OSPF Application-Specific Link Attributes
Cisco Systems
Eurovea Centre, Central 3
Pribinova Street 10
Bratislava
81109
Slovakia
ppsenak@cisco.com
Cisco Systems
821 Alder Drive
Milpitas
CA
United States of America
95035
ginsberg@cisco.com
Nokia
Copernicuslaan 50
Antwerp
Belgium
2018 94089
wim.henderickx@nokia.com
Apstra
United States of America
jefftant.ietf@gmail.com
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale
California
94089
United States of America
jdrake@juniper.net
Routing
LSR Working Group
Existing traffic-engineering-related link attribute advertisements
have been defined and are used in RSVP-TE deployments. Since the
original RSVP-TE use case was defined, additional applications (e.g.,
Segment Routing Policy and Loop-Free Alternates) that also make use of the
link attribute advertisements have been defined. In
cases where multiple applications wish to make use of these link
attributes, the current advertisements do not support application-specific values for a given attribute, nor do they support indication
of which applications are using the advertised value for a given
link. This document introduces new link attribute advertisements in OSPFv2
and OSPFv3 that address both of these shortcomings.
Introduction
Advertisement of link attributes by the OSPFv2 and OSPFv3 protocols in support of traffic engineering (TE) was
introduced by and , respectively. It has been extended
by , , and . Use
of these extensions has been associated with deployments supporting
Traffic Engineering over Multiprotocol Label Switching (MPLS) in the
presence of the Resource Reservation Protocol (RSVP), more succinctly
referred to as RSVP-TE .
For the purposes of this document, an application is a technology
that makes use of link attribute advertisements, examples of which are
listed in .
In recent years, new applications have been introduced that have use
cases for many of the link attributes historically used by RSVP-TE.
Such applications include Segment Routing (SR) Policy and
Loop-Free Alternates (LFAs) . This has introduced ambiguity in that if a
deployment includes a mix of RSVP-TE support and SR Policy support, for
example, it is not possible to unambiguously indicate which
advertisements are to be used by RSVP-TE and which advertisements are
to be used by SR Policy. If the topologies are fully congruent, this
may not be an issue, but any incongruence leads to ambiguity.
An example of where this ambiguity causes a problem is a network
where RSVP-TE is enabled only on a subset of its links. A link
attribute is advertised for the purpose of another application (e.g.,
SR Policy) for a link that is not enabled for RSVP-TE. As soon as the
router that is an RSVP-TE head end sees the link attribute being
advertised for that link, it assumes RSVP-TE is enabled on that link,
even though it is not. If such an RSVP-TE head-end router tries to set
up an RSVP-TE path via that link, it will result in the path setup
failure.
An additional issue arises in cases where both applications are
supported on a link but the link attribute values associated with each
application differ. Current advertisements do not support advertising
application-specific values for the same attribute on a specific
link.
This document defines extensions that address these issues. Also,
as evolution of use cases for link attributes can be expected to
continue in the years to come, this document defines a solution that
is easily extensible for the introduction of new applications and new
use cases.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 when, and only when, they appear in all
capitals, as shown here.
Requirements Discussion
As stated previously, evolution of use cases for link attributes can
be expected to continue. Therefore, any discussion of existing use cases
is limited to requirements that are known at the time of this writing.
However, in order to determine the functionality required beyond what
already exists in OSPF, it is only necessary to discuss use cases that
justify the key points identified in the introduction, which are:
- Support for indicating which applications are using the link
attribute advertisements on a link
- Support for advertising application-specific values for the same
attribute on a link
discusses use cases and requirements for Segment Routing
(SR). Included among these use cases is SR Policy, which is defined in
. If both RSVP-TE
and SR Policy are deployed in a network, link attribute advertisements
can be used by one or both of these applications. There is no
requirement for the link attributes advertised on a given link used by
SR Policy to be identical to the link attributes advertised on that same
link used by RSVP-TE; thus, there is a clear requirement to indicate
independently which link attribute advertisements are to be used by each
application.
As the number of applications that may wish to utilize link
attributes may grow in the future, an additional requirement is that the
extensions defined allow the association of additional applications to
link attributes without altering the format of the advertisements or
introducing new backwards-compatibility issues.
Finally, there may still be many cases where a single attribute value
can be shared among multiple applications, so the solution must minimize
advertising duplicate link/attribute pairs whenever possible.
Existing Advertisement of Link Attributes
There are existing advertisements used in support of RSVP-TE. These
advertisements are carried in the OSPFv2 TE Opaque Link State
Advertisement (LSA) and
OSPFv3 Intra-Area-TE-LSA . Additional RSVP-TE link attributes have been
defined by , , and .
Extended Link Opaque LSAs as defined in for OSPFv2 and
E-Router-LSAs for OSPFv3 are used to advertise link
attributes that are used by applications other than RSVP-TE or GMPLS .
These LSAs were defined as generic containers for distribution of the extended link attributes.
Advertisement of Link Attributes
This section outlines the solution for advertising link attributes
originally defined for RSVP-TE or GMPLS when they are used for other applications.
OSPFv2 Extended Link Opaque LSA and OSPFv3 E-Router-LSA
The following are the advantages of Extended Link Opaque LSAs as defined in
for OSPFv2 and E-Router-LSAs for OSPFv3 with respect
to the advertisement of link attributes originally defined for RSVP-TE when used in packet
networks and in GMPLS:
- Advertisement of the link attributes does not make the link part of the RSVP-TE topology.
It avoids any conflicts and is fully compatible with and
.
- The OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA remain
truly opaque to OSPFv2 and OSPFv3 as originally defined in and , respectively. Their contents are not inspected
by OSPF, which instead acts as a pure transport.
- There is a clear distinction between link attributes used by RSVP-TE and
link attributes used by other OSPFv2 or OSPFv3 applications.
- All link attributes that are used by other applications are advertised in the Extended Link Opaque LSA in OSPFv2 or the OSPFv3
E-Router-LSA in OSPFv3.
The disadvantage of this approach is that in rare cases, the same link attribute is
advertised in both the TE Opaque and Extended Link Attribute LSAs in OSPFv2 or
the Intra-Area-TE-LSA and E-Router-LSA in OSPFv3.
The Extended Link Opaque LSA and E-Router-LSA
are used to advertise any link attributes used
for non-RSVP-TE applications in OSPFv2 or OSPFv3, respectively, including those that have
been originally defined for RSVP-TE applications (see ).
TE link attributes used for RSVP-TE/GMPLS continue to use the OSPFv2 TE Opaque LSA
and OSPFv3 Intra-Area-TE-LSA .
The format of the link attribute TLVs that have been defined for
RSVP-TE applications will be kept unchanged even when they are used
for non-RSVP-TE applications. Unique codepoints are allocated for
these link attribute TLVs from the "OSPFv2 Extended Link TLV Sub-TLVs"
registry and from the
"OSPFv3 Extended-LSA Sub-TLVs" registry , as specified in .
Advertisement of Application-Specific Values
To allow advertisement of the application-specific values of the link attribute, a new
Application-Specific Link Attributes (ASLA) sub-TLV is defined. The ASLA sub-TLV is a sub-TLV
of the OSPFv2 Extended Link TLV and OSPFv3 Router-Link TLV
.
In addition to advertising the link attributes for standardized
applications, link attributes can be advertised for the purpose of
applications that are not standardized. We call such an
application a "user-defined application" or "UDA". These applications are
not subject to standardization and are outside of the scope
of this specification.
The ASLA sub-TLV is an optional sub-TLV of the OSPFv2 Extended Link TLV and
OSPFv3 Router-Link TLV. Multiple ASLA sub-TLVs can be present in a parent
TLV when different applications want to control different link attributes or
when a different value
of the same attribute needs to be advertised by multiple applications. The ASLA sub-TLV
MUST be used for advertisement of the link attributes listed at the end of this section
if these are advertised inside the OSPFv2 Extended Link TLV and OSPFv3 Router-Link TLV.
It has the following format:
where:
- Type:
- 10 (OSPFv2), 11 (OSPFv3)
- Length:
- Variable
- SABM Length:
- Standard Application Identifier Bit Mask Length in octets.
The value MUST be 0, 4, or 8.
If the Standard Application Identifier Bit Mask is not present, the SABM
Length MUST be set to 0.
- UDABM Length:
- User-Defined Application Identifier Bit Mask Length in octets.
The value MUST be 0, 4, or 8.
If the User-Defined Application Identifier Bit Mask is not present, the
UDABM Length MUST be set to 0.
- Standard Application Identifier Bit Mask:
- Optional
set of bits, where each bit represents a single standard
application. Bits are defined in the "Link Attribute Applications"
registry, which is defined in . Current assignments are repeated here for
informational purposes:
- Bit 0 (R-bit):
- RSVP-TE.
- Bit 1 (S-bit):
- Segment Routing Policy.
- Bit 2 (F-bit):
- Loop-Free Alternate (LFA). Includes all LFA types.
- User-Defined Application Identifier Bit Mask:
- Optional set of bits, where each bit
represents a single user-defined application.
If the SABM or UDABM Length is other than 0, 4, or 8, the ASLA sub-TLV MUST be ignored
by the receiver.
Standard Application Identifier Bits are defined and sent starting with
bit 0. Undefined bits that are transmitted 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 receipt. Bits that are not supported by an
implementation MUST be ignored on receipt.
User-Defined Application Identifier Bits have no relationship to
Standard Application Identifier Bits and are not managed by IANA or
any other standards body. It is recommended that these bits be used
starting with bit 0 so as to minimize the number of octets required
to advertise all UDAs. Undefined bits that are transmitted 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 receipt. Bits that are not
supported by an implementation MUST be ignored on receipt.
If the link attribute advertisement is intended to be only used by a specific set of applications,
corresponding bit masks MUST be present, and application-specific bit(s) MUST be set for all
applications that use the link attributes advertised in the ASLA sub-TLV.
Application Identifier Bit Masks apply to all link attributes that support application-specific
values and are advertised in the ASLA sub-TLV.
The advantage of not making the Application Identifier Bit Masks part of the attribute advertisement
itself is that the format of any previously defined link attributes
can be kept and reused when advertising them in the ASLA sub-TLV.
If the same attribute is advertised in more than one ASLA sub-TLVs with the application
listed in the Application Identifier Bit Masks, the application SHOULD use the first instance of
advertisement and ignore any subsequent advertisements of that attribute.
If link attributes are advertised with zero-length
Application Identifier Bit Masks for both standard applications and
user-defined applications, then any standard application and/or any
user-defined application is permitted to use that set of link
attributes. If support for a new application is introduced
on any node in a network in the presence of such advertisements,
these advertisements are permitted to be used by the new application.
If this is not what is intended, then existing advertisements MUST be
readvertised with an explicit set of applications specified before a
new application is introduced.
An application-specific advertisement (Application Identifier Bit
Mask with a matching Application Identifier Bit set) for an attribute
MUST always be preferred over the advertisement of the same attribute
with the zero-length Application Identifier Bit Masks for both
standard applications and user-defined applications on the same link.
This document defines the initial set of link attributes that MUST use the ASLA sub-TLV if
advertised in the OSPFv2 Extended Link TLV or in the OSPFv3 Router-Link TLV.
Documents that define new link attributes MUST state whether the new attributes support
application-specific values and, as such, are advertised in an ASLA sub-TLV. The standard
link attributes that are advertised in ASLA sub-TLVs are:
- Shared Risk Link Group
- Unidirectional Link Delay
- Min/Max Unidirectional Link Delay
- Unidirectional Delay Variation
- Unidirectional Link Loss
- Unidirectional Residual Bandwidth
- Unidirectional Available Bandwidth
- Unidirectional Utilized Bandwidth
- Administrative Group
- Extended Administrative Group
- TE Metric
Reused TE Link Attributes
This section defines the use case and indicates the codepoints () from the "OSPFv2 Extended Link TLV
Sub-TLVs" registry and "OSPFv3 Extended-LSA Sub-TLVs" registry for some of
the link attributes that have been originally defined for RSVP-TE or
GMPLS.
Shared Risk Link Group (SRLG)
The SRLG of a link can be used in OSPF-calculated IPFRR (IP Fast Reroute)
to compute a backup path
that does not share any SRLG group with the protected link.
To advertise the SRLG of the link in the OSPFv2 Extended Link TLV, the same format
for the sub-TLV defined in is used with TLV
type 11. Similarly, for OSPFv3 to advertise the SRLG in the OSPFv3 Router-Link
TLV, TLV type 12 is used.
Extended Metrics
defines several link bandwidth types.
defines extended link metrics that are based on link bandwidth, delay, and loss
characteristics. All of these can be used to compute primary and backup paths within an
OSPF area to satisfy requirements for bandwidth, delay (nominal or worst case), or loss.
To advertise extended link metrics in the OSPFv2 Extended Link TLV, the same format
for the sub-TLVs defined in is used with the following
TLV types:
- 12:
- Unidirectional Link Delay
- 13:
- Min/Max Unidirectional Link Delay
- 14:
- Unidirectional Delay Variation
- 15:
- Unidirectional Link Loss
- 16:
- Unidirectional Residual Bandwidth
- 17:
- Unidirectional Available Bandwidth
- 18:
- Unidirectional Utilized Bandwidth
To advertise extended link metrics in the Router-Link TLV inside
the OSPFv3 E-Router-LSA, the same format for the sub-TLVs defined in is used with the following
TLV types:
- 13:
- Unidirectional Link Delay
- 14:
- Min/Max Unidirectional Link Delay
- 15:
- Unidirectional Delay Variation
- 16:
- Unidirectional Link Loss
- 17:
- Unidirectional Residual Bandwidth
- 18:
- Unidirectional Available Bandwidth
- 19:
- Unidirectional Utilized Bandwidth
Administrative Group
and define the Administrative Group and
Extended Administrative Group sub-TLVs, respectively.
To advertise the Administrative Group and Extended Administrative Group in the OSPFv2
Extended Link TLV, the same format for the sub-TLVs defined in
and is used with the following TLV types:
- 19:
- Administrative Group
- 20:
- Extended Administrative Group
To advertise the Administrative Group and Extended Administrative Group in the OSPFv3
Router-Link TLV, the same format for the sub-TLVs defined in
and is used with the following TLV types:
- 20:
- Administrative Group
- 21:
- Extended Administrative Group
Traffic Engineering Metric
defines the Traffic Engineering Metric.
To advertise the Traffic Engineering Metric in the OSPFv2 Extended Link TLV,
the same format for the sub-TLV defined in
is used with TLV type 22. Similarly, for OSPFv3 to advertise the
Traffic Engineering Metric in the OSPFv3 Router-Link TLV, TLV type 22 is used.
Maximum Link Bandwidth
Maximum link bandwidth is an application-independent attribute of the
link that is defined in . Because
it is an application-independent attribute, it MUST NOT be
advertised in the ASLA sub-TLV.
Instead, it MAY be
advertised as a sub-TLV of the Extended Link TLV in the Extended Link Opaque
LSA in OSPFv2 or as a sub-TLV of
the Router-Link TLV in the E-Router-LSA Router-Link TLV in OSPFv3
.
To advertise the maximum link bandwidth in the OSPFv2 Extended Link TLV, the same
format for the sub-TLV defined in is used with
TLV type 23.
To advertise the maximum link bandwidth in the OSPFv3 Router-Link TLV, the same
format for the sub-TLV defined in is used with
TLV type 23.
Considerations for Extended TE Metrics
defines a number of dynamic performance metrics associated
with a link. It is conceivable that such metrics could be measured
specific to traffic associated with a specific application.
Therefore, this document includes support for advertising these link
attributes specific to a given application. However, in practice, it
may well be more practical to have these metrics reflect the
performance of all traffic on the link regardless of application. In
such cases, advertisements for these attributes can be associated
with all of the applications utilizing that link. This can be done
either by explicitly specifying the applications in the Application
Identifier Bit Mask or by using a zero-length Application Identifier
Bit Mask.
Local Interface IPv6 Address Sub-TLV
The Local Interface IPv6 Address sub-TLV is an application-independent attribute of the
link that is defined in . Because it is an application-independent attribute, it MUST NOT be advertised in the ASLA sub-TLV. Instead, it MAY be
advertised as a sub-TLV of the Router-Link TLV inside the OSPFv3 E-Router-LSA .
To advertise the Local Interface IPv6 Address sub-TLV in the OSPFv3 Router-Link TLV,
the same format for the sub-TLV defined in is used with
TLV type 24.
Remote Interface IPv6 Address Sub-TLV
The Remote Interface IPv6 Address sub-TLV is an application-independent attribute of the
link that is defined in . Because it is an application-independent attribute, it MUST NOT be advertised in the ASLA sub-TLV. Instead, it MAY be
advertised as a sub-TLV of the Router-Link TLV inside the OSPFv3 E-Router-LSA .
To advertise the Remote Interface IPv6 Address sub-TLV in the OSPFv3 Router-Link TLV,
the same format for the sub-TLV defined in is used with
TLV type 25.
Attribute Advertisements and Enablement
This document defines extensions to support the advertisement of
application-specific link attributes.
There are applications where the application enablement on the link
is relevant; for example, with RSVP-TE, one needs to make sure that RSVP
is enabled on the link before sending an RSVP-TE signaling message over it.
There are applications where the enablement of the application on the link is
irrelevant and has nothing to do with the fact that some link attributes are advertised
for the purpose of such application. An example of this is LFA.
Whether the presence of link attribute advertisements for a given
application indicates that the application is enabled on that link
depends upon the application. Similarly, whether the absence of link
attribute advertisements indicates that the application is not
enabled depends upon the application.
In the case of RSVP-TE, the advertisement of application-specific
link attributes has no implication of RSVP-TE being enabled on that link.
The RSVP-TE enablement is solely derived from the information carried in
the OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA
.
In the case of SR Policy, advertisement of application-specific link
attributes does not indicate enablement of SR Policy. The advertisements
are only used to support constraints that may be applied when
specifying an explicit path. SR Policy is implicitly enabled on all links
that are part of the SR-enabled topology independent of
the existence of link attribute advertisements.
In the case of LFA, the advertisement of application-specific link
attributes does not indicate enablement of LFA on that link.
Enablement is controlled by local configuration.
In the future, if additional standard applications are defined to
use this mechanism, the specification defining this use MUST define
the relationship between application-specific link attribute
advertisements and enablement for that application.
This document allows the advertisement of application-specific link
attributes with no application identifiers, i.e., both the Standard
Application Identifier Bit Mask and the User-Defined Application
Identifier Bit Mask are not present (see ).
This supports the use of the link attribute by any application. In the presence of
an application where the advertisement of link attributes is used to infer the enablement of an application on
that link (e.g., RSVP-TE), the absence of the application identifier
leaves ambiguous whether that application is enabled on such a link.
This needs to be considered when making use of the "any application"
encoding.
Deployment Considerations
Use of Legacy RSVP-TE LSA Advertisements
Bit identifiers for standard applications are defined in .
All of the identifiers defined in this document are associated with
applications that were already deployed in some networks prior to
the writing of this document. Therefore, such applications have been
deployed using the RSVP-TE LSA advertisements. The standard applications
defined in this document may continue to use RSVP-TE LSA advertisements
for a given link so long as at least one of the following conditions
is true:
- The application is RSVP-TE.
- The application is SR Policy or LFA, and RSVP-TE is not deployed
anywhere in the network.
- The application is SR Policy or LFA, RSVP-TE is deployed in the
network, and both the set of links on which SR Policy and/or LFA
advertisements are required and the attribute values used by SR Policy
and/or LFA on all such links are fully congruent with the links and
attribute values used by RSVP-TE.
Under the conditions defined above, implementations that support the
extensions defined in this document have the choice of using RSVP-TE LSA
advertisements or application-specific advertisements in support of
SR Policy and/or LFA. This will require implementations to provide
controls specifying which types of advertisements are to be sent and processed on receipt for these applications. Further discussion of
the associated issues can be found in .
New applications that future documents define to make use of the
advertisements defined in this document MUST NOT make use of RSVP-TE LSA
advertisements. This simplifies deployment of new applications by
eliminating the need to support multiple ways to advertise attributes
for the new applications.
Interoperability, Backwards Compatibility, and Migration Concerns
Existing deployments of RSVP-TE, SR Policy, and/or LFA utilize the
legacy advertisements listed in . Routers that do not
support the extensions defined in this document will only process
legacy advertisements and are likely to infer that RSVP-TE is enabled
on the links for which legacy advertisements exist. It is expected
that deployments using the legacy advertisements will persist for a
significant period of time. Therefore, deployments using the
extensions defined in this document in the presence of routers that
do not support these extensions need to be able to interoperate with
the use of legacy advertisements by the legacy routers. The following subsections
discuss interoperability and backwards-compatibility concerns for a number of
deployment scenarios.
Multiple Applications: Common Attributes with RSVP-TE
In cases where multiple applications are utilizing a given link,
one of the applications is RSVP-TE, and all link attributes for a
given link are common to the set of applications utilizing that
link, interoperability is achieved by using legacy advertisements for RSVP-TE.
Attributes for applications other than RSVP-TE MUST be advertised using
application-specific advertisements. This results in duplicate
advertisements for those attributes.
Multiple Applications: Some Attributes Not Shared with RSVP-TE
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
shared with RSVP-TE, interoperability is achieved by using legacy advertisements
for RSVP-TE. Attributes for applications other than RSVP-TE MUST be advertised using
application-specific advertisements. In cases where some link attributes are
shared with RSVP-TE, this requires duplicate advertisements for those attributes.
Interoperability with Legacy Routers
For the applications defined in this document, routers that do
not support the extensions defined in this document will send and
receive only legacy link attribute advertisements. So long as there
is any legacy router in the network that has any of the
applications enabled, all routers MUST continue to advertise link
attributes using legacy advertisements. In addition, the link
attribute values associated with the set of applications supported
by legacy routers (RSVP-TE, SR Policy, and/or LFA) are always shared
since legacy routers have no way of advertising or processing
application-specific values. Once all legacy routers have been
upgraded, migration from legacy advertisements to
application-specific advertisements can be achieved via the
following steps:
- Send new application-specific advertisements while continuing to
advertise using the legacy advertisement (all advertisements are
then duplicated). Receiving routers continue to use legacy advertisements.
- Enable the use of the application-specific advertisements on
all routers.
- Keep legacy advertisements if needed for RSVP-TE purposes.
When the migration is complete, it then becomes possible to
advertise incongruent values per application on a given link.
Documents defining new applications that make use of the
application-specific advertisements defined in this document MUST
discuss interoperability and backwards-compatibility issues that
could occur in the presence of routers that do not support the new
application.
Use of Application-Specific Advertisements for RSVP-TE
The extensions defined in this document support RSVP-TE as one of
the supported applications. It is, however, RECOMMENDED to advertise all
link attributes for RSVP-TE in the existing OSPFv2 TE Opaque LSA
and OSPFv3 Intra-Area-TE-LSA
to maintain backwards compatibility. RSVP-TE can eventually
utilize the application-specific advertisements for newly defined
link attributes that are defined as application specific.
Link attributes that are not allowed to be advertised in the ASLA sub-TLV,
such as maximum reservable link bandwidth and unreserved bandwidth, MUST use the
OSPFv2 TE Opaque LSA and OSPFv3 Intra-Area-TE-LSA
and MUST
NOT be advertised in the ASLA sub-TLV.
Security Considerations
Existing security extensions as described in ,
, and apply to extensions
defined in this document. While OSPF is under a single administrative domain,
there can be deployments where potential attackers have access to one or more
networks in the OSPF routing domain. In these deployments, stronger authentication
mechanisms such as those specified in ,
, , or
SHOULD be
used.
Implementations must ensure that if any of the TLVs and sub-TLVs
defined in this document are malformed, they are detected and do not
facilitate a vulnerability for attackers to crash the OSPF router or routing process. Reception of a
malformed TLV or sub-TLV SHOULD be counted and/or logged
for further analysis. Logging of malformed TLVs and sub-TLVs
SHOULD be rate-limited to prevent a denial-of-service
(DoS) attack (distributed or otherwise) from overloading the OSPF
control plane.
This document defines a new way to advertise link attributes.
Tampering with the information defined in this document may have an
effect on applications using it, including impacting traffic
engineering, which uses various link attributes for its path
computation. This is similar in nature to the impacts associated with,
for example, . As the
advertisements defined in this document limit the scope to specific
applications, the impact of tampering is similarly limited in scope.
IANA Considerations
This specification updates two existing registries:
- the "OSPFv2 Extended Link TLV Sub-TLVs" registry
- the "OSPFv3 Extended-LSA Sub-TLVs" registry
The new values defined in this document have been allocated using the
IETF Review procedure as described in
.
OSPFv2
The "OSPFv2 Extended Link TLV Sub-TLVs" registry defines sub-TLVs at any level of
nesting for OSPFv2 Extended Link TLVs. IANA has assigned the following
sub-TLV types from the "OSPFv2 Extended Link TLV Sub-TLVs" registry:
- 10:
- Application-Specific Link Attributes
- 11:
- Shared Risk Link Group
- 12:
- Unidirectional Link Delay
- 13:
- Min/Max Unidirectional Link Delay
- 14:
- Unidirectional Delay Variation
- 15:
- Unidirectional Link Loss
- 16:
- Unidirectional Residual Bandwidth
- 17:
- Unidirectional Available Bandwidth
- 18:
- Unidirectional Utilized Bandwidth
- 19:
- Administrative Group
- 20:
- Extended Administrative Group
- 22:
- TE Metric
- 23:
- Maximum link bandwidth
OSPFv3
The "OSPFv3 Extended-LSA Sub-TLVs" registry defines sub-TLVs at any level of nesting for OSPFv3
Extended LSAs. IANA has assigned the following sub-TLV types from the
"OSPFv3 Extended-LSA Sub-TLVs" registry:
- 11:
- Application-Specific Link Attributes
- 12:
- Shared Risk Link Group
- 13:
- Unidirectional Link Delay
- 14:
- Min/Max Unidirectional Link Delay
- 15:
- Unidirectional Delay Variation
- 16:
- Unidirectional Link Loss
- 17:
- Unidirectional Residual Bandwidth
- 18:
- Unidirectional Available Bandwidth
- 19:
- Unidirectional Utilized Bandwidth
- 20:
- Administrative Group
- 21:
- Extended Administrative Group
- 22:
- TE Metric
- 23:
- Maximum link bandwidth
- 24:
- Local Interface IPv6 Address
- 25:
- Remote Interface IPv6 Address
References
Normative References
IS-IS Application-Specific Link Attributes
Informative References
Acknowledgments
Thanks to for his review and comments.
Thanks to for his detailed review and comments.
Contributors
The following people contributed to the content
of this document and should be considered as coauthors:
Cisco Systems
301 Midenhall Way
Cary
NC27513
United States of America
acee@cisco.com
Cisco Systems, Inc.
India
ketant@cisco.com
RtBrick Inc.
Austria
hannes@rtbrick.com