draft-ietf-isis-mpls-elc-06.txt   draft-ietf-isis-mpls-elc-07.txt 
Network Working Group X. Xu Network Working Group X. Xu
Internet-Draft Alibaba Inc Internet-Draft Alibaba Inc
Intended status: Standards Track S. Kini Intended status: Standards Track S. Kini
Expires: March 29, 2019 Expires: November 15, 2019
S. Sivabalan P. Psenak
C. Filsfils C. Filsfils
Cisco Cisco
S. Litkowski S. Litkowski
Orange Orange
September 25, 2018 May 14, 2019
Signaling Entropy Label Capability and Entropy Readable Label Depth Signaling Entropy Label Capability and Entropy Readable Label Depth
Using IS-IS Using IS-IS
draft-ietf-isis-mpls-elc-06 draft-ietf-isis-mpls-elc-07
Abstract Abstract
Multiprotocol Label Switching (MPLS) has defined a mechanism to load Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
balance traffic flows using Entropy Labels (EL). An ingress Label balance traffic flows using Entropy Labels (EL). An ingress Label
Switching Router (LSR) cannot insert ELs for packets going into a Switching Router (LSR) cannot insert ELs for packets going into a
given tunnel unless an egress LSR has indicated via signaling that it given Label Switched Path (LSP) unless an egress LSR has indicated
has the capability of processing ELs, referred to as Entropy Label via signaling that it has the capability of processing ELs, referred
Capability (ELC), on that tunnel. In addition, it would be useful to as Entropy Label Capability (ELC), on that tunnel. In addition,
for ingress LSRs to know each LSR's capability of reading the maximum it would be useful for ingress LSRs to know each LSR's capability of
label stack depth and performing EL-based load-balancing, referred to reading the maximum label stack depth and performing EL-based load-
as Entropy Readable Label Depth (ERLD), in the cases where stacked balancing, referred to as Entropy Readable Label Depth (ERLD). This
LSPs are used for whatever reasons. This document defines mechanisms document defines a mechanism to signal these two capabilities using
to signal these two capabilities using IS-IS. These mechanisms are IS-IS. These mechanisms are particularly useful, where label
useful when the label advertisement is also done via IS-IS. In advertisements are done via protocols like IS-IS.
addition, this document introduces the Non-IGP Functional
Capabilities Sub-TLV for advertising IS-IS router's actual non-IGP
functional capabilities. ELC is one of such non-IGP functional
capabilities.
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.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Non-IGP Functional Capabilities Sub-TLV . . . . . . . . . . . 3 3. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 3
4. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 4 4. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3
5. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
[RFC6790] describes a method to load balance Multiprotocol Label [RFC6790] describes a method to load-balance Multiprotocol Label
Switching (MPLS) traffic flows using Entropy Labels (EL). [RFC6790] Switching (MPLS) traffic flows using Entropy Labels (EL). "The Use
introduces the concept of Entropy Label Capability (ELC) and defines of Entropy Labels in MPLS Forwarding" [RFC6790] introduces the
the signalings of this capability via MPLS signaling protocols. concept of Entropy Label Capability (ELC) and defines the signalings
Recently, mechanisms are being defined to signal labels via link- of this capability via MPLS signaling protocols. Recently,
state Interior Gateway Protocols (IGP) such as IS-IS mechanisms have been defined to signal labels via link-state Interior
Gateway Protocols (IGP) such as IS-IS
[I-D.ietf-isis-segment-routing-extensions]. In such scenario, the [I-D.ietf-isis-segment-routing-extensions]. In such scenario, the
signaling mechanisms defined in [RFC6790] are inadequate. This draft defined signaling mechanisms are inadequate. This draft defines a
defines a mechanism to signal the ELC [RFC6790] using IS-IS. This mechanism to signal the ELC using IS-IS. This mechanism is useful
mechanism is useful when the label advertisement is also done via IS- when the label advertisement is also done via IS-IS.
IS.
In addition, in the cases where stacked LSPs are used for whatever In addition, in the cases where stacked LSPs are used for whatever
reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it
would be useful for ingress LSRs to know each intermediate LSR's would be useful for ingress LSRs to know each intermediate LSR's
capability of reading the maximum label stack depth and performing capability of reading the maximum label stack depth and performing
EL-based load-balancing. This capability, referred to as Entropy EL-based load-balancing. This capability, referred to as Entropy
Readable Label Depth (ERLD) as defined in Readable Label Depth (ERLD) as defined in
[I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to [I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to
determine whether it's necessary to insert an EL for a given LSP of determine whether it's necessary to insert an EL for a given LSP in
the stacked LSP tunnel in the case where there has already been at the case where there has already been at least one EL in the label
least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label]. stack [I-D.ietf-mpls-spring-entropy-label].
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC6790] and [RFC4971]. This memo makes use of the terms defined in [RFC6790] and [RFC4971].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
3. Non-IGP Functional Capabilities Sub-TLV capitals, as shown here.
This document defines the Non-IGP Functional Capabilities Sub-TLV
with Sub-TLV type of TBD1 within the body of the IS-IS Router
Capability TLV. An IS-IS router advertising an IS-IS Router
Capability TLV MAY include the Non-IGP Functional Capabilities Sub-
TLV. The Sub-TLV MUST reflect the advertising IS-IS router's actual
non-IGP functional capabilities in the flooding scope of the
containing Router Capability TLV.
The format of the Router Non-IGP Functional Capabilities Sub-TLV is
as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD1 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Non-IGP Functional Capabilities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Non-IGP Functional Capabilities Sub-TLV Format
Type: TBD1.
Length: Indicates the length of the value portion in octets and 3. Advertising ERLD Using IS-IS
will be a multiple of 4 octets dependent on the number of
capabilities advertised. Initially, the length will be 4,
denoting 4 octets of non-IGP functional capability bits.
Value: A variable-length sequence of capability bits rounded to a A new MSD-type of the Node MSD sub-TLV [RFC8491], called ERLD is
multiple of 4 octets padded with undefined bits. Initially, there defined to advertise the ERLD of a given router. As shown in
are 4 octets of capability bits. Bits are numbered left to right Figure 2, it is formatted as described in [RFC8491] with a new MSD-
starting with the most significant bit being bit 0. Type code to be assigned by IANA (the type code of 2 is desired) and
the Value field is set to the ERLD in the range between 0 to 255.
The scope of the advertisement depends on the application. If a
router has multiple linecards with different capabilities of reading
the maximum label stack depth, the router MUST advertise the smallest
one.
The Non-IGP Functional Capabilities Sub-TLV MAY be followed by 0 1 2 3
optional Sub-TLVs that further specify a non-IGP functional 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
capability. The specifications for non-IGP functional capabilities +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
advertised in this Sub-TLV MUST describe protocol behavior and | MSD-Type=TBD2 | ERLD |
address backwards compatibility. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: ERLD MSD-Type Format
4. Advertising ELC Using IS-IS 4. Advertising ELC Using IS-IS
One bit of the Non-IGP Functional Capability Bits (Bit 0 is desired) Even though ELC is a property of the node, in some cases it is
is to be assigned by the IANA for the ELC [RFC6790]. If a router has advantageous to associate and advertise the ELC with a prefix. In a
multiple line cards, the router MUST NOT announce the ELC [RFC6790] multi-area network, routers may not know the identity of the prefix
unless all of its linecards are capable of processing ELs. originator in the remote area, or may not know the capabilities of
such originator. Similarly in a multi-domain network, the identity
of the prefix originator and its capabilities may not be known to the
ingress LSR.
How to apply the ELC advertisement to the inter-area, inter-AS and One bit of the "Bit Values for Prefix Attribute Flags Sub-TLV"
inter-protocol scenarios is outside the scope of this document. registry defined in [RFC7794] (Bit 3 is desired) is to be assigned by
the IANA for the ELC. If a router has multiple line cards, the
router MUST NOT announce the ELC for any prefixes that are locally
attached unless all of its linecards are capable of processing ELs.
5. Advertising ERLD Using IS-IS If a router supports ELs on all of its linecards, it SHOULD set the
ELC for every local host prefix it advertises in IS-IS.
A new MSD-type of the Node MSD sub-TLV When a router leaks a prefix between two levels (upwards or
[I-D.ietf-isis-segment-routing-msd], called ERLD is defined to downwards), it MUST preserve the ELC signalling for this prefix.
advertise the ERLD of a given router. As shown in Figure 2, it is
formatted as described in [I-D.ietf-isis-segment-routing-msd] with a
new MSD-Type code to be assigned by IANA (the type code of 2 is
desired) and the Value field is set to the ERLD in the range between
0 to 255. The scope of the advertisement depends on the application.
If a router has multiple linecards with different capabilities of
reading the maximum label stack deepth, the router MUST advertise the
smallest one.
0 1 2 3 0 1 2 3 4 5 6 7...
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 +-+-+-+-+-+-+-+-+...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |X|R|N|E| ...
| MSD-Type=TBD2 | ERLD | +-+-+-+-+-+-+-+-+...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: ERLD MSD-Type Format
6. Acknowledgements When redistributing a prefix between two IS-IS protocol instances or
redistributed from another protocol to an IS-IS protocol instance, a
router SHOULD preserve the ELC signalling for that prefix. The exact
mechanism on how to exchange ELC between protocol instances running
on an ASBR is outside of the scope of this document and is
implementation specific.
5. Acknowledgements
The authors would like to thank Yimin Shen, George Swallow, Acee The authors would like to thank Yimin Shen, George Swallow, Acee
Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno Decraene Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno Decraene
and Carlos Pignataro for their valuable comments. Carlos Pignataro, Wim Hendrickx, and Gunter Van De Velde for their
valuable comments.
7. IANA Considerations
This document requests IANA to allocate one sub-TLV type of the
Router Capability TLV registry for the Non-IGP Functional
Capabilities Sub-TLV. Futhermore, this document requests IANA to
creat a subregistry for "Non-IGP Functional Capability Bits" within
the "Interior Gateway Protocol (IGP) Parameters" registry. This
subregistry is comprised of the fields Bit Number, Capability Name,
and Reference. Initially, one bit is reqested to be assigned for the
ELC. The registration procedure is "Expert Review" as defined in
[RFC8126]. The following values are defined by this document:
Bit No. Capability Name Reference 6. IANA Considerations
----- --------------------- -------------
0 ELC This document
1-31 Unassigned This document
Figure 3: Non-IGP Functional Capability Bits Registry IANA is requested to allocate the E-bit (bit position 3 is desired)
from the "Bit Values for Prefix Attribute Flags Sub-TLV" registry.
IANA is requested to allocate a MSD type (the type code of 2 is IANA is requested to allocate a MSD type (the type code of 2 is
desired) from the "IGP MSD Types" registry for ERLD. desired) from the "IGP MSD Types" registry for ERLD.
8. Security Considerations 7. Security Considerations
The security considerations as described in [RFC4971] is applicable The security considerations as described in [RFC4971] are applicable
to this document. This document does not introduce any new security to this document. This document does not introduce any new security
risk. risks.
9. References
9.1. Normative References 8. Normative References
[I-D.ietf-isis-segment-routing-extensions] [I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, Gredler, H., and B. Decraene, "IS-IS Extensions for
"IS-IS Extensions for Segment Routing", draft-ietf-isis- Segment Routing", draft-ietf-isis-segment-routing-
segment-routing-extensions-19 (work in progress), July extensions-24 (work in progress), April 2019.
2018.
[I-D.ietf-isis-segment-routing-msd] [I-D.ietf-mpls-spring-entropy-label]
Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
"Signaling MSD (Maximum SID Depth) using IS-IS", draft- Shakir, R., and J. Tantsura, "Entropy label for SPRING
ietf-isis-segment-routing-msd-16 (work in progress), tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in
September 2018. progress), July 2018.
[I-D.ietf-spring-segment-routing-mpls] [I-D.ietf-spring-segment-routing-mpls]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-14 data plane", draft-ietf-spring-segment-routing-mpls-22
(work in progress), June 2018. (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>.
[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed., [RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
"Intermediate System to Intermediate System (IS-IS) "Intermediate System to Intermediate System (IS-IS)
Extensions for Advertising Router Information", RFC 4971, Extensions for Advertising Router Information", RFC 4971,
DOI 10.17487/RFC4971, July 2007, DOI 10.17487/RFC4971, July 2007,
skipping to change at page 6, line 41 skipping to change at page 5, line 47
[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <https://www.rfc-editor.org/info/rfc7794>. March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
9.2. Informative References [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[I-D.ietf-mpls-spring-entropy-label] [RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
Shakir, R., and J. Tantsura, "Entropy label for SPRING DOI 10.17487/RFC8491, November 2018,
tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in <https://www.rfc-editor.org/info/rfc8491>.
progress), July 2018.
Authors' Addresses Authors' Addresses
Xiaohu Xu Xiaohu Xu
Alibaba Inc Alibaba Inc
Email: xiaohu.xxh@alibaba-inc.com Email: xiaohu.xxh@alibaba-inc.com
Sriganesh Kini Sriganesh Kini
Email: sriganeshkini@gmail.com Email: sriganeshkini@gmail.com
Siva Sivabalan Peter Psenak
Cisco Cisco
Email: msiva@cisco.com Email: ppsenak@cisco.com
Clarence Filsfils Clarence Filsfils
Cisco Cisco
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
Stephane Litkowski Stephane Litkowski
Orange Orange
Email: stephane.litkowski@orange.com Email: stephane.litkowski@orange.com
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