wdiff rfc7917.original rfc7917.txt

IS-IS for IP Internets
Internet Engineering Task Force (IETF) P. Sarkar, Ed.
Internet-Draft H. Gredler
Intended status: Standards Track
Request for Comments: 7917 Individual Contributor
Expires: November 10, 2016
Category: Standards Track H. Gredler
ISSN: 2070-1721 RtBrick Inc.
S. Hegde
Juniper Networks, Inc.
S. Litkowski
B. Decraene
Orange
May 9,
July 2016

Advertising Node Administrative Tags in IS-IS
draft-ietf-isis-node-admin-tag-11

Abstract

This document describes an extension to the IS-IS routing protocol to
add an
advertise node administrative tags. This optional capability that allows
tagging and grouping of the nodes in an IS-IS domain. This allows simple management and easy
control over route and path selection, based on local configured
policies. This document describes an extension to the IS-IS protocol
to advertise node administrative tags. The node
administrative tags can be used to express and apply locally defined
network policies
which is policies, thereby providing a very useful operational
capability. Node administrative tags may be used either by either IS-IS
itself or by other applications consuming information propagated via IS-IS.

This document describes the protocol extensions to disseminate node
administrative tags in IS-IS protocols.

Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. IS-
IS.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on November 10, 2016.
http://www.rfc-editor.org/info/rfc7917.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Node Administrative Tags
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
3.
2. Node Administrative Tag Sub-TLV Tags . . . . . . . . . . . . . . . . . . 3
3. Node Administrative Tag (Node-Admin-Tag) Sub-TLV . . . . . . 3
3.1. TLV format Format . . . . . . . . . . . . . . . . . . . . . . . 4 3
4. Elements of Procedure . . . . . . . . . . . . . . . . . . . . 4
4.1. Interpretation of Node Administrative Tags . . . . . . . 5 4
4.2. Use of Node Administrative Tags . . . . . . . . . . . . . 5
4.3. Processing Node Administrative Tag Changes . . . . . . . 6 5
5. Applications . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6
7. Operational Considerations . . . . . . . . . . . . . . . . . 7
8. Manageability Considerations . . . . . . . . . . . . . . . . 8 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7
10. Contributors . . . . References . . . . . . . . . . . . . . . . . . . . 8
11. Acknowledgments . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
12.
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . 8
12.1. Normative References . . . . . . . . . . . . . . . . . . 8
12.2. Informative References . . . . . . . . . . . . . . . . . 9
12.3. URIs 9
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10

1. Introduction

It is useful to assign a node administrative tag to a router in the
IS-IS domain and use it as an attribute associated with the node.
The node administrative tag can be used in variety of applications,
for applications.
For example:

(a) Traffic-engineering applications to provide different path-
selection
path-selection criteria.

(b) Prefer Preference for, or prune pruning of, certain paths in Loop Free Loop-Free
Alternate (LFA) [RFC5286] backup selection via local policies
as defined in
[I-D.ietf-rtgwg-lfa-manageability]. [RFC7916].

This document provides mechanisms to advertise node administrative
tags in IS-IS for various applications, including (but not limited
to) route and path selection. Route and path selection functionality
applies to both Traffic Engineering (TE) and non-TE applications.
Hence

Hence, the new sub-TLV for carrying node administrative tags is
included in the Router CAPABILITY TLV [RFC4971].

1.1. Requirements Language

2. Node Administrative Tags

An administrative tag is a 32-bit unsigned integer value that can be
used to identify a group of nodes in the IS-IS domain. An IS-IS
router should advertise in the specific IS-IS level the set of groups
of which it is part of in the
specific IS-IS level. a part.

As an example, all edge network devices in a given network may be
configured with a certain tag value, whereas all core network devices
may be configured with another, different tag value.

3. Node Administrative Tag (Node-Admin-Tag) Sub-TLV

The new sub-TLV defined in this document is carried within an IS-IS
Router CAPABILITY TLV (IS-IS TLV type 242) [RFC4971] in the Link
State PDUs originated by the device. Router CAPABILITY TLVs
[RFC4971] can have 'level-
wide' "level-wide" or 'domain-wide' "domain-wide" flooding scope. The
choice of flooding scope in which a specific node administrative tag
shall be flooded, flooded is purely a matter of local policy, policy and is defined by
the needs of the operator's usage. usage needs. An operator MAY choose to advertise a
set of node administrative tags across levels and another different
set of node administrative tags within the specific level.
Alternatively, the operator may use the same node administrative tags both
within both the
'domain-wide' "domain-wide" flooding scope as well as within and one or more 'level-
wide'
"level-wide" flooding scope. scopes.

The format of the Node Administrative Tag (Node-Admin-Tag) sub-TLV
(see Section 3.1) does not include a topology identifier. Therefore Therefore,
it is not possible to indicate a topology-specific context when
advertising node administrative tags. Hence, in deployments using
multi-topology routing [RFC5120], advertising a separate set of node
administrative tags for each topology SHOULD NOT be supported.

3.1. TLV format

[RFC4971], Format

[RFC4971] defines the Router CAPABILITY TLV TLV, which may be used to
advertise properties of the originating router. The payload of the
Router CAPABILITY TLV consists of one or more nested Type/Length/ Type-Length-
Value (TLV) triplets.

The new Node Administrative Tag Node-Admin-Tag sub-TLV, like other IS-IS sub-TLVs, is
formatted as Type/Length/Value (TLV) TLV triplets. Figure 1 below shows the format of the
new sub-TLV.

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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Administrative Tag #N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type : TBA, Suggested value

Type: 21

** RFC Editor** Please replace above suggested value with the IANA-assigned value. (Node-Admin-Tag)

Length: An 8-bit field that indicates the length of the value Value
portion in octets and octets; this will be a multiple of 4-octets
dependent 4 octets,
depending on the number of tags advertised.

Value: A set of multiple 4-octets defining Defines the node administrative tags. tags (Administrative Tag #1,
Administrative Tag #2, etc.). Multiples of 4 octets.

Figure 1: IS-IS Node Administrative Tag sub-TLV Node-Admin-Tag Sub-TLV

4. Elements of Procedure

4.1. Interpretation of Node Administrative Tags

The meaning of node administrative tags is generally opaque to IS-IS.
A router advertising one or more node administrative tag(s) tags may be
configured to do so without knowing (or even explicitly supporting)
the functionality implied by the tag. This section describes general
rules/regulations
rules, regulations, and guidelines for using and interpreting a node
administrative tag which tag; these rules, regulations, and guidelines will
facilitate interoperable implementations by between vendors.

Interpretation of tag values is specific to the administrative domain
of a particular network operator. Hence Hence, tag values SHOULD NOT be
propagated outside the administrative domain to which they apply.
The meaning of a node administrative tag is defined by the network
local policy and is controlled via configuration. If a receiving
node does not understand the tag value, it ignores the specific tag
and floods the Router CAPABILITY TLV without any change, as defined
in [RFC4971].

The semantics of the tag order has no meaning. There is no implied
meaning to the ordering of the tags that indicates a certain
operation or set of operations that need to be performed based on the
ordering.

Each tag SHOULD be treated as an independent identifier that may be
used in a policy to perform a policy action. Each tag carried by the
Node Administrative Tag
Node-Admin-Tag sub-TLVs should be used to indicate a characteristic
of a node that is independent of the characteristics indicated by
other administrative tags within the same instance or another
instance of a Node Administrative Tag Node-Admin-Tag sub-TLV. The list of Node node
administrative tags carried in a Node Administrative Tag Node-Admin-Tag sub-TLV MUST be
considered as an unordered list. Whilst policies may be implemented
based on the presence of multiple tags (e.g., if tag A AND tag B are
present), they MUST NOT be reliant upon the order of the tags (i.e.,
all policies should be considered commutative operations, such that
tag A preceding or following tag B does not change their outcome).

4.2. Use of Node Administrative Tags

The node administrative tags are not meant to be extended by future
IS-IS standards. New IS-IS extensions are not expected to require
the use of node administrative tags or define well-known tag values.
Node administrative tags are for generic use and do not require IANA
registry.
registration. Future IS-IS extensions requiring well-known values
MAY define their own data signalling signaling tailored to the needs of the
feature or MAY use the capability Router CAPABILITY TLV as defined in [RFC4971].

Node administrative tags are expected to be associated with a stable
attribute. In particular, node administrative tags MUST NOT be
associated with something whose state can oscillate frequently, e.g.,
the reachability of a specific destination.

While no specific limit on the number of node administrative tags
that may be advertised has been defined, it is expected that only a
modest number of tags will be required in any deployment.

4.3. Processing Node Administrative Tag Changes

Multiple Node Administrative Tag Node-Admin-Tag sub-TLVs MAY appear in a Router CAPABILITY TLV
TLV, or Node Administrative Tag Node-Admin-Tag sub-TLVs MAY be contained in different
instances of Router CAPABILITY TLVs. The node administrative tags
associated with a node that originates tags for the purpose of any
computation or processing at a receiving node SHOULD be a superset of
node administrative tags from all the TLVs in all the instances of
Router CAPABILITY TLVs received in the Link- Link State PDU(s) advertised
by the corresponding IS-IS router. When a Router CAPABILITY TLV is
received that changes the set of node administrative tags applicable
to any originating node, a receiving node MUST repeat any computation
or processing that makes use of node administrative tags.

When there is a change to, or removal of of, an administrative
affiliation of a node, the node MUST re-originate the Router
CAPABILITY TLV(s) with the latest set of node administrative tags.
On a receiving router, on detecting a change in contents (or removal)
of existing Node
Administrative Tag Node-Admin-Tag sub-TLV(s) or the addition of new Node Administrative
Tag
Node-Admin-Tag sub-TLV(s) in any instance of Router CAPABILITY
TLV(s), implementations MUST take appropriate measures to update
their state according to the changed set of node administrative tags.
The exact actions needed depend will vary, depending on what features working are
associated with node administrative
tags and tags; this topic is outside of the
scope of this specification.

5. Applications

[RFC7777] lists several non-normative examples of how implementations
might use node administrative tags. These examples are given only to
demonstrate the generic usefulness of the router tagging mechanism.
An implementation supporting this specification is not required to
implement any of the use cases. The following is a brief list of
non-normative use cases listed in [RFC7777]. Please refer to RFC7777
section
Section 3 [1] of [RFC7777] for more details.

1. Auto-discovery of Services services

2. Policy-based Fast-Re-Route Fast Reroute (FRR)

(a) Administrative limitation of LFA scope

(b) Optimizing LFA calculations

3. Controlling Remote remote LFA tunnel termination

4. Mobile back-haul backhaul network service deployment

5. Policy-based Explicit Routing explicit routing

6. Security Considerations

This document does not introduce any new security issues. Node
administrative tags, like link administrative tags (a.k.a.
administrative groups) [RFC5305], can be used by operators to
indicate geographical location or other sensitive information. The
information carried in node administrative tags, like link
administrative tags, can be leaked to an IGP snooper. Hence this document does not introduce any new
security issues.

Advertisement of tag values for one administrative domain into
another involves the risk of misinterpretation of the tag values (if
the two domains have assigned different meanings to the same values), values)
and may have undesirable and unanticipated side effects.

Security concerns for IS-IS are already addressed in [ISO10589],
[RFC5304], and [RFC5310] and are applicable to the mechanisms
described in this document. Extended authentication mechanisms
described in [RFC5304] or [RFC5310] SHOULD be used in deployments
where attackers have access to the physical networks and networks, because nodes
included in the IS-IS domain are vulnerable.

7. Operational Considerations

Operators can assign a meaning to the node administrative tags which that
is local to the operator's administrative domain. The operational
use of node administrative tags is analogical to the IS-IS prefix
tags [RFC5130] and BGP communities [RFC1997]. Operational discipline
and procedures followed in configuring and using BGP communities and IS-
IS Prefix
IS-IS prefix tags are also applicable to the usage of node
administrative tags.

Defining a language for local policies is outside the scope of this
document. As in is the case of with other policy applications, the pruning
policies can cause the path to be completely removed from the
forwarding plane, plane and hence have the potential for a more severe
operational
impact on operations (e.g., node unreachability due to path removal) by
comparison
as compared to preference policies that only affect path selection.

8. Manageability Considerations

Node administrative tags are configured and managed using routing
policy enhancements. YANG [RFC6020] is a data modeling language used
to specify configuration data models. The IS-IS YANG data model is
described in [I-D.ietf-isis-yang-isis-cfg] [YANG-ISIS-CFG], and the routing policy configuration
model is described in [I-D.ietf-rtgwg-policy-model]. [RTG-POLICY-MODEL]. At the time of writing
this document, some work to enhance these two
documents, to other documents so that
they include the configurations related to node administrative tag related
configurations, tags is
either already in progress, progress or shall be taken up soon.

9. IANA Considerations

This specification updates one IS-IS registry: IS-IS Router
CAPABILITY (TLV-242) Sub-TLVs Registry

i) Node-Admin-Tag Sub-TLV, Type: TBD, suggested the "Sub-TLVs for
TLV 242" registry. The following value has been registered.

Value Description
----- -----------
21

** RFC Editor** Please replace above suggested value with the IANA-
assigned value. Node-Admin-Tag

10. Contributors

Many many thanks to Ebben Aries and Rafael Rodriguez for their help
with reviewing and improving the text of this document. Many thanks
to Harish Raguveer for his contributions to initial versions of the
draft as well. Finally, many thanks to Li Zhenbin for providing some
valuable use cases.

11. Acknowledgments

Many thanks to Les Ginsberg, Dhruv Dhody, Uma Chunduri, and Chris
Bowers for providing useful inputs.

12. References

12.1.

10.1. Normative References

[ISO10589]
International Organization for Standardization,
"Intermediate system System to Intermediate system System intra-domain
routeing information exchange protocol for use in
conjunction with the protocol for providing the
connectionless-mode Network Service network service (ISO 8473), ISO/IEC
10589:2002, Second Edition.", Nov 8473)",
ISO Standard 10589, 2002.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
"Intermediate System to Intermediate System (IS-IS)
Extensions for Advertising Router Information", RFC 4971,
DOI 10.17487/RFC4971, July 2007,
<http://www.rfc-editor.org/info/rfc4971>.

[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <http://www.rfc-editor.org/info/rfc5304>.

[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <http://www.rfc-editor.org/info/rfc5310>.

12.2.

10.2. Informative References

[I-D.ietf-isis-yang-isis-cfg]
Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L.
Lhotka, "YANG Data Model for IS-IS protocol", draft-ietf-
isis-yang-isis-cfg-08 (work in progress), March 2016.

[I-D.ietf-rtgwg-lfa-manageability]
Litkowski, S., Decraene, B., Filsfils, C., Raza, K., and
M. Horneffer, "Operational management of Loop Free
Alternates", draft-ietf-rtgwg-lfa-manageability-11 (work
in progress), June 2015.

[I-D.ietf-rtgwg-policy-model]
Shaikh, A., Shakir, R., D'Souza, K., and C. Chase,
"Routing Policy Configuration Model for Service Provider
Networks", draft-ietf-rtgwg-policy-model-01 (work in
progress), April 2016.

[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>.

[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<http://www.rfc-editor.org/info/rfc5120>.

[RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy
Control Mechanism in IS-IS Using Administrative Tags",
RFC 5130, DOI 10.17487/RFC5130, February 2008,
<http://www.rfc-editor.org/info/rfc5130>.

[RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
IP Fast Reroute: Loop-Free Alternates", RFC 5286,
DOI 10.17487/RFC5286, September 2008,
<http://www.rfc-editor.org/info/rfc5286>.

[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <http://www.rfc-editor.org/info/rfc5305>.

[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.

[RFC7777] Hegde, S., Shakir, R., Smirnov, A., Li, Z., and B.
Decraene, "Advertising Node Administrative Tags in OSPF",
RFC 7777, DOI 10.17487/RFC7777, March 2016,
<http://www.rfc-editor.org/info/rfc7777>.

12.3. URIs

[1] http://tools.ietf.org/html/rfc7777#section-3

[RFC7916] Litkowski, S., Ed., Decraene, B., Filsfils, C., Raza, K.,
Horneffer, M., and P. Sarkar, "Operational Management of
Loop-Free Alternates", RFC 7916, DOI 10.17487/RFC7916,
July 2016, <http://www.rfc-editor.org/info/rfc7916>.

[RTG-POLICY-MODEL]
Shaikh, A., Shakir, R., D'Souza, K., and C. Chase,
"Routing Policy Configuration Model for Service Provider
Networks", Work in Progress, draft-ietf-rtgwg-policy-
model-01, April 2016.

[YANG-ISIS-CFG]
Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L.
Lhotka, "YANG Data Model for IS-IS protocol", Work in
Progress, draft-ietf-isis-yang-isis-cfg-08, March 2016.

Acknowledgments

Many thanks to Les Ginsberg, Dhruv Dhody, Uma Chunduri, and Chris
Bowers for providing useful inputs.

Contributors

Many many thanks to Ebben Aries and Rafael Rodriguez for their help
with reviewing and improving the text of this document. Many thanks
to Harish Raguveer for his contributions to initial draft versions of
the document as well. Finally, many thanks to Zhenbin Li for
providing some valuable use cases.

Authors' Addresses

Pushpasis Sarkar (editor)
Individual Contributor

Email: pushpasis.ietf@gmail.com

Hannes Gredler
Individual Contributor
RtBrick Inc.

Email: hannes@gredler.at hannes@rtbrick.com

Shraddha Hegde
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India

Email: shraddha@juniper.net

Stephane Litkowski
Orange

Email: stephane.litkowski@orange.com

Bruno Decraene
Orange

Email: bruno.decraene@orange.com