draft-ietf-isis-segment-routing-msd-19.txt   rfc8491.txt 
IS-IS Working Group J. Tantsura Internet Engineering Task Force (IETF) J. Tantsura
Internet-Draft Apstra, Inc. Request for Comments: 8491 Apstra, Inc.
Intended status: Standards Track U. Chunduri Category: Standards Track U. Chunduri
Expires: April 12, 2019 Huawei Technologies ISSN: 2070-1721 Huawei Technologies
S. Aldrin S. Aldrin
Google, Inc Google, Inc.
L. Ginsberg L. Ginsberg
Cisco Systems Cisco Systems
October 9, 2018 November 2018
Signaling MSD (Maximum SID Depth) using IS-IS Signaling Maximum SID Depth (MSD) Using IS-IS
draft-ietf-isis-segment-routing-msd-19
Abstract Abstract
This document defines a way for an Intermediate System to This document defines a way for an Intermediate System to
Intermediate System (IS-IS) router to advertise multiple types of Intermediate System (IS-IS) router to advertise multiple types of
supported Maximum SID Depths (MSDs) at node and/or link granularity. supported Maximum SID Depths (MSDs) at node and/or link granularity.
Such advertisements allow entities (e.g., centralized controllers) to Such advertisements allow entities (e.g., centralized controllers) to
determine whether a particular SID (Segment ID) stack can be determine whether a particular Segment ID (SID) stack can be
supported in a given network. This document only defines one type of supported in a given network. This document only defines one type of
MSD (Base MPLS Imposition), but defines an encoding that can support MSD: Base MPLS Imposition. However, it defines an encoding that can
other MSD types. This document focuses on MSD use in a Segment support other MSD types. This document focuses on MSD use in a
Routing enabled network, but MSD may also be useful when Segment network that is Segment Routing (SR) enabled, but MSD may also be
Routing is not enabled. useful when SR is not enabled.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on April 12, 2019. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8491.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 32 skipping to change at page 2, line 32
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4 2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
3. Link MSD Advertisement . . . . . . . . . . . . . . . . . . . 5 3. Link MSD Advertisement . . . . . . . . . . . . . . . . . . . 5
4. Procedures for Defining and Using Node and Link MSD 4. Procedures for Defining and Using Node and Link MSD
Advertisements . . . . . . . . . . . . . . . . . . . . . . . 6 Advertisements . . . . . . . . . . . . . . . . . . . . . . . 6
5. Base MPLS Imposition MSD . . . . . . . . . . . . . . . . . . 6 5. Base MPLS Imposition MSD . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 9 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
When Segment Routing (SR) paths are computed by a centralized When Segment Routing (SR) paths are computed by a centralized
controller, it is critical that the controller learns the Maximum SID controller, it is critical that the controller learn the Maximum SID
Depth (MSD) that can be imposed at each node/link of a given SR path Depth (MSD) that can be imposed at each node/link of a given SR path.
to ensure that the Segment Identifier (SID) stack depth of a computed This ensures that the Segment Identifier (SID) stack depth of a
path does not exceed the number of SIDs the node is capable of computed path does not exceed the number of SIDs the node is capable
imposing. of imposing.
[I-D.ietf-pce-segment-routing] defines how to signal MSD in the Path [PCEP-EXT] defines how to signal MSD in the Path Computation Element
Computation Element communication Protocol (PCEP). However, if PCEP Communication Protocol (PCEP). However, if PCEP is not supported/
is not supported/configured on the head-end of an SR tunnel or a configured on the head-end of an SR tunnel or a Binding-SID anchor
Binding-SID anchor node and controller does not participate in IGP node, and the controller does not participate in IGP routing, it has
routing, it has no way to learn the MSD of nodes and links. BGP-LS no way of learning the MSD of nodes and links. BGP-LS (Distribution
(Distribution of Link-State and TE Information using Border Gateway of Link-State and TE Information Using Border Gateway Protocol)
Protocol) [RFC7752] defines a way to expose topology and associated [RFC7752] defines a way to expose topology and associated attributes
attributes and capabilities of the nodes in that topology to a and capabilities of the nodes in that topology to a centralized
centralized controller. MSD signaling by BGP-LS has been defined in controller. MSD signaling by BGP-LS has been defined in [MSD-BGP].
[I-D.ietf-idr-bgp-ls-segment-routing-msd]. Typically, BGP-LS is Typically, BGP-LS is configured on a small number of nodes that do
configured on a small number of nodes that do not necessarily act as not necessarily act as head-ends. In order for BGP-LS to signal MSD
head-ends. In order for BGP-LS to signal MSD for all the nodes and for all the nodes and links in the network for which MSD is relevant,
links in the network MSD is relevant, MSD capabilities SHOULD be MSD capabilities SHOULD be advertised by every Intermediate System to
advertised by every Intermediate System to Intermediate System(IS-IS) Intermediate System (IS-IS) router in the network.
router in the network.
Other types of MSD are known to be useful. For example, Other types of MSDs are known to be useful. For example, [ELC-ISIS]
[I-D.ietf-isis-mpls-elc] defines Readable Label Depth Capability defines Entropy Readable Label Depth (ERLD), which is used by a head-
(RLDC) that is used by a head-end to insert an Entropy Label (EL) at end to insert an Entropy Label (EL) at a depth where it can be read
a depth, that could be read by transit nodes. by transit nodes.
This document defines an extension to IS-IS used to advertise one or This document defines an extension to IS-IS used to advertise one or
more types of MSD at node and/or link granularity. It also creates more types of MSDs at node and/or link granularity. It also creates
an IANA registry for assigning MSD-type identifiers. It also defines an IANA registry for assigning MSD-Type identifiers and defines the
the Base MPLS Imposition MSD-type. In the future it is expected that Base MPLS Imposition MSD-Type. In the future, it is expected that
new MSD-types will be defined to signal additional capabilities e.g., new MSD-Types will be defined to signal additional capabilities,
entropy labels, SIDs that can be imposed through recirculation, or e.g., entropy labels, SIDs that can be imposed through recirculation,
SIDs associated with another dataplane e.g., IPv6. or SIDs associated with another data plane such as IPv6.
MSD advertisements MAY be useful even if Segment Routing itself is MSD advertisements MAY be useful even if Segment Routing itself is
not enabled. For example, in a non-SR MPLS network, MSD defines the not enabled. For example, in a non-SR MPLS network, MSD defines the
maximum label depth. maximum label depth.
1.1. Terminology 1.1. Terminology
BMI: Base MPLS Imposition is the number of MPLS labels which can be BMI: Base MPLS Imposition is the number of MPLS labels that can be
imposed inclusive of all service/transport/special labels imposed inclusive of all service/transport/special labels.
MSD: Maximum SID Depth - the number of SIDs supported by a node or a MSD: Maximum SID Depth is the number of SIDs supported by a node or
link on a node a link on a node.
SID: Segment Identifier as defined in [RFC8402] SID: Segment Identifier is defined in [RFC8402].
Label Imposition: Imposition is the act of modifying and/or adding Label Imposition: Imposition is the act of modifying and/or adding
labels to the outgoing label stack associated with a packet. This labels to the outgoing label stack associated with a packet.
includes: This includes:
o replacing the label at the top of the label stack with a new label * replacing the label at the top of the label stack with a new
label
* pushing one or more new labels onto the label stack
o pushing one or more new labels onto the label stack
The number of labels imposed is then the sum of the number of labels The number of labels imposed is then the sum of the number of labels
which are replaced and the number of labels which are pushed. See that are replaced and the number of labels that are pushed. See
[RFC3031] for further details. [RFC3031] for further details.
1.2. Requirements Language 1.2. 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 BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here . capitals, as shown here.
2. Node MSD Advertisement 2. Node MSD Advertisement
The node MSD sub-TLV is defined within the body of the IS-IS Router The Node MSD sub-TLV is defined within the body of the IS-IS Router
Capability TLV [RFC7981], to carry the provisioned SID depth of the CAPABILITY TLV [RFC7981] to carry the provisioned SID depth of the
router originating the Router Capability TLV. Node MSD is the router originating the IS-IS Router CAPABILITY TLV. Node MSD is the
smallest MSD supported by the node on the set of interfaces smallest MSD supported by the node on the set of interfaces
configured for use by the advertising IGP instance. MSD values may configured for use by the advertising IGP instance. MSD values may
be learned via a hardware API or may be provisioned. be learned via a hardware API or may be provisioned.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | | MSD-Type | MSD-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// ................... // // ................... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | | MSD-Type | MSD-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Node MSD Sub-TLV Figure 1: Node MSD Sub-TLV
Type: 23 (allocated by IANA via the early assignment process) Type: 23
Length: variable (multiple of 2 octets) and represents the total
length of value field.
Value: field consists of one or more pairs of a 1 octet MSD-Type and Length: variable (multiple of 2 octets); represents the total length
1 octet MSD-Value. of the Value field
MSD-Type is a value defined in the IGP MSD-Types registry created by Value: field consists of one or more pairs of a 1-octet MSD-Type and
the IANA Section of this document. 1-octet MSD-Value
MSD-Value is a number in the range of 0-255. For all MSD-Types, 0 MSD-Type: value defined in the "IGP MSD-Types" registry created by
represents lack of the ability to support SID stack of any depth; any the IANA Considerations section of this document Section 6
other value represents that of the node. This value MUST represent MSD-Value: number in the range of 0-255 (for all MSD-Types, 0
the lowest value supported by any link configured for use by the represents the lack of ability to support a SID stack of any depth;
advertising IS-IS instance. any other value represents that of the node. This value MUST
represent the lowest value supported by any link configured for use
by the advertising IS-IS instance.)
This sub-TLV is optional. The scope of the advertisement is specific This sub-TLV is optional. The scope of the advertisement is specific
to the deployment. to the deployment.
If there exist multiple Node MSD advertisements for the same MSD-Type If there exist multiple Node MSD advertisements for the same MSD-Type
originated by the same router, the procedures defined in [RFC7981] originated by the same router, the procedures defined in [RFC7981]
apply. These procedures may result in different MSD values being apply. These procedures may result in different MSD values being
used by (for example) different controllers - but this does not used, for example, by different controllers. This does not, however,
create any interoperability issue. create any interoperability issue.
3. Link MSD Advertisement 3. Link MSD Advertisement
The link MSD sub-TLV is defined for TLVs 22, 23, 25, 141, 222, and The Link MSD sub-TLV is defined for TLVs 22, 23, 25, 141, 222, and
223 to carry the MSD of the interface associated with the link. MSD 223 to carry the MSD of the interface associated with the link. MSD
values may be signaled by the forwarding plane or may be provisioned. values may be signaled by the forwarding plane or may be provisioned.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | | MSD-Type | MSD-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// ................... // // ................... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | | MSD-Type | MSD-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Link MSD Sub-TLV Figure 2: Link MSD Sub-TLV
Type: 15 (allocated by IANA via the early assignment process) Type: 15
Length: variable (multiple of 2 octets) and represents the total
length of value field.
Value: consists of one or more pairs of a 1 octet MSD-Type and 1 Length: variable (multiple of 2 octets); represents the total length
octet MSD-Value. of the Value field
MSD-Type is a value defined in the MSD-Types registry created by the Value: field consists of one or more pairs of a 1-octet MSD-Type and
IANA Section of this document. 1-octet MSD-Value
MSD-Value is a number in the range of 0-255. For all MSD-Types, 0 MSD-Type: value defined in the "IGP MSD-Types" registry created by
represents lack of the ability to support SID stack of any depth; any the IANA Considerations section of this document Section 6
other value represents that of the particular link when used as an MSD-Value: number in the range of 0-255 (for all MSD-Types, 0
outgoing interface. represents the lack of ability to support a SID stack of any depth;
any other value represents that of the particular link when used as
an outgoing interface.)
This sub-TLV is optional. This sub-TLV is optional.
If multiple Link MSD advertisements for the same MSD-Type and the If multiple Link MSD advertisements for the same MSD-Type and the
same link are received, the procedure used to select which copy is same link are received, the procedure to select which copy to use is
used is undefined. undefined.
If the advertising router performs label imposition in the context of If the advertising router performs label imposition in the context of
the ingress interface, it is not possible to meaningfully advertise the ingress interface, it is not possible to meaningfully advertise
per link values. In such a case only the Node MSD SHOULD be per-link values. In such a case, only the Node MSD SHOULD be
advertised. advertised.
4. Procedures for Defining and Using Node and Link MSD Advertisements 4. Procedures for Defining and Using Node and Link MSD Advertisements
When Link MSD is present for a given MSD-type, the value of the Link When Link MSD is present for a given MSD-Type, the value of the Link
MSD MUST take precedence over the Node MSD. When a Link MSD-type is MSD MUST take precedence over the Node MSD. If a Link MSD-Type is
not signaled but the Node MSD-type is, then the Node MSD-type value not signaled, but the Node MSD-Type is, then the Node MSD-Type value
MUST be considered as the MSD value for that link. MUST be considered to be the MSD value for that link.
In order to increase flooding efficiency, it is RECOMMENDED that In order to increase flooding efficiency, it is RECOMMENDED that
routers with homogenous link MSD values advertise just the Node MSD routers with homogenous Link MSD values advertise just the Node MSD
value. value.
The meaning of the absence of both Node and Link MSD advertisements The meaning of the absence of both Node and Link MSD advertisements
for a given MSD-type is specific to the MSD-type. Generally it can for a given MSD-Type is specific to the MSD-Type. Generally, it can
only be inferred that the advertising node does not support only be inferred that the advertising node does not support
advertisement of that MSD-type. However, in some cases the lack of advertisement of that MSD-Type. In some cases, however, the lack of
advertisement might imply that the functionality associated with the advertisement might imply that the functionality associated with the
MSD-type is not supported. The correct interpretation MUST be MSD-Type is not supported. The correct interpretation MUST be
specified when an MSD-type is defined. specified when an MSD-Type is defined.
5. Base MPLS Imposition MSD 5. Base MPLS Imposition MSD
Base MPLS Imposition MSD (BMI-MSD) signals the total number of MPLS Base MPLS Imposition MSD (BMI-MSD) signals the total number of MPLS
labels which can be imposed, including all service/transport/special labels that can be imposed, including all service/transport/special
labels. labels.
Absence of BMI-MSD advertisements indicates solely that the The absence of BMI-MSD advertisements indicates only that the
advertising node does not support advertisement of this capability. advertising node does not support advertisement of this capability.
6. IANA Considerations 6. IANA Considerations
This document requests IANA to allocate a sub-TLV type for the new IANA has allocated a sub-TLV type for the new sub-TLV proposed in
sub TLV proposed in Section 2 of this document from IS-IS Router Section 2 of this document from the "Sub-TLVs for TLV 242 (IS-IS
Capability TLV Registry as defined by [RFC7981]. Router CAPABILITY TLV)" registry as defined by [RFC7981].
IANA has allocated the following value through the early assignment IANA has allocated the following value:
process:
Value Description Reference Value Description Reference
----- --------------- ------------- ----- --------------- -------------
23 Node MSD This document 23 Node MSD This document
Figure 3: Node MSD Figure 3: Node MSD
This document requests IANA to allocate a sub-TLV type as defined in IANA has allocated a sub-TLV type as defined in Section 3 from the
Section 3 from Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223 "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223 (Extended IS
registry. reachability, IS Neighbor Attribute, L2 Bundle Member Attributes,
inter-AS reachability information, MT-ISN, and MT IS Neighbor
Attribute TLVs)" registry.
IANA has allocated the following value through the early assignment IANA has allocated the following value:
process:
Value Description Reference Value Description Reference
----- --------------- ------------- ----- --------------- -------------
15 Link MSD This document 15 Link MSD This document
Figure 4: Link MSD Figure 4: Link MSD
Per TLV information where Link MSD sub-TLV can be part of: Per-TLV information where Link MSD sub-TLV can be part of:
TLV 22 23 25 141 222 223 TLV 22 23 25 141 222 223
--- -------------------- --- --------------------
y y y y y y y y y y y y
Figure 5: TLVs where LINK MSD Sub-TLV can be present Figure 5: TLVs Where LINK MSD Sub-TLV Can Be Present
This document requests creation of an IANA managed registry under the IANA has created an IANA-managed registry titled "IGP MSD-Types"
category of "Interior Gateway Protocol (IGP) Parameters" IANA under the "Interior Gateway Protocol (IGP) Parameters" registry to
registries to identify MSD-types as proposed in Section 2 and identify MSD-Types as proposed in Sections 2 and 3. The registration
Section 3. The registration procedure is "Expert Review" as defined procedure is "Expert Review" as defined in [RFC8126]. Types are an
in [RFC8126]. Suggested registry name is "IGP MSD-Types". Types are unsigned 8-bit number. The following values are defined by this
an unsigned 8 bit number. The following values are defined by this
document: document:
Value Name Reference Value Name Reference
----- --------------------- ------------- ----- --------------------- -------------
0 Reserved This document 0 Reserved This document
1 Base MPLS Imposition MSD This document 1 Base MPLS Imposition MSD This document
2-250 Unassigned This document 2-250 Unassigned
251-254 Experimental Use This document 251-254 Experimental Use This document
255 Reserved This document 255 Reserved This document
Figure 6: MSD-Types Codepoints Registry Figure 6: MSD-Types Codepoints Registry
General guidance for the Designated Experts is as defined in General guidance for the designated experts is defined in [RFC7370].
[RFC7370]
7. Security Considerations 7. Security Considerations
Security considerations as specified by [RFC7981] are applicable to Security considerations as specified by [RFC7981] are applicable to
this document. this document.
Advertisement of an incorrect MSD value may have negative The advertisement of an incorrect MSD value may have negative
consequences. If the value is smaller than supported, path consequences. If the value is smaller than supported, path
computation may fail to compute a viable path. If the value is computation may fail to compute a viable path. If the value is
larger than supported, an attempt to instantiate a path that can't be larger than supported, an attempt to instantiate a path that can't be
supported by the head-end (the node performing the SID imposition) supported by the head-end (the node performing the SID imposition)
may occur. may occur.
The presence of this information also may inform an attacker of how The presence of this information may also inform an attacker of how
to induce any of the aforementioned conditions. to induce any of the aforementioned conditions.
8. Contributors 8. References
The following people contributed to this document:
Peter Psenak
Email: ppsenak@cisco.com
9. Acknowledgements
The authors would like to thank Acee Lindem, Ketan Talaulikar,
Stephane Litkowski and Bruno Decraene for their reviews and valuable
comments.
10. References 8.1. Normative References
10.1. Normative References
[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>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001, DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>. <https://www.rfc-editor.org/info/rfc3031>.
skipping to change at page 9, line 39 skipping to change at page 9, line 28
[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>.
10.2. Informative References 8.2. Informative References
[I-D.ietf-idr-bgp-ls-segment-routing-msd]
Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
"Signaling MSD (Maximum SID Depth) using Border Gateway
Protocol Link-State", draft-ietf-idr-bgp-ls-segment-
routing-msd-02 (work in progress), August 2018.
[I-D.ietf-isis-mpls-elc] [ELC-ISIS] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
Litkowski, "Signaling Entropy Label Capability and Entropy Litkowski, "Signaling Entropy Label Capability and Entropy
Readable Label Depth Using IS-IS", draft-ietf-isis-mpls- Readable Label Depth Using IS-IS", Work in Progress,
elc-06 (work in progress), September 2018. draft-ietf-isis-mpls-elc-06, September 2018.
[I-D.ietf-pce-segment-routing] [MSD-BGP] Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., "Signaling MSD (Maximum SID Depth) using Border Gateway
Protocol Link-State", Work in Progress, draft-ietf-idr-
bgp-ls-segment-routing-msd-02, August 2018.
[PCEP-EXT] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "PCEP Extensions for Segment Routing", and J. Hardwick, "PCEP Extensions for Segment Routing",
draft-ietf-pce-segment-routing-12 (work in progress), June Work in Progress, draft-ietf-pce-segment-routing-13,
2018. October 2018.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
Acknowledgements
The authors would like to thank Acee Lindem, Ketan Talaulikar,
Stephane Litkowski, and Bruno Decraene for their reviews and valuable
comments.
Contributors
The following people contributed to this document:
Peter Psenak
Email: ppsenak@cisco.com
Authors' Addresses Authors' Addresses
Jeff Tantsura Jeff Tantsura
Apstra, Inc. Apstra, Inc.
Email: jefftant.ietf@gmail.com Email: jefftant.ietf@gmail.com
Uma Chunduri Uma Chunduri
Huawei Technologies Huawei Technologies
Email: uma.chunduri@huawei.com Email: uma.chunduri@huawei.com
Sam Aldrin Sam Aldrin
Google, Inc Google, Inc.
Email: aldrin.ietf@gmail.com Email: aldrin.ietf@gmail.com
Les Ginsberg Les Ginsberg
Cisco Systems Cisco Systems
Email: ginsberg@cisco.com Email: ginsberg@cisco.com
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