draft-ietf-idr-sr-policy-path-mtu-00.txt   draft-ietf-idr-sr-policy-path-mtu-01.txt 
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Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Intended status: Standards Track Y. Zhu Intended status: Standards Track Y. Zhu
Expires: October 30, 2020 China Telecom Expires: October 30, 2020 China Telecom
A. Sawaf A. Sawaf
Saudi Telecom Company Saudi Telecom Company
Z. Li Z. Li
Huawei Technologies Huawei Technologies
April 28, 2020 April 28, 2020
Segment Routing Path MTU in BGP Segment Routing Path MTU in BGP
draft-ietf-idr-sr-policy-path-mtu-00 draft-ietf-idr-sr-policy-path-mtu-01
Abstract Abstract
Segment Routing is a source routing paradigm that explicitly Segment Routing is a source routing paradigm that explicitly
indicates the forwarding path for packets at the ingress node. An SR indicates the forwarding path for packets at the ingress node. An SR
policy is a set of candidate SR paths consisting of one or more policy is a set of candidate SR paths consisting of one or more
segment lists with necessary path attributes. However, the path segment lists with necessary path attributes. However, the path
maximum transmission unit (MTU) information for SR path is not maximum transmission unit (MTU) information for SR path is not
available in the SR policy since the SR does not require signaling. available in the SR policy since the SR does not require signaling.
This document defines extensions to BGP to distribute path MTU This document defines extensions to BGP to distribute path MTU
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. SR Policy for Path MTU . . . . . . . . . . . . . . . . . . . 3 3. SR Policy for Path MTU . . . . . . . . . . . . . . . . . . . 3
3.1. SR Path MTU Sub-TLV . . . . . . . . . . . . . . . . . . . 4 3.1. Path MTU Sub-TLV . . . . . . . . . . . . . . . . . . . . 4
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5.1. Huawei's Commercial Delivery . . . . . . . . . . . . . . 6
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 7 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
Segment routing (SR) [RFC8402] is a source routing paradigm that Segment routing (SR) [RFC8402] is a source routing paradigm that
explicitly indicates the forwarding path for packets at the ingress explicitly indicates the forwarding path for packets at the ingress
node. The ingress node steers packets into a specific path according node. The ingress node steers packets into a specific path according
to the Segment Routing Policy ( SR Policy) as defined in to the Segment Routing Policy ( SR Policy) as defined in
[I-D.ietf-spring-segment-routing-policy]. In order to distribute SR [I-D.ietf-spring-segment-routing-policy]. In order to distribute SR
policies to the headend, [I-D.ietf-idr-segment-routing-te-policy] policies to the headend, [I-D.ietf-idr-segment-routing-te-policy]
specifies a mechanism by using BGP. specifies a mechanism by using BGP.
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Policy Name Policy Name
Explicit NULL Label Policy (ENLP) Explicit NULL Label Policy (ENLP)
Segment List Segment List
Weight Weight
Path MTU Path MTU
Segment Segment
Segment Segment
... ...
... ...
3.1. SR Path MTU Sub-TLV 3.1. Path MTU Sub-TLV
An SR Path MTU sub-TLV is an Optional sub-TLV. When it appears, it A Path MTU sub-TLV is an Optional sub-TLV. When it appears, it must
must appear only once at most within a Segment List sub-TLV. If appear only once at most within a Segment List sub-TLV. If multiple
multiple Path MTU sub-TLVs appear within a Segment List sub-TLV, the Path MTU sub-TLVs appear within a Segment List sub-TLV, the NLRI MUST
first one will be processed, and the rest will be ignored. An SR be treated as a malformed NLRI.
Path MTU sub-TLV is associated with an SR path specified by a segment
list sub-TLV or path segment as defined in As per [I-D.ietf-idr-segment-routing-te-policy], when the error
[I-D.ietf-spring-mpls-path-segment] and determined allows for the router to skip the malformed NLRI(s) and
[I-D.li-spring-srv6-path-segment]. It has the following format: continue processing of the rest of the update message, then it MUST
handle such malformed NLRIs as 'Treat-as-withdraw'. This document
does not define new error handling rules for Path MTU sub-TLV, and
the error handling rules defined in
[I-D.ietf-idr-segment-routing-te-policy] apply to this document.
A Path MTU sub-TLV is associated with an SR path specified by a
segment list sub-TLV or a path segment
[I-D.ietf-spring-mpls-path-segment]
[I-D.li-spring-srv6-path-segment]. The Path MTU sub-TLV has the
following format:
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 | RESERVED | | Type | Length | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path MTU | | Path MTU |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. Path MTU sub-TLV Figure 1. Path MTU sub-TLV
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Path MTU: 4 bytes value of path MTU in octets. The value can be Path MTU: 4 bytes value of path MTU in octets. The value can be
calculated by a central controller or other devices based on the calculated by a central controller or other devices based on the
information that learned via IGP of BGP-LS or other means. information that learned via IGP of BGP-LS or other means.
Whenever the path MTU of a physical or logical interface is changed, Whenever the path MTU of a physical or logical interface is changed,
a new SR policy with new path MTU information should be updated a new SR policy with new path MTU information should be updated
accordingly by BGP. accordingly by BGP.
4. Operations 4. Operations
The document does not bring new operation beyong the description of The document does not bring new operation beyond the description of
operations defined in [I-D.ietf-idr-segment-routing-te-policy]. The operations defined in [I-D.ietf-idr-segment-routing-te-policy]. The
existing operations defined in existing operations defined in
[I-D.ietf-idr-segment-routing-te-policy] can apply to this document [I-D.ietf-idr-segment-routing-te-policy] can apply to this document
directly. directly.
Typically but not limit to, the SR policies carrying path MTU Typically but not limit to, the SR policies carrying path MTU
infomation are configured by a controller. infomation are configured by a controller.
After configuration, the SR policies carrying path MTU infomation After configuration, the SR policies carrying path MTU infomation
will be advertised by BGP update messages. The operation of will be advertised by BGP update messages. The operation of
advertisement is the same as defined in advertisement is the same as defined in
[I-D.ietf-idr-segment-routing-te-policy], as well as the receiption. [I-D.ietf-idr-segment-routing-te-policy], as well as the receiption.
The consumer of the SR policies is not the BGP process. The The consumer of the SR policies is not the BGP process. The
operation of sending information to consumers is out of scope of this operation of sending information to consumers is out of scope of this
document. document.
5. IANA Considerations 5. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to [RFC7942].
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
5.1. Huawei's Commercial Delivery
The feature has been implemented on Huawei VRP8.
o Organization: Huawei
o Implementation: Huawei's Commercial Delivery implementation based
on VRP8.
o Description: The implementation has been done.
o Maturity Level: Product
o Contact: guokeqiang@huawei.com
6. IANA Considerations
This document defines a new Sub-TLV in registries "SR Policy List This document defines a new Sub-TLV in registries "SR Policy List
Sub- TLVs" [I-D.ietf-idr-segment-routing-te-policy]: Sub- TLVs" [I-D.ietf-idr-segment-routing-te-policy]:
Value Description Reference Value Description Reference
--------------------------------------------------------------------- ---------------------------------------------------------------------
TBA Path MTU sub-TLV This document TBA Path MTU sub-TLV This document
6. Security Considerations 7. Security Considerations
TBA TBA
7. Contributors 8. Contributors
Jun Qiu Jun Qiu
Huawei Technologies Huawei Technologies
China China
Email: qiujun8@huawei.com Email: qiujun8@huawei.com
8. Acknowledgements 9. Acknowledgements
Authors would like to thank Ketan Talaulikar, Aijun Wang, Weiqiang Authors would like to thank Ketan Talaulikar, Aijun Wang, Weiqiang
Cheng, Huanan Chen, Chongfeng Xie, Stefano Previdi, Taishan Tang, Cheng, Huanan Chen, Chongfeng Xie, Stefano Previdi, Taishan Tang,
Keqiang Guo, Chen Zhang, Susan Hares, Weiguo Hao, Gong Xia, Bing Keqiang Guo, Chen Zhang, Susan Hares, Weiguo Hao, Gong Xia, Bing
Yang, Linda Dunbar, Shunwan Zhuang, Huaimo Chen, Mach Chen, Jingring Yang, Linda Dunbar, Shunwan Zhuang, Huaimo Chen, Mach Chen, Jingring
Xie, Zhibo Hu, Jimmy Dong and Jianwei Mao for their proprefessional Xie, Zhibo Hu, Jimmy Dong and Jianwei Mao for their proprefessional
comments and help. comments and help.
9. References 10. References
9.1. Normative References 10.1. Normative References
[I-D.ietf-idr-segment-routing-te-policy] [I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
Rosen, E., Jain, D., and S. Lin, "Advertising Segment Rosen, E., Jain, D., and S. Lin, "Advertising Segment
Routing Policies in BGP", draft-ietf-idr-segment-routing- Routing Policies in BGP", draft-ietf-idr-segment-routing-
te-policy-08 (work in progress), November 2019. te-policy-08 (work in progress), November 2019.
[I-D.ietf-spring-segment-routing-policy] [I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft- P. Mattes, "Segment Routing Policy Architecture", draft-
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[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>.
9.2. Informative References 10.2. Informative References
[I-D.ietf-spring-mpls-path-segment] [I-D.ietf-spring-mpls-path-segment]
Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler, Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler,
"Path Segment in MPLS Based Segment Routing Network", "Path Segment in MPLS Based Segment Routing Network",
draft-ietf-spring-mpls-path-segment-02 (work in progress), draft-ietf-spring-mpls-path-segment-02 (work in progress),
February 2020. February 2020.
[I-D.li-spring-srv6-path-segment] [I-D.li-spring-srv6-path-segment]
Li, C., Cheng, W., Chen, M., Dhody, D., and R. Gandhi, Li, C., Cheng, W., Chen, M., Dhody, D., and R. Gandhi,
"Path Segment for SRv6 (Segment Routing in IPv6)", draft- "Path Segment for SRv6 (Segment Routing in IPv6)", draft-
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[I-D.zhu-idr-bgp-ls-path-mtu] [I-D.zhu-idr-bgp-ls-path-mtu]
Zhu, Y., Hu, Z., Yan, G., and J. Yao, "BGP-LS Extensions Zhu, Y., Hu, Z., Yan, G., and J. Yao, "BGP-LS Extensions
for Advertising Path MTU", draft-zhu-idr-bgp-ls-path- for Advertising Path MTU", draft-zhu-idr-bgp-ls-path-
mtu-02 (work in progress), January 2020. mtu-02 (work in progress), January 2020.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>. <https://www.rfc-editor.org/info/rfc3209>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., [RFC8201] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201, "Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017, DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>. <https://www.rfc-editor.org/info/rfc8201>.
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China China
Email: chengli13@huawei.com Email: chengli13@huawei.com
YongQing Zhu YongQing Zhu
China Telecom China Telecom
109, West Zhongshan Road, Tianhe District. 109, West Zhongshan Road, Tianhe District.
Guangzhou Guangzhou
China China
Email: zhuyq.gd@chinatelecom.cn Email: zhuyq8@chinatelecom.cn
Ahmed El Sawaf Ahmed El Sawaf
Saudi Telecom Company Saudi Telecom Company
Riyadh Riyadh
Saudi Arabia Saudi Arabia
Email: aelsawaf.c@stc.com.sa Email: aelsawaf.c@stc.com.sa
Zhenbin Li Zhenbin Li
Huawei Technologies Huawei Technologies
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