Inter-Domain Routing S. Previdi
Internet-Draft
Intended status: Standards Track K. Talaulikar, Ed.
Expires: 10 September 2023 Cisco Systems
J. Dong
Huawei Technologies
H. Gredler
RtBrick Inc.
J. Tantsura
Microsoft
9 March 2023
Advertisement of Traffic Engineering Paths using BGP Link-State
draft-ietf-idr-bgp-ls-te-path-00
Abstract
This document describes a mechanism to collect the Traffic
Engineering Path 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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 10 September 2023.
Copyright Notice
Copyright (c) 2023 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 to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Carrying TE Policy Information in BGP . . . . . . . . . . . . 5
3. TE Path NLRI Types . . . . . . . . . . . . . . . . . . . . . 5
4. TE Path Descriptors . . . . . . . . . . . . . . . . . . . . . 7
4.1. Tunnel Identifier . . . . . . . . . . . . . . . . . . . . 7
4.2. LSP Identifier . . . . . . . . . . . . . . . . . . . . . 8
4.3. IPv4/IPv6 Tunnel Head-End Address . . . . . . . . . . . . 8
4.4. IPv4/IPv6 Tunnel Tail-End Address . . . . . . . . . . . . 9
4.5. Local MPLS Cross Connect . . . . . . . . . . . . . . . . 9
4.5.1. MPLS Cross Connect Interface . . . . . . . . . . . . 11
4.5.2. MPLS Cross Connect FEC . . . . . . . . . . . . . . . 12
5. MPLS-TE Path State TLV . . . . . . . . . . . . . . . . . . . 13
5.1. RSVP Objects . . . . . . . . . . . . . . . . . . . . . . 14
5.2. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 15
6. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 16
7. Manageability Considerations . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8.1. BGP-LS NLRI-Types . . . . . . . . . . . . . . . . . . . . 17
8.2. BGP-LS Protocol-IDs . . . . . . . . . . . . . . . . . . . 17
8.3. BGP-LS TLVs . . . . . . . . . . . . . . . . . . . . . . . 17
8.4. BGP-LS TE State Object Origin . . . . . . . . . . . . . . 18
8.5. BGP-LS TE State Address Family . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
12.1. Normative References . . . . . . . . . . . . . . . . . . 19
12.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
In many network environments, traffic engineering (TE) paths are
instantiated into various forms:
* MPLS Traffic Engineering Label Switched Paths (TE-LSPs).
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* Local MPLS cross-connect configuration
All this information can be grouped into the same term: TE Paths. In
the rest of this document we refer to TE Paths as the set of
information related to the various instantiation of policies: MPLS TE
LSPs, Local MPLS cross-connects, etc.
TE Paths 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.
In many network environments, the configuration, and state of each TE
Path 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 optimization.
While some extensions are proposed in the 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
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 a TE Path state collection
mechanism complementary to the mechanism defined in [RFC8231].
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-----------
| ----- |
Service | | TED |<-+----------->
Request | ----- | TED synchronization
| | | | mechanism (e.g.,
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 Path information to the PCE nodes. An external
component may also need to collect the TE Path 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 Paths in its domain, in addition, a parent PCE
needs to collect TE Path 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 Path state information is quite
important for making appropriate service placement decisions with the
purpose of both meeting the application's requirements and utilizing
network resources efficiently.
The Network Management System (NMS) may need to provide global
visibility of the TE Paths 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]. BGP-LS is
extended to carry TE Path information via #draft-ietf-idr-bgp-ls-sr-
policy# so that the same protocol may be used to also collect Segment
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Routing traffic engineering paths information such that external
components like controllers can use the same protocol for network
information collection. This document specifies similar extensions
to BGP-LS for the advertisement of information other TE Paths to
external components.
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
The "Link-State NLRI" defined in [RFC7752] is extended to carry the
TE Path information. New TLVs carried in the Link_State Attribute
defined in [RFC7752] are also defined to carry the attributes of a TE
Path 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) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Additional "NLRI Types" are defined for TE Path Information as
following:
* MPLS-TE LSP NLRI (value TBD)
* MPLS Local Cross-connect NLRI (value TBD)
The common format for these NLRI types is defined in Section 3 below.
3. TE Path NLRI Types
This document defines TE Path NLRI Types with their common format as
shown in the following figure:
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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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node Descriptor TLV (for the Headend) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TE Path Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* Protocol-ID field specifies the component that owns the TE Path
state in the advertising node. The existing protocol-id value of
5 for Static Configuration applies for some of the NLRI types and
the "RSVP-TE" Protocol-ID (value 8) is defined for some of the
other types in this document.
* "Identifier" is an 8 octet value as defined in [RFC7752].
* "Local Node Descriptor" (TLV 256) as defined in [RFC7752] that
describes the headend node.
* "TE Path Descriptors" consists of one or more of the TLVs listed
as below for use with the respective NLRI type advertisements as
specified in Section 4:
+-----------+----------------------------------+
| Codepoint | Descriptor TLVs |
+-----------+----------------------------------+
| 550 | Tunnel ID |
| 551 | LSP ID |
| 552 | IPv4/6 Tunnel Head-end address |
| 553 | IPv4/6 Tunnel Tail-end address |
| 555 | Local MPLS Cross Connect |
+-----------+----------------------------------+
The Local Node Descriptor TLV MUST include the following Node
Descriptor TLVs:
* BGP Router-ID (TLV 516) [RFC9086], which contains a valid BGP
Identifier of the node originating the TE Path advertisement.
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* Autonomous System Number (TLV 512) [RFC7752], which contains the
ASN or AS Confederation Identifier (ASN) [RFC5065], if
confederations are used, of the node originating the TE Path
advertisement.
The Local Node Descriptor TLV SHOULD include at least one of the
following Node Descriptor TLVs:
* IPv4 Router-ID of Local Node (TLV 1028) [RFC7752], which contains
the IPv4 TE Router-ID of the local node when one is provisioned.
* 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:
* BGP Confederation Member (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.
* Node Descriptors as defined in [RFC7752].
4. TE Path Descriptors
This section defines the TE Path Descriptors TLVs which are used to
describe the TE Path being advertised by using the NLRI types defined
in Section 3.
4.1. Tunnel Identifier
The Tunnel Identifier TLV contains the Tunnel ID defined in [RFC3209]
and is used with the Protocol-ID set to RSVP-TE to advertise the
MPLS-TE LSP NLRI Type. It is a mandatory TE Path Descriptor TLV for
MPLS-TE LSP NLRI type. 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:
* Type: 550
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* Length: 2 octets.
* Tunnel ID: 2 octets as defined in [RFC3209].
4.2. LSP Identifier
The LSP Identifier TLV contains the LSP ID defined in [RFC3209] and
is used with the Protocol-ID set to RSVP-TE to advertise the MPLS-TE
LSP NLRI Type. It is a mandatory TE Path Descriptor TLV for MPLS-TE
LSP NLRI type. 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:
* Type: 551
* Length: 2 octets.
* LSP ID: 2 octets as defined in [RFC3209].
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 with the Protocol-ID set
to RSVP-TE to advertise the MPLS-TE LSP NLRI Type. It is a mandatory
TE Path Descriptor TLV for MPLS-TE LSP NLRI type. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IPv4/IPv6 Tunnel Head-End Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* Type: 552
* Length: 4 or 16 octets.
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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 with the Protocol-ID set
to RSVP-TE to advertise the MPLS-TE LSP NLRI Type. It is a mandatory
TE Path Descriptor TLV for MPLS-TE LSP NLRI type. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// IPv4/IPv6 Tunnel Tail-End Address (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
* Type: 553
* Length: 4 or 16 octets.
When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv4
address, its length is 4 (octets).
When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv6
address, its length is 16 (octets).
4.5. Local MPLS Cross Connect
The Local MPLS Cross Connect TLV identifies a local MPLS state in the
form of an incoming label and interface followed by an outgoing label
and interface. The 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]. It is a mandatory TE
Path Descriptor TLV for MPLS Local Cross-connect NLRI type.
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:
* Type: 555
* Length: variable.
* Incoming and Outgoing labels: 4 octets each.
* 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 an 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.
4.5.1. 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:
* Type: 556
* Length: 9 or 21.
* 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.
* Local Interface Identifier: a 4-octet identifier.
* Interface address: a 4-octet IPv4 address or a 16-octet IPv6
address.
4.5.2. MPLS Cross Connect FEC
The MPLS Cross Connect FEC sub-TLV is optional and contains the FEC
associated with 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:
* Type: 557
* Length: variable.
* 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.
* Mask Length: 1 octet of prefix length.
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* Prefix: an IPv4 or IPv6 prefix whose mask length is given by the "
Mask Length" field padded to an octet boundary.
5. MPLS-TE Path State TLV
A new TLV called "MPLS-TE Path State TLV", is used to describe the
characteristics of the MPLS-TE LSP NLRI type and it is carried in the
optional non-transitive BGP Attribute "LINK_STATE Attribute" defined
in [RFC7752]. These MPLS-TE LSP characteristics include the
characteristics and attributes of the LSP, its dataplane, explicit
path, Quality of Service (QoS) parameters, route information, the
protection mechanisms, etc.
The MPLS-TE Path 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 Path State Objects (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Figure 1: MPLS-TE Path State TLV
* Type: 1200
* Length: the total length of the MPLS-TE Path State TLV not
including the Type and Length fields.
* 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. The
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 |
+----------+------------------+
* Address Family: describes the address family used to set up the
MPLS-TE path. The following address family values are defined in
this document:
+----------+------------------+
| Code | Dataplane |
| Point | |
+----------+------------------+
| 1 | MPLS-IPv4 |
| 2 | MPLS-IPv6 |
+----------+------------------+
* RESERVED: 16-bit field. SHOULD be set to 0 on transmission and
MUST be ignored on receipt.
* TE Path 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 Path 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 Path State Objects" field
of the MPLS-TE Path 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 Path State TLV.
When carrying RSVP-TE objects, the "Object-Origin" field is set to
"RSVP-TE".
The following RSVP-TE Objects are defined:
* SENDER_TSPEC and FLOW_SPEC [RFC2205]
* SESSION_ATTRIBUTE [RFC3209]
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* EXPLICIT_ROUTE Object (ERO) [RFC3209]
* ROUTE_RECORD Object (RRO) [RFC3209]
* FAST_REROUTE Object [RFC4090]
* DETOUR Object [RFC4090]
* EXCLUDE_ROUTE Object (XRO) [RFC4874]
* SECONDARY_EXPLICIT_ROUTE Object (SERO) [RFC4873]
* SECONDARY_RECORD_ROUTE (SRRO) [RFC4873]
* LSP_ATTRIBUTES Object [RFC5420]
* LSP_REQUIRED_ATTRIBUTES Object [RFC5420]
* PROTECTION Object [RFC3473][RFC4872][RFC4873]
* ASSOCIATION Object [RFC4872]
* PRIMARY_PATH_ROUTE Object [RFC4872]
* ADMIN_STATUS Object [RFC3473]
* 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 Path State Objects" field of
the MPLS-TE Path State TLV and consist 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 Path State TLV.
When carrying PCEP objects, the "Object-Origin" field is set to
"PCEP".
The following PCEP Objects are defined:
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* METRIC Object [RFC5440]
* 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 Path
State TLV.
6. Procedures
The BGP-LS advertisements for the TE Path NLRI types are originated
by the headend node for the TE Paths 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 Path 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 Path State TLV SHOULD be used to
encode the related PCEP objects corresponding to the LSP as defined
in Section 5.2.
When a SR Policy [RFC9256] is setup with the help of PCEP signaling
[RFC8664] then a MPLS-TE Path State TLV MAY be used 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 SR Policy State TLVs specified in #draft-ietf-idr-bgp-
ls-sr-policy#. In the event of a conflict of information, the
receiver MUST prefer the information originated via the SR Policy
State TLVs over the PCEP objects reported via the TE Path State TLV.
7. 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.
In general, it is assumed that the TE Path head-end nodes are
responsible for the advertisement of TE Path state information, while
other nodes, e.g. the nodes in the path of a policy, MAY report the
TE Path 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.
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8. IANA Considerations
This section describes the code point allocation by IANA for this
document.
8.1. BGP-LS NLRI-Types
IANA maintains a registry called "BGP-LS NLRI-Types" in the "Border
Gateway Protocol - Link State (BGP-LS) Parameters" registry group.
The following table lists the code points pending allocation by IANA:
+------+-------------------------------+---------------+
| Type | NLRI Type | Reference |
+------+-------------------------------+---------------+
| TBD | MPLS-TE LSP NLRI | this document |
| TBD | MPLS Local Cross-connect NLRI | this document |
+------+-------------------------------+---------------+
8.2. BGP-LS Protocol-IDs
IANA maintains a registry called "BGP-LS Protocol-IDs" in the "Border
Gateway Protocol - Link State (BGP-LS) Parameters" registry group.
The following Protocol-ID codepoints have been allocated by IANA:
+-------------+----------------------------------+---------------+
| Protocol-ID | NLRI information source protocol | Reference |
+-------------+----------------------------------+---------------+
| 8 | RSVP-TE | this document |
+-------------+----------------------------------+---------------+
8.3. BGP-LS TLVs
IANA maintains a registry called "Node Anchor, Link Descriptor and
Link Attribute TLVs" in the "Border Gateway Protocol - Link State
(BGP-LS) Parameters" registry group.
The following table lists the status of TLV code points that have
been allocated by IANA:
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+-------+----------------------------------------+---------------+
| Code | Description | Value defined |
| Point | | in |
+-------+----------------------------------------+---------------+
| 550 | Tunnel ID | this document |
| 551 | LSP ID | this document |
| 552 | IPv4/6 Tunnel Head-end address | this document |
| 553 | IPv4/6 Tunnel Tail-end address | this document |
| 555 | MPLS Local Cross Connect | this document |
| 556 | MPLS Cross Connect Interface | this document |
| 557 | MPLS Cross Connect FEC | this document |
| 1200 | MPLS-TE Path State | this document |
+-------+----------------------------------------+---------------+
8.4. BGP-LS TE State Object Origin
This document requests IANA to maintain a new registry under "Border
Gateway Protocol - Link State (BGP-LS) Parameters" registry group
with the allocation policy of "Expert Review" [RFC8126] using the
guidelines for Designated Experts as specified in [RFC9029]. 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 with the reference set to this document:
+----------+------------------------------------------+
| Code | Object |
| Point | Origin |
+----------+------------------------------------------+
| 0 | Reserved (not to be used) |
| 1 | RSVP-TE |
| 2 | PCEP |
| 3 | Local/Static |
| 4-250 | Unassigned |
| 251-255 | Private Use (not to be assigned by IANA) |
+----------+------------------------------------------+
8.5. BGP-LS TE State Address Family
This document requests IANA to maintain a new registry under "Border
Gateway Protocol - Link State (BGP-LS) Parameters" registry group
with the allocation policy of "Expert Review" [RFC8126] using the
guidelines for Designated Experts as specified in [RFC9029]. 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 with the reference set to this
document:
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+----------+------------------------------------------+
| Code | Address |
| Point | Family |
+----------+------------------------------------------+
| 0 | Reserved (not to be used) |
| 1 | MPLS-IPv4 |
| 2 | MPLS-IPv6 |
| 3-250 | Unassigned |
| 251-255 | Private Use (not to be assigned by IANA) |
+----------+------------------------------------------+
9. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See [RFC6952] for details.
10. Contributors
The following people have substantially contributed to the editing of
this document:
Clarence Filsfils
Cisco Systems
Email: cfilsfil@cisco.com
Mach (Guoyi) Chen
Huawei Technologies
Email: mach.chen@huawei.com
11. Acknowledgements
The authors would like to thank Dhruv Dhody, Mohammed Abdul Aziz
Khalid, Lou Berger, Acee Lindem, Siva Sivabalan, Arjun Sreekantiah,
Dhanendra Jain, Francois Clad, Zafar Ali, Stephane Litkowski, and
Aravind Babu Mahendra Babu for their review and valuable comments.
12. References
12.1. Normative References
[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>.
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[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>.
[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>.
[RFC4872] Lang, J.P., 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>.
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[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>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[RFC9029] Farrel, A., "Updates to the Allocation Policy for the
Border Gateway Protocol - Link State (BGP-LS) Parameters
Registries", RFC 9029, DOI 10.17487/RFC9029, June 2021,
<https://www.rfc-editor.org/info/rfc9029>.
[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>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
12.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., 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>.
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[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>.
[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
India
Email: ketant.ietf@gmail.com
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: jie.dong@huawei.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
Jeff Tantsura
Microsoft
Email: jefftant.ietf@gmail.com
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