draft-ietf-spring-mpls-path-segment-01.txt   draft-ietf-spring-mpls-path-segment-02.txt 
Network Working Group W. Cheng SPRING Working Group W. Cheng
Internet-Draft H. Li Internet-Draft H. Li
Intended status: Standards Track China Mobile Intended status: Standards Track China Mobile
Expires: March 19, 2020 M. Chen Expires: August 29, 2020 M. Chen
Huawei Huawei
R. Gandhi R. Gandhi
Cisco Systems, Inc. Cisco Systems, Inc.
R. Zigler R. Zigler
Broadcom Broadcom
September 16, 2019 February 26, 2020
Path Segment in MPLS Based Segment Routing Network Path Segment in MPLS Based Segment Routing Network
draft-ietf-spring-mpls-path-segment-01 draft-ietf-spring-mpls-path-segment-02
Abstract Abstract
A Segment Routing (SR) path is identified by an SR segment list. A Segment Routing (SR) path is identified by an SR segment list.
Only the full segment list identifies the full end-to-end path, and Only the complete segment list can identify the end-to-end SR path,
one segment or a partial set of segments from the list cannot and a sub-set of segments from the segment list cannot distinguish
identify the SR path and distinguish it from other SR paths that may one SR path from another as they may be partially congruent. SR path
be partially congruent. But path identification is a pre-requisite identification is a pre-requisite for various use-cases such as
for various use-cases such as performance measurement (PM) of an SR Performance Measurement (PM), bidirectional paths correlation, and
path. end-to-end 1+1 path protection.
In SR for MPLS (SR-MPLS) the segment identifiers are stripped from In SR for MPLS data plane (SR-MPLS), the segment identifiers are
the packet through label popping as the packet transits the network. stripped from the packet through label popping as the packet transits
This means that when a packet reaches the egress of the SR path, it the network. This means that when a packet reaches the egress of the
is not possible to determine on which SR path it traversed the SR path, it is not possible to determine on which SR path it
network. traversed the network.
This document defines a new type of segment that is referred to as This document defines a new type of segment that is referred to as
Path Segment, which is used to identify an SR path in an SR-MPLS Path Segment, which is used to identify an SR path in an SR-MPLS
network. When used, it is inserted at the ingress node of the SR network. When used, it is inserted by the ingress node of the SR
path and immediately follows the last segment identifier in the path and immediately follows the last segment identifier in the
segment list of the SR path. The Path Segment will not be popped off segment list of the SR path. The Path Segment will not be popped off
until it reaches the egress node of the SR path. until it reaches the egress node of the SR path. The Path Segment
then can be used by the egress node to implement SR path
A Path Segment can be used by the egress node to implement path identification and correlation.
identification hence to support various use-cases including SR path
PM, end-to-end 1+1 SR path protection, and bidirectional SR paths
correlation.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2. Path Segment . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Path Segment . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Nesting of Path Segments . . . . . . . . . . . . . . . . . . 5 3. Path Segment Allocation . . . . . . . . . . . . . . . . . . . 6
4. Path Segment Allocation . . . . . . . . . . . . . . . . . . . 6 4. Nesting of Path Segments . . . . . . . . . . . . . . . . . . 6
5. Path Segment for PM . . . . . . . . . . . . . . . . . . . . . 7 5. Path Segment for Performance Measurement . . . . . . . . . . 7
6. Path Segment for Bi-directional SR Path . . . . . . . . . . . 7 6. Path Segment for Bidirectional SR Path . . . . . . . . . . . 8
7. Path Segment for End-to-end Path Protection . . . . . . . . . 7 7. Path Segment for End-to-end Path Protection . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 10.1. Normative References . . . . . . . . . . . . . . . . . . 9
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 10.2. Informative References . . . . . . . . . . . . . . . . . 9
12.1. Normative References . . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11
12.2. Informative References . . . . . . . . . . . . . . . . . 9 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
Segment Routing (SR) [RFC8402] is a source routed forwarding method Segment Routing (SR) [RFC8402] is a source routed forwarding method
that allows to directly encode forwarding instructions (called that allows to directly encode forwarding instructions (called
segments) in each packet, hence it enables steering traffic through a segments) in each packet, hence it enables steering traffic through a
network without the per-flow states maintained on the transit nodes. network without the per-flow states maintained on the transit nodes.
Segment Routing can be instantiated on an MPLS data plane or an IPv6 Segment Routing can be instantiated on an MPLS data plane or an IPv6
data plane. The former is called SR-MPLS data plane. The former is called SR-MPLS [RFC8660], the latter is
[I-D.ietf-spring-segment-routing-mpls], the latter is called SRv6 called SRv6 [RFC8402]. SR-MPLS leverages the MPLS label stack to
[RFC8402]. SR-MPLS leverages the MPLS label stack to construct SR construct an SR path.
paths.
In an SR-MPLS network, when a packet is transmitted along an SR path, In an SR-MPLS network, when a packet is transmitted along an SR path,
the labels in the MPLS label stack will be swapped or popped. So the labels in the MPLS label stack will be swapped or popped. So
that no label or only the last label may be left in the MPLS label that no label or only the last label (e.g. Explicit-Null label) may
stack when the packet reaches the egress node. Thus, the egress node be left in the MPLS label stack when the packet reaches the egress
cannot determine along which SR path the packet came. node. Thus, the egress node cannot determine along which SR path the
packet came.
However, to support use cases like end-to-end 1+1 path protection However, to support various use-cases in SR-MPLS networks, like end-
(Live-Live case), bidirectional path correlation or performance to-end 1+1 path protection (Live-Live case) [RFC4426], bidirectional
measurement (PM), the ability to implement path identification is a path [RFC5654], or Performance Measurement (PM) [RFC7799], the
pre-requisite. More detail can be found in Section 5, 6, and 7. ability to implement path identification on the egress node is a pre-
requisite.
Therefore, this document introduces a new segment that is referred to Therefore, this document introduces a new segment type that is
as the Path Segment. A Path Segment is defined to uniquely identify referred to as the Path Segment. A Path Segment is defined to
an SR path in an SR-MPLS network in the context of the egress node. uniquely identify an SR path in an SR-MPLS network in the context of
It is normally used by egress nodes for path identification or the egress node. It is normally used by the egress nodes for path
identification hence to support various use-cases including SR path
PM, end-to-end 1+1 SR path protection, and bidirectional SR paths
correlation. correlation.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP14 [RFC2119][RFC8174] when, and only when, they appear in all [RFC2119] [RFC8174] when, and only when, they appear in all capitals,
capitals, as shown here. as shown here.
1.2. Abbreviations 1.2. Abbreviations
DM: Delay Measurement. DM: Delay Measurement.
LM: Loss Measurement. LM: Loss Measurement.
MPLS: Multiprotocol Label Switching. MPLS: Multiprotocol Label Switching.
MSD: Maximum SID Depth.
PM: Performance Measurement. PM: Performance Measurement.
PSID: Path Segment ID. PSID: Path Segment ID.
SID: Segment ID. SID: Segment ID.
SL: Segment List. SL: Segment List.
SR: Segment Routing. SR: Segment Routing.
SR-MPLS: Segment Routing instantiated on MPLS data plane. SR-MPLS: Segment Routing instantiated on MPLS data plane.
SRv6: Segment Routing instantiated on IPv6 data plane
2. Path Segment 2. Path Segment
A Path Segment is a single label that is assigned from the Segment A Path Segment is a single label that is assigned from the Segment
Routing Local Block (SRLB) or Segment Routing Global Block (SRGB) of Routing Local Block (SRLB) or Segment Routing Global Block (SRGB) or
the egress node of an SR path. It means that the Path Segment is dynamic MPLS label pool of the egress node of an SR path. It means
unique in the context of the egress node of the SR path. When a Path that the Path Segment is unique in the context of the egress node of
Segment is used, the Path Segment MUST be inserted at the ingress the SR path. When a Path Segment is used, the Path Segment MUST be
node and MUST immediately follow the last label of the SR path. The inserted at the ingress node and MUST immediately follow the last
Path Segment may be used to identify an SR-MPLS Policy, its label of the SR path, in other words, inserted after the routing
segment (adjacency/node/prefix segment) pointing to the egress node.
The Path Segment may be used to identify an SR-MPLS Policy, its
Candidate-Path (CP), or a SID List (SL) Candidate-Path (CP), or a SID List (SL)
[I-D.ietf-spring-segment-routing-policy] terminating on an egress [I-D.ietf-spring-segment-routing-policy] terminating on an egress
node depending on the use-case. node depending on the use-case.
The value of the TTL field in the MPLS label stack entry containing The value of the TTL field in the MPLS label stack entry containing
the Path Segment MUST be set to the same value as the TTL of the last the Path Segment MUST be set to the same value as the TTL of the last
label stack entry for the last segment in the SR path. If the Path label stack entry for the last segment in the SR path. If the Path
Segment is the bottom label, the S bit MUST be set. Segment is the bottom label, the S bit MUST be set.
Normally, the intermediate nodes will not see the Path Segment label Normally, the intermediate nodes will not see the Path Segment label
and do not know how to process it. A Path Segment presenting to an and do not know how to process it. A Path Segment presenting to an
intermediate node is an error condition. intermediate node is an error condition.
A Path Segment can be used in the case of Penultimate Hop Popping
(PHP), where some labels are be popped off at the penultimate hop of
an SR path, but the Path Segment MUST NOT be popped off until it
reaches at the egress node.
The egress node MUST pop the Path Segment. The egress node MAY use The egress node MUST pop the Path Segment. The egress node MAY use
the Path Segment for further processing. For example, when the Path Segment for further processing. For example, when
performance measurement is enabled on the SR path, it can trigger performance measurement is enabled on the SR path, it can trigger
packet counting or timestamping. packet counting or timestamping.
The label stack with Path Segment is as below (Figure 1): In some deployments, service labels may be added after the Path
Segment label in the MPLS label stack. In this case, the egress node
MUST be capable of processing more than one label. The additional
processing required can have an impact on forwarding performance.
Generic Associated Label (GAL) is used for Operations, Administration
and Maintenance (OAM) in MPLS networks [RFC5586]. When GAL is used,
it MUST be added at the bottom of the label stack after the Path
Segment label.
Entropy label and Entropy Label Indicator (ELI) as described in
[RFC8662] for SR-MPLS path, can be placed before or after the Path
Segment label in the MPLS label stack.
The SR path computation needs to know the Maximum SID Depth (MSD)
that can be imposed at each node/link of a given SR path [RFC8664].
This ensures that the SID stack depth of a computed path does not
exceed the number of SIDs the node is capable of imposing. The MSD
used for path computation MUST include the Path Segment label.
The label stack with Path Segment is shown in Figure 1:
+--------------------+ +--------------------+
| ... | | ... |
+--------------------+ +--------------------+
| Label 1 | | Label 1 |
+--------------------+ +--------------------+
| Label 2 | | Label 2 |
+--------------------+ +--------------------+
| ... | | ... |
+--------------------+ +--------------------+
| Label n | | Label n |
+--------------------+ +--------------------+
| Path Segment | | Path Segment |
+--------------------+ +--------------------+
| ... | | ... |
+--------------------+ +--------------------+
~ Payload ~
+--------------------+
Figure 1: Label Stack with Path Segment Figure 1: Label Stack with Path Segment
Where: Where:
o The Labels 1 to n are the segment label stack used to direct how o The Labels 1 to n are the segment label stack used to direct how
to steer the packets along the SR path. to steer the packets along the SR path.
o The Path Segment identifies the SR path in the context of the o The Path Segment identifies the SR path in the context of the
egress node of the SR path. egress node of the SR path.
3. Nesting of Path Segments 3. Path Segment Allocation
Several ways can be used to allocate the Path Segment.
One way is to set up a communication channel (e.g., MPLS Generic
Associated Channel (G-ACh)) [RFC5586] between the ingress node and
the egress node, and the ingress node of the SR path can directly
send a request to the egress node to allocate a Path Segment.
Another way is to leverage a centralized controller (e.g., SDN
controller) to assign the Path Segment. In this case, the controller
MUST make sure (e.g., by some capability discovery mechanisms outside
the scope of this document) that the egress node knows the Path
Segment and it can process it, as well as the label does not collide
with any label allocation done by the egress node.
Path Computation Element Protocol (PCEP) based Path Segment
allocation for SR Policy is defined in
[I-D.ietf-pce-sr-path-segment]. Also, BGP based Path Segment
allocation for SR Policy is defined in
[I-D.li-idr-sr-policy-path-segment].
4. Nesting of Path Segments
Binding SID (BSID) [RFC8402] can be used for SID list compression. Binding SID (BSID) [RFC8402] can be used for SID list compression.
With BSID, an end-to-end SR path can be split into several sub-paths, With BSID, an end-to-end SR path can be split into several sub-paths,
each sub-path is identified by a BSID. Then an end-to-end SR path each sub-path is identified by a BSID. Then an end-to-end SR path
can be identified by a list of BSIDs, therefore, it can provide can be identified by a list of BSIDs, therefore, it can provide
better scalability. better scalability.
BSID and Path SID (PSID) can be combined to achieve both sub-path and BSID and Path SID (PSID) can be combined to achieve both sub-path and
end-to-end path monitoring. A reference model for such a combination end-to-end path monitoring. A reference model for such a combination
in (Figure 2) shows an end-to-end path (A->D) that spans three in (Figure 2) shows an end-to-end path (A->D) that spans three
skipping to change at page 6, line 33 skipping to change at page 7, line 29
+------------+ +------------+ +------------+ +------------+
| BSID(B->C) | |s-PSID(B->C)| | BSID(B->C) | |s-PSID(B->C)|
+------------+ +------------+ +------------+ +------------+ +------------+ +------------+
| BSID(C->D) | | BSID(C->D) | ~C->D SubPath~ | BSID(C->D) | | BSID(C->D) | ~C->D SubPath~
+------------+ +------------+ +------------+ +------------+ +------------+ +------------+ +------------+ +------------+
|e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)| |e-PSID(A->D)|
+------------+ +------------+ +------------+ +------------+ +------------+ +------------+ +------------+ +------------+
Figure 2: Nesting of Path Segments Figure 2: Nesting of Path Segments
4. Path Segment Allocation 5. Path Segment for Performance Measurement
Several ways can be used to allocate the Path Segment.
One way is to set up a communication channel (e.g., MPLS Generic
Associated Channel (G-ACh)) between the ingress node and the egress
node, and the ingress node of the SR path can directly send a request
to the egress node to ask for a Path Segment.
Another way is to leverage a centralized controller (e.g., PCE, SDN As defined in [RFC7799], performance measurement can be classified
controller) to assign the Path Segment. PCEP based Path Segment into Passive, Active, and Hybrid measurement.
allocation is defined in [I-D.li-pce-sr-path-segment], and SR-policy
based path segment allocation is defined in
[I-D.li-idr-sr-policy-path-segment-distribution].
A Path Segment can be used in the case of PHP, where some labels MAY For Passive performance measurement, path identification at the
be popped off at the penultimate hop of an SR path, but the Path measuring points is the pre-requisite. Path Segment can be used by
Segment MUST NOT be popped off until it reaches at the egress LSR. the measuring points (e.g., the ingress and egress nodes of the SR
In the case of a Path Segment that is assigned by a centralized path or a centralized controller) to correlate the packet counts and
controller, the controller must make sure (e.g., by some capability timestamps from the ingress and egress nodes for a specific SR path,
discovery mechanisms) that the egress LSR knows and can process the then packet loss and delay can be calculated for the end-to-end path,
Path Segment. respectively.
5. Path Segment for PM Path Segment can also be used for Active performance measurement for
an SR path in SR-MPLS networks for collecting packet counters and
timestamps from the egress node using probe messages
[I-D.gandhi-mpls-rfc6374-sr] and [I-D.gandhi-spring-twamp-srpm].
As defined in [RFC7799], performance measurement can be classified Path Segment can also be used for In-situ OAM for SR-MPLS to identify
into Active, Passive and Hybrid measurement. For Passive the SR Path associated with the in-situ data fields in the data
measurement, path identification at the measuring points is the pre- packets on the egress node [I-D.gandhi-mpls-ioam-sr].
requisite. Path segment can be used by the measuring points (e.g.,
the ingress/egress nodes of an SR path) or a centralized controller
to correlate the packets counts/timestamps that are from the ingress
and egress nodes to a specific SR path, then packet loss/delay can be
calculated.
Performance Delay Measurement (DM) and Loss Measurements (LM) in SR Path Segment can also be used for In-band PM for SR-MPLS to identify
networks with MPLS data plane can be found in the SR Path associated with the collected performance metrics
[I-D.gandhi-spring-sr-mpls-pm] and [I-D.gandhi-spring-udp-pm]. [I-D.cheng-mpls-inband-pm-encapsulation].
6. Path Segment for Bi-directional SR Path 6. Path Segment for Bidirectional SR Path
With the current SR architecture, an SR path is a unidirectional In some scenarios, for example, mobile backhaul transport networks,
path. In some scenarios, for example, mobile backhaul transport there are requirements to support bidirectional paths, and the path
network, there are requirements to support bidirectional paths, and is normally treated as a single entity. The both directions of the
the path is normally treated as a single entity and both directions path have the same fate, for example, failure in one direction will
of the path have the same fate, for example, failure in one direction result in switching traffic at both directions. MPLS supports this
will result in switching at both directions. by introducing the concepts of co-routed bidirectional LSP and
associated bidirectional LSP [RFC5654].
MPLS supports this by introducing the concepts of co-routed In the current SR architecture, an SR path is a unidirectional path
bidirectional LSP and associated bidirectional LSP. With SR, to [RFC8402]. In order to support bidirectional SR paths, a
support bidirectional paths, a straightforward way is to bind two straightforward way is to bind two unidirectional SR paths to a
unidirectional SR paths to a single bidirectional path. Path single bidirectional SR path. Path Segments can then be used to
Segments can be used to correlate the two unidirectional SR paths at identify and correlate the traffic for the two unidirectional SR
both ends of the paths. paths at both ends of the bidirectional path.
[I-D.li-pce-sr-bidir-path] defines how to use PCEP and Path segment [I-D.ietf-pce-sr-bidir-path] defines procedures on how to use PCEP
to initiate a bidirectional SR path, and for SR Policy to initiate a bidirectional SR path. Also,
[I-D.li-idr-sr-policy-path-segment-distribution] defines how to use [I-D.li-idr-sr-policy-path-segment] defines procedures on how to use
SR policy and Path segment to initiate a bidirectional SR path. BGP for SR Policy to initiate a bidirectional SR path.
7. Path Segment for End-to-end Path Protection 7. Path Segment for End-to-end Path Protection
For end-to-end 1+1 path protection (i.e., Live-Live case), the egress For end-to-end 1+1 path protection (i.e., Live-Live case), the egress
node of an SR path needs to know the set of paths that constitute the node of the path needs to know the set of paths that constitute the
primary and the secondaries, in order to select the primary packet primary and the secondaries, in order to select the primary path
for onward transmission, and to discard the packets from the packets for onward transmission, and to discard the packets from the
secondaries. secondaries [RFC4426].
To do this, each path needs a path identifier that is unique at the
egress node. Depending on the design, this is a single unique path
segment label chosen by the egress PE.
There then needs to be a method of binding this path identifiers into
equivalence groups such that the egress PE can determine the set of
packets that represent a single path and its secondary.
It is obvious that this group can be instantiated in the network by
an SDN controller and that the Path Segment achieves the desired
function.
8. IANA Considerations To do this in Segment Routing, each SR path needs a path identifier
that is unique at the egress node. For SR-MPLS, this can be the Path
Segment label allocated by the egress node.
This document does not require any IANA actions. There then needs to be a method of binding this SR path identifiers
into equivalence groups such that the egress node can determine for
example, the set of packets that represent a single primary path. It
is obvious that this equivalence group can be instantiated in the
network by an SDN controller using the Path Segments of the SR paths.
9. Security Considerations 8. Security Considerations
This document does not introduce additional security requirements and This document does not introduce additional security requirements and
mechanisms other than the ones described in [RFC8402]. mechanisms other than the ones described in [RFC8402].
10. Contributors 9. IANA Considerations
The following individuals also contribute to this document.
o Cheng Li, Huawei
o Lei Wang, China Mobile
o Shuangping Zhan, ZTE
o Greg
11. Acknowledgements
The authors would like to thank Adrian Farrel, Stewart Bryant,
Alexander Vainshtein, Andrew G. Malis and Loa Andersson for their
review, suggestions and comments to this document.
The authors would like to acknowledge the contribution from Alexander This document does not require any IANA actions.
Vainshtein on "Nesting of Path Segments".
12. References 10. References
12.1. Normative References
[I-D.ietf-spring-segment-routing-mpls] 10.1. Normative References
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-22
(work in progress), May 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>. July 2018, <https://www.rfc-editor.org/info/rfc8402>.
12.2. Informative References [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
[I-D.gandhi-spring-sr-mpls-pm] 10.2. Informative References
Gandhi, R., Filsfils, C., daniel.voyer@bell.ca, d.,
Salsano, S., Ventre, P., and M. Chen, "Performance
Measurement in Segment Routing Networks with MPLS Data
Plane", draft-gandhi-spring-sr-mpls-pm-03 (work in
progress), September 2018.
[I-D.gandhi-spring-udp-pm] [I-D.cheng-mpls-inband-pm-encapsulation]
Gandhi, R., Filsfils, C., daniel.voyer@bell.ca, d., Cheng, W., Xiao, M., Zhou, T., Dong, X., and Y. Peleg,
Salsano, S., Ventre, P., and M. Chen, "UDP Path for In- "Encapsulation For MPLS Performance Measurement with
band Performance Measurement for Segment Routing Alternate Marking Method", draft-cheng-mpls-inband-pm-
Networks", draft-gandhi-spring-udp-pm-02 (work in encapsulation-02 (work in progress), November 2019.
progress), September 2018.
[I-D.ietf-6man-segment-routing-header] [I-D.gandhi-mpls-ioam-sr]
Filsfils, C., Dukes, D., Previdi, S., Leddy, J., Gandhi, R., Ali, Z., Filsfils, C., Brockners, F., Wen, B.,
Matsushima, S., and d. daniel.voyer@bell.ca, "IPv6 Segment and V. Kozak, "Segment Routing with MPLS Data Plane
Routing Header (SRH)", draft-ietf-6man-segment-routing- Encapsulation for In-situ OAM Data", draft-gandhi-mpls-
header-22 (work in progress), August 2019. ioam-sr-01 (work in progress), December 2019.
[I-D.ietf-spring-segment-routing-policy] [I-D.gandhi-mpls-rfc6374-sr]
Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d., Gandhi, R., Filsfils, C., Voyer, D., Salsano, S., and M.
bogdanov@google.com, b., and P. Mattes, "Segment Routing Chen, "Performance Measurement for Segment Routing
Policy Architecture", draft-ietf-spring-segment-routing- Networks with MPLS Data Plane", draft-gandhi-mpls-
policy-03 (work in progress), May 2019. rfc6374-sr-01 (work in progress), December 2019.
[I-D.li-idr-sr-policy-path-segment-distribution] [I-D.gandhi-spring-twamp-srpm]
Li, C., Chen, M., Dong, J., and Z. Li, "Segment Routing Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Policies for Path Segment and Bidirectional Path", draft- Janssens, "Performance Measurement Using TWAMP Light for
li-idr-sr-policy-path-segment-distribution-01 (work in Segment Routing Networks", draft-gandhi-spring-twamp-
progress), October 2018. srpm-05 (work in progress), December 2019.
[I-D.li-pce-sr-bidir-path] [I-D.ietf-pce-sr-bidir-path]
Li, C., Chen, M., Cheng, W., Li, Z., Dong, J., Gandhi, R., Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
and Q. Xiong, "PCEP Extensions for Associated "PCEP Extensions for Associated Bidirectional Segment
Bidirectional Segment Routing (SR) Paths", draft-li-pce- Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-01 (work
sr-bidir-path-06 (work in progress), August 2019. in progress), February 2020.
[I-D.li-pce-sr-path-segment] [I-D.ietf-pce-sr-path-segment]
Li, C., Chen, M., Cheng, W., Dong, J., Li, Z., Gandhi, R., Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
and Q. Xiong, "Path Computation Element Communication "Path Computation Element Communication Protocol (PCEP)
Protocol (PCEP) Extension for Path Segment in Segment Extension for Path Segment in Segment Routing (SR)",
Routing (SR)", draft-li-pce-sr-path-segment-08 (work in draft-ietf-pce-sr-path-segment-00 (work in progress),
October 2019.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-06 (work in progress),
December 2019.
[I-D.li-idr-sr-policy-path-segment]
Li, C., Telecom, C., Chen, M., Dong, J., and Z. Li, "SR
Policy Extensions for Path Segment and Bidirectional
Path", draft-li-idr-sr-policy-path-segment-01 (work in
progress), August 2019. progress), August 2019.
[RFC4426] Lang, J., Ed., Rajagopalan, B., Ed., and D. Papadimitriou,
Ed., "Generalized Multi-Protocol Label Switching (GMPLS)
Recovery Functional Specification", RFC 4426,
DOI 10.17487/RFC4426, March 2006,
<https://www.rfc-editor.org/info/rfc4426>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
Sprecher, N., and S. Ueno, "Requirements of an MPLS
Transport Profile", RFC 5654, DOI 10.17487/RFC5654,
September 2009, <https://www.rfc-editor.org/info/rfc5654>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with [RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>. May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy Label for Source
Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
DOI 10.17487/RFC8662, December 2019,
<https://www.rfc-editor.org/info/rfc8662>.
[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>.
Acknowledgements
The authors would like to thank Adrian Farrel, Stewart Bryant,
Shuangping Zhan, Alexander Vainshtein, Andrew G. Malis, Ketan
Talaulikar, Shraddha Hegde, and Loa Andersson for their review,
suggestions and comments to this document.
The authors would like to acknowledge the contribution from Alexander
Vainshtein on "Nesting of Path Segments".
Contributors
The following people have substantially contributed to this document:
Cheng Li
Huawei Technologies
EMail: chengli13@huawei.com
Lei Wang
China Mobile
Email: wangleiyj@chinamobile.com
Aihua Liu
ZTE Corp
Email: liu.aihua@zte.com.cn
Greg Mirsky
ZTE Corp
Email: gregimirsky@gmail.com
Authors' Addresses Authors' Addresses
Weiqiang Cheng Weiqiang Cheng
China Mobile China Mobile
Email: chengweiqiang@chinamobile.com Email: chengweiqiang@chinamobile.com
Han Li Han Li
China Mobile China Mobile
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