remote Node Global Address: 16 octet value which carries the
IPv6 global address associated with the remote node. This is
optional and MAY be set to 0 when not used (e.g. when identifying
point-to-point links).
o Remote Node Interface ID : 4 octet value which carries the
interface ID of the remote node identified by the Remote Node
Address. This is optional and MAY be set to 0 when not used (e.g.
when identifying point-to-point links).
6.8.1.8. Type 8: SR-MPLS Adjacency SID for IPv6 with interface address
The Segment is SR-MPLS Adjacency SID type and is specified as a pair
of IPv6 Global addresses for local and remote interface addresses.
The format of its Segment Descriptor is as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global IPv6 Local Interface Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global IPv6 Remote Interface Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPv6 Local Address: 16 octet value which carries the local IPv6
address associated with the node
o IPv6 Remote Address: 16 octet value which carries the remote IPv6
address associated with the node's neighbor
6.8.1.9. Type 9: SRv6 END SID as IPv6 Node Address
The Segment is SRv6 END SID type and is specified as an IPv6 global
address. The format of its Segment Descriptor is 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
+-+-+-+-+-+-+-+-+
| Algorithm |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o Algorithm: 1 octet value that indicates the algorithm used for
picking the SID
o IPv6 Node Global Address: 16 octet value which carries the IPv6
global address associated with the node
6.8.1.10. Type 10: SRv6 END.X SID as interface ID
The Segment is SRv6 END.X SID type and is specified as a pair of IPv6
global address and interface ID for local and remote nodes. The
format of its Segment Descriptor is as follows:
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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 Local Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Node Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Remote Node Global Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Node Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
o IPv6 Local Node Global Address: 16 octet value which carries the
IPv6 global address associated with the local node
o Local Node Interface ID : 4 octet value which carries the
interface ID of the local node identified by the Local Node
Address
o IPv6 Remote Node Global Address: 16 octet value which carries the
IPv6 global address associated with the remote node. This is
optional and MAY be set to 0 when not used (e.g. when identifying
point-to-point links).
o Remote Node Interface ID : 4 octet value which carries the
interface ID of the remote node identified by the Remote Node
Address. This is optional and MAY be set to 0 when not used (e.g.
when identifying point-to-point links).
6.8.1.11. Type 11: SRv6 END.X SID as interface address
The Segment is SRv6 END.X SID type and is specified as a pair of IPv6
Global addresses for local and remote interface addresses. The
format of its Segment Descriptor is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global IPv6 Local Interface Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global IPv6 Remote Interface Address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
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o IPv6 Local Address: 16 octet value which carries the local IPv6
address associated with the node
o IPv6 Remote Address: 16 octet value which carries the remote IPv6
address associated with the node's neighbor
6.9. SR Segment List Metric
The SR Segment List Metric sub-TLV describes the metric used for
computation of the SID-List. It is used to report the type of metric
used in the computation of a dynamic path either on the headend or
when the path computation is delegated to a PCE/controller. When the
path computation is done on the headend, it is also used to report
the calculated metric for the path.
It is a sub-TLV of the SR Segment List TLV and has following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric Type | Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric Margin |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric Bound |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 1207
o Length: 16 octets
o Metric Type : 1 octet field which identifies the type of metric
used for path computation. Following metric type codepoints are
defined in this document.
+------------+-----------------------------------------+
| Code Point | Metric Type |
+------------+-----------------------------------------+
| 0 | IGP Metric |
| 1 | Min Unidirectional Link Delay [RFC7471] |
| 2 | TE Metric [RFC3630] |
+------------+-----------------------------------------+
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o Flags: 1 octet field that indicates the validity of the metric
fields and their semantics. The following bit positions are
defined and the other bits SHOULD be cleared by originator and
MUST be ignored by receiver.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|M|A|B|V| |
+-+-+-+-+-+-+-+-+
where:
* M-Flag : Indicates that the metric margin allowed for path
computation is specified when set
* A-Flag : Indicates that the metric margin is specified as an
absolute value when set and is expressed as a percentage of the
minimum metric when clear.
* B-Flag : Indicates that the metric bound allowed for the path
is specified when set.
* V-Flag : Indicates that the metric value computed is being
reported when set.
o RESERVED: 2 octets. SHOULD be set to 0 by originator and MUST be
ignored by receiver.
o Metric Margin : 4 octets which indicate the metric margin value
when M-flag is set. The metric margin is specified as either an
absolute value or as a percentage of the minimum computed path
metric based on the A-flag. The metric margin loosens the
criteria for minimum metric path calculation up to the specified
metric to accomodate for other factors such as bandwidth
availability, minimal SID stack depth and maximizing of ECMP for
the SR path computed.
o Metric Bound : 4 octects which indicate the maximum metric value
that is allowed when B-flag is set. If the computed path metric
crosses the specified bound value then the path is considered as
invalid.
o Metric Value : 4 octets which indicate the metric value of the
computed path when V-flag is set. This value is available and
reported when the computation is successful and a valid path is
available.
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7. Procedures
The BGP-LS advertisements for the TE Policy NLRI are originated by
the headend node for the TE Policies that are instantiated on its
local node.
For MPLS TE LSPs signaled via RSVP-TE, the NLRI descriptor TLVs as
specified in Section 4.1, Section 4.2, Section 4.3 and Section 4.4
are used. Then the TE LSP state is encoded in the BGP-LS Attribute
field as MPLS-TE Policy State TLV as described in Section 5. The
RSVP-TE objects that reflect the state of the LSP are included as
defined in Section 5.1. When the TE LSP is setup with the help of
PCEP signaling then another MPLS-TE Policy State TLV SHOULD be used
to to encode the related PCEP objects corresponding to the LSP as
defined in Section 5.2.
For SR Policies, the NLRI descriptor TLV as specified in Section 4.5
is used. An SR Policy candidate path (CP) may be instantiated on the
headend node via a local configuration, PCEP or BGP SR Policy
signaling and this is indicated via the SR Protocol Origin. Then the
SR Policy Candidate Path's attribute and state is encoded in the BGP-
LS Attribute field as SR Policy State TLVs and sub-TLVs as described
in Section 6. The SR Candidate Path State TLV as defined in
Section 6.3 is included to report the state of the CP. The SR BSID
TLV as defined in Section 6.1 or Section 6.2 is included to report
the BSID of the CP when one is either specified or allocated by the
headend. The constraints for the SR Policy Candidate Path are
reported using the SR Candidate Path Constraints TLV as described in
Section 6.6.The SR Segment List TLV is included for each of the SID-
List(s) associated with the CP. Each SR Segment List TLV in turn
includes SR Segment sub-TLV(s) to report the segment(s) and their
status. The SR Segment List Metric sub-TLV is used to report the
metric values and constraints for the specific SID List.
When the SR Policy CP is setup with the help of PCEP signaling then
another MPLS-TE Policy State TLV MAY be used to to encode the related
PCEP objects corresponding to the LSP as defined in Section 5.2
specifically to report information and status that is not covered by
the defined TLVs under Section 6. In the event of a conflict of
information, the receiver MUST prefer the information originated via
TLVs defined in Section 6 over the PCEP objects reported via the TE
Policy State TLV.
8. Manageability Considerations
The Existing BGP operational and management procedures apply to this
document. No new procedures are defined in this document. The
considerations as specified in [RFC7752] apply to this document.
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In general, it is assumed that the TE Policy head-end nodes are
responsible for the distribution of TE Policy state information,
while other nodes, e.g. the nodes in the path of a policy, MAY report
the TE Policy information (if available) when needed. For example,
the border routers in the inter-domain case will also distribute LSP
state information since the ingress node may not have the complete
information for the end-to-end path.
9. IANA Considerations
This document requires new IANA assigned codepoints.
9.1. BGP-LS NLRI-Types
IANA maintains a registry called "Border Gateway Protocol - Link
State (BGP-LS) Parameters" with a sub-registry called "BGP-LS NLRI-
Types".
The following codepoints have been assigned by early allocation
process by IANA:
+------+----------------------------+---------------+
| Type | NLRI Type | Reference |
+------+----------------------------+---------------+
| 5 | TE Policy NLRI type | this document |
+------+----------------------------+---------------+
9.2. BGP-LS Protocol-IDs
IANA maintains a registry called "Border Gateway Protocol - Link
State (BGP-LS) Parameters" with a sub-registry called "BGP-LS
Protocol-IDs".
The following Protocol-ID codepoints have been assigned by early
allocation process by IANA:
+-------------+----------------------------------+---------------+
| Protocol-ID | NLRI information source protocol | Reference |
+-------------+----------------------------------+---------------+
| 8 | RSVP-TE | this document |
| 9 | Segment Routing | this document |
+-------------+----------------------------------+---------------+
9.3. BGP-LS TLVs
IANA maintains a registry called "Border Gateway Protocol - Link
State (BGP-LS) Parameters" with a sub-registry called "Node Anchor,
Link Descriptor and Link Attribute TLVs".
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The following TLV codepoints have been assigned by early allocation
process by IANA:
+----------+----------------------------------------+---------------+
| TLV Code | Description | Value defined |
| Point | | in |
+----------+----------------------------------------+---------------+
| 550 | Tunnel ID TLV | this document |
| 551 | LSP ID TLV | this document |
| 552 | IPv4/6 Tunnel Head-end address TLV | this document |
| 553 | IPv4/6 Tunnel Tail-end address TLV | this document |
| 554 | SR Policy CP Descriptor TLV | this document |
| 555 | MPLS Local Cross Connect TLV | this document |
| 556 | MPLS Cross Connect Interface TLV | this document |
| 557 | MPLS Cross Connect FEC TLV | this document |
| 1200 | MPLS-TE Policy State TLV | this document |
| 1201 | SR BSID TLV | this document |
| 1202 | SR CP State TLV | this document |
| 1203 | SR CP Name TLV | this document |
| 1204 | SR CP Constraints TLV | this document |
| 1205 | SR Segment List TLV | this document |
| 1206 | SR Segment sub-TLV | this document |
| 1207 | SR Segment List Metric sub-TLV | this document |
| 1208 | SR Affinity Constraint sub-TLV | this document |
| 1209 | SR SRLG Constraint sub-TLV | this document |
| 1210 | SR Bandwidth Constraint sub-TLV | this document |
| 1211 | SR Disjoint Group Constraint sub-TLV | this document |
| TBD | SRv6 BSID TLV | this document |
| TBD | SR Policy Name TLV | this document |
+----------+----------------------------------------+---------------+
9.4. BGP-LS SR Policy Protocol Origin
This document requests IANA to maintain a new sub-registry under
"Border Gateway Protocol - Link State (BGP-LS) Parameters". The new
registry is called "SR Policy Protocol Origin" and contains the
codepoints allocated to the "Protocol Origin" field defined in
Section 4.5. The registry contains the following codepoints, with
initial values, to be assigned by IANA:
+------------+---------------------------------------------------------+
| Code Point | Protocol Origin |
+------------+---------------------------------------------------------+
| 1 | PCEP |
| 2 | BGP SR Policy |
| 3 | Local (via CLI, Yang model through NETCONF, gRPC, etc.) |
+------------+---------------------------------------------------------+
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9.5. BGP-LS TE State Object Origin
This document requests IANA to maintain a new sub-registry under
"Border Gateway Protocol - Link State (BGP-LS) Parameters". The new
registry is called "TE State Path Origin" and contains the codepoints
allocated to the "Object Origin" field defined in Section 5. The
registry contains the following codepoints, with initial values, to
be assigned by IANA:
+----------+------------------+
| Code | Object |
| Point | Origin |
+----------+------------------+
| 1 | RSVP-TE |
| 2 | PCEP |
| 3 | Local/Static |
+----------+------------------+
9.6. BGP-LS TE State Address Family
This document requests IANA to maintain a new sub-registry under
"Border Gateway Protocol - Link State (BGP-LS) Parameters". The new
registry is called "TE State Address Family" and contains the
codepoints allocated to the "Address Family" field defined in
Section 5. The registry contains the following codepoints, with
initial values, to be assigned by IANA:
+----------+------------------+
| Code | Address |
| Point | Family |
+----------+------------------+
| 1 | MPLS-IPv4 |
| 2 | MPLS-IPv6 |
+----------+------------------+
9.7. BGP-LS SR Segment Descriptors
This document requests IANA to maintain a new sub-registry under
"Border Gateway Protocol - Link State (BGP-LS) Parameters". The new
registry is called "SR Segment Descriptor Types" and contains the
codepoints allocated to the "Segment Type" field defined in
Section 6.8 and described in Section 6.8.1. The registry contains
the following codepoints, with initial values, to be assigned by
IANA:
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+-------+--------------------------------------------------------------+
| Code | Segment Description |
| Point | |
+-------+--------------------------------------------------------------+
| 0 | Invalid |
| 1 | SR-MPLS Label |
| 2 | SRv6 SID as IPv6 address |
| 3 | SR-MPLS Prefix SID as IPv4 Node Address |
| 4 | SR-MPLS Prefix SID as IPv6 Node Global Address |
| 5 | SR-MPLS Adjacency SID as IPv4 Node Address & Local |
| | Interface ID |
| 6 | SR-MPLS Adjacency SID as IPv4 Local & Remote Interface |
| | Addresses |
| 7 | SR-MPLS Adjacency SID as pair of IPv6 Global Address & |
| | Interface ID for Local & Remote nodes |
| 8 | SR-MPLS Adjacency SID as pair of IPv6 Global Addresses for |
| | the Local & Remote Interface |
| 9 | SRv6 END SID as IPv6 Node Global Address |
| 10 | SRv6 END.X SID as pair of IPv6 Global Address & Interface ID |
| | for Local & Remote nodes |
| 11 | SRv6 END.X SID as pair of IPv6 Global Addresses for the |
| | Local & Remote Interface |
+-------+--------------------------------------------------------------+
9.8. BGP-LS Metric Type
This document requests IANA to maintain a new sub-registry under
"Border Gateway Protocol - Link State (BGP-LS) Parameters". The new
registry is called "Metric Type" and contains the codepoints
allocated to the "metric type" field defined in Section 6.9. The
registry contains the following codepoints, with initial values, to
be assigned by IANA:
+------------+-----------------------------------------+
| Code Point | Metric Type |
+------------+-----------------------------------------+
| 0 | IGP Metric |
| 1 | Min Unidirectional Link Delay [RFC7471] |
| 2 | TE Metric [RFC3630] |
+------------+-----------------------------------------+
10. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See [RFC6952] for details.
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11. Contributors
The following people have substantially contributed to the editing of
this document:
Clarence Filsfils
Cisco Systems
Email: cfilsfil@cisco.com
12. Acknowledgements
The authors would like to thank Dhruv Dhody, Mohammed Abdul Aziz
Khalid, Lou Berger, Acee Lindem, Siva Sivabalan, Arjun Sreekantiah,
and Dhanendra Jain for their review and valuable comments.
13. References
13.1. Normative References
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
Bernier, D., and B. Decraene, "BGP Link State Extensions
for SRv6", draft-ietf-idr-bgpls-srv6-ext-08 (work in
progress), June 2021.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-13 (work in progress),
May 2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
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[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003,
<https://www.rfc-editor.org/info/rfc3473>.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
DOI 10.17487/RFC4090, May 2005,
<https://www.rfc-editor.org/info/rfc4090>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[RFC4872] Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
Ed., "RSVP-TE Extensions in Support of End-to-End
Generalized Multi-Protocol Label Switching (GMPLS)
Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
<https://www.rfc-editor.org/info/rfc4872>.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
May 2007, <https://www.rfc-editor.org/info/rfc4873>.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
Extension to Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874,
April 2007, <https://www.rfc-editor.org/info/rfc4874>.
[RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
Ayyangar, "Encoding of Attributes for MPLS LSP
Establishment Using Resource Reservation Protocol Traffic
Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
February 2009, <https://www.rfc-editor.org/info/rfc5420>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
[RFC9086] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Patel, K.,
Ray, S., and J. Dong, "Border Gateway Protocol - Link
State (BGP-LS) Extensions for Segment Routing BGP Egress
Peer Engineering", RFC 9086, DOI 10.17487/RFC9086, August
2021, <https://www.rfc-editor.org/info/rfc9086>.
13.2. Informative References
[RFC2702] Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J.
McManus, "Requirements for Traffic Engineering Over MPLS",
RFC 2702, DOI 10.17487/RFC2702, September 1999,
<https://www.rfc-editor.org/info/rfc2702>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
<https://www.rfc-editor.org/info/rfc4202>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065,
DOI 10.17487/RFC5065, August 2007,
<https://www.rfc-editor.org/info/rfc5065>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.
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[RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>.
[RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
<https://www.rfc-editor.org/info/rfc7471>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
Authors' Addresses
Stefano Previdi
Email: stefano@previdi.net
Ketan Talaulikar (editor)
Cisco Systems, Inc.
India
Email: ketant.ietf@gmail.com
Jie Dong (editor)
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
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Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
Jeff Tantsura
Apstra
Email: jefftant.ietf@gmail.com
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