draft-ietf-isis-te-app-07.txt   draft-ietf-isis-te-app-08.txt 
Networking Working Group L. Ginsberg Networking Working Group L. Ginsberg
Internet-Draft P. Psenak Internet-Draft P. Psenak
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: April 6, 2020 S. Previdi Expires: April 19, 2020 S. Previdi
Huawei Huawei
W. Henderickx W. Henderickx
Nokia Nokia
J. Drake J. Drake
Juniper Networks Juniper Networks
October 4, 2019 October 17, 2019
IS-IS TE Attributes per application IS-IS TE Attributes per application
draft-ietf-isis-te-app-07 draft-ietf-isis-te-app-08
Abstract Abstract
Existing traffic engineering related link attribute advertisements Existing traffic engineering related link attribute advertisements
have been defined and are used in RSVP-TE deployments. Since the have been defined and are used in RSVP-TE deployments. Since the
original RSVP-TE use case was defined, additional applications (e.g., original RSVP-TE use case was defined, additional applications (e.g.,
SRTE, LFA) have been defined which also make use of the link SRTE, LFA) have been defined which also make use of the link
attribute advertisements. In cases where multiple applications wish attribute advertisements. In cases where multiple applications wish
to make use of these link attributes the current advertisements do to make use of these link attributes the current advertisements do
not support application specific values for a given attribute nor do not support application specific values for a given attribute nor do
skipping to change at page 2, line 12 skipping to change at page 2, line 12
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 April 6, 2020. This Internet-Draft will expire on April 19, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 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.
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 43 skipping to change at page 2, line 43
3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4 3. Legacy Advertisements . . . . . . . . . . . . . . . . . . . . 4
3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4 3.1. Legacy sub-TLVs . . . . . . . . . . . . . . . . . . . . . 4
3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5 3.2. Legacy SRLG Advertisements . . . . . . . . . . . . . . . 5
4. Advertising Application Specific Link Attributes . . . . . . 5 4. Advertising Application Specific Link Attributes . . . . . . 5
4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 6 4.1. Application Identifier Bit Mask . . . . . . . . . . . . . 6
4.2. Application Specific Link Attributes sub-TLV . . . . . . 8 4.2. Application Specific Link Attributes sub-TLV . . . . . . 8
4.2.1. Special Considerations for Maximum Link Bandwidth . . 9 4.2.1. Special Considerations for Maximum Link Bandwidth . . 9
4.2.2. Special Considerations for Unreserved Bandwidth . . . 9 4.2.2. Special Considerations for Unreserved Bandwidth . . . 9
4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 9 4.3. Application Specific SRLG TLV . . . . . . . . . . . . . . 9
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 10 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 10
6. Attribute Advertisements and Enablement . . . . . . . . . . . 11 5.1. Use of Legacy Advertisements . . . . . . . . . . . . . . 11
5.2. Use of Zero Length Application Identifier Bit Masks . . . 11
6. Attribute Advertisements and Enablement . . . . . . . . . . . 12
7. Interoperability, Backwards Compatibility and Migration 7. Interoperability, Backwards Compatibility and Migration
Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1. RSVP-TE only deployments . . . . . . . . . . . . . . . . 12 7.1. Multiple Applications: Common Attributes with RSVP-TE . 13
7.2. Multiple Applications: Common Attributes with RSVP-TE . 12 7.2. Multiple Applications: All Attributes Not Shared w RSVP-
7.3. Multiple Applications: All Attributes Not Shared w RSVP- TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.3. Use of Application Specific Advertisements for RSVP-TE . 14
7.4. Use of Application Specific Advertisements for RSVP-TE . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
11.1. Normative References . . . . . . . . . . . . . . . . . . 15 11.1. Normative References . . . . . . . . . . . . . . . . . . 16
11.2. Informative References . . . . . . . . . . . . . . . . . 16 11.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
Advertisement of link attributes by the Intermediate-System-to- Advertisement of link attributes by the Intermediate-System-to-
Intermediate-System (IS-IS) protocol in support of traffic Intermediate-System (IS-IS) protocol in support of traffic
engineering (TE) was introduced by [RFC5305] and extended by engineering (TE) was introduced by [RFC5305] and extended by
[RFC5307], [RFC6119], and [RFC8570]. Use of these extensions has [RFC5307], [RFC6119], and [RFC8570]. Use of these extensions has
been associated with deployments supporting Traffic Engineering over been associated with deployments supporting Traffic Engineering over
Multiprotocol Label Switching (MPLS) in the presence of Resource Multiprotocol Label Switching (MPLS) in the presence of Resource
Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE. Reservation Protocol (RSVP) - more succinctly referred to as RSVP-TE.
skipping to change at page 6, line 16 skipping to change at page 6, line 16
Identification of the set of applications associated with link Identification of the set of applications associated with link
attribute advertisements utilizes two bit masks. One bit mask is for attribute advertisements utilizes two bit masks. One bit mask is for
standard applications where the definition of each bit is defined in standard applications where the definition of each bit is defined in
a new IANA controlled registry. A second bit mask is for non- a new IANA controlled registry. A second bit mask is for non-
standard User Defined Applications(UDAs). standard User Defined Applications(UDAs).
The encoding defined below is used by both the Application Specific The encoding defined below is used by both the Application Specific
Link Attributes sub-TLV and the Application Specific SRLG TLV. Link Attributes sub-TLV and the Application Specific SRLG TLV.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +--+--+--+--+--+--+--+--+
| SABML+F | 1 octet | SABM Length + Flag | 1 octet
+-+-+-+-+-+-+-+-+ +--+--+--+--+--+--+--+--+
| UDABML+F | 1 octet | UDABM Length + Flag | 1 octet
+-+-+-+-+-+-+-+-+ +--+--+--+--+--+--+--+--+
| SABM ... 0 - 127 octets | SABM ... 0 - 127 octets
+-+-+-+-+-+-+-+-+ +--+--+--+--+--+--+--+--+
| UDABM ... 0 - 127 octets | UDABM ... 0 - 127 octets
+-+-+-+-+-+-+-+-+ +--+--+--+--+--+--+--+--+
SABML+F (1 octet) SABM Length + Flag (1 octet)
Standard Application Identifier Bit Mask Standard Application Identifier Bit Mask
Length/Flags Length + Flag
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|L| SA-Length | |L| SABM Length |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
L-flag: When set, applications listed (both Standard L-flag: When set, applications listed (both Standard
and User Defined) MUST use the legacy advertisements and User Defined) MUST use the legacy advertisements
for the corresponding link found in TLVs 22, 23, for the corresponding link found in TLVs 22, 23,
25, 141, 222, and 223 or TLV 138 or TLV 139 as 25, 141, 222, and 223 or TLV 138 or TLV 139 as
appropriate. appropriate.
SA-Length: Indicates the length in octets (0-127) of the Bit Mask SABM Length: Indicates the length in octets (0-127) of the
for Standard Applications. Bit Mask for Standard Applications.
UDABML+F (1 octet) UDABM Length + Flag (1 octet)
User Defined Application Identifier Bit Mask User Defined Application Identifier Bit Mask
Length/Flags Length + Flag
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|R| UDA-Length | |R| UDABM Length|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
R: Reserved. SHOULD be transmitted as 0 and R: Reserved. SHOULD be transmitted as 0 and
MUST be ignored on receipt MUST be ignored on receipt
UDA-Length: Indicates the length in octets (0-127) of the Bit Mask UDABM Length: Indicates the length in octets (0-127) of the
for User Defined Applications. Bit Mask for User Defined Applications.
SABM (variable length) SABM (variable length)
Standard Application Identifier Bit Mask Standard Application Identifier Bit Mask
(SA-Length * 8) bits (SABM Length * 8) bits
This is omitted if SA-Length is 0. This is omitted if SABM Length is 0.
0 1 2 3 4 5 6 7 ... 0 1 2 3 4 5 6 7 ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
|R|S|F| ... |R|S|F| ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
R-bit: Set to specify RSVP-TE R-bit: Set to specify RSVP-TE
S-bit: Set to specify Segment Routing S-bit: Set to specify Segment Routing
Traffic Engineering Traffic Engineering (SRTE)
F-bit: Set to specify Loop Free Alternate F-bit: Set to specify Loop Free Alternate (LFA)
(includes all LFA types) (includes all LFA types)
UDABM (variable length) UDABM (variable length)
User Defined Application Identifier Bit Mask User Defined Application Identifier Bit Mask
(UDA-Length * 8) bits (UDABM Length * 8) bits
0 1 2 3 4 5 6 7 ... 0 1 2 3 4 5 6 7 ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
| ... | ...
+-+-+-+-+-+-+-+-+... +-+-+-+-+-+-+-+-+...
This is omitted if UDA-Length is 0. This is omitted if UDABM Length is 0.
NOTE: If both SA-length and UDA-Length are zero, then the NOTE: If both SABM Length and UDABM Length are zero, then the
attributes associated with this Attribute Identifier Bit Mask attributes associated with this Attribute Identifier Bit Mask
MAY be used by any Standard Application and any User Defined MAY be used by any Standard Application and any User Defined
Application. Application.
Standard Application Identifier Bits are defined/sent starting with Standard Application Identifier Bits are defined/sent starting with
Bit 0. Additional bit definitions that may be defined in the future Bit 0. Additional bit definitions that may be defined in the future
SHOULD be assigned in ascending bit order so as to minimize the SHOULD be assigned in ascending bit order so as to minimize the
number of octets that will need to be transmitted. Undefined bits number of octets that will need to be transmitted. Undefined bits
MUST be transmitted as 0 and MUST be ignored on receipt. Bits that MUST be transmitted as 0 and MUST be ignored on receipt. Bits that
are NOT transmitted MUST be treated as if they are set to 0 on are NOT transmitted MUST be treated as if they are set to 0 on
skipping to change at page 10, line 46 skipping to change at page 10, line 46
the corresponding legacy TLV (see Section 3.2) can be identified and the corresponding legacy TLV (see Section 3.2) can be identified and
the SRLG values advertised in the legacy TLV MUST be used by the set the SRLG values advertised in the legacy TLV MUST be used by the set
of applications specified in the Application Identifier Bit Mask. of applications specified in the Application Identifier Bit Mask.
For a given application, the setting of the L-flag MUST be the same For a given application, the setting of the L-flag MUST be the same
in all TLVs for a given link. In cases where this constraint is in all TLVs for a given link. In cases where this constraint is
violated, the L-flag MUST be considered set for this application. violated, the L-flag MUST be considered set for this application.
5. Deployment Considerations 5. Deployment Considerations
This section discuss deployment considerations associated with the
use of application specific link attribute advertisements.
5.1. Use of Legacy Advertisements
Bit Identifers for Standard Applications are defined in Section 4.1.
All of the identifiers defined in this document are associated with
applications which were already deployed in some networks prior to
the writing of this document. Therefore, such applications have been
deployed using the legacy advertisements. The Standard Applications
defined in this document MAY continue to use legacy advertisements
for a given link so long as at least one of the following conditions
is true:
o The application is RSVP-TE
o The application is SRTE or LFA and RSVP-TE is not deployed
anywhere in the network
o The application is SRTE or LFA, RSVP-TE is deployed in the
network, and both the set of links on which SRTE and/or LFA
advertisements are required and the attribute values used by SRTE
and/or LFA on all such links is fully congruent with the links and
attribute values used by RSVP-TE
Under the conditions defined above, implementations which support the
extensions defined in this document have the choice of using legacy
advertisements or application specific advertisements in support of
SRTE and/or LFA. This will require implementations to provide
controls specifying which type of advertisements are to be sent/
processed on receive for these applications. Further discussion of
the associated issues can be found in Section 7.
New applications which future documents define to make use of the
advertisements defined in this document MUST NOT make use of legacy
advertisements.
5.2. Use of Zero Length Application Identifier Bit Masks
If link attributes are advertised associated with zero length If link attributes are advertised associated with zero length
Application Identifier Bit Masks for both standard applications and Application Identifier Bit Masks for both standard applications and
user defined applications, then that set of link attributes MAY be user defined applications, then that set of link attributes MAY be
used by any application. If support for a new application is used by any application. If support for a new application is
introduced on any node in a network in the presence of such introduced on any node in a network in the presence of such
advertisements, these advertisements MAY be used by the new advertisements, these advertisements MAY be used by the new
application. If this is not what is intended, then existing application. If this is not what is intended, then existing
advertisements MUST be readvertised with an explicit set of advertisements MUST be readvertised with an explicit set of
applications specified before a new application is introduced. applications specified before a new application is introduced.
skipping to change at page 11, line 19 skipping to change at page 12, line 17
This document defines extensions to support the advertisement of This document defines extensions to support the advertisement of
application specific link attributes. application specific link attributes.
Whether the presence of link attribute advertisements for a given Whether the presence of link attribute advertisements for a given
application indicates that the application is enabled on that link application indicates that the application is enabled on that link
depends upon the application. Similarly, whether the absence of link depends upon the application. Similarly, whether the absence of link
attribute advertisements indicates that the application is not attribute advertisements indicates that the application is not
enabled depends upon the application. enabled depends upon the application.
In the case of RSVP-TE, the advertisement of application specific In the case of RSVP-TE, the advertisement of application specific
link attributes implies that RSVP is enabled on that link. link attributes implies that RSVP is enabled on that link. The
absence of RSVP-TE application specific link attributes in
combination with the absence of legacy advertisements implies that
RSVP is NOT enabled on that link.
In the case of SRTE, advertisement of application specific link In the case of SRTE, advertisement of application specific link
attributes does NOT indicate enablement of SRTE. The advertisements attributes does NOT indicate enablement of SRTE. The advertisements
are only used to support constraints which may be applied when are only used to support constraints which may be applied when
specifying an explicit path. SRTE is implicitly enabled on all links specifying an explicit path. SRTE is implicitly enabled on all links
which are part of the Segment Routing enabled topology independent of which are part of the Segment Routing enabled topology independent of
the existence of link attribute advertisements the existence of link attribute advertisements
In the case of LFA, advertisement of application specific link In the case of LFA, advertisement of application specific link
attributes does NOT indicate enablement of LFA on that link. attributes does NOT indicate enablement of LFA on that link.
skipping to change at page 12, line 7 skipping to change at page 13, line 7
the use of the link attribute by any application. In the presence of the use of the link attribute by any application. In the presence of
an application where the advertisement of link attribute an application where the advertisement of link attribute
advertisements is used to infer the enablement of an application on advertisements is used to infer the enablement of an application on
that link (e.g., RSVP-TE), the absence of the application identifier that link (e.g., RSVP-TE), the absence of the application identifier
leaves ambiguous whether that application is enabled on such a link. leaves ambiguous whether that application is enabled on such a link.
This needs to be considered when making use of the "any application" This needs to be considered when making use of the "any application"
encoding. encoding.
7. Interoperability, Backwards Compatibility and Migration Concerns 7. Interoperability, Backwards Compatibility and Migration Concerns
Existing deployments of RSVP-TE utilize the legacy advertisements Existing deployments of RSVP-TE, SRTE, and/or LFA utilize the legacy
listed in Section 3. Routers which do not support the extensions advertisements listed in Section 3. Routers which do not support the
defined in this document will only process legacy advertisements and extensions defined in this document will only process legacy
are likely to infer that RSVP-TE is enabled on the links for which advertisements and are likely to infer that RSVP-TE is enabled on the
legacy advertisements exist. It is expected that deployments using links for which legacy advertisements exist. It is expected that
the legacy advertisements will persist for a significant period of deployments using the legacy advertisements will persist for a
time - therefore deployments using the extensions defined in this significant period of time - therefore deployments using the
document must be able to co-exist with use of the legacy extensions defined in this document must be able to co-exist with use
advertisements by routers which do not support the extensions defined of the legacy advertisements by routers which do not support the
in this document. The following sub-sections discuss extensions defined in this document. The following sub-sections
interoperability and backwards compatibility concerns for a number of discuss interoperability and backwards compatibility concerns for a
deployment scenarios. number of deployment scenarios.
Note that in all cases the defined strategy can be employed on a per Note that in all cases the defined strategy can be employed on a per
link basis. link basis.
7.1. RSVP-TE only deployments 7.1. Multiple Applications: Common Attributes with RSVP-TE
In deployments where RSVP-TE is the only application utilizing link
attribute advertisements, use of the the legacy advertisements can
continue without change.
7.2. Multiple Applications: Common Attributes with RSVP-TE
In cases where multiple applications are utilizing a given link, one In cases where multiple applications are utilizing a given link, one
of the applications is RSVP-TE, and all link attributes for a given of the applications is RSVP-TE, and all link attributes for a given
link are common to the set of applications utilizing that link, link are common to the set of applications utilizing that link,
interoperability is achieved by using legacy advertisements and interoperability is achieved by using legacy advertisements and
sending application specific advertisements with L-bit set and no sending application specific advertisements with L-bit set and no
link attribute values. This avoids duplication of link attribute link attribute values. This avoids duplication of link attribute
advertisements. advertisements.
7.3. Multiple Applications: All Attributes Not Shared w RSVP-TE 7.2. Multiple Applications: All Attributes Not Shared w RSVP-TE
In cases where one or more applications other than RSVP-TE are In cases where one or more applications other than RSVP-TE are
utilizing a given link and one or more link attribute values are NOT utilizing a given link and one or more link attribute values are NOT
shared with RSVP-TE, it is necessary to use application specific shared with RSVP-TE, it is necessary to use application specific
advertisements as defined in this document. Attributes for advertisements as defined in this document. Attributes for
applications other than RSVP-TE MUST be advertised using application applications other than RSVP-TE MUST be advertised using application
specific advertisements which have the L-bit clear. In cases where specific advertisements which have the L-bit clear. In cases where
some link attributes are shared with RSVP-TE, this requires duplicate some link attributes are shared with RSVP-TE, this requires duplicate
advertisements for those attributes. advertisements for those attributes.
The discussion in this section applies to cases where RSVP-TE is NOT The discussion in this section applies to cases where RSVP-TE is NOT
using any advertised attributes on a link and to cases where RSVP-TE using any advertised attributes on a link and to cases where RSVP-TE
is using some link attribute advertisements on the link but some link is using some link attribute advertisements on the link but some link
attributes cannot be shared with RSVP-TE. attributes cannot be shared with RSVP-TE.
7.4. Use of Application Specific Advertisements for RSVP-TE 7.3. Use of Application Specific Advertisements for RSVP-TE
The extensions defined in this document support RSVP-TE as one of the The extensions defined in this document support RSVP-TE as one of the
supported applications. This allows that RSVP-TE could eventually supported applications. This allows that RSVP-TE could eventually
utilize the application specific advertisements. This can be done in utilize the application specific advertisements. This can be done in
the following step-wise manner: the following step-wise manner:
1)Upgrade all routers to support extensions in this document 1)Upgrade all routers to support extensions in this document
2)Readvertise all legacy link attributes using application specific 2)Readvertise all legacy link attributes using application specific
advertisements with L-bit clear and R-bit set. advertisements with L-bit clear and R-bit set.
 End of changes. 28 change blocks. 
67 lines changed or deleted 105 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/