draft-ietf-ospf-segment-routing-msd-21.txt   draft-ietf-ospf-segment-routing-msd-22.txt 
OSPF Working Group J. Tantsura OSPF Working Group J. Tantsura
Internet-Draft Nuage Networks Internet-Draft Apstra, Inc.
Intended status: Standards Track U. Chunduri Intended status: Standards Track U. Chunduri
Expires: March 29, 2019 Huawei Technologies Expires: April 14, 2019 Huawei Technologies
S. Aldrin S. Aldrin
Google, Inc Google, Inc
P. Psenak P. Psenak
Cisco Systems Cisco Systems
September 25, 2018 October 11, 2018
Signaling MSD (Maximum SID Depth) using OSPF Signaling MSD (Maximum SID Depth) using OSPF
draft-ietf-ospf-segment-routing-msd-21 draft-ietf-ospf-segment-routing-msd-22
Abstract Abstract
This document defines a way for an Open Shortest Path First (OSPF) This document defines a way for an Open Shortest Path First (OSPF)
Router to advertise multiple types of supported Maximum SID Depths Router to advertise multiple types of supported Maximum SID(Segment
(MSDs) at node and/or link granularity. Such advertisements allow Identifier) Depths (MSDs) at node and/or link granularity. Such
entities (e.g., centralized controllers) to determine whether a advertisements allow entities (e.g., centralized controllers) to
particular SID stack can be supported in a given network. This determine whether a particular SID stack can be supported in a given
document defines only one type of MSD, but defines an encoding that network. This document defines only one type of MSD, but defines an
can support other MSD types. Here the term OSPF means both OSPFv2 encoding that can support other MSD types. Here the term OSPF means
and OSPFv3. 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
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 29, 2019. This Internet-Draft will expire on April 14, 2019.
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 22 skipping to change at page 2, line 22
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
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 sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5 3. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
4. Using Node and Link MSD Advertisements . . . . . . . . . . . 6 4. Procedures for Defining and Using Node and Link MSD
Advertisements . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9 9.2. Informative References . . . . . . . . . . . . . . . . . 9
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 learns the Maximum SID
Depth (MSD) that can be imposed at each node/link on a given SR path (Segment Identifier) Depth (MSD) that can be imposed at each node/
to insure that the SID stack depth of a computed path doesn't exceed link on a given SR path to ensure that the Segment Identifier (SID)
the number of SIDs the node is capable of imposing. stack depth of a computed path doesn't exceed the number of SIDs the
node is capable of imposing.
Path Computation Element Protocol(PCEP) SR draft [I-D.ietf-pce-segment-routing] defines how to signal MSD in the Path
[I-D.ietf-pce-segment-routing] signals MSD in SR Path Computation Computation Element communication Protocol (PCEP). However, if PCEP
Element Capability TLV and METRIC Object. However, if PCEP is not is not supported/configured on the head-end of an SR tunnel or a
supported/configured on the head-end of an SR tunnel or a Binding-SID Binding-SID anchor node and controller does not participate in IGP
anchor node and controller does not participate in IGP routing, it routing, it has no way to learn the MSD of nodes and links. BGP-LS
has no way to learn 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
[I-D.ietf-idr-bgp-ls-segment-routing-msd]. Typically, BGP-LS is [I-D.ietf-idr-bgp-ls-segment-routing-msd]. Typically, BGP-LS is
configured on a small number of nodes that do not necessarily act as configured on a small number of nodes that do not necessarily act as
head-ends. In order for BGP-LS to signal MSD for all the nodes and head-ends. In order for BGP-LS to signal MSD for all the nodes and
links in the network where MSD is relevant, MSD capabilities should links in the network MSD is relevant, MSD capabilities SHOULD be
be advertised by every OSPF router in the network. advertised by every OSPF router in the network.
Other types of MSD are known to be useful. For example, Other types of MSD are known to be useful. For example,
[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 an Entropy Label (EL) at (RLDC) that is used by a head-end to insert an Entropy Label (EL) at
a depth that can be read by transit nodes. a depth that could be read by transit nodes.
This document defines an extension to OSPF used to advertise one or This document defines an extension to OSPF used to advertise one or
more types of MSD at node and/or link granularity. In the future it more types of MSD at node and/or link granularity. In the future it
is expected, that new MSD types will be defined to signal additional is expected, that new MSD-types will be defined to signal additional
capabilities e.g., entropy labels, SIDs that can be imposed through capabilities e.g., entropy labels, SIDs that can be imposed through
recirculation, or SIDs associated with another dataplane e.g., IPv6. recirculation, or SIDs associated with another dataplane e.g., IPv6.
Although MSD advertisements are associated with Segment Routing, the
advertisements MAY be present even if Segment Routing itself is not MSD advertisements MAY be useful even if Segment Routing itself is
enabled. Note that in a non-SR MPLS network, label depth is what is not enabled. For example, in a non-SR MPLS network, MSD defines the
defined by the MSD advertisements. maximum label depth.
1.1. Terminology 1.1. Terminology
This memo makes use of the terms defined in [RFC7770] This memo makes use of the terms defined in [RFC7770]
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
MSD: Maximum SID Depth - the number of SIDs a node or one of its MSD: Maximum SID Depth - the number of SIDs supported by a node or a
links can support link on a node
SID: Segment Identifier as defined in [RFC8402]
Label Imposition: Imposition is the act of modifying and/or adding
labels to the outgoing label stack associated with a packet. This
includes:
o replacing the label at the top of the label stack with a new label
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
which are replaced and the number of labels which are pushed. See
[RFC3031] for further details.
PCC: Path Computation Client PCC: Path Computation Client
PCE: Path Computation Element PCE: Path Computation Element
PCEP: Path Computation Element Protocol PCEP: Path Computation Element Protocol
SR: Segment Routing SR: Segment Routing
SID: Segment Identifier SID: Segment Identifier
LSA: Link state advertisement LSA: Link state advertisement
RI: OSPF Router Information LSA RI: OSPF Router Information LSA
skipping to change at page 5, line 13 skipping to change at page 5, line 25
scope of the advertisement is specific to the deployment. scope of the advertisement is specific to the deployment.
When multiple Node MSD TLVs are received from a given router, the When multiple Node MSD TLVs are received from a given router, the
receiver MUST use the first occurrence of the TLV in the Router receiver MUST use the first occurrence of the TLV in the Router
Information LSA. If the Node MSD TLV appears in multiple Router Information LSA. If the Node MSD TLV appears in multiple Router
Information LSAs that have different flooding scopes, the Node MSD Information LSAs that have different flooding scopes, the Node MSD
TLV in the Router Information LSA with the area-scoped flooding scope TLV in the Router Information LSA with the area-scoped flooding scope
MUST be used. If the Node MSD TLV appears in multiple Router MUST be used. If the Node MSD TLV appears in multiple Router
Information LSAs that have the same flooding scope, the Node MSD TLV Information LSAs that have the same flooding scope, the Node MSD TLV
in the Router Information (RI) LSA with the numerically smallest in the Router Information (RI) LSA with the numerically smallest
Instance ID MUST be used and subsequent instances of the Node MSD TLV Instance ID MUST be used and other instances of the Node MSD TLV MUST
MUST be ignored. The RI LSA can be advertised at any of the defined be ignored. The RI LSA can be advertised at any of the defined
opaque flooding scopes (link, area, or Autonomous System (AS)). For opaque flooding scopes (link, area, or Autonomous System (AS)). For
the purpose of Node MSD TLV advertisement, area-scoped flooding is the purpose of Node MSD TLV advertisement, area-scoped flooding is
RECOMMENDED. RECOMMENDED.
3. Link MSD sub-TLV 3. Link MSD sub-TLV
The link sub-TLV is defined to carry the MSD of the interface The link sub-TLV is defined to carry the MSD of the interface
associated with the link. MSD values may be learned via a hardware associated with the link. MSD values may be learned via a hardware
API or may be provisioned. API or may be provisioned.
skipping to change at page 6, line 30 skipping to change at page 6, line 40
TLV MUST be used by receiving OSPF routers. This situation SHOULD be TLV MUST be used by receiving OSPF routers. This situation SHOULD be
logged as an error. logged as an error.
If this sub-TLV is advertised multiple times for the same link in If this sub-TLV is advertised multiple times for the same link in
different OSPF Extended Link Opaque LSAs/E-Router-LSAs originated by different OSPF Extended Link Opaque LSAs/E-Router-LSAs originated by
the same OSPF router, the OSPFv2 Extended Link TLV in the OSPFv2 the same OSPF router, the OSPFv2 Extended Link TLV in the OSPFv2
Extended Link Opaque LSA with the smallest Opaque ID or in the OSPFv3 Extended Link Opaque LSA with the smallest Opaque ID or in the OSPFv3
E-Router-LSA with the smallest Link State ID MUST be used by E-Router-LSA with the smallest Link State ID MUST be used by
receiving OSPF routers. This situation MAY be logged as a warning. receiving OSPF routers. This situation MAY be logged as a warning.
4. 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 preference over the Node MSD. When a Link MSD type is MSD MUST take precedence over the Node MSD. When a Link MSD-type is
not signalled but the Node MSD type is, then the value of that Node not signaled but the Node MSD-type is, then the Node MSD-type value
MSD type MUST be considered as the corresponding Link MSD type value. MUST be considered as the MSD value for that link.
In order to increase flooding efficiency, it is RECOMMENDED, that
routers with homogenous Link MSD values advertise just the Node MSD
value.
Information received in an MSD advertisements is to to ensure that In order to increase flooding efficiency, it is RECOMMENDED that
the controller learns the Maximum SID Depth (MSD) that can be imposed routers with homogenous link MSD values advertise just the Node MSD
at each node/link on a given SR path so that the SID stack depth of a value.
computed path doesn't exceed the number of SIDs the node is capable
of imposing
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. However, in some cases 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. IANA Considerations 5. IANA Considerations
This document requests IANA to allocate TLV type (TBD1) from the OSPF This document requests IANA to allocate TLV type (TBD1) from the OSPF
Router Information (RI) TLVs Registry as defined by [RFC7770]. IANA Router Information (RI) TLVs Registry as defined by [RFC7770]. IANA
has allocated the value 12 through the early assignment process. has allocated the value 12 through the early assignment process.
Value Description Reference Value Description Reference
----- --------------- ------------- ----- --------------- -------------
12 Node MSD This document 12 Node MSD This document
skipping to change at page 8, line 8 skipping to change at page 8, line 16
[RFC7684] and [RFC8362] are applicable to this document. [RFC7684] and [RFC8362] are applicable to this document.
Implementations MUST assure that malformed TLV and Sub-TLV defined in Implementations MUST assure that malformed TLV and Sub-TLV defined in
this document are detected and do not provide a vulnerability for this document are detected and do not provide a vulnerability for
attackers to crash the OSPF router or routing process. Reception of attackers to crash the OSPF router or routing process. Reception of
malformed TLV or Sub-TLV SHOULD be counted and/or logged for further malformed TLV or Sub-TLV SHOULD be counted and/or logged for further
analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be rate- analysis. Logging of malformed TLVs and Sub-TLVs SHOULD be rate-
limited to prevent a Denial of Service (DoS) attack (distributed or limited to prevent a Denial of Service (DoS) attack (distributed or
otherwise) from overloading the OSPF control plane. otherwise) from overloading the OSPF control plane.
Advertisement of an incorrect MSD value may result: Advertisement of an incorrect MSD value may have negative
consequences. If the value is smaller than supported, path
If the value is smaller than supported - path computation failing to computation may fail to compute a viable path. If the value is
compute a viable path. larger than supported, an attempt to instantiate a path that can't be
supported by the head-end (the node performing the SID imposition)
If the value is larger than supported - instantiation of a path that may occur.
can't be supported by the head-end (the node performing the SID
imposition).
The MSD discloses capabilities of the nodes (how many SIDs it The presence of this information also may inform an attacker of how
supports), which could provide an indication of the abilities or even to induce any of the aforementioned conditions.
types of the nodes being used. This information could be used to
gain intelligence about devices in the network.
There's no Denial of Service risk specific to this extension, and it There's no Denial of Service risk specific to this extension, and it
is not vulnerable to replay attacks. is not vulnerable to replay attacks.
7. Contributors 7. Contributors
The following people contributed to this document: The following people contributed to this document:
Les Ginsberg Les Ginsberg
skipping to change at page 8, line 46 skipping to change at page 8, line 50
Mizrahi, Stephane Litkowski and Bruno Decraene for their reviews and Mizrahi, Stephane Litkowski and Bruno Decraene for their reviews and
valuable comments. valuable comments.
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.ietf-isis-segment-routing-msd] [I-D.ietf-isis-segment-routing-msd]
Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
"Signaling MSD (Maximum SID Depth) using IS-IS", draft- "Signaling MSD (Maximum SID Depth) using IS-IS", draft-
ietf-isis-segment-routing-msd-16 (work in progress), ietf-isis-segment-routing-msd-19 (work in progress),
September 2018. October 2018.
[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
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[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, <https://www.rfc-editor.org/info/rfc7684>. 2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and [RFC7770] 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 7770, DOI 10.17487/RFC7770, Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <https://www.rfc-editor.org/info/rfc7770>. February 2016, <https://www.rfc-editor.org/info/rfc7770>.
[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>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA) F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>. 2018, <https://www.rfc-editor.org/info/rfc8362>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-idr-bgp-ls-segment-routing-msd] [I-D.ietf-idr-bgp-ls-segment-routing-msd]
Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan, Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
"Signaling MSD (Maximum SID Depth) using Border Gateway "Signaling MSD (Maximum SID Depth) using Border Gateway
Protocol Link-State", draft-ietf-idr-bgp-ls-segment- Protocol Link-State", draft-ietf-idr-bgp-ls-segment-
routing-msd-02 (work in progress), August 2018. routing-msd-02 (work in progress), August 2018.
[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.
skipping to change at page 10, line 30 skipping to change at page 10, line 40
[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>.
Authors' Addresses Authors' Addresses
Jeff Tantsura Jeff Tantsura
Nuage Networks 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
Peter Psenak Peter Psenak
Cisco Systems Cisco Systems
Email: ppsenak@cisco.com Email: ppsenak@cisco.com
 End of changes. 29 change blocks. 
72 lines changed or deleted 86 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/