PCE-initiated IP Tunnel
draft-chen-pce-pce-initiated-ip-tunnel-01
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| Authors | Xia Chen , Hang Shi , Zhenbin Li | ||
| Last updated | 2022-10-20 | ||
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draft-chen-pce-pce-initiated-ip-tunnel-01
Network Working Group X. Chen
Internet-Draft H. Shi
Intended status: Standards Track Z. Li
Expires: 23 April 2023 Huawei Technologies
20 October 2022
PCE-initiated IP Tunnel
draft-chen-pce-pce-initiated-ip-tunnel-01
Abstract
This document specifies a set of extensions to PCEP to support PCE-
initiated IP Tunnel to satisfy the requirement which is introduced in
[I-D.li-spring-tunnel-segment]. The extensions include the setup,
maintenance and teardown of PCE-initiated IP Tunnels, without the
need for local configuration on the PCC.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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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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 23 April 2023.
Copyright Notice
Copyright (c) 2022 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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Procedures for PCE-initiated IP Tunnel . . . . . . . . . . . 3
3.1. Overview of Procedures . . . . . . . . . . . . . . . . . 3
3.2. Capability Advertisement . . . . . . . . . . . . . . . . 4
3.3. Tunnel Operations . . . . . . . . . . . . . . . . . . . . 4
3.3.1. PCE IP Tunnel Instantiation . . . . . . . . . . . . . 5
3.3.2. PCE IP Tunnel Update . . . . . . . . . . . . . . . . 5
3.3.3. PCE IP Tunnel Deletion . . . . . . . . . . . . . . . 6
4. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. PCTunnelInitiate Message . . . . . . . . . . . . . . . . 7
4.2. PCTunnelUpd Message . . . . . . . . . . . . . . . . . . . 9
4.3. PCTunnelRpt Message . . . . . . . . . . . . . . . . . . . 9
5. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 10
5.1.1. PCE Initiated Tunnel Capability TLV . . . . . . . . . 10
5.2. SRP Object . . . . . . . . . . . . . . . . . . . . . . . 11
5.3. TUNNEL Object . . . . . . . . . . . . . . . . . . . . . . 12
5.3.1. Tunnel Identifier TLV . . . . . . . . . . . . . . . . 13
5.3.2. Tunnel Name TLV . . . . . . . . . . . . . . . . . . . 15
5.3.3. Tunnel Parameter TLV . . . . . . . . . . . . . . . . 16
5.3.4. Tunnel Attribute TLV . . . . . . . . . . . . . . . . 19
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
7. Security Considerations . . . . . . . . . . . . . . . . . . . 21
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
[I-D.li-spring-tunnel-segment] introduces a new type of segment,
Tunnel Segment, for the segment routing. Tunnel segment can be used
to reduce SID stack depth of SR path, span the non-SR domain or
provide differentiated services. The tunnel segment can be allocated
for MPLS RSVP-TE tunnel, SR-TE tunnel or IP Tunnel.
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[I-D.li-spring-tunnel-segment] introduces two ways to set up the
tunnel which is used as tunnel segment: one is to configure tunnel on
the device, the other is PCE-initiated tunnel.
[RFC8231], [RFC8281] and [RFC8664] has defined how to set up the PCE
initiated RSVP-TE LSP and SR-TE LSP. This document specifies a set
of extensions to PCEP to support PCE-initiated IP Tunnel. The
extensions include the setup, maintenance and teardown of PCE-
initiated IP Tunnels, without the need for local configuration on the
PCC.
2. Terminology
SR: Segment Routing
SR-TE: Segment Routing Traffic Engineering
This document uses the terms defined in [RFC5440]: PCC, PCE, PCEP
Peer.
The following terms are defined in [RFC8281]:
PCE-initiated LSP: LSP that is instantiated as a result of a request
from the PCE.
The following terms are defined in this document:
IP Tunnel: Tunnel that uses IP encapsulation.
PCE-initiated IP Tunnel: IP Tunnel that is instantiated as a result
of a request from the PCE.
The message formats in this document are specified using Routing
Backus-Naur Format (RBNF) encoding as specified in [RFC5511].
3. Procedures for PCE-initiated IP Tunnel
3.1. Overview of Procedures
A PCC or PCE indicates its ability to support PCE Initiated dynamic
tunnel during the PCEP Initialization Phase via "PCE Initiated Tunnel
Capability" TLV (see details in Section 5.1).
In this document the procedure is only about PCE Initiated dynamic IP
Tunnel. The decision when to instantiate or delete a PCE-initiated
IP Tunnel is out of the scope of this document.
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This section introduces the procedure to support PCE provisioned IP
Tunnel as follows:
Firstly both the PCC and the PCE negotiate the PCE Initiated Tunnel
Capability for tunnel types during the PCE session initiation phase.
On the PCEP session with PCE Initiated Tunnel Capability PCE
communicates with PCC to set up, maintain and tear down PCE-initiated
IP Tunnels.
The procedure about tunnel state synchronization, PCC local policy
and timeout process, the session failure process, etc. will be
specified in the future version.
3.2. Capability Advertisement
During PCEP session establishment, both the PCC and the PCE must
announce their support of PCEP extensions defined in this document.
A PCEP Speaker (PCE or PCC) includes the "PCE Initiated Tunnel
Capability" TLV, described in Section 5.1, in the OPEN Object to
advertise its support for PCEP extensions for PCE Initiated IP Tunnel
Capability.
The PCE Initiated Tunnel Capability TLV includes the tunnel types
that are supported by PCEP Speaker. Each tunnel type is indicated by
one bit.
The presence of the PCE Initiated Tunnel Capability TLV in PCE's OPEN
message indicates that the PCE can support the instantiation of PCE-
initiated Tunnels and the types of the tunnels which PCE can
initiate.
The presence of such Capability TLV in PCC's OPEN Object indicates
that the PCC can support to instantiate the tunnel according to the
PCE's indication and the types of the tunnels which PCC can setup
automatically according to the PCE's request.
If PCE has such capability TLV and PCC has no such capability TLV PCE
MUST NOT send the PCE messages for procedure of PCE initiated IP
Tunnel. And if PCC receives such messages it should send PCErr
message to PCE.
If both PCE and PCC have such capability TLV they only negotiate the
types of the tunnels both PCE and PCC can support. PCE MUST only
initiate the specific tunnel which both PCE and PCC can support.
Otherwise PCC MUST send the PCErr message.
3.3. Tunnel Operations
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3.3.1. PCE IP Tunnel Instantiation
To instantiate a tunnel, the PCE sends a Path Computation Tunnel
Initiate (PCTunnelInitiate) message to the PCC. The PCTunnelInitiate
message MUST include the SRP object (see details in Section 5.2) and
TUNNEL object (see details in Section 5.3) . The TUNNEL object MUST
have a PTUNNEL-ID of 0 and MUST include the Tunnel Identifier TLV
with the TUNNEL-ID 0 and the Tunnel Name TLV. The TUNNEL object MAY
have the Tunnel Parameter TLV.
The PCC creates the different type of tunnel using the end point
address carried in Tunnel Identifier TLV and sends the Path
Computation Tunnel State Report (PCTunneRpt) message to PCE. The
PCTunneRpt message MUST include the SRP object and TUNNEL object.
PCC assigns a unique PTUNNEL-ID carried via TUNNEL object and a
unique TUNNEL-ID carried via Tunnel Identifier TLV(see details in
Section 5.3) in TUNNEL object for the tunnel. PCC indicates the
operational state in the TUNNEL object.
The PCTunneRpt message MUST include the SRP object, with the SRP-ID-
NUMBER used in the SRP object of the PCTunnelInitiate message.
+-+-+ +-+-+
|PCE| |PCC|
+-+-+ +-+-+
| |
1) add new tunnel |-- PCTunnelInitiate --> |
| PTUNNEL-ID=0, |
| TUNNEL-ID=0 |
| R=0 |
| . |
| |
|<---- PCTunneRpt ------| 2) Tunnel Status Report sent
| PTUNNEL-ID=1, |
| TUNNEL-ID=1 |
| Up |
| |
3.3.2. PCE IP Tunnel Update
To update the parameters used to create a tunnel, the PCE sends a
Path Computation Tunnel Update (PCTunnelUpd) message to the PCC. The
PCTunnelUpd message MUST include the SRP object and TUNNEL object.
The TUNNEL object MUST have specific PTUNNEL-ID and MUST have
specific Tunnel Identifier TLV. The TUNNEL object MUST carry any of
the Tunnel Parameter TLV and Tunnel Attribute TLV.
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The PCC updates the encapsulation parameters and/or attributes of the
tunnel and PCC sends the PCTunneRpt message to PCE to report updated
state.
The PCTunneRpt message MUST include the SRP object, with the SRP-ID-
NUMBER used in the SRP object of the PCTunnelUpd message.
+-+-+ +-+-+
|PCE| |PCC|
+-+-+ +-+-+
| |
1) update tunnel |---- PCTunnelUpd ----> |
parameter | PTUNNEL-ID=1, |
| TUNNEL-ID=1 |
| . |
| |
|<---- PCTunneRpt ------| 2) Tunnel Status Report sent
| PTUNNEL-ID=1, |
| TUNNEL-ID=1 |
| Up |
| |
3.3.3. PCE IP Tunnel Deletion
To delete a tunnel, the PCE sends a Path Computation Tunnel Initiate
(PCTunnelInitiate) message to the PCC. The PCTunnelInitiate message
MUST include the SRP object and TUNNEL object and the 'R' flag in SRP
object SHOULD be set. The TUNNEL object MUST have specific PTUNNEL-
ID and MUST have specific Tunnel Identifier TLV.
The PCC delete the tunnel specified by PTUNNEL-ID and PCC sends the
PCTunneRpt message to PCE to report updated state.
The PCTunneRpt message MUST include the SRP object, with the SRP-ID-
NUMBER used in the SRP object of the PCTunnelInitiate message.
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+-+-+ +-+-+
|PCE| |PCC|
+-+-+ +-+-+
| |
1) delete tunnel |-- PCTunnelInitiate --> |
| PTUNNEL-ID=1, |
| TUNNEL-ID=1 |
| R=1 |
| . |
| |
|<---- PCTunneRpt ------| 2) Tunnel Status Report sent
| PTUNNEL-ID=1, |
| TUNNEL-ID=1 |
| DOWN |
| |
4. PCEP Messages
To initiate a tunnel, a PCE sends a PCTunnelInitiate message to a
PCC.
To report the state of a tunnel, a PCC sends a PCTunnelRpt message to
a PCE.
To modify the parameters of a tunnel, a PCE sends a PCTunnelUpd
message to a PCC.
The message format, objects and TLVs are discussed separately below
for the creation and the deletion cases.
4.1. PCTunnelInitiate Message
A Path Computation Tunnel Initiate message which is also referred to
as PCTunnelInitiate message is a PCEP message sent by a PCE to a PCC
to trigger tunnel instantiation or deletion.
The Message-Type field of the PCEP common header for the
PCTunnelInitiate message is to be assigned by IANA. The
PCTunnelInitiate message MUST include the SRP and the TUNNEL objects.
If the SRP object is missing, the PCC MUST send a PCErr with error-
type 6 (Mandatory Object missing) and error-value=10 (SRP Object
missing) (per [RFC8231]). If the TUNNEL object is missing, the PCC
MUST send a PCErr with error-type 6 (Mandatory Object missing) and
error-value which means TUNNEL Object missing.
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Tunnel instantiation is done by sending an Tunnel Initiate Message
with an TUNNEL object with the reserved PTUNNEL-ID 0. Tunnel
deletion is done by sending an Tunnel Initiate Message with an TUNNEL
object carrying the PTUNNEL-ID of the tunnel to be removed and an SRP
object with the R flag set.
The format of a PCTunnelInitiate message for tunnel instantiation is
as follows:
<PCTunnelInitiate Message> ::= <Common Header>
<PCE-initiated-tunnel-list>
Where:
<PCE-initiated-tunnel-list> ::= <PCE-initiated-tunnel-request>
[<PCE-initiated-tunnel-request>]
<PCE-initiated-tunnel-request> ::= (<PCE-initiated-tunnel-instantiation>
|<PCE-initiated-tunnel-deletion>)
<PCE-initiated-tunnel-instantiation> ::= <SRP>
<TUNNEL>
<PCE-initiated-tunnel-deletion> ::= <SRP>
<TUNNEL>
The SRP object defined in [RFC8231] can be used in this document to
correlate tunnel initiate requests and update requests sent by the
PCE with the error reports and tunnel state reports sent by the PCC.
Every request from the PCE sends a new SRP- ID-NUMBER. This number
is unique per PCEP session and is incremented each time an operation
(initiation, update, etc) is requested from the PCE. The value of
the SRP-ID-NUMBER MUST be echoed back by the PCC in PCErr and
PCTunnelRpt messages to allow for correlation between requests made
by the PCE and errors or state reports generated by the PCC.
Procedure of PCE-initiated IP Tunnel share the same number space of
the SRP-ID-NUMBER with procedure of stateful PCE.
The <TUNNEL> object is an new object introduced in this document.
<TUNNEL> object in PCTunnelInitiate message MUST include Tunnel
Identifier TLV and Tunnel Name TLV. Tunnel Parameter TLV is
optionally included.
The Tunnel Initiate message for tunnel instantiation has the TUNNEL
object with the TUNNEL-ID in Tunnel Identifier TLV 0. The Tunnel
Initiate message for tunnel deletion has the TUNNEL object carrying
the TUNNEL-ID of the TUNNEL to be removed.
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4.2. PCTunnelUpd Message
A Path Computation Tunnel Update Request message (also referred to as
PCTunnelUpd message) is a PCEP message sent by a PCE to a PCC to
update the encapsulation parameters and/or attributes of a tunnel. A
PCTunnelUpd message can carry more than one Tunnel Update Request.
The Message-Type field of the PCEP common header for the PCUpd
message is to be assigned by IANA.
The PCTunnelUpd message MUST include the SRP and the TUNNEL objects.
If the SRP object is missing, the PCC MUST send a PCErr with error-
type 6 (Mandatory Object missing) and error-value=10 (SRP Object
missing) (per [RFC8231]). If the TUNNEL object is missing, the PCC
MUST send a PCErr with error-type 6 (Mandatory Object missing) and
error-value which means TUNNEL Object missing.
The format of a PCTunnelUpd message for tunnel parameter update is as
follows:
<PCETunnelUpd Message> ::= <Common Header>
<tunnel-update-request-list>
Where:
<tunnel-update-request-list> ::= <tunnel-update-request>
[<tunnel-update-request-list>]
<tunnel-update-request> ::= <SRP>
<TUNNEL>
<TUNNEL> object in PCTunnelUpd message MUST include Tunnel Identifier
TLV and any of Tunnel Parameter TLV and Tunnel Attribute TLV. Tunnel
Name TLV is not included.
4.3. PCTunnelRpt Message
A Path Computation Tunnel State Report message which is also referred
to as PCTunnelRpt message is a PCEP message sent by a PCC to a PCE to
report the current state of a tunnel. A PCTunnelRpt message can
carry more than one Tunnel State Reports. A PCC sends an Tunnel
State Report in response to a Tunnel Initiate Request for creation or
a Tunnel Update Request from a PCE.
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The Message-Type field of the PCEP common header for the PCTunnelRpt
message is to be assigned by IANA. The PCTunnelRpt message MUST
include the SRP and the TUNNEL objects. If the SRP object is
missing, the PCE MUST send a PCErr with error-type 6 (Mandatory
Object missing) and error-value=10 (SRP Object missing) (per
[RFC8231]). If the TUNNEL object is missing, the PCE MUST send a
PCErr with error-type 6 (Mandatory Object missing) and error-value
which means TUNNEL Object missing.
The format of a PCTunnelRpt message for tunnel instantiation is as
follows:
<PCTunnelRpt Message> ::= <Common Header>
<tunnel-state-report-list>
Where:
<tunnel-state-report-list> ::= <tunnel-state-report>
[<tunnel-state-report-list>]
<tunnel-state-report> ::= <SRP>
<TUNNEL>
<TUNNEL> object in PCTunnelRpt message MUST include Tunnel Identifier
TLV.
Tunnel Parameter TLV and Tunnel Attribute TLV is optionally included
in PCTunnelRpt message. In the first PCTunnelRpt message in response
to the PCTunnelInitiate message Tunnel Name TLV MUST be included.
And in the subsequent PCTunnelRpt message Tunnel Name TLV is
optionally included.
5. PCEP Objects
5.1. OPEN Object
5.1.1. PCE Initiated Tunnel Capability TLV
The PCE-INITIATE-TUNNEL-CAPABILITY TLV is an optional TLV associated
with the OPEN Object [RFC5440] to exchange PCE-initiated tunnel
capability of PCEP speakers.
Its format is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Types |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 1: PCE-INITIATE-TUNNEL-CAPABILITY TLV
The type of the TLV is to be assigned by IANA and it has a fixed
length of 4 octets.
The value comprises a single field - Tunnel Types (32 bits):
Each bit indicates one kind of tunnel. Each bit from right to left
successively represents the value of tunnel type which is 0 to 31.
The value of tunnel types refer to the registry for "BGP Tunnel
Encapsulation Attribute Tunnel Types" [RFC5512] assigned by IANA.
This document only use the IP tunnel type.
The assignments used by this document are as follows:
Tunnel Type Value
--------------- -----
Reserved 0
GRE 2
VXLAN 8
NVGRE 9
MPLS in GRE 11
VxLAN GPE 12
MPLS in UDP 13
Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt.
5.2. SRP Object
<SRP> object is defined in [RFC8231]. In this document <SRP> is used
to correlate PCTunnelInitiate and PCTunnelRpt or PCErr message.
'R' Flag in <SRP> object is defined in
[RFC8281]. When PCE requests PCC to create
the IP tunnel 'R' Flag in <SRP> is set to 0. When PCE requests PCC
to delete the IP tunnel 'R' Flag in <SRP> is set to 1.
Other flags must be set to 0 and if PCC receive the PCTunnelInitiate
message with other reserved flags in <SRP > set to 1 PCC will send
the PCErr message.
In procedure of PCE-initiated IP tunnel <SRP> object carries no
optional TLVs.
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5.3. TUNNEL Object
The TUNNEL object MUST be present within PCTunnelInitiate,
PCTunnelRpt and PCTunnelUpd messages. The TUNNEL object contains a
set of fields used to specify the target tunnel, the flags to
indicate the state of the tunnel or operation to be performed on the
tunnel and TLVs.
TUNNEL Object-Class is to be assigned by IANA.
TUNNEL Object-Type is 1.
The format of the TUNNEL object body is shown in 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PTUNNEL-ID | Flag | O|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: TUNNEL Object
PTUNNEL-ID (24 bits): A PCEP-specific identifier for the tunnel. A
PCC creates a unique PTUNNEL-ID for each tunnel that is constant for
the lifetime of a PCEP session. The PCC will advertise the same
PTUNNEL-ID on all PCEP sessions. The mapping of the Tunnel Name to
PTUNNEL-ID is communicated to the PCE by sending a PCTunnelRpt
message containing the TUNNEL-NAME TLV. All subsequent PCEP messages
then address the tunnel by the PTUNNEL-ID. The values of 0 and
0xFFFFFF are reserved.
Flags (8 bits):
O(Operational - 3 bits): On PCTunnelRpt messages, the O Field
represents the operational status of the tunnel.
The following values are defined:
0 - DOWN: The tunnel can't carry the traffic.
1 - UP: The tunnel can carry the traffic.
2-7 - Reserved: these values are reserved for future use.
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Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt.
TLVs that may be included in the TUNNEL Object are described in the
following sections.
5.3.1. Tunnel Identifier TLV
The Tunnel Identifier TLV MUST be included in the TUNNEL object in
PCTunnelInitiate, PCTunnelRpt and PCTunnelUpd messages for PCE-
initiated IP Tunnels. If the TLV is missing, the PCE will generate
an error with error-type 6 (mandatory object missing) and error-value
which means Tunnel Identifier TLV missing and close the session.
There are two Tunnel Identifier TLVs, one for IPv4 and one for IPv6.
The format of the IPV4-TUNNEL-Identifier TLV is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Source Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Tunnel Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: IPV4-TUNNEL-Identifier TLV
The type of the TLV is to be assigned by IANA and it has a fixed
length of 12 octets. The value contains the following fields:
IPv4 Tunnel Source Address: contains the source IPv4 address of the
ingress node of the tunnel.
IPv4 Tunnel Destination Address: contains the destination IPv4
address of the egress node of the tunnel.
Tunnel Type: contains the type of tunnel. The value of tunnel types
refer to the registry for "BGP Tunnel Encapsulation Attribute Tunnel
Types" [RFC5512] IANA set up. This document only use the IP tunnel
type.
The assignments used by this document are as follows:
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Tunnel Type Value
--------------- -----
Reserved 0
GRE 2
VXLAN 8
NVGRE 9
MPLS in GRE 11
VxLAN GPE 12
MPLS in UDP 13
Tunnel ID: Tunnel ID remains constant over the life time of a tunnel.
A PCC creates a unique Tunnel ID for each tunnel. Each tunnel type
has individual identifier space. The Tunnel ID is allocated on id
space of the tunnel type and is unique in the same id space.
The PCC will advertise the same Tunnel ID on all PCEP sessions. The
mapping of the Tunnel Name to Tunnel ID is communicated to the PCE by
sending a PCTunnelRpt message containing the TUNNEL-NAME TLV. The
values of 0 and 0xFFFF are reserved.
The format of the IPV6-TUNNEL-Identifier TLV is shown in 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=36 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel source address |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel destination address |
+ (16 octets) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: IPV6-TUNNEL-Identifier TLV
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The type of the TLV is to be assigned by IANA and it has a fixed
length of 36 octets. The value contains the following fields:
IPv6 Tunnel Source Address: contains the source IPv6 address of the
ingress node of the tunnel.
IPv6 Tunnel Destination Address: contains the destination IPv6
address of the egress node of the tunnel.
Tunnel Type: contains the type of tunnel. The value of tunnel types
refer to the registry for "BGP Tunnel Encapsulation Attribute Tunnel
Types" [RFC5512] IANA set up.
This document only use the IP tunnel type. The assignments used by
this document are as follows:
Tunnel Type Value
--------------- -----
Reserved 0
GRE 2
VXLAN 8
NVGRE 9
MPLS in GRE 11
MPLS in UDP 13
Tunnel ID: Tunnel ID remains constant over the life time of a tunnel.
A PCC creates a unique Tunnel ID for each TUNNEL. Each tunnel type
has individual identifier space. The tunnel ID is allocated on id
space of the tunnel type and is unique in the same id space.
The PCC will advertise the same Tunnel ID on all PCEP sessions. The
mapping of the Tunnel Name to Tunnel ID is communicated to the PCE by
sending a PCTunnelRpt message containing the TUNNEL-NAME TLV. The
values of 0 and 0xFFFF are reserved.
5.3.2. Tunnel Name TLV
The Tunnel Name TLV MUST be included in the TUNNEL object in
PCTunnelInitiate messages for PCE-initiated IP Tunnels. If the TLV
is missing, the PCE will generate an error with error-type 6
(mandatory object missing) and error-value which means Tunnel Name
TLV missing and close the session.
Each tunnel MUST have a tunnel name that is unique in the PCC. This
tunnel name MUST remain constant throughout a tunnel's lifetime.
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The TUNNEL-NAME TLV MUST be included in the PCTunnelRpt message when
a tunnel is first reported to a PCE in response to the
PCTunnelInitiate message to create the tunnel. The tunnel name MAY
be included in subsequent PCTunnelRpt messages for the tunnel.
The format of the TUNNEL-NAME TLV is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Tunnel Name //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: TUNNEL-NAME TLV
The type of the TLV is to be assigned by IANA and it has a variable
length, which MUST be greater than 0.
5.3.3. Tunnel Parameter TLV
The Tunnel Parameter TLV and/or Tunnel Attribute TLV(see details in
following section) MUST be included in the TUNNEL object in
PCTunnelUpd messages for PCE-initiated IP Tunnels. If both of the
TLVs are missing, the PCE will generate an error with error-type 6
(mandatory object missing) and error-value which means Tunnel
Parameter TLV and Tunnel Attribute TLV missing and close the session.
The Tunnel Parameter TLV MAY be included in the TUNNEL object in
PCTunnelInitiate and PCTunnelRpt messages for PCE-initiated IP
Tunnels.
Tunnel Parameter TLV specifies information needed to construct the
encapsulation header when sending packets through that tunnel.
The tunnel with different type has different encapsulation mode and
each tunnel with same type MAY has different encapsulation
parameters. When PCE initiate setup of the tunnel PCE can specify
the encapsulation parameter of the tunnel and PCC will setup the
tunnel and encapsulate the packet according to the parameters.
After the tunnel has been triggered to instantiate PCE can send
PCTunnelUpd message to modify the encapsulation parameter.
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The format of the TUNNEL-PARAMETER TLV is shown in 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length=variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
// Tunnel Encapsulation Parameter //
+ (variable) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: TUNNEL-PARAMETER TLV
The type of the TLV is to be assigned by IANA and it has a variable
length, which MUST be greater than 0. The minimum value of length is
4 without any parameter. The value contains the following fields:
Tunnel Type: contains the type of tunnel. The value of tunnel types
refer to the registry for "BGP Tunnel Encapsulation Attribute Tunnel
Types" [RFC5512] IANA set up. This document only use the IP tunnel
type.
The assignments used by this document are as follows:
Tunnel Type Value
--------------- -----
Reserved 0
GRE 2
VXLAN 8
NVGRE 9
MPLS in GRE 11
VxLAN GPE 12
MPLS in UDP 13
MPLS in GRE has the same encapsulation with GRE.
5.3.3.1. GRE
When the tunnel type of the TLV is GRE, the following is the
structure of the value field of Tunnel Encapsulation Parameter:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GRE Key (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: GRE Encapsulation TLV
* GRE Key: 4-octet field [RFC2890]. The actual method by which the
key is obtained by PCE is beyond the scope of this document. The key
is inserted into the GRE encapsulation header of the payload packets
sent by ingress router to the egress router. It is intended to be
used for identifying extra context information about the received
payload.
Note that the key is optional. Unless a key value is being used, the
GRE encapsulation MUST NOT be present. If GRE tunnel didn't use the
GRE key the PCTunnelInitiate message needn't carry the TUNNEL-
PARAMETER TLV. If GRE tunnel firstly use the GRE key the
PCTunnelInitiate message need carry the TUNNEL-PARAMETER TLV. Then
if the GRE tunnel quit using the GRE key the PCTunnelUpd message can
carry the TUNNEL-PARAMETER TLV without GRE key to delete the
parameter previously set.
5.3.3.2. VXLAN
When the tunnel type of the TLV is VXLAN, the following is the
structure of the value field of Tunnel Encapsulation Parameter:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V|M|R|R|R|R|R|R| VN-ID (3 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address (4 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address (2 Octets) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: VXLAN Encapsulation TLV
The definition of the fields refer to [I-D.rosen-idr-tunnel-encaps].
5.3.3.3. NVGRE
When the tunnel type of the TLV is NVGRE, the following is the
structure of the value field of Tunnel Encapsulation Parameter:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V|M|R|R|R|R|R|R| VN-ID (3 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address (4 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address (2 Octets) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: NVGRE Encapsulation TLV
The definition of the fields refer to [I-D.rosen-idr-tunnel-encaps].
5.3.3.4. MPLS-in-UDP
When the tunnel type of the TLV is MPLS-in-UDP, the following is the
structure of the value field of Tunnel Encapsulation Parameter:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Port (2 Octets) | Destination Port (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: MPLS-in-UDP Encapsulation TLV
Source Port: UDP source port.
Destination Port: UDP destination port.
5.3.4. Tunnel Attribute TLV
The Tunnel Attribute TLV MAY be included in the TUNNEL object in
PCTunnelInitiate, PCTunnelUpd, PCTunnelRpt messages for PCE-initiated
IP Tunnels.
Tunnel Attribute TLV specifies some of the information of the tunnel
such as metric or TE metric which are carried in sub-TLVs.
The format of the TUNNEL-ATTRIBUTE TLV is shown in 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// sub-TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Tunnel Attribute TLV Format
The type of the TLV is to be assigned by IANA and it has a variable
length. The minimum value of length is 0 without any parameter. The
value contains the following fields:
sub-TLVs: Each sub-TLV has the Type(two octets), Length(two octets),
Value. The length is the length of the value of the sub-TLV.
Unknown sub-TLVs are to be ignored and skipped upon receipt.
This document defines the following sub-TLVs.
5.3.4.1. Metric Sub-TLV
The following is the structure of the sub-TLV of metric:
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=[TBD] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Metric Sub-TLV
The type of the sub-TLV is to be assigned by IANA and it has a fixed
length of 4 octets.
The value comprises a single field - Metric Value (32 bits): value of
metric.
5.3.4.2. TE Metric Sub-TLV
The following is the structure of the sub-TLV of traffic engineering
metric:
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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=[TBD] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Metric Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: TE Metric Sub-TLV
The type of the sub-TLV is to be assigned by IANA and it has a fixed
length of 4 octets.
The value comprises a single field - TE Metric Value (32 bits): value
of traffic engineering metric.
6. IANA Considerations
TBD.
7. Security Considerations
TBD.
8. References
8.1. Normative References
[I-D.li-spring-tunnel-segment]
Li, Z. and N. Wu, "Tunnel Segment in Segment Routing",
Work in Progress, Internet-Draft, draft-li-spring-tunnel-
segment-02, 14 April 2021,
<https://www.ietf.org/archive/id/draft-li-spring-tunnel-
segment-02.txt>.
[I-D.rosen-idr-tunnel-encaps]
Rosen, E. C., Patel, K., and G. V. D. Velde, "Using the
BGP Tunnel Encapsulation Attribute without the BGP
Encapsulation SAFI", Work in Progress, Internet-Draft,
draft-rosen-idr-tunnel-encaps-03, 6 August 2015,
<https://www.ietf.org/archive/id/draft-rosen-idr-tunnel-
encaps-03.txt>.
[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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[RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE",
RFC 2890, DOI 10.17487/RFC2890, September 2000,
<https://www.rfc-editor.org/info/rfc2890>.
[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>.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, DOI 10.17487/RFC5511, April
2009, <https://www.rfc-editor.org/info/rfc5511>.
[RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation
Subsequent Address Family Identifier (SAFI) and the BGP
Tunnel Encapsulation Attribute", RFC 5512, April 2009,
<https://www.rfc-editor.org/info/rfc5512>.
8.2. Informative References
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC8231 8231,
DOI 10.17487/RFC8231, 1 September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC8281 8281, DOI 10.17487/RFC8281, 1 December
2017, <https://www.rfc-editor.org/info/rfc8281>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing",
RFC8664 8664, DOI 10.17487/RFC8664, 1 December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
Authors' Addresses
Xia Chen
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: jescia.chenxia@huawei.com
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Hang Shi
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: shihang9@huawei.com
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
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