PCEP Operational Clarification
draft-koldychev-pce-operational-02
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Authors | Mike Koldychev , Siva Sivabalan , Mahendra Singh Negi , Diego Achaval , Hari Kotni | ||
| Last updated | 2020-08-26 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-koldychev-pce-operational-02
PCE Working Group M. Koldychev
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Sivabalan
Expires: February 27, 2021 Ciena Corporation
M. Negi
Huawei Technologies
D. Achaval
Nokia
H. Kotni
Juniper Networks, Inc
August 26, 2020
PCEP Operational Clarification
draft-koldychev-pce-operational-02
Abstract
This document is meant to provide better clarity about how PCEP
operates and hence to facilitate better interoperability between
different equipment vendors. The content of this document has been
compiled based on the feedback from several multi-vendor interop
exercises. Several constructs are introduced to facilitate this,
such as the LSP-DB and the ASSO-DB.
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."
Koldychev, et al. Expires February 27, 2021 [Page 1]
Internet-Draft PCEP CLARIFICATION August 2020
This Internet-Draft will expire on February 27, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PCEP LSP Database . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Synchronization . . . . . . . . . . . . . . . . . . . . . 5
3.3. Stateful Bringup . . . . . . . . . . . . . . . . . . . . 6
3.4. Successful MBB . . . . . . . . . . . . . . . . . . . . . 7
3.5. Aborted MBB . . . . . . . . . . . . . . . . . . . . . . . 8
4. PCEP Association Database . . . . . . . . . . . . . . . . . . 9
4.1. 2 LSPs in same Association . . . . . . . . . . . . . . . 9
4.2. Switch Association during MBB . . . . . . . . . . . . . . 11
5. Computation Constraints . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
Path Computation Element (PCE) Communication Protocol (PCEP)
[RFC5440] enables the communication between a Path Computation Client
(PCC) and a Path Control Element (PCE), or between two PCEs based on
the PCE architecture [RFC4655].
Koldychev, et al. Expires February 27, 2021 [Page 2]
Internet-Draft PCEP CLARIFICATION August 2020
PCEP Extensions for the Stateful PCE Model [RFC8231] describes a set
of extensions to PCEP to enable active control of Multiprotocol Label
Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS)
tunnels. [RFC8281] describes the setup and teardown of PCE-initiated
LSPs under the active stateful PCE model, without the need for local
configuration on the PCC, thus allowing for dynamic centralized
control of a network.
PCEP Extensions for Establishing Relationships Between Sets of LSPs
[RFC8697] introduces a generic mechanism to create a grouping of LSPs
which can then be used to define associations between a set of LSPs
and a set of attributes (such as configuration parameters or
behaviors) and is equally applicable to stateful PCE (active and
passive modes) and stateless PCE.
The PCEP protocol has evolved from a simple stateless model into a
stateful model with more features being added. Due to subtle
differences in interpretation of existing PCEP standards, it was
found that networking equipment vendors often had to adjust their
implementations, in order to interoperate. This informational
document is meant to clarify these subtle differences and agree on a
final model that all major vendors have agreed on and that all other
vendors can adopt. This document applies to RSVP-TE and Segment-
Routing.
2. Terminology
The following terminologies are used in this document:
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
PCEP: Path Computation Element Protocol.
MBB: Make-Before-Break. A procedure during which the head-end of a
traffic-engineered path wishes to move traffic to a new path
without losing any traffic, by first "making" a new path and then
"breaking" the old path.
Association parameters: As described in [RFC8697], the combination
of the mandatory fields Association type, Association ID and
Association Source in the ASSOCIATION object uniquely identify the
association group. If the optional TLVs - Global Association
Koldychev, et al. Expires February 27, 2021 [Page 3]
Internet-Draft PCEP CLARIFICATION August 2020
Source or Extended Association ID are included, then they MUST be
included in combination with mandatory fields to uniquely identify
the association group.
Association information: As described in [RFC8697], the ASSOCIATION
object could also include other optional TLVs based on the
association types, that provides 'information' related to the
association type.
ERO: Explicit Route Object is the path of the LSP encoded into a
PCEP object. To represent an empty ERO object, i.e., without any
subobjects, we use the notation "ERO={}". To represent an ERO
object containing some given sequence of subobjects, we use the
notation "ERO={A}".
3. PCEP LSP Database
We introduce the concept of the LSP-DB, as a database of actual LSP
state in the network. This concept is not explicitly defined in
[RFC8231], but is fully compatible with it. We use the LSP-DB to
describe how certain actions are performed, because it is easier to
define actions as a function of database state, rather than as a
function of previously received messages. The structure and format
of the LSP-DB MUST be common among all dataplane types (i.e., RSVP-
TE/SR-TE/SRv6), all instantiation methods (i.e., PCC-initiated/PCE-
initiated), all destination types (i.e., point-to-point/point-to-
multipoint).
Note that we use the term "Tunnel" somewhat loosely here, to mean
"the object identified by the PLSP-ID". It may or may not be an
actual tunnel in the implementation. For example, working and
protect paths can be implemented as one tunnel interface, but in PCEP
we would refer to them as two different Tunnels, because they would
have different PLSP-IDs.
Note that the term "LSP", which stands for "Label Switched Path", if
taken too literally would restrict our discussion to MPLS dataplane
only. In this document, we allow the term "LSP" to refer to any
path, regardless of the dataplane format. So that an LSP can refer
to MPLS and SRv6 dataplane paths.
3.1. Structure
[RFC8231] states that the LSP-IDENTIFIERS TLV contains the key that
MUST be used to differentiate different LSPs during make before break
procedure. We further clarify here that PCEP LSPs exist in a 2-tier
structure. The top tier is the "Tunnel", identified by the PLSP-ID
and/or SYMBOLIC-NAME, while the lower tier is the "LSP", identified
Koldychev, et al. Expires February 27, 2021 [Page 4]
Internet-Draft PCEP CLARIFICATION August 2020
by the values in LSP-IDENTIFIERS TLV. A single Tunnel may contain
multiple LSPs at the same time, i.e., a Tunnel is a container for
LSPs. A Tunnel MUST have at least one LSP and when the last LSP is
removed from the Tunnel, the Tunnel itself is removed.
3.2. Synchronization
The stateful PCE MUST maintain the PCE LSP-DB, which stores Tunnels
and LSPs. The PCE LSP DB is only modified by PCRpt messages. No
other PCEP message may modify the PCE LSP DB. The PCC MUST also
maintain the PCC LSP DB, which it MUST synchronize with the PCE LSP
DB by sending PCRpt messages.
The PCC adds/removes entries to/from its LSP-DB based on what LSPs it
creates/destroys in the network. There can be many trigger types for
updating the PCC LSP-DB, some examples include PCUpd messages, local
computation on the PCC, local configuration on the PCC, etc. The
trigger type does not affect the content of the PCC LSP-DB, i.e., the
content of the PCC LSP-DB is updated identically regardless of the
trigger type.
Whenever a PCC modifies an entry it its PCC LSP-DB, it MUST send a
PCRpt message to the PCE (or multiple PCEs), to synchronize this
change. Ensuring this synchronization is always in place allows one
to define behavior as a function of LSP-DB state, instead of defining
behavior as a function of what PCEP messages were sent or received.
The PCE MUST always act on the latest state of the PCE LSP DB. Note
that this does not mean that the PCE cannot use information from
outside of LSP-DB. For example, the PCE can use other mechanisms to
collect traffic statistics and use them in the computation. However,
these traffic statistics are not part of the LSP-DB, but only
reference it.
The LSP-DB on both the PCC and the PCE only stores the actual state
in the network, it does not store the desired state. For example,
consider the case of PCE Initiated LSP, configured on the PCE. When
the operator modifies the configuration of this LSP, that is a change
in desired state. The actual state has not yet changed, so LSP-DB is
not modified yet. The LSP-DB is only modified after the PCE sends
PCInit/PCUpd message to the PCC and the PCC decides to act on that
message. When the PCC acts on message, it would update its own PCC
LSP DB and immediately send PCRpt to the PCE to synchronize the
change. When the PCE receives the PCRpt msg, it updates its own PCE
LSP DB. After this, the PCC LSP DB and PCE LSP DB are in sync.
Koldychev, et al. Expires February 27, 2021 [Page 5]
Internet-Draft PCEP CLARIFICATION August 2020
3.3. Stateful Bringup
[RFC8231] in section 5.8.2, allows delegation of an LSP in
operationally down state, but at the same time mandates the use of
PCReq, before sending PCRpt. In this document, we would like to make
it clear that sending PCReq is optional.
We shall refer to the process of sending PCReq before PCRpt as
"stateless bringup". In reality, stateless bringup introduces
overhead and is not possible to enforce from the PCE, because the
stateless PCE is not supposed to keep any per-LSP state about
previous PCReq messages. It was found that many vendors choose to
ignore this requirement and send the PCRpt directly, without going
through PCReq. This section will serve to explain and to validate
this behavior.
Even though all the major vendors today are moving to the stateful
PCE model, it does not deprecate the need for stateless PCEP. The
key property of stateless PCEP is that PCReq messages MUST NOT modify
the state of the PCE LSP-DB in any way. Therefore, PCReq messages
are useful for many OAM ping/traceroute applications where the PCC
wishes to probe the network without having any effect on the existing
LSPs.
The PCC MAY delegate an empty LSP to the PCE and then wait for the
PCE to send PCUpd, without sending PCReq. We shall refer to this
process as "stateful bringup". The PCE MUST support the original
stateless bringup, for backward compatibility purposes. Supporting
stateful bringup should not require introducing any new behavior on
the PCE, because as mentioned earlier, the PCE MUST NOT modify LSP-DB
state based on PCReq messages. So whether the PCE has received a
PCReq or not, it MUST process the PCRpt all the same.
An example of stateful bringup follows. In our example the PCC
starts off by using LSP-ID of 0. The value 0 does not hold any
special meaning, any other 16-bit value could have been used.
PCC has no LSP yet, but wants to establish a path. PCC sends
PCRpt(R-FLAG=0, D-flag=1, OPER-FLAG=DOWN, PLSP-ID=100, LSP-ID=0,
ERO={}).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=0, D-flag=1, OPER=DOWN, ERO={} |
+---------------------------------------------------------------+
Figure 1: Content of LSP DB
Koldychev, et al. Expires February 27, 2021 [Page 6]
Internet-Draft PCEP CLARIFICATION August 2020
PCC received a PCUpd from the PCE and has decided to install the
ERO={A} from that PCUpd. PCC sends PCRpt(R-FLAG=0, D-flag=1, OPER-
FLAG=UP, PLSP-ID=100, LSP-ID=0, ERO={A}).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=0, D-flag=1, OPER=UP, ERO={A} |
+---------------------------------------------------------------+
Figure 2: Content of LSP DB
3.4. Successful MBB
Below we give an example of doing MBB to switch the tunnel from one
path to another. We represent the path encoded into the ERO object
as ERO={A} and ERO={B}.
PCC has an existing LSP in UP state, with LSP-ID=2. PCC sends
PCRpt(R-FLAG=0, PLSP-ID=100, LSP-ID=2, ERO={A}, OPER-FLAG=UP).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=2, ERO={A}, OPER=UP |
+---------------------------------------------------------------+
Figure 3: Content of LSP DB
PCC initiates the MBB procedure by creating a new LSP with LSP-ID=3.
It does not matter what triggered the creation of the new LSP, it
could have been due to a new path received via PCUpd (if the given
tunnel is delegated), or it could have been local computation on the
PCC (if the tunnel is locally computed on the PCC), or it could have
been a change in configuration on the PCC (if the tunnel's path is
explicitly configured on the PCC). It is important to emphasize that
the procedure for updating the LSP-DB is common, regardless of the
trigger that caused the change.
PCC sends PCRpt(R-FLAG=0, PLSP-ID=100, LSP-ID=3, ERO={B}, OPER-
FLAG=UP).
Koldychev, et al. Expires February 27, 2021 [Page 7]
Internet-Draft PCEP CLARIFICATION August 2020
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=2, ERO={A}, OPER=UP |
| | LSP-ID=3, ERO={B}, OPER=UP |
+---------------------------------------------------------------+
Figure 4: Content of LSP DB
After some time, the PCC decides to destroy the old LSP. PCC sends
PCRpt(R-FLAG=1, PLSP-ID=100, LSP-ID=2).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=3, ERO={B}, OPER=UP |
+---------------------------------------------------------------+
Figure 5: Content of LSP DB
3.5. Aborted MBB
The MBB process can abort when the newly created LSP is destroyed
before it is installed as traffic carrying. This scenario is
described below.
PCC has an existing LSP in UP state, with LSP-ID=2. PCC sends
PCRpt(R-FLAG=0, OPER-FLAG=UP, PLSP-ID=100, LSP-ID=2).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=2, OPER=UP |
+---------------------------------------------------------------+
Figure 6: Content of LSP DB
MBB procedure is initiated, a new LSP is created with LSP-ID=3. LSP
is currently being established, so its oper state is DOWN. PCC sends
PCRpt(R-FLAG=0, OPER-FLAG=DOWN, PLSP-ID=100, LSP-ID=3).
Koldychev, et al. Expires February 27, 2021 [Page 8]
Internet-Draft PCEP CLARIFICATION August 2020
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=2, OPER=UP |
| | LSP-ID=3, OPER=DOWN |
+---------------------------------------------------------------+
Figure 7: Content of LSP DB
MBB procedure is aborted. PCC sends PCRpt(R-FLAG=1, PLSP-ID=100,
LSP-ID=3).
+---------------------------------------------------------------+
| TUNNEL | LSP |
+-----------------+---------------------------------------------+
| PLSP-ID=100 | LSP-ID=2, OPER=UP |
+---------------------------------------------------------------+
Figure 8: Content of LSP DB
4. PCEP Association Database
PCEP Association is a group of zero or more LSPs.
The PCE ASSO DB is populated by PCRpt messages and MAY also be
populated via configuration on the PCE itself. An Association is
identified by the Association Parameters. The Association parameters
contain many fields, so for convenience we will group all the fields
into a single value. We will use ASSO_PARAM=A, ASSO_PARAM=B, to
refer to different PCEP Associations: A and B, respectively.
4.1. 2 LSPs in same Association
Below, we give an example of LSPs joining the same Association.
PCC creates the first LSP. PCC sends PCRpt(R-FLAG=0, PLSP-ID=100,
LSP-ID=1, ASSO_PARAM=A, ASSO_R_FLAG=0).
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
+---------------------------------------------------------------+
Figure 9: Content of PCE ASSO DB
PCC creates the second LSP. PCC sends PCRpt(R-FLAG=0, PLSP-ID=200,
LSP-ID=1, ASSO_PARAM=A, ASSO_R_FLAG=0).
Koldychev, et al. Expires February 27, 2021 [Page 9]
Internet-Draft PCEP CLARIFICATION August 2020
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
| | PLSP-ID=200, LSP-ID=1 |
+---------------------------------------------------------------+
Figure 10: Content of PCE ASSO DB
PCC updates the first LSP, the PCC is NOT REQUIRED to send the
ASSOCIATION object in this PCRpt, since the LSP is already in the
Association. PCC sends PCRpt(R-FLAG=0, PLSP-ID=100, LSP-ID=1). The
content of the PCE ASSO DB is unchanged. Note that the PCC MUST send
the ASSOCIATION OBJECT in the first PCRpt during SYNC state, even if
it has already issued a PCRpt with the association object sometime in
the past with this PCE. The synchronization steps outlined in
[RFC8697] are to be followed.
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
| | PLSP-ID=200, LSP-ID=1 |
+---------------------------------------------------------------+
Figure 11: Content of PCE ASSO DB
PCC decides to delete the second LSP. PCC sends PCRpt(R-FLAG=1,
PLSP-ID=200, LSP-ID=1).
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
+---------------------------------------------------------------+
Figure 12: Content of PCE ASSO DB
PCC decides to remove the first LSP from the Association, but not
delete the LSP itself. PCC sends PCRpt(R-FLAG=0, PLSP-ID=100, LSP-
ID=1, ASSO_PARAM=A, ASSO_R_FLAG=1). The PCE ASSO DB is now empty.
Koldychev, et al. Expires February 27, 2021 [Page 10]
Internet-Draft PCEP CLARIFICATION August 2020
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | |
+---------------------------------------------------------------+
Figure 13: Content of PCE ASSO DB
4.2. Switch Association during MBB
Each new LSP (identified by the LSP-ID) does not inherit the
Association membership of any previous LSPs within the same Tunnel.
This is done so that a Tunnel can have two LSPs that are in different
Associations, this may be required when switching from one
Association to another.
Below, we give an example a Tunnel going through MBB and switching
from Association A to Association B.
PCC creates the first LSP. PCC sends PCRpt(R-FLAG=0, PLSP-ID=100,
LSP-ID=1, ASSO_PARAM=A, ASSO_R_FLAG=0).
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
+---------------------------------------------------------------+
Figure 14: Content of PCE ASSO DB
PCC creates the MBB LSP in a different Association. PCC sends
PCRpt(R-FLAG=0, PLSP-ID=100, LSP-ID=2, ASSO_PARAM=B, ASSO_R_FLAG=0).
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=A | PLSP-ID=100, LSP-ID=1 |
+---------------------------------------------------------------+
| ASSO_PARAM=B | PLSP-ID=100, LSP-ID=2 |
+---------------------------------------------------------------+
Figure 15: Content of PCE ASSO DB
PCC deletes the old LSP. PCC sends PCRpt(R-FLAG=1, PLSP-ID=100, LSP-
ID=1).
Koldychev, et al. Expires February 27, 2021 [Page 11]
Internet-Draft PCEP CLARIFICATION August 2020
+---------------------------------------------------------------+
| ASSO | LSP |
+-----------------+---------------------------------------------+
| ASSO_PARAM=B | PLSP-ID=100, LSP-ID=2 |
+---------------------------------------------------------------+
Figure 16: Content of PCE ASSO DB
5. Computation Constraints
For any PCEP object that does not have an explicit removal flag, the
absence of that object indicates removal of the constraint specified
by that object. For example, suppose the first state-report contains
an LSPA object with some affinity constraints. Then if a subsequent
state-report does not contain an LSPA object, then this means that
the previously specified affinity constraints do not apply anymore.
Same applies to all PCEP objects, like METRIC, BANDWIDTH, etc., which
do not have an explicit flag for removal. This simply ensures that
it is possible to remove a constraint without using an explicit
removal flag.
6. Security Considerations
None at this time.
7. IANA Considerations
None at this time.
8. Acknowledgement
9. References
9.1. 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>.
[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>.
[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>.
Koldychev, et al. Expires February 27, 2021 [Page 12]
Internet-Draft PCEP CLARIFICATION August 2020
[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>.
[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>.
[RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing
Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>.
9.2. Informative References
[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>.
Appendix A. Contributors
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Andrew Stone
Nokia
Ottawa, Canada
Email: andrew.stone@nokia.com
Authors' Addresses
Koldychev, et al. Expires February 27, 2021 [Page 13]
Internet-Draft PCEP CLARIFICATION August 2020
Mike Koldychev
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, Ontario K2K 3E8
Canada
Email: mkoldych@cisco.com
Siva Sivabalan
Ciena Corporation
385 Terry Fox Dr.
Kanata, Ontario K2K 0L1
Canada
Email: ssivabal@ciena.com
Mahendra Singh Negi
Huawei Technologies
Email: mahendrasingh@huawei.com
Diego Achaval
Nokia
Email: diego.achaval@nokia.com
Hari Kotni
Juniper Networks, Inc
Email: hkotni@juniper.net
Koldychev, et al. Expires February 27, 2021 [Page 14]