PCE Working Group D. Dhody
Internet-Draft Y. Lee
Intended status: Experimental Huawei Technologies
Expires: August 19, 2019 D. Ceccarelli
Ericsson
February 15, 2019
PCEP Extension for Distribution of Link-State and TE Information.
draft-dhodylee-pce-pcep-ls-13
Abstract
In order to compute and provide optimal paths, Path Computation
Elements (PCEs) require an accurate and timely Traffic Engineering
Database (TED). Traditionally this TED has been obtained from a link
state (LS) routing protocol supporting traffic engineering
extensions.
This document extends the Path Computation Element Communication
Protocol (PCEP) with Link-State and TE Information.
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.
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 August 19, 2019.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Requirements for PCEP extension . . . . . . . . . . . . . . . 6
5. New Functions to distribute link-state (and TE) via PCEP . . 7
6. Overview of Extension to PCEP . . . . . . . . . . . . . . . . 7
6.1. New Messages . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Capability Advertisement . . . . . . . . . . . . . . . . 8
6.3. Initial Link-State (and TE) Synchronization . . . . . . . 8
6.3.1. Optimizations for LS Synchronization . . . . . . . . 11
6.4. LS Report . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. LS Report Message . . . . . . . . . . . . . . . . . . . . 12
8.2. The PCErr Message . . . . . . . . . . . . . . . . . . . . 12
9. Objects and TLV . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . 13
9.2. Open Object . . . . . . . . . . . . . . . . . . . . . . . 13
9.2.1. LS Capability TLV . . . . . . . . . . . . . . . . . . 13
9.3. LS Object . . . . . . . . . . . . . . . . . . . . . . . . 14
9.3.1. Routing Universe TLV . . . . . . . . . . . . . . . . 16
9.3.2. Route Distinguisher TLV . . . . . . . . . . . . . . . 17
9.3.3. Virtual Network TLV . . . . . . . . . . . . . . . . . 17
9.3.4. Local Node Descriptors TLV . . . . . . . . . . . . . 17
9.3.5. Remote Node Descriptors TLV . . . . . . . . . . . . . 18
9.3.6. Node Descriptors Sub-TLVs . . . . . . . . . . . . . . 19
9.3.7. Link Descriptors TLV . . . . . . . . . . . . . . . . 19
9.3.8. Prefix Descriptors TLV . . . . . . . . . . . . . . . 21
9.3.9. PCEP-LS Attributes . . . . . . . . . . . . . . . . . 21
9.3.9.1. Node Attributes TLV . . . . . . . . . . . . . . . 22
9.3.9.2. Link Attributes TLV . . . . . . . . . . . . . . . 22
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9.3.9.3. Prefix Attributes TLV . . . . . . . . . . . . . . 24
9.3.10. Removal of an Attribute . . . . . . . . . . . . . . . 25
10. Other Considerations . . . . . . . . . . . . . . . . . . . . 25
10.1. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . 25
11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
12. Manageability Considerations . . . . . . . . . . . . . . . . 26
12.1. Control of Function and Policy . . . . . . . . . . . . . 26
12.2. Information and Data Models . . . . . . . . . . . . . . 26
12.3. Liveness Detection and Monitoring . . . . . . . . . . . 27
12.4. Verify Correct Operations . . . . . . . . . . . . . . . 27
12.5. Requirements On Other Protocols . . . . . . . . . . . . 27
12.6. Impact On Network Operations . . . . . . . . . . . . . . 27
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
13.1. PCEP Messages . . . . . . . . . . . . . . . . . . . . . 27
13.2. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 28
13.3. LS Object . . . . . . . . . . . . . . . . . . . . . . . 28
13.4. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 29
13.5. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 29
13.6. PCEP-LS Sub-TLV Type Indicators . . . . . . . . . . . . 30
14. TLV Code Points Summary . . . . . . . . . . . . . . . . . . . 32
15. Implementation Status . . . . . . . . . . . . . . . . . . . . 33
15.1. Hierarchical Transport PCE controllers . . . . . . . . . 33
15.2. ONOS-based Controller (MDSC and PNC) . . . . . . . . . . 33
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 34
17.1. Normative References . . . . . . . . . . . . . . . . . . 34
17.2. Informative References . . . . . . . . . . . . . . . . . 35
Appendix A. Reusing BGP-LS codepoints . . . . . . . . . . . . . 38
Appendix B. Relevant OSPF TLV and sub-TLV . . . . . . . . . . . 38
Appendix C. Examples . . . . . . . . . . . . . . . . . . . . . . 39
C.1. All Nodes . . . . . . . . . . . . . . . . . . . . . . . . 39
C.2. Designated Node . . . . . . . . . . . . . . . . . . . . . 41
C.3. Between PCEs . . . . . . . . . . . . . . . . . . . . . . 41
Appendix D. Contributor Addresses . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43
1. Introduction
In Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS),
a Traffic Engineering Database (TED) is used in computing paths for
connection oriented packet services and for circuits. The TED
contains all relevant information that a Path Computation Element
(PCE) needs to perform its computations. It is important that the
TED be complete and accurate each time, the PCE performs a path
computation.
In MPLS and GMPLS, interior gateway routing protocols (IGPs) have
been used to create and maintain a copy of the TED at each node
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running the IGP. One of the benefits of the PCE architecture
[RFC4655] is the use of computationally more sophisticated path
computation algorithms and the realization that these may need
enhanced processing power not necessarily available at each node
participating in an IGP.
Section 4.3 of [RFC4655] describes the potential load of the TED on a
network node and proposes an architecture where the TED is maintained
by the PCE rather than the network nodes. However, it does not
describe how a PCE would obtain the information needed to populate
its TED. PCE may construct its TED by participating in the IGP
([RFC3630] and [RFC5305] for MPLS-TE; [RFC4203] and [RFC5307] for
GMPLS). An alternative is offered by BGP-LS [RFC7752] .
[RFC8231] describes a set of extensions to PCEP to provide stateful
control. A stateful PCE has access to not only the information
carried by the network's Interior Gateway Protocol (IGP), but also
the set of active paths and their reserved resources for its
computations. PCC can delegate the rights to modify the LSP
parameters to an Active Stateful PCE. This requires PCE to quickly
be updated on any changes in the Topology and TEDB, so that PCE can
meet the need for updating LSPs effectively and in a timely manner.
The fastest way for a PCE to be updated on TED changes is via a
direct interface with each network node and with incremental update
from each network node with only the attribute that is modified.
[RFC8281] describes the setup, maintenance and teardown of PCE-
initiated LSPs under the stateful PCE model, without the need for
local configuration on the PCC, thus allowing for a dynamic network
that is centrally controlled and deployed. This model requires
timely topology and TED update at the PCE.
[RFC5440] describes the specifications for the Path Computation
Element Communication Protocol (PCEP). PCEP specifies the
communication between a Path Computation Client (PCC) and a Path
Computation Element (PCE), or between two PCEs based on the PCE
architecture [RFC4655].
This document describes a mechanism by which Link State and TE
information can be collected from networks and shared with PCE using
the PCEP itself. This is achieved using a new PCEP message format.
The mechanism is applicable to physical and virtual links as well as
further subjected to various policies.
A network node maintains one or more databases for storing link-state
and TE information about nodes and links in any given area. Link
attributes stored in these databases include: local/remote IP
addresses, local/ remote interface identifiers, link metric and TE
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metric, link bandwidth, reservable bandwidth, per CoS class
reservation state, preemption and Shared Risk Link Groups (SRLG).
The node's PCEP process can retrieve topology from these databases
and distribute it to a PCE, either directly or via another PCEP
Speaker, using the encoding specified in this document.
Further [RFC6805] describes Hierarchical-PCE architecture, where a
parent PCE maintains a domain topology map. To build this domain
topology map, the child PCE can carry the border nodes and inter-
domain link information to the parent PCE using the mechanism
described in this document. Further as described in
[I-D.ietf-pce-applicability-actn], the child PCE can also transport
abstract Link-State and TE information from child PCE to a Parent PCE
using the mechanism described in this document to build an abstract
topology at the parent PCE.
[RFC8231] describe LSP state synchronization between PCCs and PCEs in
case of stateful PCE. This document does not make any change to the
LSP state synchronization process. The mechanism described in this
document are on top of the existing LSP state synchronization.
2. Terminology
The terminology is as per [RFC4655] and [RFC5440].
3. Applicability
The mechanism specified in this draft is applicable to deployments:
o Where there is no IGP or BGP-LS running in the network.
o Where there is no IGP or BGP-LS running at the PCE to learn link-
state and TE information.
o Where there is IGP or BGP-LS running but with a need for a faster
and direct TE and link-state population and convergence at the
PCE.
* A PCE may receive partial information (say basic TE, link-
state) from IGP and other information (optical and impairment)
from PCEP.
* A PCE may receive an incremental update (as opposed to the
entire information of the node/link).
* A PCE may receive full information from both existing mechanism
(IGP or BGP) and PCEP.
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o Where there is a need for transporting (abstract) Link-State and
TE information from child PCE to a Parent PCE in H-PCE [RFC6805];
as well as for Provisioning Network Controller (PNC) to Multi-
Domain Service Coordinator (MDSC) in Abstraction and Control of TE
Networks (ACTN) [RFC8453].
o Where there is an existing PCEP session between all the nodes and
the PCE-based central controller (PCECC) [RFC8283], and the
operator would like to use PCEP as a direct south bound interface
to the all the nodes in the network. This enables operator to use
PCEP as single direct protocol between the controller and all the
nodes in the network. In this mode all nodes send the only local
information.
Based on the local policy and deployment scenario, a PCC chooses to
send only local information or both local and remote learned
information.
How a PCE manages the link-state (and TE) information is
implementation specific and thus out of scope of this document.
The prefix information in PCEP-LS can also help in determining the
domain of the endpoints in H-PCE (and ACTN). Section 4.5 of
[RFC6805] describe various mechanism and procedures that might be
used, PCEP-LS provides a simple mechanism to exchange this
information within PCEP. [RFC8453] defines three types of topology
abstraction - (1) Native/White Topology; (2) Black Topology; and (3)
Grey Topology. Based on the local policy, the PNC (or child PCE)
would share the domain topology to the MDSC (or Parent PCE) based on
the abstraction type. The protocol extention defined in this
document can carry any type of topology abstraction.
4. Requirements for PCEP extension
Following key requirements associated with link-state (and TE)
distribution are identified for PCEP:
1. The PCEP speaker supporting this draft MUST be a mechanism to
advertise the Link-State (and TE) distribution capability.
2. PCC supporting this draft MUST have the capability to report the
link-state (and TE) information to the PCE. This MUST includes
self originated information and also allow remote information
learned via routing protocols. PCC MUST be capable to do the
initial bulk sync at the time of session initialization as well
as changes after.
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3. A PCE MAY learn link-state (and TE) from PCEP as well as from
existing mechanism like IGP/BGP-LS. PCEP extension MUST have a
mechanism to link the information learned via other means. There
MUST NOT be any changes to the existing link-state (and TE)
population mechanism via IGP/BGP-LS. PCEP extension SHOULD keep
the properties in a protocol (IGP or BGP-LS) neutral way, such
that an implementation may not need to know about any OSPF or IS-
IS or BGP protocol specifics.
4. It SHOULD be possible to encode only the changes in link-state
(and TE) properties (after the initial sync) in PCEP messages.
This leads to faster convergance.
5. The same mechanism should be used for both MPLS TE as well as
GMPLS, optical and impairment aware properties.
6. The same mechanism should be used for PCE to PCE Link-state (and
TE) synchronization.
5. New Functions to distribute link-state (and TE) via PCEP
Several new functions are required in PCEP to support distribution of
link-state (and TE) information. A function can be initiated either
from a PCC towards a PCE (C-E) or from a PCE towards a PCC (E-C).
The new functions are:
o Capability advertisement (E-C,C-E): both the PCC and the PCE MUST
announce during PCEP session establishment that they support PCEP
extensions for distribution of link-state (and TE) information
defined in this document.
o Link-State (and TE) synchronization (C-E): after the session
between the PCC and a PCE is initialized, the PCE must learn Link-
State (and TE) information before it can perform path
computations. In case of stateful PCE it is RECOMENDED that this
operation be done before LSP state synchronization.
o Link-State (and TE) Report (C-E): a PCC sends a LS (and TE) report
to a PCE whenever the Link-State and TE information changes.
6. Overview of Extension to PCEP
6.1. New Messages
In this document, we define a new PCEP messages called LS Report
(LSRpt), a PCEP message sent by a PCC to a PCE to report link-state
(and TE) information. Each LS Report in a LSRpt message can contain
the node or link properties. An unique PCEP specific LS identifier
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(LS-ID) is also carried in the message to identify a node or link and
that remains constant for the lifetime of a PCEP session. This
identifier on its own is sufficient when no IGP or BGP-LS running in
the network for PCE to learn link-state (and TE) information. Incase
PCE learns some information from PCEP and some from the existing
mechanism, the PCC SHOULD include the mapping of IGP or BGP-LS
identifier to map the information populated via PCEP with IGP/BGP-LS.
See Section 8.1 for details.
6.2. Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
advertise their support of LS (and TE) distribution via PCEP
extensions. A PCEP Speaker includes the "LS Capability" TLV,
described in Section 9.2.1, in the OPEN Object to advertise its
support for PCEP-LS extensions. The presence of the LS Capability
TLV in PCC's OPEN Object indicates that the PCC is willing to send LS
Reports whenever local link-state (and TE) information changes. The
presence of the LS Capability TLV in PCE's OPEN message indicates
that the PCE is interested in receiving LS Reports whenever local
link-state (and TE) information changes.
The PCEP extensions for LS (and TE) distribution MUST NOT be used if
one or both PCEP Speakers have not included the LS Capability TLV in
their respective OPEN message. If the PCE that supports the
extensions of this draft but did not advertise this capability, then
upon receipt of a LSRpt message from the PCC, it SHOULD generate a
PCErr with error-type 19 (Invalid Operation), error-value TBD1
(Attempted LS Report if LS capability was not advertised) and it will
terminate the PCEP session.
The LS reports sent by PCC MAY carry the remote link-state (and TE)
information learned via existing means like IGP and BGP-LS only if
both PCEP Speakers set the R (remote) Flag in the "LS Capability" TLV
to 'Remote Allowed (R Flag = 1)'. If this is not the case and LS
reports carry remote link-state (and TE) information, then a PCErr
with error-type 19 (Invalid Operation) and error-value TBD1
(Attempted LS Report if LS remote capability was not advertised) and
it will terminate the PCEP session.
6.3. Initial Link-State (and TE) Synchronization
The purpose of LS Synchronization is to provide a checkpoint-in- time
state replica of a PCC's link-state (and TE) data base in a PCE.
State Synchronization is performed immediately after the
Initialization phase (see [RFC5440]). In case of stateful PCE
([RFC8231]) it is RECOMENDED that the LS synchronization should be
done before LSP state synchronization.
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During LS Synchronization, a PCC first takes a snapshot of the state
of its database, then sends the snapshot to a PCE in a sequence of LS
Reports. Each LS Report sent during LS Synchronization has the SYNC
Flag in the LS Object set to 1. The end of synchronization marker is
a LSRpt message with the SYNC Flag set to 0 for an LS Object with LS-
ID equal to the reserved value 0. If the PCC has no link-state to
synchronize, it will only send the end of synchronization marker.
Either the PCE or the PCC MAY terminate the session using the PCEP
session termination procedures during the synchronization phase. If
the session is terminated, the PCE MUST clean up state it received
from this PCC. The session re-establishment MUST be re-attempted per
the procedures defined in [RFC5440], including use of a back-off
timer.
If the PCC encounters a problem which prevents it from completing the
LS synchronization, it MUST send a PCErr message with error-type TBD2
(LS Synchronization Error) and error-value 2 (indicating an internal
PCC error) to the PCE and terminate the session.
The PCE does not send positive acknowledgments for properly received
LS synchronization messages. It MUST respond with a PCErr message
with error-type TBD2 (LS Synchronization Error) and error-value 1
(indicating an error in processing the LSRpt) if it encounters a
problem with the LS Report it received from the PCC and it MUST
terminate the session.
The LS reports can carry local as well as remote link-state (and TE)
information depending on the R flag in LS capability TLV.
The successful LS Synchronization sequences is shown in Figure 1.
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+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----LSRpt, SYNC=1----->| (Sync start)
| |
|-----LSRpt, SYNC=1----->|
| . |
| . |
| . |
|-----LSRpt, SYNC=1----->|
| . |
| . |
| . |
| |
|-----LSRpt, SYNC=0----->| (End of sync marker
| | LS Report
| | for LS-ID=0)
| | (Sync done)
Figure 1: Successful LS synchronization
The sequence where the PCE fails during the LS Synchronization phase
is shown in Figure 2.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----LSRpt, SYNC=1----->|
| |
|-----LSRpt, SYNC=1----->|
| . |
| . |
| . |
|-----LSRpt, SYNC=1----->|
| |
|---LSRpt,SYNC=1 |
| \ ,-PCErr---|
| \ / |
| \/ |
| /\ |
| / `-------->| (Ignored)
|<--------` |
Figure 2: Failed LS synchronization (PCE failure)
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The sequence where the PCC fails during the LS Synchronization phase
is shown in Figure 3.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
|-----LSRpt, SYNC=1----->|
| |
|-----LSRpt, SYNC=1----->|
| . |
| . |
| . |
|-------- PCErr--------->|
| |
Figure 3: Failed LS synchronization (PCC failure)
6.3.1. Optimizations for LS Synchronization
These optimizations are described in
[I-D.kondreddy-pce-pcep-ls-sync-optimizations].
6.4. LS Report
The PCC MUST report any changes in the link-state (and TE)
information to the PCE by sending a LS Report carried on a LSRpt
message to the PCE. Each node and Link would be uniquely identified
by a PCEP LS identifier (LS-ID). The LS reports may carry local as
well as remote link-state (and TE) information depending on the R
flag in LS capability TLV. In case R flag is set, It MAY also
include the mapping of IGP or BGP-LS identifier to map the
information populated via PCEP with IGP/BGP-LS.
More details about LSRpt message are in Section 8.1.
7. Transport
A permanent PCEP session MUST be established between a PCE and PCC
supporting link-state (and TE) distribution via PCEP. In the case of
session failure, session re-establishment MUST be re-attempted per
the procedures defined in [RFC5440].
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8. PCEP Messages
As defined in [RFC5440], a PCEP message consists of a common header
followed by a variable-length body made of a set of objects that can
be either mandatory or optional. An object is said to be mandatory
in a PCEP message when the object must be included for the message to
be considered valid. For each PCEP message type, a set of rules is
defined that specify the set of objects that the message can carry.
An implementation MUST form the PCEP messages using the object
ordering specified in this document.
8.1. LS Report Message
A PCEP LS Report message (also referred to as LSRpt message) is a
PCEP message sent by a PCC to a PCE to report the link-state (and TE)
information. A LSRpt message can carry more than one LS Reports.
The Message-Type field of the PCEP common header for the LSRpt
message is set to [TBD3].
The format of the LSRpt message is as follows:
<LSRpt Message> ::= <Common Header>
<ls-report-list>
Where:
<ls-report-list> ::= <LS>[<ls-report-list>]
The LS object is a mandatory object which carries LS information of a
node or a link. Each LS object has an unique LS-ID as described in
Section 9.3. If the LS object is missing, the receiving PCE MUST
send a PCErr message with Error-type=6 (Mandatory Object missing) and
Error-value=[TBD4] (LS object missing).
A PCE may choose to implement a limit on the LS information a single
PCC can populate. If a LSRpt is received that causes the PCE to
exceed this limit, it MUST send a PCErr message with error-type 19
(invalid operation) and error-value 4 (indicating resource limit
exceeded) in response to the LSRpt message triggering this condition
and SHOULD terminate the session.
8.2. The PCErr Message
If a PCEP speaker has advertised the LS capability on the PCEP
session, the PCErr message MAY include the LS object. If the error
reported is the result of an LS report, then the LS-ID number MUST be
the one from the LSRpt that triggered the error.
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The format of a PCErr message from [RFC5440] is extended as follows:
The format of the PCErr message is as follows:
<PCErr Message> ::= <Common Header>
( <error-obj-list> [<Open>] ) | <error>
[<error-list>]
<error-obj-list>::=<PCEP-ERROR>[<error-obj-list>]
<error>::=[<request-id-list> | <ls-id-list>]
<error-obj-list>
<request-id-list>::=<RP>[<request-id-list>]
<ls-id-list>::=<LS>[<ls-id-list>]
<error-list>::=<error>[<error-list>]
9. Objects and TLV
The PCEP objects defined in this document are compliant with the PCEP
object format defined in [RFC5440]. The P flag and the I flag of the
PCEP objects defined in this document MUST always be set to 0 on
transmission and MUST be ignored on receipt since these flags are
exclusively related to path computation requests.
9.1. TLV Format
The TLV and the sub-TLV format (and padding) in this document, is as
per section 7.1 of [RFC5440].
9.2. Open Object
This document defines a new optional TLV for use in the OPEN Object.
9.2.1. LS Capability TLV
The LS-CAPABILITY TLV is an optional TLV for use in the OPEN Object
for link-state (and TE) distribution via PCEP capability
advertisement. Its format is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=[TBD5] | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The type of the TLV is [TBD5] and it has a fixed length of 4 octets.
The value comprises a single field - Flags (32 bits):
o R (remote allowed - 1 bit): if set to 1 by a PCC, the R Flag
indicates that the PCC allows reporting of remote LS information
learned via other means like IGP and BGP-LS; if set to 1 by a PCE,
the R Flag indicates that the PCE is capable of receiving remote
LS information (from the PCC point of view). The R Flag must be
advertised by both a PCC and a PCE for LSRpt messages to report
remote as well as local LS information on a PCEP session. The
TLVs related to IGP/BGP-LS identifier MUST be encoded when both
PCEP speakers have the R Flag set.
Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt.
Advertisement of the LS capability implies support of local link-
state (and TE) distribution, as well as the objects, TLVs and
procedures defined in this document.
9.3. LS Object
The LS (link-state) object MUST be carried within LSRpt messages and
MAY be carried within PCErr messages. The LS object contains a set
of fields used to specify the target node or link. It also contains
a flag indicating to a PCE that the LS synchronization is in
progress. The TLVs used with the LS object correlate with the IGP/
BGP-LS encodings.
LS Object-Class is [TBD6].
Four Object-Type values are defined for the LS object so far:
o LS Node: LS Object-Type is 1.
o LS Link: LS Object-Type is 2.
o LS IPv4 Topology Prefix: LS Object-Type is 3.
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o LS IPv6 Topology Prefix: LS Object-Type is 4.
The format of all types of LS object 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol-ID | Flag |R|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS-ID |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Protocol-ID (8-bit): The field provide the source information. The
protocol could be an IGP, BGP-LS or an abstraction algorithm. Incase
PCC only provides local information of the PCC, it MUST use Protocol-
ID as Direct. The following values are defined (some of them are
same as [RFC7752]):
+-------------+----------------------------------+
| Protocol-ID | Source protocol |
+-------------+----------------------------------+
| 1 | IS-IS Level 1 |
| 2 | IS-IS Level 2 |
| 3 | OSPFv2 |
| 4 | Direct |
| 5 | Static configuration |
| 6 | OSPFv3 |
| 7 | BGP |
| 8 | PCEP |
| 9 | Abstraction |
| 10 | Unspecified |
+-------------+----------------------------------+
Flags (24-bit):
o S (SYNC - 1 bit): the S Flag MUST be set to 1 on each LSRpt sent
from a PCC during LS Synchronization. The S Flag MUST be set to 0
in other LSRpt messages sent from the PCC.
o R (Remove - 1 bit): On LSRpt messages the R Flag indicates that
the node/link/prefix has been removed from the PCC and the PCE
SHOULD remove from its database. Upon receiving an LS Report with
the R Flag set to 1, the PCE SHOULD remove all state for the
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node/link/prefix identified by the LS Identifiers from its
database.
LS-ID(64-bit): A PCEP-specific identifier for the node or link or
prefix information. A PCC creates an unique LS-ID for each
node/link/prefix that is constant for the lifetime of a PCEP session.
The PCC will advertise the same LS-ID on all PCEP sessions it
maintains at a given times. All subsequent PCEP messages then
address the node/link/prefix by the LS-ID. The values of 0 and
0xFFFFFFFFFFFFFFFF are reserved.
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 LS Object are described in the
following sections.
9.3.1. Routing Universe TLV
In case of remote link-state (and TE) population when existing IGP/
BGP-LS are also used, OSPF and IS-IS may run multiple routing
protocol instances over the same link as described in [RFC7752]. See
[RFC8202] and [RFC6549] for more information. These instances define
independent "routing universes". The 64-Bit 'Identifier' field is
used to identify the "routing universe" where the LS object belongs.
The LS objects representing IGP objects (nodes or links or prefix)
from the same routing universe MUST have the same 'Identifier' value;
LS objects with different 'Identifier' values MUST be considered to
be from different routing universes.
The format of the optional ROUTING-UNIVERSE 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=[TBD7] | Length=8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Below table lists the 'Identifier' values that are defined as well-
known in this draft (same as [RFC7752]).
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+------------+-----------------------------------+
| Identifier | Routing Universe |
+------------+-----------------------------------+
| 0 | Default Layer 3 Routing topology |
+------------+-----------------------------------+
If this TLV is not present the default value 0 is assumed.
9.3.2. Route Distinguisher TLV
To allow identification of VPN link, node and prefix information in
PCEP-LS, a Route Distinguisher (RD) [RFC4364] is used. The LS
objects from the same VPN MUST have the same RD; LS objects with
different RD values MUST be considered to be from different VPNs.
The ROUTE-DISTINGUISHER TLV is defined in
[I-D.ietf-pce-pcep-flowspec] as a Flow Specification TLVs with a
seperate registry. This document also adds the ROUTE-DISTINGUISHER
TLV with TBD15 in the PCEP TLV registry to be used inside the LS
object.
9.3.3. Virtual Network TLV
To realize ACTN, the MDSC needs to build an multi-domain topology.
This topology is best served, if this is an abstracted view of the
underlying network resources of each domain. It is also important to
provide a customer view of network slice for each customer. There is
a need to control the level of abstraction based on the deployment
scenario and business relationship between the controllers.
Virtual service coordination function in ACTN incorporates customer
service-related knowledge into the virtual network operations in
order to seamlessly operate virtual networks while meeting customer's
service requirements. [I-D.ietf-teas-actn-requirements] describes
various VN operations initiated by a customer/application. In this
context, there is a need for associating the abstracted link state
and TE topology with a VN "construct" to facilitate VN operations in
PCE architecture.
VIRTUAL-NETWORK-TLV as per [I-D.leedhody-pce-vn-association] can be
included in LS object to identify the link, node and prefix
information belongs to a particular VN.
9.3.4. Local Node Descriptors TLV
As described in [RFC7752], each link is anchored by a pair of Router-
IDs that are used by the underlying IGP, namely, 48 Bit ISO System-ID
for IS-IS and 32 bit Router-ID for OSPFv2 and OSPFv3. Incase of
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additional auxiliary Router-IDs used for TE, these MUST also be
included in the link attribute TLV (see Section 9.3.9.2).
It is desirable that the Router-ID assignments inside the Node
Descriptor are globally unique. Some considerations for globally
unique Node/Link/Prefix identifiers are described in [RFC7752].
The Local Node Descriptors TLV contains Node Descriptors for the node
anchoring the local end of the link. This TLV MUST be included in
the LS Report when during a given PCEP session a node/link/prefix is
first reported to a PCE. A PCC sends to a PCE the first LS Report
either during State Synchronization, or when a new node/link/prefix
is learned at the PCC. The value contains one or more Node
Descriptor Sub-TLVs, which allows specification of a flexible key for
any given node/link/prefix information such that global uniqueness of
the node/link/prefix is ensured.
This TLV is applicable for all LS Object-Type.
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=[TBD8] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value contains one or more Node Descriptor Sub-TLVs defined in
Section 9.3.6.
9.3.5. Remote Node Descriptors TLV
The Remote Node Descriptors contains Node Descriptors for the node
anchoring the remote end of the link. This TLV MUST be included in
the LS Report when during a given PCEP session a link is first
reported to a PCE. A PCC sends to a PCE the first LS Report either
during State Synchronization, or when a new link is learned at the
PCC. The length of this TLV is variable. The value contains one or
more Node Descriptor Sub-TLVs defined in Section 9.3.6.
This TLV is applicable for LS Link Object-Type.
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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=[TBD9] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9.3.6. Node Descriptors Sub-TLVs
The Node Descriptor Sub-TLV type Type and lengths are listed in the
following table:
+----------+-------------------+----------+----------------+
| Sub-TLV | Description | Length |Value defined in|
+----------+-------------------+----------+----------------+
| 0 | Reserved | - | - |
| 1 | Autonomous System | 4 | [RFC7752] |
| 2 | BGP-LS Identifier | 4 | / section |
| 3 | OSPF Area-ID | 4 | 3.2.1.4 |
| 4 | Router-ID | Variable | |
+----------+-------------------+----------+----------------+
The sub-TLV values in Node Descriptor TLVs are defined as follows
(similar to [RFC7752]):
o Autonomous System: opaque value (32 Bit AS Number)
o BGP-LS Identifier: opaque value (32 Bit ID). In conjunction with
ASN, uniquely identifies the BGP-LS domain as described in
[RFC7752]. This sub-TLV is present only if the node implements
BGP-LS and the ID is set by the operator.
o OSPF Area ID: It is used to identify the 32 Bit area to which the
LS object belongs. Area Identifier allows the different LS
objects of the same node to be discriminated.
o Router ID: opaque value. Usage is described in [RFC7752] as IGP
Router ID. In case this is not learned from IGP, it SHOULD
contain the unique router ID, such as TE router ID.
9.3.7. Link Descriptors TLV
The Link Descriptors TLV contains Link Descriptors for each link.
This TLV MUST be included in the LS Report when during a given PCEP
session a link is first reported to a PCE. A PCC sends to a PCE the
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first LS Report either during State Synchronization, or when a new
link is learned at the PCC. The length of this TLV is variable. The
value contains one or more Link Descriptor Sub-TLVs.
The 'Link descriptor' TLVs uniquely identify a link among multiple
parallel links between a pair of anchor routers similar to [RFC7752].
This TLV is applicable for LS Link Object-Type.
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=[TBD10] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Link Descriptor Sub-TLV type and lengths are listed in the
following table:
+-----------+---------------------+---------------+-----------------+
| Sub-TLV | Description | IS-IS TLV | Value defined |
| | | /Sub-TLV | in: |
+-----------+---------------------+---------------+-----------------+
| 6 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| 7 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | |
| 8 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | |
| 9 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | |
| 10 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
| 5 | Multi-Topology | - | [RFC7752]/ |
| | identifier | | 3.2.1.5 |
+-----------+---------------------+---------------+-----------------+
The format and semantics of the 'value' fields in most 'Link
Descriptor' sub-TLVs correspond to the format and semantics of value
fields in IS-IS Extended IS Reachability sub-TLVs, defined in
[RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link
Descriptor' TLVs were originally defined for IS-IS, the TLVs can
carry data sourced either by IS-IS or OSPF or direct.
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The information about a link present in the LSA/LSP originated by the
local node of the link determines the set of sub-TLVs in the Link
Descriptor of the link as described in [RFC7752].
9.3.8. Prefix Descriptors TLV
The Prefix Descriptors TLV contains Prefix Descriptors uniquely
identify an IPv4 or IPv6 Prefix originated by a Node. This TLV MUST
be included in the LS Report when during a given PCEP session a
prefix is first reported to a PCE. A PCC sends to a PCE the first LS
Report either during State Synchronization, or when a new prefix is
learned at the PCC. The length of this TLV is variable.
This TLV is applicable for LS Prefix Object-Types for both IPv4 and
IPv6.
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=[TBD11] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Prefix Descriptor Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The value contains one or more Prefix Descriptor Sub-TLVs defined
below -
+--------------+-----------------------+----------+-----------------+
| TLV Code | Description | Length | Value defined |
| Point | | | in: |
+--------------+-----------------------+----------+-----------------+
| 5 | Multi-Topology | variable | [RFC7752] |
| | Identifier | | /3.2.1.5 |
| 11 | OSPF Route Type | 1 | [RFC7752] |
| | | | /3.2.3.1 |
| 12 | IP Reachability | variable | [RFC7752] |
| | Information | | /3.2.3.2 |
+--------------+-----------------------+----------+-----------------+
9.3.9. PCEP-LS Attributes
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9.3.9.1. Node Attributes TLV
This is an optional attribute that is used to carry node attributes.
This TLV is applicable for LS Node Object-Type.
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=[TBD12] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Node Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Node Attributes Sub-TLV type and lengths are listed in the
following table:
+--------------+-----------------------+----------+-----------------+
| Sub TLV | Description | Length | Value defined |
| | | | in: |
+--------------+-----------------------+----------+-----------------+
| 5 | Multi-Topology | variable | [RFC7752] |
| | Identifier | | /3.2.1.5 |
| 13 | Node Flag Bits | 1 | [RFC7752] |
| | | | /3.3.1.1 |
| 14 | Opaque Node | variable | [RFC7752] |
| | Properties | | /3.3.1.5 |
| 15 | Node Name | variable | [RFC7752] |
| | | | /3.3.1.3 |
| 16 | IS-IS Area Identifier | variable | [RFC7752] |
| | | | /3.3.1.2 |
| 17 | IPv4 Router-ID of | 4 | [RFC5305]/4.3 |
| | Local Node | | |
| 18 | IPv6 Router-ID of | 16 | [RFC6119]/4.1 |
| | Local Node | | |
+--------------+-----------------------+----------+-----------------+
9.3.9.2. Link Attributes TLV
This TLV is applicable for LS Link Object-Type. The format and
semantics of the 'value' fields in some 'Link Attribute' sub-TLVs
correspond to the format and semantics of value fields in IS-IS
Extended IS Reachability sub-TLVs, defined in [RFC5305], [RFC5307]
and [RFC7752]. Although the encodings for 'Link Attribute' TLVs were
originally defined for IS-IS, the TLVs can carry data sourced either
by IS-IS or OSPF or direct.
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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=[TBD13] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following 'Link Attribute' sub-TLVs are valid :
+-----------+---------------------+--------------+------------------+
| Sub-TLV | Description | IS-IS TLV | Defined in: |
| | | /Sub-TLV | |
| | | BGP-LS TLV | |
+-----------+---------------------+--------------+------------------+
| 17 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Local Node | | |
| 18 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Local Node | | |
| 19 | IPv4 Router-ID of | 134/--- | [RFC5305]/4.3 |
| | Remote Node | | |
| 20 | IPv6 Router-ID of | 140/--- | [RFC6119]/4.1 |
| | Remote Node | | |
| 6 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| 22 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | |
| 23 | Maximum link | 22/9 | [RFC5305]/3.3 |
| | bandwidth | | |
| 24 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | |
| 25 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | |
| 26 | TE Default Metric | 22/18 | [RFC7752] |
| | | | /3.3.2.3 |
| 27 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | |
| 28 | MPLS Protocol Mask | 1094 | [RFC7752] |
| | | | /3.3.2.2 |
| 29 | IGP Metric | 1095 | [RFC7752] |
| | | | /3.3.2.4 |
| 30 | Shared Risk Link | 1096 | [RFC7752] |
| | Group | | /3.3.2.5 |
| 31 | Opaque link | 1097 | [RFC7752] |
| | attributes | | /3.3.2.6 |
| 32 | Link Name attribute | 1098 | [RFC7752] |
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| | | | /3.3.2.7 |
| 33 | Unidirectional | 22/33 | [RFC7810]/4.1 |
| | Link Delay | | |
| 34 | Min/Max | 22/34 | [RFC7810]/4.2 |
| | Unidirectional Link | | |
| | Delay | | |
| 35 | Unidirectional | 22/35 | [RFC7810]/4.3 |
| | Delay Variation | | |
| 36 | Unidirectional | 22/36 | [RFC7810]/4.4 |
| | Link Loss | | |
| 37 | Unidirectional | 22/37 | [RFC7810]/4.5 |
| | Residual Bandwidth | | |
| 38 | Unidirectional | 22/38 | [RFC7810]/4.6 |
| | Available Bandwidth | | |
| 39 | Unidirectional | 22/39 | [RFC7810]/4.7 |
| | Bandwidth | | |
| | Utilization | | |
| 40 | Extended Admin | 22/14 | [RFC7308]/2.1 |
| | Group (EAG) | | |
+-----------+---------------------+--------------+------------------+
9.3.9.3. Prefix Attributes TLV
This TLV is applicable for LS Prefix Object-Types for both IPv4 and
IPv6. Prefixes are learned from the IGP (IS-IS or OSPF) or BGP
topology with a set of IGP attributes (such as metric, route tags,
etc.). This section describes the different attributes related to
the IPv4/IPv6 prefixes. Prefix Attributes TLVs SHOULD be encoded in
the LS Prefix Object.
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=[TBD14] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Prefix Attributes Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following 'Prefix Attribute' sub-TLVs are valid :
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+-----------+---------------------+--------------+------------------+
| Sub-TLV | Description | BGP-LS TLV | Defined in: |
+-----------+---------------------+--------------+------------------+
| 41 | IGP Flags | 1152 | [RFC7752] |
| | | | /3.3.3.1 |
| 42 | Route Tag | 1153 | [RFC7752] |
| | | | /3.3.3.2 |
| 43 | Extended Tag | 1154 | [RFC7752] |
| | | | /3.3.3.3 |
| 44 | Prefix Metric | 1155 | [RFC7752] |
| | | | /3.3.3.4 |
| 45 | OSPF Forwarding | 1156 | [RFC7752] |
| | Address | | /3.3.3.5 |
| 46 | Opaque Prefix | 1157 | [RFC7752] |
| | Attribute | | /3.3.3.6 |
+-----------+---------------------+--------------+------------------+
9.3.10. Removal of an Attribute
One of a key objective of PCEP-LS is to encode and carry only the
impacted attributes of a Node, a Link or a Prefix. To accommodate
this requirement, incase of a removal of an attribute, the sub-TLV
MUST be included with no 'value' field and length=0 to indicate that
the attribute is removed. On receiving a sub-TLV with zero length,
the receiver removes the attribute from the database.
10. Other Considerations
10.1. Inter-AS Links
The main source of LS (and TE) information is the IGP, which is not
active on inter-AS links. In some cases, the IGP may have
information of inter-AS links ([RFC5392], [RFC5316]). In other
cases, an implementation SHOULD provide a means to inject inter-AS
links into PCEP. The exact mechanism used to provision the inter-AS
links is outside the scope of this document.
11. Security Considerations
This document extends PCEP for LS (and TE) distribution including a
new LSRpt message with new object and TLVs. Procedures and protocol
extensions defined in this document do not effect the overall PCEP
security model. See [RFC5440], [RFC8253]. Tampering with the LSRpt
message may have an effect on path computations at PCE. It also
provides adversaries an opportunity to eavesdrop and learn sensitive
information and plan sophisticated attacks on the network
infrastructure. The PCE implementation SHOULD provide mechanisms to
prevent strains created by network flaps and amount of LS (and TE)
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information. Thus it is suggested that any mechanism used for
securing the transmission of other PCEP message be applied here as
well. As a general precaution, it is RECOMMENDED that these PCEP
extensions only be activated on authenticated and encrypted sessions
belonging to the same administrative authority.
Further, as stated in [RFC6952], PCEP implementations SHOULD support
the TCP-AO [RFC5925] and not use TCP MD5 because of TCP MD5's known
vulnerabilities and weakness. PCEP also support Transport Layer
Security (TLS) [RFC8253] as per the recommendations and best current
practices in [RFC7525].
12. Manageability Considerations
All manageability requirements and considerations listed in [RFC5440]
apply to PCEP protocol extensions defined in this document. In
addition, requirements and considerations listed in this section
apply.
12.1. Control of Function and Policy
A PCE or PCC implementation MUST allow configuring the PCEP-LS
capabilities as described in this document.
A PCC implementation SHOULD allow configuration to suggest if remote
information learned via routing protocols should be reported or not.
An implementation SHOULD allow the operator to specify the maximum
number of LS data to be reported.
An implementation SHOULD also allow the operator to create abstracted
topologies that are reported to the peers and create different
abstractions for different peers.
An implementation SHOULD allow the operator to configure a 64-bit
Instance-ID for Routing Universe TLV.
12.2. Information and Data Models
An implementation SHOULD allow the operator to view the LS
capabilities advertised by each peer. To serve this purpose, the
PCEP YANG module [I-D.ietf-pce-pcep-yang]" can be extended to include
advertised capabilities.
An implementation SHOULD also provide the statistics:
o Total number of LSRpt sent/received, as well as per neighbor
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o Number of error received for LSRpt, per neighbor
o Total number of locally originated Link-State Information
These statistics should be recorded as absolute counts since system
or session start time. An implementation MAY also enhance this
information by recording peak per-second counts in each case.
An operator SHOULD define an import policy to limit inbound LSRpt to
"drop all LSRpt from a particular peers" as well provide means to
limit inbound LSRpts.
12.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440]".
12.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440] .
12.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
12.6. Impact On Network Operations
Mechanisms defined in this document do not have any impact on network
operations in addition to those already listed in [RFC5440].
13. IANA Considerations
This document requests IANA actions to allocate code points for the
protocol elements defined in this document.
13.1. PCEP Messages
IANA created a registry for PCEP messages. Each PCEP message has a
message type value. This document defines a new PCEP message value.
Value Meaning Reference
TBD3 LSRpt [This I-D]
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13.2. PCEP Objects
This document defines the following new PCEP Object-classes and
Object-values:
Object-Class Value Name Reference
TBD6 LS Object [This I-D]
Object-Type=1
(LS Node)
Object-Type=2
(LS Link)
Object-Type=3
(LS IPv4 Prefix)
Object-Type=4
(LS IPv6 Prefix)
13.3. LS Object
This document requests that a new sub-registry, named "LS Object
Protocol-ID Field", is created within the "Path Computation Element
Protocol (PCEP) Numbers" registry to manage the Flag field of the LSP
object. New values are to be assigned by Standards Action [RFC8126].
Value Meaning Reference
0 Reserved [This I-D]
1 IS-IS Level 1 [This I-D]
2 IS-IS Level 2 [This I-D]
3 OSPFv2 [This I-D]
4 Direct [This I-D]
5 Static configuration [This I-D]
6 OSPFv3 [This I-D]
7 BGP-LS [This I-D]
8 PCEP-LS [This I-D]
9 Abstraction [This I-D]
10 Unspecified [This I-D]
Further, this document also requests that a new sub-registry, named
"LS Object Flag Field", is created within the "Path Computation
Element Protocol (PCEP) Numbers" registry to manage the Flag field of
the LSP object.New values are to be assigned by Standards Action
[RFC8126]. Each bit should be tracked with the following qualities:
o Bit number (counting from bit 0 as the most significant bit)
o Capability description
o Defining RFC
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The following values are defined in this document:
Bit Description Reference
0-21 Unassigned
22 R (Remove bit) [This I-D]
23 S (Sync bit) [This I-D]
13.4. PCEP-Error Object
IANA is requested to make the following allocation in the "PCEP-ERROR
Object Error Types and Values" registry.
Error-Type Meaning Reference
6 Mandatory Object missing [RFC5440]
Error-Value=TBD4 [This I-D]
(LS object missing)
19 Invalid Operation [RFC8231]
Error-Value=TBD1 [This I-D]
(Attempted LS Report if LS
remote capability was not
advertised)
TBD2 LS Synchronization Error [This I-D]
Error-Value=1
(An error in processing the
LSRpt)
Error-Value=2
(An internal PCC error)
13.5. PCEP TLV Type Indicators
This document defines the following new PCEP TLVs.
Value Meaning Reference
TBD5 LS-CAPABILITY TLV [This I-D]
TBD7 ROUTING-UNIVERSE TLV [This I-D]
TBD15 ROUTE-DISTINGUISHER TLV [This I-D]
TBD8 Local Node Descriptors TLV [This I-D]
TBD9 Remote Node Descriptors TLV [This I-D]
TBD10 Link Descriptors TLV [This I-D]
TBD11 Prefix Descriptors TLV [This I-D]
TBD12 Node Attributes TLV [This I-D]
TBD13 Link Attributes TLV [This I-D]
TBD14 Prefix Attributes TLV [This I-D]
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13.6. PCEP-LS Sub-TLV Type Indicators
This document specifies the PCEP-LS Sub-TLVs. IANA is requested to
create an "PCEP-LS Sub-TLV Types" sub-registry in the "PCEP TLV Type
Indicators" for the sub-TLVs carried in the PCEP-LS TLV (Local and
Remote Node Descriptors TLV, Link Descriptors TLV, Prefix Descriptors
TLV, Node Attributes TLV, Link Attributes TLV and Prefix Attributes
TLV. This document defines the following types:
+-----------+---------------------+---------------+-----------------+
| Sub-TLV | Description | Ref | Value defined |
| | | Sub-TLV | in: |
+-----------+---------------------+---------------+-----------------+
| 1 | Autonomous System | 512 | [RFC7752] |
| | | | /3.2.1.4 |
| 2 | BGP-LS Identifier | 513 | [RFC7752] |
| | | | /3.2.1.4 |
| 3 | OSPF Area-ID | 514 | [RFC7752] |
| | | | /3.2.1.4 |
| 4 | Router-ID | 515 | [RFC7752] |
| | | | /3.2.1.4 |
| 5 | Multi-Topology-ID | 263 | [RFC7752] |
| | | | /3.2.1.5 |
| 6 | Link Local/Remote | 22/4 | [RFC5307]/1.1 |
| | Identifiers | | |
| 7 | IPv4 interface | 22/6 | [RFC5305]/3.2 |
| | address | | |
| 8 | IPv4 neighbor | 22/8 | [RFC5305]/3.3 |
| | address | | |
| 9 | IPv6 interface | 22/12 | [RFC6119]/4.2 |
| | address | | |
| 10 | IPv6 neighbor | 22/13 | [RFC6119]/4.3 |
| | address | | |
| 11 | OSPF Route Type | 264 | [RFC7752] |
| | | | /3.2.3.1 |
| 12 | IP Reachability | 265 | [RFC7752] |
| | Information | | /3.2.3.2 |
| 13 | Node Flag Bits | 1024 | [RFC7752] |
| | | | /3.3.1.1 |
| 14 | Opaque Node | 1025 | [RFC7752] |
| | Properties | | /3.3.1.5 |
| 15 | Node Name | 1026 | [RFC7752] |
| | | | /3.3.1.3 |
| 16 | IS-IS Area | 1027 | [RFC7752] |
| | Identifier | | /3.3.1.2 |
| 17 | IPv4 Router-ID of | 134/-- | [RFC5305]/4.3 |
| | Local Node | | |
| 18 | IPv6 Router-ID of | 140/-- | [RFC6119]/4.1 |
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| | Local Node | | |
| 19 | IPv4 Router-ID of | 134/-- | [RFC5305]/4.3 |
| | Remote Node | | |
| 20 | IPv6 Router-ID of | 140/-- | [RFC6119]/4.1 |
| | Remote Node | | |
| 22 | Administrative | 22/3 | [RFC5305]/3.1 |
| | group (color) | | |
| 23 | Maximum link | 22/9 | [RFC5305]/3.3 |
| | bandwidth | | |
| 24 | Max. reservable | 22/10 | [RFC5305]/3.5 |
| | link bandwidth | | |
| 25 | Unreserved | 22/11 | [RFC5305]/3.6 |
| | bandwidth | | |
| 26 | TE Default Metric | 22/18 | [RFC7752] |
| | | | /3.3.2.3 |
| 27 | Link Protection | 22/20 | [RFC5307]/1.2 |
| | Type | | |
| 28 | MPLS Protocol Mask | 1094 | [RFC7752] |
| | | | /3.3.2.2 |
| 29 | IGP Metric | 1095 | [RFC7752] |
| | | | /3.3.2.4 |
| 30 | Shared Risk Link | 1096 | [RFC7752] |
| | Group | | /3.3.2.5 |
| 31 | Opaque link | 1097 | [RFC7752] |
| | attributes | | /3.3.2.6 |
| 32 | Link Name attribute | 1098 | [RFC7752] |
| | | | /3.3.2.7 |
| 33 | Unidirectional | 22/33 | [RFC7810]/4.1 |
| | Link Delay | | |
| 34 | Min/Max | 22/34 | [RFC7810]/4.2 |
| | Unidirectional Link | | |
| | Delay | | |
| 35 | Unidirectional | 22/35 | [RFC7810]/4.3 |
| | Delay Variation | | |
| 36 | Unidirectional | 22/36 | [RFC7810]/4.4 |
| | Link Loss | | |
| 37 | Unidirectional | 22/37 | [RFC7810]/4.5 |
| | Residual Bandwidth | | |
| 38 | Unidirectional | 22/38 | [RFC7810]/4.6 |
| | Available Bandwidth | | |
| 39 | Unidirectional | 22/39 | [RFC7810]/4.7 |
| | Bandwidth | | |
| | Utilization | | |
| 40 | Extended Admin | 22/14 | [RFC7308]/2.1 |
| | Group (EAG) | | |
| 41 | IGP Flags | 1152 | [RFC7752] |
| | | | /3.3.3.1 |
| 42 | Route Tag | 1153 | [RFC7752] |
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| | | | /3.3.3.2 |
| 43 | Extended Tag | 1154 | [RFC7752] |
| | | | /3.3.3.3 |
| 44 | Prefix Metric | 1155 | [RFC7752] |
| | | | /3.3.3.4 |
| 45 | OSPF Forwarding | 1156 | [RFC7752] |
| | Address | | /3.3.3.5 |
| 46 | Opaque Prefix | 1157 | [RFC7752] |
| | Attribute | | /3.3.3.6 |
+-----------+---------------------+---------------+-----------------+
New values are to be assigned by Standards Action [RFC8126].
14. TLV Code Points Summary
This section contains the global table of all TLVs in LS object
defined in this document.
+-----------+---------------------+---------------+-----------------+
| TLV | Description | Ref TLV | Value defined |
| | | | in: |
+-----------+---------------------+---------------+-----------------+
| TBD7 | Routing Universe | -- | Sec 9.2.1 |
| TBD15 | Route | -- | Sec 9.2.2 |
| | Distinguisher | | |
| * | Virtual Network | -- | [leedhody-pce- |
| | | | vn-association] |
| TBD8 | Local Node | 256 | [RFC7752] |
| | Descriptors | | /3.2.1.2 |
| TBD9 | Remote Node | 257 | [RFC7752] |
| | Descriptors | | /3.2.1.3 |
| TBD10 | Link Descriptors | -- | Sec 9.2.8 |
| TBD11 | Prefix Descriptors | -- | Sec 9.2.9 |
| TBD12 | Node Attributes | -- | Sec 9.2.10.1 |
| TBD13 | Link Attributes | -- | Sec 9.2.10.2 |
| TBD14 | Prefix Attributes | -- | Sec 9.2.10.3 |
+-----------+---------------------+---------------+-----------------+
* this TLV is defined in a different PCEP document
TLV Table
Refer Section 13.6 for the table of Sub-TLVs.
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15. Implementation Status
The PCEP-LS protocol extension as described in this I-D were
implemented and tested for a variety of applications. Apart from the
below implementation, there exist other experimental implementations
done for optical networks.
15.1. Hierarchical Transport PCE controllers
The PCEP-LS has been implemented as part of IETF97 Hackathon and
Bits-N-Bites demonstration. The use-case demonstrated was DCI use-
case of ACTN architecture in which to show the following scenarios:
- connectivity services on the ACTN based recursive hierarchical
SDN/PCE platform that has the three tier level SDN controllers
(two-tier level MDSC and PNC) on the top of the PTN systems
managed by EMS.
- Integration test of two tier-level MDSC: The SBI of the low
level MDSC is the YANG based Korean national standards and the one
of the high level MDSC the PCEP-LS based ACTN protocols.
- Performance test of three types of SDN controller based recovery
schemes including protection, reactive and proactive restoration.
PCEP-LS protocol was used to demonstrate quick report of failed
network components.
15.2. ONOS-based Controller (MDSC and PNC)
Huawei (PNC, MDSC) and SKT (MDSC) implemented PCEP-LS during
Hackathon and IETF97 Bits-N-Bites demonstration. The demonstration
was ONOS-based ACTN architecture in which to show the following
capabilities:
Both packet PNC and optical PNC (with optical PCEP-LS extension)
implemented PCEP-LS on its SBI and well as its NBI (towards MDSC).
SKT orchestrator (acting as MDSC) also supported PCEP-LS (as well
as RestConf) towards packet and optical PNCs on its SBI.
Further description can be found at <ONOS-PCEP> and the code at
<ONOS-PCEP-GITHUB>.
16. Acknowledgments
This document borrows some of the structure and text from the
[RFC7752].
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Thanks to Eric Wu, Venugopal Kondreddy, Mahendra Singh Negi,
Avantika, and Zhengbin Li for the reviews.
Thanks to Ramon Casellas for his comments and suggestions based on
his implementation experience.
17. References
17.1. 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>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
<https://www.rfc-editor.org/info/rfc5307>.
[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>.
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119,
February 2011, <https://www.rfc-editor.org/info/rfc6119>.
[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>.
[RFC7810] Previdi, S., Ed., Giacalone, S., Ward, D., Drake, J., and
Q. Wu, "IS-IS Traffic Engineering (TE) Metric Extensions",
RFC 7810, DOI 10.17487/RFC7810, May 2016,
<https://www.rfc-editor.org/info/rfc7810>.
[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>.
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17.2. Informative References
[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>.
[RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<https://www.rfc-editor.org/info/rfc4203>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
2006, <https://www.rfc-editor.org/info/rfc4364>.
[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>.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
December 2008, <https://www.rfc-editor.org/info/rfc5316>.
[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in
Support of Inter-Autonomous System (AS) MPLS and GMPLS
Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392,
January 2009, <https://www.rfc-editor.org/info/rfc5392>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, DOI 10.17487/RFC6549,
March 2012, <https://www.rfc-editor.org/info/rfc6549>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
DOI 10.17487/RFC6805, November 2012,
<https://www.rfc-editor.org/info/rfc6805>.
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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>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[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>.
[RFC8202] Ginsberg, L., Previdi, S., and W. Henderickx, "IS-IS
Multi-Instance", RFC 8202, DOI 10.17487/RFC8202, June
2017, <https://www.rfc-editor.org/info/rfc8202>.
[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>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[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", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An
Architecture for Use of PCE and the PCE Communication
Protocol (PCEP) in a Network with Central Control",
RFC 8283, DOI 10.17487/RFC8283, December 2017,
<https://www.rfc-editor.org/info/rfc8283>.
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[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-09 (work in progress), October 2018.
[I-D.ietf-pce-applicability-actn]
Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of
Path Computation Element (PCE) for Abstraction and Control
of TE Networks (ACTN)", draft-ietf-pce-applicability-
actn-08 (work in progress), December 2018.
[I-D.ietf-teas-actn-requirements]
Lee, Y., Ceccarelli, D., Miyasaka, T., Shin, J., and K.
Lee, "Requirements for Abstraction and Control of TE
Networks", draft-ietf-teas-actn-requirements-09 (work in
progress), March 2018.
[I-D.ietf-pce-pcep-flowspec]
Dhody, D., Farrel, A., and Z. Li, "PCEP Extension for Flow
Specification", draft-ietf-pce-pcep-flowspec-02 (work in
progress), October 2018.
[I-D.kondreddy-pce-pcep-ls-sync-optimizations]
Kondreddy, V. and M. Negi, "Optimizations of PCEP Link-
State(LS) Synchronization Procedures", draft-kondreddy-
pce-pcep-ls-sync-optimizations-00 (work in progress),
October 2015.
[I-D.leedhody-pce-vn-association]
Lee, Y., Zhang, X., and D. Ceccarelli, "PCEP Extensions
for Establishing Relationships Between Sets of LSPs and
Virtual Networks", draft-leedhody-pce-vn-association-07
(work in progress), February 2019.
[ONOS-PCEP]
"Support for PCEP in ONOS",
<https://wiki.onosproject.org/display/ONOS/PCEP+Protocol>.
[ONOS-PCEP-GITHUB]
"Github for PCEP code in ONOS",
<https://github.com/opennetworkinglab/onos/tree/master/
protocols/pcep>.
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Appendix A. Reusing BGP-LS codepoints
This document creates a new registry for the PCEP-LS sub-TLVs
(Section 13.6) and define new sub-TLV codepoints. Another approach
could be to use the BGP-LS registry which is already defined for use
in BGP. This is possible because the "BGP-LS Node Descriptor, Link
Descriptor, Prefix Descriptor, and Attribute TLVs" registry marks
0-255 as reserved. Thus the space of the sub-TLV values for the Type
field can be partitioned as shown below -
Range |
---------------+---------------------------------------------
0 | Reserved - must not be allocated.
|
1 .. 255 | New PCEP sub-TLV allocated according to the
| registry defined in this document.
|
256 .. 65535 | Per BGP registry defined by [RFC7752].
| Not to be allocated in this registry.
[Editor's Note - If this approach is agreed by the WG, the document
would be updated with new sub-TLV type values.]
Appendix B. Relevant OSPF TLV and sub-TLV
This section list the relevant TLVs and sub-TLVs defined for OSPF.
+-----------+---------------------+---------------+-----------------+
| Sub-TLV | Description | OSPF-TE | Value defined |
| | | Sub-TLV | in: |
+-----------+---------------------+---------------+-----------------+
| 6 | Link Local/Remote | 11 | [RFC4203]/1.1 |
| | Identifiers | | |
| 7 | IPv4 interface | 3 | [RFC3630]/2.5.3 |
| | address | | |
| 8 | IPv4 neighbor | 4 | [RFC3630]/2.5.4 |
| | address | | |
| 9 | IPv6 interface | 19 | [RFC5329]/4.3 |
| | address | | |
| 10 | IPv6 neighbor | 20 | [RFC5329]/4.4 |
| | address | | |
| 17 | IPv4 Router-ID of | 1 | [RFC3630]/2.4.1 |
| | Local Node | | |
| 18 | IPv6 Router-ID of | 3 | [RFC5329]/3 |
| | Local Node | | |
| 19 | IPv4 Router-ID of | 1 | [RFC3630]/2.4.1 |
| | Remote Node | | |
| 20 | IPv6 Router-ID of | 3 | [RFC5329]/3 |
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| | Remote Node | | |
| 22 | Administrative | 9 | [RFC3630]/2.5.9 |
| | group (color) | | |
| 23 | Maximum link | 6 | [RFC3630]/2.5.6 |
| | bandwidth | | |
| 24 | Max. reservable | 7 | [RFC3630]/2.5.7 |
| | link bandwidth | | |
| 25 | Unreserved | 8 | [RFC3630]/2.5.8 |
| | bandwidth | | |
| 27 | Link Protection | 14 | [RFC4203]/1.2 |
| | Type | | |
| 30 | Shared Risk Link | 16 | [RFC4203]/1.3 |
| | Group | | |
| 33 | Unidirectional | 27 | [RFC7471]/4.1 |
| | Link Delay | | |
| 34 | Min/Max | 28 | [RFC7471]/4.2 |
| | Unidirectional Link | | |
| | Delay | | |
| 35 | Unidirectional | 29 | [RFC7471]/4.3 |
| | Delay Variation | | |
| 36 | Unidirectional | 30 | [RFC7471]/4.4 |
| | Link Loss | | |
| 37 | Unidirectional | 31 | [RFC7471]/4.5 |
| | Residual Bandwidth | | |
| 38 | Unidirectional | 32 | [RFC7471]/4.6 |
| | Available Bandwidth | | |
| 39 | Unidirectional | 33 | [RFC7471]/4.7 |
| | Bandwidth | | |
| | Utilization | | |
| 40 | Extended Admin | 26 | [RFC7308]/2.1 |
| | Group (EAG) | | |
+-----------+---------------------+---------------+-----------------+
Appendix C. Examples
These examples are for illustration purposes only to show how the new
PCEP-LS message could be encoded. They are not meant to be an
exhaustive list of all possible use cases and combinations.
C.1. All Nodes
Each node (PCC) in the network chooses to provide its own local node
and link information, and in this way PCE can build the full link
state and TE information.
+--------------------+ +--------------------+
| | | |
| RTA |10.1.1.1 | RTB |
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| 1.1.1.1 |--------------------| 2.2.2.2 |
| Area 0 | 10.1.1.2| Area 0 |
| | | |
+--------------------+ +--------------------+
RTA
---
LS Node
TLV - Local Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 1.1.1.1
TLV - Node Attributes TLV
Sub-TLV(s)
LS Link
TLV - Local Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 1.1.1.1
TLV - Remote Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 2.2.2.2
TLV - Link Descriptors
Sub-TLV - 7: IPv4 interface: 10.1.1.1
Sub-TLV - 8: IPv4 neighbor: 10.1.1.2
TLV - Link Attributes TLV
Sub-TLV(s)
RTB
---
LS Node
TLV - Local Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 2.2.2.2
TLV - Node Attributes TLV
Sub-TLV(s)
LS Link
TLV - Local Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 2.2.2.2
TLV - Remote Node Descriptors
Sub-TLV - 3: OSPF Area-ID: 0.0.0.0
Sub-TLV - 4: Router-ID: 1.1.1.1
TLV - Link Descriptors
Sub-TLV - 7: IPv4 interface: 10.1.1.2
Sub-TLV - 8: IPv4 neighbor: 10.1.1.1
TLV - Link Attributes TLV
Sub-TLV(s)
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C.2. Designated Node
A designated node(s) in the network will provide its own local node
as well as all learned remote information, and in this way PCE can
build the full link state and TE information.
As described in Appendix C.1, the same LS Node and Link objects will
be generated with a difference that it would be a designated router
say RTA that generate all this information.
C.3. Between PCEs
As per Hierarchical-PCE [RFC6805], Parent PCE builds an abstract
domain topology map with each domain as an abstract node and inter-
domain links as an abstract link. Each child PCE may provide this
information to the parent PCE. Considering the example in figure 1
of [RFC6805], following LS object will be generated:
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PCE1
----
LS Node
TLV - Local Node Descriptors
Sub-TLV - 1: Autonomous System: 100 (Domain 1)
Sub-TLV - 4: Router-ID: 11.11.11.11 (abstract)
LS Link
TLV - Local Node Descriptors
Sub-TLV - 1: Autonomous System: 100
Sub-TLV - 4: Router-ID: 11.11.11.11 (abstract)
TLV - Remote Node Descriptors
Sub-TLV - 1: Autonomous System: 200 (Domain 2)
Sub-TLV - 4: Router-ID: 22.22.22.22 (abstract)
TLV - Link Descriptors
Sub-TLV - 7: IPv4 interface: 11.1.1.1
Sub-TLV - 8: IPv4 neighbor: 11.1.1.2
TLV - Link Attributes TLV
Sub-TLV(s)
LS Link
TLV - Local Node Descriptors
Sub-TLV - 1: Autonomous System: 100
Sub-TLV - 4: Router-ID: 11.11.11.11 (abstract)
TLV - Remote Node Descriptors
Sub-TLV - 1: Autonomous System: 200
Sub-TLV - 4: Router-ID: 22.22.22.22 (abstract)
TLV - Link Descriptors
Sub-TLV - 7: IPv4 interface: 12.1.1.1
Sub-TLV - 8: IPv4 neighbor: 12.1.1.2
TLV - Link Attributes TLV
Sub-TLV(s)
LS Link
TLV - Local Node Descriptors
Sub-TLV - 1: Autonomous System: 100
Sub-TLV - 4: Router-ID: 11.11.11.11 (abstract)
TLV - Remote Node Descriptors
Sub-TLV - 1: Autonomous System: 400 (Domain 4)
Sub-TLV - 4: Router-ID: 44.44.44.44 (abstract)
TLV - Link Descriptors
Sub-TLV - 7: IPv4 interface: 13.1.1.1
Sub-TLV - 8: IPv4 neighbor: 13.1.1.2
TLV - Link Attributes TLV
Sub-TLV(s)
* similar information will be generated by other PCE
to help form the abstract domain topology.
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Further the exact border nodes and abstract internal path between the
border nodes may also be transported to the Parent PCE to enable ACTN
as described in [I-D.ietf-pce-applicability-actn] using the similar
LS node and link objects encodings.
Appendix D. Contributor Addresses
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: udayasreereddy@gmail.com
Sergio Belotti
Alcatel-Lucent
Italy
EMail: sergio.belotti@alcatel-lucent.com
Satish Karunanithi
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: satishk@huawei.com
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: chengli13@huawei.com
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
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Young Lee
Huawei Technologies
5340 Legacy Drive, Building 3
Plano, TX 75023
USA
EMail: leeyoung@huawei.com
Daniele Ceccarelli
Ericsson
Torshamnsgatan,48
Stockholm
Sweden
EMail: daniele.ceccarelli@ericsson.com
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