PCEP Procedures and Protocol Extensions for Using PCE as a Central Controller (PCECC) for SRv6
draft-dhody-pce-pcep-extension-pce-controller-srv6-03
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Mahendra Singh Negi , Zhenbin Li , Xuesong Geng , Shuping Peng | ||
| Last updated | 2020-03-09 | ||
| Replaced by | draft-ietf-pce-pcep-extension-pce-controller-srv6 | ||
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draft-dhody-pce-pcep-extension-pce-controller-srv6-03
PCE Working Group M. Negi
Internet-Draft Z. Li
Intended status: Standards Track X. Geng
Expires: September 10, 2020 S. Peng
Huawei Technologies
March 9, 2020
PCEP Procedures and Protocol Extensions for Using PCE as a Central
Controller (PCECC) for SRv6
draft-dhody-pce-pcep-extension-pce-controller-srv6-03
Abstract
The Path Computation Element (PCE) is a core component of Software-
Defined Networking (SDN) systems. It can compute optimal paths for
traffic across a network and can also update the paths to reflect
changes in the network or traffic demands.
PCE was developed to derive paths for MPLS Label Switched Paths
(LSPs), which are supplied to the head end of the LSP using the Path
Computation Element Communication Protocol (PCEP). But SDN has a
broader applicability than signaled (G)MPLS traffic-engineered (TE)
networks, and the PCE may be used to determine paths in a range of
use cases. PCEP has been proposed as a control protocol for use in
these environments to allow the PCE to be fully enabled as a central
controller.
A PCE-based central controller (PCECC) can simplify the processing of
a distributed control plane by blending it with elements of SDN and
without necessarily completely replacing it. This document specifies
the procedures and PCEP protocol extensions when a PCE-based
controller is also responsible for configuring the forwarding actions
on the routers for Segment Routing in IPv6 (SRv6), in addition to
computing the SRv6 paths for packet flows and telling the edge
routers what instructions to attach to packets as they enter the
network.
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/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 10, 2020.
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. PCECC SRv6 . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 6
5. Procedures for Using the PCE as the Central Controller
(PCECC) in SRv6 . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Stateful PCE Model . . . . . . . . . . . . . . . . . . . 6
5.2. New Functions . . . . . . . . . . . . . . . . . . . . . . 6
5.3. PCECC Capability Advertisement . . . . . . . . . . . . . 7
5.4. PCEP session IP address and TEDB Router ID . . . . . . . 7
5.5. SRv6 Path Operations . . . . . . . . . . . . . . . . . . 7
5.5.1. PCECC Segment Routing in IPv6 (SRv6) . . . . . . . . 7
5.5.1.1. PCECC SRv6 Node/Prefix SID allocation . . . . . . 7
5.5.1.2. PCECC SRv6 Adjacency SID allocation . . . . . . . 8
5.5.1.3. Redundant PCEs . . . . . . . . . . . . . . . . . 9
5.5.1.4. Re Delegation and Cleanup . . . . . . . . . . . . 9
5.5.1.5. Synchronization of SRv6 SID Allocations . . . . . 9
6. PCEP messages . . . . . . . . . . . . . . . . . . . . . . . . 9
7. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 9
7.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 9
7.2. PATH-SETUP-TYPE TLV . . . . . . . . . . . . . . . . . . . 10
7.3. CCI Object . . . . . . . . . . . . . . . . . . . . . . . 10
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7.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 11
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. Manageability Considerations . . . . . . . . . . . . . . . . 11
9.1. Control of Function and Policy . . . . . . . . . . . . . 11
9.2. Information and Data Models . . . . . . . . . . . . . . . 11
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 12
9.6. Impact On Network Operations . . . . . . . . . . . . . . 12
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
10.1. PCECC-CAPABILITY TLV . . . . . . . . . . . . . . . . . . 12
10.2. New Path Setup Type Registry . . . . . . . . . . . . . . 12
10.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 13
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
12.1. Normative References . . . . . . . . . . . . . . . . . . 13
12.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The Path Computation Element (PCE) [RFC4655] was developed to offload
path computation function from routers in an MPLS traffic-engineered
network. Since then, the role and function of the PCE has grown to
cover a number of other uses (such as GMPLS [RFC7025]) and to allow
delegated control [RFC8231] and PCE-initiated use of network
resources [RFC8281].
According to [RFC7399], Software-Defined Networking (SDN) refers to a
separation between the control elements and the forwarding components
so that software running in a centralized system, called a
controller, can act to program the devices in the network to behave
in specific ways. A required element in an SDN architecture is a
component that plans how the network resources will be used and how
the devices will be programmed. It is possible to view this
component as performing specific computations to place traffic flows
within the network given knowledge of the availability of network
resources, how other forwarding devices are programmed, and the way
that other flows are routed. This is the function and purpose of a
PCE, and the way that a PCE integrates into a wider network control
system (including an SDN system) is presented in [RFC7491].
In early PCE implementations, where the PCE was used to derive paths
for MPLS Label Switched Paths (LSPs), paths were requested by network
elements (known as Path Computation Clients (PCCs)), and the results
of the path computations were supplied to network elements using the
Path Computation Element Communication Protocol (PCEP) [RFC5440].
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This protocol was later extended to allow a PCE to send unsolicited
requests to the network for LSP establishment [RFC8281].
[RFC8283] introduces the architecture for PCE as a central controller
as an extension of the architecture described in [RFC4655] and
assumes the continued use of PCEP as the protocol used between PCE
and PCC. [RFC8283] further examines the motivations and
applicability for PCEP as a Southbound Interface (SBI), and
introduces the implications for the protocol.
[I-D.ietf-teas-pcecc-use-cases] describes the use cases for the PCECC
architecture.
[I-D.ietf-pce-pcep-extension-for-pce-controller] specify the
procedures and PCEP protocol extensions for using the PCE as the
central controller for static LSPs, where LSPs can be provisioned as
explicit label instructions at each hop on the end-to-end path.
Segment Routing (SR) technology leverages the source routing and
tunneling paradigms. A source node can choose a path without relying
on hop-by-hop signaling protocols such as LDP or RSVP-TE. Each path
is specified as a set of "segments" advertised by link-state routing
protocols (IS-IS or OSPF). [RFC8402] provides an introduction to SR
architecture. The corresponding IS-IS and OSPF extensions are
specified in [RFC8667] and [RFC8665] , respectively. It relies on a
series of forwarding instructions being placed in the header of a
packet. The list of segment forming the path is called the Segment
List and is encoded in the packet header. Segment Routing can be
applied to the IPv6 architecture with the Segment Routing Header
(SRH) [I-D.ietf-6man-segment-routing-header]. A segment is encoded
as an IPv6 address. An ordered list of segments is encoded as an
ordered list of IPv6 addresses in the routing header. The active
segment is indicated by the Destination Address of the packet. Upon
completion of a segment, a pointer in the new routing header is
incremented and indicates the next segment. The segment routing
architecture supports operations that can be used to steer packet
flows in a network, thus providing a form of traffic engineering.
[RFC8664] and [I-D.ietf-pce-segment-routing-ipv6] specify the SR
specific PCEP extensions.
PCECC may further use PCEP protocol for SR SID (Segment Identifier)
distribution on the SR nodes with some benefits.
[I-D.zhao-pce-pcep-extension-pce-controller-sr] specifies the
procedures and PCEP protocol extensions when a PCE-based controller
is also responsible for configuring the forwarding actions on the
routers (SR SID distribution in this case), in addition to computing
the paths for packet flows in a segment routing network and telling
the edge routers what instructions to attach to packets as they enter
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the network. This document extends this to include SRv6 SID
distribution as well.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
Terminologies used in this document is same as described in the draft
[RFC8283] and [I-D.ietf-teas-pcecc-use-cases].
3. PCECC SRv6
[RFC8664] specifies extensions to PCEP that allow a stateful PCE to
compute, update or initiate SR-TE paths for MPLS dataplane. An
ingress node of an SR-TE path appends all outgoing packets with a
list of MPLS labels (SIDs). This is encoded in SR-ERO subobject,
capable of carrying a label (SID) as well as the identity of the
node/adjacency label (SID). [I-D.ietf-pce-segment-routing-ipv6]
extends the procedure to include support for SRv6 paths.
As per [I-D.ietf-6man-segment-routing-header], an SRv6 Segment is a
128-bit value. "SRv6 SID" or simply "SID" are often used as a
shorter reference for "SRv6 Segment". Further details are in an
illustration provided in [I-D.ietf-spring-srv6-network-programming].
The SR is applied to IPV6 forwarding plane using SRH. A SR path can
be derived from an IGP Shortest Path Tree (SPT), but SR-TE paths may
not follow IGP SPT. Such paths may be chosen by a suitable network
planning tool, or a PCE and provisioned on the ingress node.
[I-D.ietf-pce-segment-routing-ipv6] extended SR-ERO subobject capable
of carrying an SRv6 SID as well as the identity of the node/adjacency
represented by the SID.
As per [RFC8283], PCE as a central controller can allocate and
provision the node/prefix/adjacency label (SID) via PCEP. As per
[I-D.ietf-teas-pcecc-use-cases] this is also applicable to SRv6 SIDs.
Rest of the processing is similar to existing stateful PCE with SRv6
mechanism.
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4. PCEP Requirements
Following key requirements for PCECC-SRv6 should be considered when`
designing the PCECC based solution:
o PCEP speaker supporting this draft MUST have the capability to
advertise its PCECC-SRv6 capability to its peers.
o PCEP speaker not supporting this draft MUST be able to reject
PCECC-SRv6 related message with a reason code that indicates no
support for it.
o PCEP procedures MUST provide a means to update (or cleanup) the
SRv6 SID to the PCC.
o PCEP procedures SHOULD provide a means to synchronize the SRv6 SID
allocations between PCE to PCC in the PCEP messages.
5. Procedures for Using the PCE as the Central Controller (PCECC) in
SRv6
5.1. Stateful PCE Model
Active stateful PCE is described in [RFC8231]. PCE as a central
controller (PCECC) reuses existing Active stateful PCE mechanism as
much as possible to control the LSP.
5.2. New Functions
This document uses the same PCEP messages and its extensions which
are described in [I-D.ietf-pce-pcep-extension-for-pce-controller] and
[I-D.zhao-pce-pcep-extension-pce-controller-sr] for PCECC-SRv6 as
well.
PCEP messages PCRpt, PCInitiate, PCUpd are also used to send LSP
Reports, LSP setup and LSP update respectively. The extended
PCInitiate message described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] is used to download
or cleanup central controller's instructions (CCIs) (SRv6 SID in
scope of this document). The extended PCRpt message described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] is also used to
report the CCIs (SRv6 SIDs) from PCC to PCE.
[I-D.ietf-pce-pcep-extension-for-pce-controller] specify an object
called CCI for the encoding of central controller's instructions.
[I-D.zhao-pce-pcep-extension-pce-controller-sr] extends the CCI by
defining a object-type for segment routing. This document further
extends the CCI by defining another object-type for SRv6.
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5.3. PCECC Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
advertise their support of PCECC extensions. A PCEP Speaker includes
the "PCECC Capability" sub-TLV, described in
[I-D.ietf-pce-pcep-extension-for-pce-controller].
A S-bit is added in PCECC-CAPABILITY sub-TLV to indicate support for
PCECC-SR in [I-D.zhao-pce-pcep-extension-pce-controller-sr]. This
document adds another I-bit to indicate support for SR in IPv6. A
PCC MUST set I-bit in PCECC-CAPABILITY sub-TLV and include SRv6-PCE-
CAPABILITY sub-TLV ([I-D.ietf-pce-segment-routing-ipv6]) in OPEN
Object (inside the the PATH-SETUP-TYPE-CAPABILITY TLV) to support the
PCECC SRv6 extensions defined in this document. If I-bit is set in
PCECC-CAPABILITY sub-TLV and SRv6-PCE-CAPABILITY sub-TLV is not
advertised in OPEN Object, PCE SHOULD send a PCErr message with
Error-Type=19 (Invalid Operation) and Error-value=TBD(SRv6 capability
was not advertised) and terminate the session.
5.4. PCEP session IP address and TEDB Router ID
As described in [I-D.zhao-pce-pcep-extension-pce-controller-sr], it
is important to link the session IP address with the Router ID in
TEDB for successful PCECC operations.
5.5. SRv6 Path Operations
The PCEP messages pertaining to PCECC-SRv6 MUST include PATH-SETUP-
TYPE TLV [RFC8408] with PST=TBD in the SRP object to clearly identify
the PCECC-SRv6 setup is intended.
5.5.1. PCECC Segment Routing in IPv6 (SRv6)
Segment Routing (SR) as described in [RFC8402] depends on "segments"
that are advertised by Interior Gateway Protocols (IGPs). The SR-
node allocates and advertises the SID (node, adj etc) and flood via
the IGP. This document proposes a new mechanism where PCE allocates
the SRv6 SID centrally and uses PCEP to advertise the SRv6 SID. In
some deployments PCE (and PCEP) are better suited than IGP because of
centralized nature of PCE and direct TCP based PCEP session to the
node.
5.5.1.1. PCECC SRv6 Node/Prefix SID allocation
Each node (PCC) is allocated a node SRv6 SID by the PCECC. The PCECC
sends PCInitiate message to update the SID table of each node. The
TE router ID is determined from the TEDB or from "IPv4/IPv6 Router-
ID" Sub-TLV [I-D.dhodylee-pce-pcep-ls], in the OPEN Object.
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On receiving the SRv6 node SID allocation, each node (PCC) uses the
local routing information to determine the next-hop and download the
forwarding instructions accordingly. The PCInitiate message in this
case MUST have FEC object.
On receiving the SRv6 node SID allocation:
For the local SID, node (PCC) needs to update SID with associated
function (END function in this case) in "My Local SID Table"
([I-D.ietf-spring-srv6-network-programming]).
For the non-local SID, node (PCC) uses the local routing
information to determine the next-hop and download the forwarding
instructions accordingly.
The PCInitiate message in this case MUST have FEC object.
The forwarding behavior and the end result is similar to IGP based
"Node-SID" in SRv6. Thus, from anywhere in the domain, it enforces
the ECMP-aware shortest-path forwarding of the packet towards the
related node.
PCE relies on the Node/Prefix SRv6 SID cleanup using the same
PCInitiate message.
5.5.1.2. PCECC SRv6 Adjacency SID allocation
[RFC8664] extends PCEP to allow a stateful PCE to compute and
initiate SR-TE paths, as well as a PCC to request a path subject to
certain constraint(s) and optimization criteria in SR networks.
For PCECC SR, apart from node-SID, Adj-SID is used where each
adjacency is allocated an Adj-SID by the PCECC. The PCECC sends
PCInitiate message to update the label map of each Adj to the
corresponding nodes in the domain. Each node (PCC) download the SRv6
SID instructions accordingly. Similar to SRv6 Node/Prefix Label
allocation, the PCInitiate message in this case uses the FEC object.
The forwarding behavior and the end result is similar to IGP based
"Adj-SID" in SRv6.
The Path Setup Type for segment routing MUST be set for PCECC SRv6 =
TBD (see Section 7.2). All PCEP procedures and mechanism are similar
to [RFC8664].
PCE relies on the Adj label cleanup using the same PCInitiate
message.
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5.5.1.3. Redundant PCEs
[I-D.litkowski-pce-state-sync] describes synchronization mechanism
between the stateful PCEs. The SRv6 SIDs allocated by a PCE MUST
also be synchronized among PCEs for PCECC SRv6 state synchronization.
Note that the SRv6 SIDs are independent to the PCECC-SRv6 paths, and
remains intact till any topology change. The redundant PCEs MUST
have a common view of all SRv6 SIDs allocated in the domain.
5.5.1.4. Re Delegation and Cleanup
[I-D.ietf-pce-pcep-extension-for-pce-controller] describes the action
needed for CCIs for the Basic PCECC LSP on this terminated session.
Similarly actions should be applied for the SRv6 SID as well.
5.5.1.5. Synchronization of SRv6 SID Allocations
[I-D.ietf-pce-pcep-extension-for-pce-controller] describes the
synchronization of Central Controller's Instructions (CCI) via LSP
state synchronization as described in [RFC8231] and [RFC8232]. Same
procedures should be applied for SRv6 SIDs as well.
6. PCEP messages
The PCEP message is as per
[I-D.zhao-pce-pcep-extension-pce-controller-sr].
7. PCEP Objects
7.1. OPEN Object
7.1.1. PCECC Capability sub-TLV
[I-D.ietf-pce-pcep-extension-for-pce-controller] defined the PCECC-
CAPABILITY TLV.
A new I-bit is defined in PCECC-CAPABILITY sub-TLV for PCECC-SRv6:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |I|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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I (PCECC-SRv6-CAPABILITY - 1 bit): If set to 1 by a PCEP speaker, it
indicates that the PCEP speaker is capable for PCECC-SRv6 capability
and PCE would allocate node and Adj SRv6 SID on this session.
7.2. PATH-SETUP-TYPE TLV
The PATH-SETUP-TYPE TLV is defined in [RFC8408]. PST = TBD is used
when Path is setup via PCECC SRv6 mode.
On a PCRpt/PCUpd/PCInitiate message, the PST=TBD indicates that this
path was setup via a PCECC-SRv6 based mechanism where either the SIDs
were allocated/instructed by PCE via PCECC mechanism.
7.3. CCI Object
The Central Control Instructions (CCI) Object is used by the PCE to
specify the forwarding instructions is defined in
[I-D.ietf-pce-pcep-extension-for-pce-controller]. This document
defines another object-type for SRv6 purpose.
CCI Object-Type is TBD for SRv6 as below -
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CC-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MT-ID | Algorithm | Flags |B|P|G|C|N|E|V|L|O|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | SRv6 Endpoint Function |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SRv6 Identifier |
| (128-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Optional TLV //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The field CC-ID is as described in
[I-D.ietf-pce-pcep-extension-for-pce-controller]. The field MT-ID,
Algorithm, Flags are defined in
[I-D.zhao-pce-pcep-extension-pce-controller-sr].
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Reserved: MUST be set to 0 while sending and ignored on receipt.
SRv6 Endpoint Function: 16 bit field representing supported functions
associated with SRv6 SIDs.
SRv6 Identifier: 128 bit IPv6 addresses representing SRv6 segment.
[Editor's Note - It might be useful to seperate the LOC:FUNC part in
the SRv6 SID]
7.4. FEC Object
The FEC Object is used to specify the FEC information and MAY be
carried within PCInitiate or PCRpt message.
FEC Object (and various Object-Types) are described in
[I-D.zhao-pce-pcep-extension-pce-controller-sr]. SRv6 Node SID MUST
includes the FEC Object-Type 2 for IPv6 Node. SRv6 Adjacency SID
MUST include the FEC Object-Type=4 for IPv6 adjacency. Further FEC
object types would be added in future revisions.
8. Security Considerations
The security considerations described in
[I-D.ietf-pce-pcep-extension-for-pce-controller] apply to the
extensions described in this document.
As per [RFC8231], it is RECOMMENDED that these PCEP extensions only
be activated on authenticated and encrypted sessions across PCEs and
PCCs belonging to the same administrative authority, using Transport
Layer Security (TLS) [RFC8253] as per the recommendations and best
current practices in [RFC7525] (unless explicitly set aside in
[RFC8253]).
9. Manageability Considerations
9.1. Control of Function and Policy
A PCE or PCC implementation SHOULD allow to configure to enable/
disable PCECC SR capability as a global configuration.
9.2. Information and Data Models
[RFC7420] describes the PCEP MIB, this MIB can be extended to get the
PCECC SR capability status.
The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to
enable/disable PCECC SR capability.
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9.3. 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].
9.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440] and [RFC8231].
9.5. Requirements On Other Protocols
PCEP extensions defined in this document do not put new requirements
on other protocols.
9.6. Impact On Network Operations
PCEP implementation SHOULD allow a limit to be placed on the rate of
PCInitiate/PCUpd messages (as per [RFC8231]) sent by PCE and
processed by PCC. It SHOULD also allow sending a notification when a
rate threshold is reached.
10. IANA Considerations
10.1. PCECC-CAPABILITY TLV
[I-D.ietf-pce-pcep-extension-for-pce-controller] defines the PCECC-
CAPABILITY TLV and requests that IANA creates a registry to manage
the value of the PCECC-CAPABILITY TLV's Flag field. IANA is
requested to allocate a new bit in the PCECC-CAPABILITY TLV Flag
Field registry, as follows:
Bit Description Reference
TBD I((PCECC-SRv6-CAPABILITY)) This document
10.2. New Path Setup Type Registry
IANA is requested to allocate new PST Field in PATH- SETUP-TYPE TLV.
The allocation policy for this new registry should be by IETF
Consensus. The new registry should contain the following value:
Value Description Reference
TBD Path is This document
setup using PCECC-SRv6 mode
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10.3. PCEP-Error Object
IANA is requested to allocate new error types and error values within
the "PCEP-ERROR Object Error Types and Values" sub-registry of the
PCEP Numbers registry for the following errors:
Error-Type Meaning
---------- -------
19 Invalid operation.
Error-value = TBD : SRv6 capability was
not advertised
11. Acknowledgments
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>.
[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>.
[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>.
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[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>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[I-D.ietf-pce-segment-routing-ipv6]
Negi, M., Li, C., Sivabalan, S., Kaladharan, P., and Y.
Zhu, "PCEP Extensions for Segment Routing leveraging the
IPv6 data plane", draft-ietf-pce-segment-routing-ipv6-03
(work in progress), October 2019.
[I-D.ietf-pce-pcep-extension-for-pce-controller]
Zhao, Q., Li, Z., Negi, M., Peng, S., and C. Zhou, "PCEP
Procedures and Protocol Extensions for Using PCE as a
Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep-
extension-for-pce-controller-04 (work in progress), March
2020.
[I-D.zhao-pce-pcep-extension-pce-controller-sr]
Zhao, Q., Li, Z., Negi, M., and C. Zhou, "PCEP Procedures
and Protocol Extensions for Using PCE as a Central
Controller (PCECC) of SR-LSPs", draft-zhao-pce-pcep-
extension-pce-controller-sr-05 (work in progress), July
2019.
12.2. 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>.
[RFC7025] Otani, T., Ogaki, K., Caviglia, D., Zhang, F., and C.
Margaria, "Requirements for GMPLS Applications of PCE",
RFC 7025, DOI 10.17487/RFC7025, September 2013,
<https://www.rfc-editor.org/info/rfc7025>.
[RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path
Computation Element Architecture", RFC 7399,
DOI 10.17487/RFC7399, October 2014,
<https://www.rfc-editor.org/info/rfc7399>.
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[RFC7491] King, D. and A. Farrel, "A PCE-Based Architecture for
Application-Based Network Operations", RFC 7491,
DOI 10.17487/RFC7491, March 2015,
<https://www.rfc-editor.org/info/rfc7491>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
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Sollins and Larry Masinter. The experiences gathered during the
first (more than a) decade of URN usage were also helpful, so
individuals and organizations which have implemented and used URNs
are also acknowledged. In particular, the experience gained with
parties wanting to make use of the URN framework and submit URN
Namespace registration documents, and their desire to obtain the
necessary collected background information has motivated and shaped
the text put into Section 1 of this document.
Many individuals in the URNbis working group have participated in the
detailed discussion of this memo. Particular thanks for detailed
review comments and text suggestions go to Juha Hakala, Mykyta
Yevstifeyev, Peter Saint-Andre, Subramanian Moonesamy, Bengt Neiss,
and Lars Svensson.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
Registration Procedures for New URI Schemes", BCP 35,
RFC 4395, February 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
11.2. Informative References
[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg]
Hoenes, A., "Uniform Resource Name (URN) Namespace
Definition Mechanisms",
draft-ietf-urnbis-rfc3406bis-urn-ns-reg-03 (work in
progress), October 2012.
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[IANA] IANA, "The Internet Assigned Numbers Authority",
<http://www.iana.org/>.
[IANA-URI]
IANA, "URI Schemes Registry",
<http://www.iana.org/assignments/uri-schemes/>.
[IANA-URN]
IANA, "URN Namespace Registry",
<http://www.iana.org/assignments/urn-namespaces/>.
[RFC0615] Crocker, D., "Proposed Network Standard Data Pathname
syntax", RFC 615, March 1974.
[RFC0645] Crocker, D., "Network Standard Data Specification syntax",
RFC 645, June 1974.
[RFC1630] Berners-Lee, T., "Universal Resource Identifiers in WWW: A
Unifying Syntax for the Expression of Names and Addresses
of Objects on the Network as used in the World-Wide Web",
RFC 1630, June 1994.
[RFC1736] Kunze, J., "Functional Recommendations for Internet
Resource Locators", RFC 1736, February 1995.
[RFC1737] Sollins, K. and L. Masinter, "Functional Requirements for
Uniform Resource Names", RFC 1737, December 1994.
[RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL)", RFC 1738, December 1994.
[RFC1808] Fielding, R., "Relative Uniform Resource Locators",
RFC 1808, June 1995.
[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
[RFC2169] Daniel, R., "A Trivial Convention for using HTTP in URN
Resolution", RFC 2169, June 1997.
[RFC2276] Sollins, K., "Architectural Principles of Uniform Resource
Name Resolution", RFC 2276, January 1998.
[RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[RFC2483] Mealling, M. and R. Daniel, "URI Resolution Services
Necessary for URN Resolution", RFC 2483, January 1999.
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[RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day,
"Service Location Protocol, Version 2", RFC 2608,
June 1999.
[RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
June 1999.
[RFC2717] Petke, R. and I. King, "Registration Procedures for URL
Scheme Names", BCP 35, RFC 2717, November 1999.
[RFC2718] Masinter, L., Alvestrand, H., Zigmond, D., and R. Petke,
"Guidelines for new URL Schemes", RFC 2718, November 1999.
[RFC3305] Mealling, M. and R. Denenberg, "Report from the Joint W3C/
IETF URI Planning Interest Group: Uniform Resource
Identifiers (URIs), URLs, and Uniform Resource Names
(URNs): Clarifications and Recommendations", RFC 3305,
August 2002.
[RFC3401] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part One: The Comprehensive DDDS", RFC 3401, October 2002.
[RFC3402] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Two: The Algorithm", RFC 3402, October 2002.
[RFC3403] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Three: The Domain Name System (DNS) Database",
RFC 3403, October 2002.
[RFC3404] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
Part Four: The Uniform Resource Identifiers (URI)",
RFC 3404, October 2002.
[RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition
Mechanisms", BCP 66, RFC 3406, October 2002.
[RFC4020] Kompella, K. and A. Zinin, "Early IANA Allocation of
Standards Track Code Points", BCP 100, RFC 4020,
February 2005.
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Appendix A. Handling of URNs by URL Resolvers/Browsers
The URN syntax has been defined so that URNs can be used in places
where URLs are expected. A resolver that conforms to the current URI
syntax specification [RFC3986] will extract a scheme value of "urn"
rather than a scheme value of "urn:<nid>".
An URN MUST be considered an opaque URI by URL resolvers and passed
(with the "urn:" tag) to a URN resolver for resolution. The URN
resolver can either be an external resolver that the URL resolver
knows of, or it can be functionality built into the URL resolver.
However note that, according to RFC 3986, the <fragment> part of a
URN will be stripped by a resolver client before passing the URN to
the resolver, and subsequently be applied to the returned result --
in the manner specified for the returned media type.
To avoid confusion of users, a URL browser SHOULD display the
complete URN (including the "urn:" tag) to ensure that there is no
confusion between URN Namespace identifiers and URI Scheme names.
Appendix B. Collected ABNF (Informative)
As a service to implementers specifically interested in URN syntax,
the complete ABNF for URNs is collected here, including the
referenced rules from [RFC5234] and [RFC3986]. In case of
(unexpected) inconsistencies, these documents remain normative for
the respective productions.
URNs conform to the <path-rootless> variant of the general URI syntax
specified in Section 3 of [RFC3986] :
URI = scheme ":" path-rootless [ "?" query ] [ "#" fragment ]
scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
path-rootless = segment-nz *( "/" segment )
query = *( pchar / "/" / "?" )
fragment = *( pchar / "/" / "?" )
segment-nz = 1*pchar
segment = *pchar
pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
pct-encoded = "%" HEXDIG HEXDIG
sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
/ "*" / "+" / "," / ";" / "="
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In the case of URNs, the above rules are subject to more specific
restrictions, specified in Section 2 of this RFC:
scheme = "urn"
; specific, fixed (assigned) value
urn-path = NID ":" NSS
; to be superimposed on <path-rootless>,
; which needs to be <segment-nz> only
NID = ( ALPHA / DIGIT ) 1*31( ALPHA / DIGIT / "-" )
; RFC 3406[bis] contains more specific rules
NSS = 1*pchar
; or equivalent: NSS = segment-nz
urn-query = directive *( "&" directive)
; to be superimposed on <query>
directive = keywd "=" value
keywd = ALPHA *( ["-"] (ALPHA / DIGIT))
value = *v-pchar
v-pchar = unreserved / pct-encoded / v-subdels
v-subdels = "!" / "$" / "'" / "(" / ")"
/ "*" / "+" / "," / ";" / "="
; this is equivalent to <sub-delims> except "&"
/ ":" / "@" / "/" / "?"
; plus the extra characters allowed in <pchar>
; and for <query>, as per RFC 3986
The above rules make use of the following "Core Rules" from Appendix
B.1 of [RFC5234] :
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
DIGIT = %x30-39 ; 0-9
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
Appendix C. Breakdown of NSS Syntax Evolution since RFC 2141
(Informative)
In order to make visible the detailed migration path from RFC 2141
and the influence of the evolution of URI syntax from RFC 2396 to RFC
3986 on it, this appendix provides a highly annotated and expanded
version of the NSS syntax provided in Section 2.2:
NSS = 1*pchar ; or equivalent: NSS = segment-nz
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In particular, the breakdown below serves to provide evidence of that
this syntax correctly reflects the addition of "&" and "~" to the
repertoire of characters allowed in the NSS portion of URNs
previously allowed by RFC 2141; it expands on the syntax specified in
RFC 2141 after translation to standard ABNF.
NSS = 1*URN-char
URN-char = trans / pct-encoded
; Note that <pct-encoded> from RFC 3986 here replaces the
; explicit, expanded form used in RFC 2141.
trans = ALPHA / DIGIT / u-other
; Note that RFC 2141's <other> has been disambiguated here
; into <u-other>.
; RFC 2141 also said:
; / reserved
; This caused an ambiguity in RFC 2141 with respect to "%", which
; now is resolved here by omission of this dangling alternative.
;
; After adoption of the generic URI syntax from RFC 3986, there
; is no more need to deal here with the higher-level separator
; characters "/", "?", and "#" contained in <reserved>
; (beyond "%", which is fully taken care of by <pct-encoded>),
; which are part of RFC 3986's <gen-delims>, as shown below.
; From RFC 2141:
; reserved = '%" / "/" / "?" / "#" ; SIC!
; ^ ^
u-other = ":" / "@"
; those from RFC 3986 <gen-delims>
; specifically allowed in <pchar>.
; From RFC 3986:
; gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
/ "!" / "$" / "'" / "(" / ")"
/ "*" / "+" / "," / ";" / "="
; this is RFC 3986 <sub-delims> except "&".
; From RFC 3986:
; sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
; / "*" / "+" / "," / ";" / "="
; The URNbis WG arrived at unanimous consensus that "&" can be
; allowed without harm to backward compatibility for existing
; URN Namespaces.
/ "-" / "." / "_" ; <unreserved> except "~"
; From RFC 3986:
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; unreserved = ALPHA / DIGIT
; / "-" / "." / "_" / "~"
; The URNbis WG arrived at unanimous consensus that "~" can be
; allowed without harm to backward compatibility for existing
; URN Namespaces.
; Since we now allow "&" and "~" , <trans> becomes <pchar> ,
; greatly simplifying the syntax rules and parsers!
; From RFC 3986:
; segment-nz = 1*pchar
; pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
Appendix D. Changes since RFC 2141 (Informative)
D.1. Essential Changes from RFC 2141
[[ RFC-Editor: please remove the Appendix D.1 headline and all
subsequent subsections starting with Appendix D.2. ]]
Expanded Introduction to cover background material frequently
requested by interested parties not well acquainted with RFCs and
past/present work in the IETF, in particular prospective URN
Namespace stakeholders and applicants for URN Namespace
registrations. The material included also serves to avoid normative
downrefs to legacy RFCs that are very unlikely to be progressed on
the Standards Track in the foreseeable future.
Document references updated and split; Normative References now only
to Full Internet Standards to allow for future progress of this memo
on the IETF Standards Track.
Formal syntax now specified using ABNF (STD 68), using productions
from Generic URI Syntax (STD 66) and STD 68.
NID Syntax slightly more restrictive than in RFC 2141 (compatible
with existing and in-progress NID registrations).
NSS syntax now allows "&" and "~" to align URN syntax with generic
<pchar> rule from STD 66; an ambiguity in the formal rules and
incompatibilities between the formal rules and the prose description
in RFC 2141 have been straightened out ("%" no more allowed outside
percent-encoding triples, other <reserved> characters no more
admitted by formal syntax rules).
Use of query and fragment part with URNs now specified, mostly by
reference to STD 66. Syntactical pattern for query part defined;
IANA registry for query keywords in URN references established.
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This document also performs the outstanding formal registration of
the 'urn' URI scheme.
Supplemental material in Appendices documents considerations and
decisions made in the development of this memo.
D.2. Changes from RFC 2141 to Individual Draft -00
Abstract amended: URI scheme, replacement for 2141, point to 3406.
Use contemporary boilerplate. Added transient "Discussion" section.
s1: added new 1st para (URI scheme) and 3rd para (hierarchy).
s1.1 (Historical Perspective) added for background & motivation.
s1.2 (Objective) added.
s1.3 (2119 keywords) added -- used now throughout normative text.
s2 (URN Syntax): Shifted from BNF to ABNF; explain relationship to
3986 and gaps, how the gaps could be bridged, distinguish between URI
generics and URN specifics; got rid of references to immature
documents (1630, 1737).
s2.1 (NID syntax): Use ABNF and RFC 5234 terminals (core rules);
removed reference to an old draft of 2396; clarified prohibition to
use "urn" as NID.
s2.2 (NSS syntax): Shifted from BNF to ABNF; made ABNF consistent
with subsequent textual description; exposition much expanded,
showing relationship with 3986 and resulting incompatibilities;
proposed how to bridge gaps, to make parsing more uniform among URIs;
updated i18n considerations and pointer to UTF-8 specification.
s.2.3, s2.3.*: reworked and much expanded, along the grouping of
delimiter characters from 3986 in new s2.3.1 (including old s.2.3.2);
made text fully consistent with ABNF in s2.2; consistent usage of
term "percent-encoded"; old s.2.3.1 became s2.3.2; old s3.4 became
s3.3.3, providing complete, annotated list of excluded characters,
ordered by ascending code point; and restating design decisions
needed to be made to close gaps to 3986.
s3 through s6: only minor editorial changes.
s7: formal registration of 'urn' URI scheme added, using 4395
template.
s8: Security Cons. slightly amended.
s9: new: IANA Cons. added wrt s7.1 and prohibition of NID "urn".
s10: Acknowledgments amended.
s11: References split into Normative and Informative; updated refs
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and added many; only FS and BCP allowed as Normative Refs to further
promotion of document.
Added Appendices A through D.
D.3. Changes from Individual Draft -00 to -02
Updated "Discussion" on front page to point to dedicated urn list.
Numerous editorial improvements and additions for clarification, in
particular in the Introduction. No technical changes.
More Informative References; missing details supplied in D.2.
D.4. Changes from Individual Draft -02 to WG Draft -00
Added new s1.2 to Introduction, with excerpts from RFC 1737 to
provide background on URN functional and syntax requirements.
Renumbered previous s1.2 and s1.3 to s1.3 and s1.4, respectively.
Supplied text in s2 regarding the envisioned use of query and
fragment parts, based on various discussion -- including a
preliminary evaluation in PersID.
Changed "SHOULD never" to "MUST NOT" for NUL character in NSS.
Various editorial and grammar fixes; corrected STD / BCP numbers.
D.5. Changes from WG Draft -00 to WG Draft -01
Reflect WG consensus on adding "&" and "~" to the set of characters
allowed in the NSS part of URNs, thus aligning URN syntax with
generic URI syntax from RFC 3986.
Moved breakdown of NSS syntax evolution from s2.2 to new Appendix C.
Avoid "[URN] character set" in favor of "character repertoire" to
minimize potential clashes with IETF terminology on charsets.
s2.3.3: URN recognition in text documents is regarded out of scope.
The previous version was ambiguous on whether eventual query and/or
fragment parts were regarded as part of the NSS; after closer
inspection of the syntax, clarification has been added that the <urn-
path> syntax is indeed superimposed on the <segment-nz> ABNF rule for
URNs, and hence does not cover the trailing higher level parts
(query, fragment) according to the URI syntax.
Hoenes Expires April 19, 2013 [Page 33]quot;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>.
[RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X.,
and D. Dhody, "Optimizations of Label Switched Path State
Synchronization Procedures for a Stateful PCE", RFC 8232,
DOI 10.17487/RFC8232, September 2017,
<https://www.rfc-editor.org/info/rfc8232>.
[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>.
[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying Path Setup Type in PCE Communication
Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
July 2018, <https://www.rfc-editor.org/info/rfc8408>.
[RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler,
H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", RFC 8665,
DOI 10.17487/RFC8665, December 2019,
<https://www.rfc-editor.org/info/rfc8665>.
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[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[I-D.ietf-teas-pcecc-use-cases]
Zhao, Q., Li, Z., Khasanov, B., Dhody, D., Ke, Z., Fang,
L., Zhou, C., Communications, T., Rachitskiy, A., and A.
Gulida, "The Use Cases for Path Computation Element (PCE)
as a Central Controller (PCECC).", draft-ietf-teas-pcecc-
use-cases-05 (work in progress), March 2020.
[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-13 (work in progress), October 2019.
[I-D.litkowski-pce-state-sync]
Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter
Stateful Path Computation Element (PCE) Communication
Procedures.", draft-litkowski-pce-state-sync-07 (work in
progress), January 2020.
[I-D.dhodylee-pce-pcep-ls]
Dhody, D., Lee, Y., and D. Ceccarelli, "PCEP Extension for
Distribution of Link-State and TE Information.", draft-
dhodylee-pce-pcep-ls-14 (work in progress), October 2019.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-12 (work in
progress), March 2020.
[I-D.ietf-6man-segment-routing-header]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", draft-ietf-6man-segment-routing-header-26 (work in
progress), October 2019.
Negi, et al. Expires September 10, 2020 [Page 16]
Internet-Draft PCECC-SRv6 March 2020
Appendix A. Contributor Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Authors' Addresses
Mahendra Singh Negi
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: mahend.ietf@gmail.com
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
EMail: lizhenbin@huawei.com
Xuesong Geng
Huawei Technologies
China
EMail: gengxuesong@huawei.com
Shuping Peng
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
EMail: pengshuping@huawei.com
Negi, et al. Expires September 10, 2020 [Page 17]