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draft-dhody-pce-pcep-extension-pce-controller-srv6-03.txt
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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/.
Negi, et al. Expires September 10, 2020 [Page 1]
Internet-Draft PCECC-SRv6 March 2020
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 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
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 . . . . . . . . . . . . . . . . . . . . . . . . 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
Negi, et al. Expires September 10, 2020 [Page 2]
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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].
Negi, et al. Expires September 10, 2020 [Page 3]
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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
Negi, et al. Expires September 10, 2020 [Page 4]
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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.
Negi, et al. Expires September 10, 2020 [Page 5]
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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,
"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.
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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
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