draft-ietf-ospf-segment-routing-msd-05.txt   draft-ietf-ospf-segment-routing-msd-06.txt 
OSPF Working Group J. Tantsura OSPF Working Group J. Tantsura
Internet-Draft Individual Internet-Draft Individual
Intended status: Standards Track U. Chunduri Intended status: Standards Track U. Chunduri
Expires: December 6, 2017 Huawei Technologies Expires: June 4, 2018 Huawei Technologies
S. Aldrin S. Aldrin
Google, Inc Google, Inc
P. Psenak P. Psenak
Cisco Systems Cisco Systems
June 04, 2017 December 01, 2017
Signaling MSD (Maximum SID Depth) using OSPF Signaling MSD (Maximum SID Depth) using OSPF
draft-ietf-ospf-segment-routing-msd-05 draft-ietf-ospf-segment-routing-msd-06
Abstract Abstract
This document proposes a way to signal Maximum SID Depth (MSD) This document proposes a way to signal Maximum SID Depth (MSD)
supported by a node at node and/or link granularity by an OSPF supported by a node at node and/or link granularity by an OSPF
Router. In a Segment Routing (SR) enabled network a centralized Router. In a Segment Routing (SR) enabled network a centralized
controller that programs SR tunnels needs to know the MSD supported controller that programs SR tunnels needs to know the MSD supported
by the head-end at node and/or link granularity to push the SID stack by the head-end at node and/or link granularity to impose the SID
of an appropriate depth. MSD is relevant to the head-end of a SR stack of an appropriate depth. MSD is relevant to the head-end of a
tunnel or Binding-SID anchor node where Binding-SID expansions might SR tunnel or Binding-SID anchor node where Binding-SID expansions
result in creation of a new SID stack. Here the term OSPF means both might result in creation of a new SID stack. Here the term OSPF
OSPFv2 and OSPFv3. means both OSPFv2 and OSPFv3.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on December 6, 2017. This Internet-Draft will expire on June 4, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Node MSD TLV . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Node MSD TLV . . . . . . . . . . . . . . . . . . . . . . . . 4
4. LINK MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5 4. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
5. Node MSD vs Link MSD conflict resolution . . . . . . . . . . 5 5. Node MSD vs Link MSD conflict resolution . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 7 10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
skipping to change at page 2, line 51 skipping to change at page 2, line 51
OSPF to signal the MSD of a node or link to a centralized controller. OSPF to signal the MSD of a node or link to a centralized controller.
PCEP SR extensions draft [I-D.ietf-pce-segment-routing] signals MSD PCEP SR extensions draft [I-D.ietf-pce-segment-routing] signals MSD
in SR PCE Capability TLV and METRIC Object. However, if PCEP is not in SR PCE Capability TLV and METRIC Object. However, if PCEP is not
supported/configured on the head-end of a SR tunnel or a Binding-SID supported/configured on the head-end of a SR tunnel or a Binding-SID
anchor node and controller does not participate in IGP routing, it anchor node and controller does not participate in IGP routing, it
has no way to learn the MSD of nodes and links which has been has no way to learn the MSD of nodes and links which has been
configured. BGP-LS [RFC7752] defines a way to expose topology and configured. BGP-LS [RFC7752] defines a way to expose topology and
associated attributes and capabilities of the nodes in that topology associated attributes and capabilities of the nodes in that topology
to a centralized controller. MSD signaling by BGP-LS has been to a centralized controller. MSD signaling by BGP-LS has been
defined in [I-D.tantsura-idr-bgp-ls-segment-routing-msd]. Typically, defined in [I-D.ietf-idr-bgp-ls-segment-routing-msd]. Typically,
BGP-LS is configured on a small number of nodes, that do not BGP-LS is configured on a small number of nodes, that do not
necessarily act as head-ends. In order, for BGP-LS to signal MSD for necessarily act as head-ends. In order, for BGP-LS to signal MSD for
the all nodes and links in the network MSD is relevant, MSD the all nodes and links in the network MSD is relevant, MSD
capabilites SHOULD be distributed to every OSPF router in the capabilites SHOULD be distributed to every OSPF router in the
network. network.
[I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability [I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability
(RLDC) that is used by a head-end to insert Entropy Label (EL) at (RLDC) that is used by a head-end to insert Entropy Label (EL) at
appropriate depth, so it could be read by transit nodes. MSD in appropriate depth, so it could be read by transit nodes. MSD in
contrary signals ability to push SID's stack of a particular depth. contrary signals ability to impose SID's stack of a particular depth.
MSD of type 1 (IANA Registry), called Base MSD is used to signal the MSD of type 1 (IANA Registry), called Base MSD is used to signal the
total number of SIDs a node is capable of imposing, to be used by a total number of SIDs a node is capable of imposing, to be used by a
path computation element/controller. In case, there are additional path computation element/controller. In case, there are additional
labels (e.g. service) that are to be pushed to the stack - this would SIDs (e.g. service) that are to be imposed to the stack - this would
be signaled with an another MSD type (TBD), no adjustment to the Base be signaled with an another MSD type (TBD), no adjustment to the Base
MSD should be made. In the future, new MSD types could be defined to MSD should be made. In the future, new MSD types could be defined to
signal additional capabilities: entropy labels, labels that can be signal additional capabilities: entropy labels, SIDs that can be
pushed thru recirculation, or another dataplane e.g IPv6. imposed thru recirculation, or another dataplane e.g IPv6.
1.1. Conventions used in this document 1.1. Conventions used in this document
1.1.1. Terminology 1.1.1. Terminology
BGP-LS: Distribution of Link-State and TE Information using Border BGP-LS: Distribution of Link-State and TE Information using Border
Gateway Protocol Gateway Protocol
OSPF: Open Shortest Path First OSPF: Open Shortest Path First
skipping to change at page 4, line 27 skipping to change at page 4, line 27
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 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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type and Value ... | Sub-Type and Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
Figure 1: Node MSD TLV Figure 1: Node MSD TLV
The Type (2 bytes) of this TLV is 12 (Suggested value - to be The Type (2 bytes) of this TLV has value of 12.
assigned by IANA).
Length is variable (minimum of 2, multiple of 2 octets) and Length is variable (minimum of 2, multiple of 2 octets) and
represents the total length of value field. represents the total length of value field.
Value field consists of a 1 octet sub-type (IANA Registry) and 1 Value field consists of a 1 octet sub-type (IANA Registry) and 1
octet value. octet value.
Sub-Type 1 (IANA Section), MSD and the Value field contains maximum Sub-Type 1 (IANA Section), MSD and the Value field contains maximum
MSD of the router originating the RI LSA. Node Maximum MSD is a MSD of the router originating the RI LSA. Node Maximum MSD is a
number in the range of 0-254. 0 represents lack of the ability to number in the range of 0-254. 0 represents lack of the ability to
push MSD of any depth; any other value represents that of the node. impose MSD stack of any depth; any other value represents that of the
This value SHOULD represent the lowest value supported by node. node. This value SHOULD represent the lowest value supported by
node.
Other Sub-types other than defined above are reserved for future Other Sub-types other than defined above are reserved for future
extensions. extensions.
This TLV is applicable to OSPFv2 and to OSPFv3 [RFC5838] and is This TLV is applicable to OSPFv2 and to OSPFv3 [RFC5838] and is
optional. The scope of the advertisement is specific to the optional. The scope of the advertisement is specific to the
deployment. deployment.
4. LINK MSD sub-TLV 4. Link MSD sub-TLV
A new sub-TLV called Link MSD sub-TLV is defined to carry the A new sub-TLV called Link MSD sub-TLV is defined to carry the
provisioned SID depth of the interface associated with the link. provisioned SID depth of the interface associated with the link.
0 1 2 3 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 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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-Type and Value ... | Sub-Type and Value ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
Figure 2: Link MSD Sub-TLV Figure 2: Link MSD Sub-TLV
The Type (2 bytes) of this TLV: The Type (2 bytes) of this TLV:
For OSPFv2, the Link level MSD value is advertised as an optional For OSPFv2, the Link level MSD value is advertised as an optional
Sub-TLV of OSPFv2 Extended Link TLV as defined in [RFC7684], and the Sub-TLV of OSPFv2 Extended Link TLV as defined in [RFC7684], and has
value is 5 (Suggested value - to be assigned by IANA) value of 6.
For OSPFv3, the Link level MSD value is advertised as an optional For OSPFv3, the Link level MSD value is advertised as an optional
Sub-TLV of the Router-Link TLV as defined in Sub-TLV of the Router-Link TLV as defined in
[I-D.ietf-ospf-ospfv3-lsa-extend], and the value is 3 (Suggested [I-D.ietf-ospf-ospfv3-lsa-extend], and has value of 3 (Suggested
value - to be assigned by IANA). value - to be assigned by IANA).
Length is variable and similar to what is defined in Section 3. Length is variable and similar to what is defined in Section 3.
Value field consists of a 1 octet sub-type (IANA Registry) and 1 Value field consists of a 1 octet sub-type (IANA Registry) and 1
octet value. octet value.
Sub-Type 1 (IANA Section), MSD and the Value field contains Link MSD Sub-Type 1 (IANA Section), MSD and the Value field contains Link MSD
of the router originating the corresponding LSA as specified for of the router originating the corresponding LSA as specified for
OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-254. 0 OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-254. 0
represents lack of the ability to push MSD of any depth; any other represents lack of the ability to impose MSD stack of any depth; any
value represents that of the particular link MSD value. other value represents that of the particular link MSD value.
Other Sub-types other than defined above are reserved for future Other Sub-types other than defined above are reserved for future
extensions. extensions.
5. Node MSD vs Link MSD conflict resolution 5. Node MSD vs Link MSD conflict resolution
When both Node MSD and Link MSD are present, the value in the Link When both Node MSD and Link MSD are present, the value in the Link
MSD MUST be used. MSD MUST be used.
6. IANA Considerations 6. IANA Considerations
skipping to change at page 7, line 9 skipping to change at page 7, line 9
The authors would like to thank Stephane Litkowski and Bruno Decraene The authors would like to thank Stephane Litkowski and Bruno Decraene
for their reviews and valuable comments. for their reviews and valuable comments.
10. References 10. References
10.1. 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,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July
2007, <http://www.rfc-editor.org/info/rfc4970>. 2007, <https://www.rfc-editor.org/info/rfc4970>.
10.2. Informative References 10.2. Informative References
[I-D.ietf-idr-bgp-ls-segment-routing-msd]
Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
"Signaling Maximum SID Depth using Border Gateway Protocol
Link-State", draft-ietf-idr-bgp-ls-segment-routing-msd-01
(work in progress), October 2017.
[I-D.ietf-ospf-mpls-elc] [I-D.ietf-ospf-mpls-elc]
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 Using Litkowski, "Signaling Entropy Label Capability Using
OSPF", draft-ietf-ospf-mpls-elc-04 (work in progress), OSPF", draft-ietf-ospf-mpls-elc-04 (work in progress),
November 2016. November 2016.
[I-D.ietf-ospf-ospfv3-lsa-extend] [I-D.ietf-ospf-ospfv3-lsa-extend]
Lindem, A., Roy, A., Goethals, D., Vallem, V., and F. Lindem, A., Roy, A., Goethals, D., Vallem, V., and F.
Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3- Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3-
lsa-extend-14 (work in progress), April 2017. lsa-extend-18 (work in progress), November 2017.
[I-D.ietf-pce-segment-routing] [I-D.ietf-pce-segment-routing]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 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-09 (work in progress), draft-ietf-pce-segment-routing-11 (work in progress),
April 2017. November 2017.
[I-D.tantsura-idr-bgp-ls-segment-routing-msd]
Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
"Signaling Maximum SID Depth using Border Gateway Protocol
Link-State", draft-tantsura-idr-bgp-ls-segment-routing-
msd-04 (work in progress), March 2017.
[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and [RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and
R. Aggarwal, "Support of Address Families in OSPFv3", R. Aggarwal, "Support of Address Families in OSPFv3",
RFC 5838, DOI 10.17487/RFC5838, April 2010, RFC 5838, DOI 10.17487/RFC5838, April 2010,
<http://www.rfc-editor.org/info/rfc5838>. <https://www.rfc-editor.org/info/rfc5838>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <http://www.rfc-editor.org/info/rfc7684>. 2015, <https://www.rfc-editor.org/info/rfc7684>.
[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,
<http://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
Authors' Addresses Authors' Addresses
Jeff Tantsura Jeff Tantsura
Individual Individual
Email: jefftant.ietf@gmail.com Email: jefftant.ietf@gmail.com
Uma Chunduri Uma Chunduri
Huawei Technologies Huawei Technologies
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