draft-ietf-idr-sr-policy-path-mtu-00.txt		draft-ietf-idr-sr-policy-path-mtu-01.txt
	skipping to change at page 1, line 14 ¶		skipping to change at page 1, line 14 ¶
	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.
	skipping to change at page 4, line 41 ¶		skipping to change at page 4, line 41 ¶
	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
	skipping to change at page 5, line 34 ¶		skipping to change at page 5, line 44 ¶
	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-
	skipping to change at page 7, line 25 ¶		skipping to change at page 8, line 25 ¶
	[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-
	skipping to change at page 7, line 49 ¶		skipping to change at page 8, line 49 ¶
	[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>.
	skipping to change at page 8, line 26 ¶		skipping to change at page 9, line 31 ¶
	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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