Francois Le Faucheur
Thomas D. Nadeau
Cisco Systems, Inc.
Angela Chiu
AT&T
William Townsend
Tenor Networks
Darek Skalecki
Nortel Networks
IETF Internet Draft
Expires: January, 2001
Document: draft-lefaucheur-diff-te-ext-00.txt July, 2000
Extensions to IS-IS, OSPF, RSVP and CR-LDP
for support of Diff-Serv-aware MPLS Traffic Engineering
Status of this Memo
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all provisions of Section 10 of RFC2026. Internet-Drafts are
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Abstract
A companion document [DIFF-TE-REQTS] defines the requirements for
support of Diff-Serv-aware MPLS Traffic Engineering on a per-Class-
Type basis, as discussed in the Traffic Engineering Working Group
Framework document [TEWG-FW].
This document proposes corresponding extensions to OSPF, ISIS, RSVP
and CR-LDP for support of Traffic Engineering on a per-Class-Type
basis.
Le Faucheur, et. al 1
Extensions for Diff-Serv Traffic Engineering July 2000
1. Introduction
As Diffserv becomes prominent in providing scalable multi-class of
services in IP networks, performing traffic engineering at a per-
class level instead of an aggregated level is needed to further
enhance networks in performance and efficiency. By mapping a traffic
trunk in a given class on a separate LSP, it allows the traffic
trunk to utilize resources available on both shortest path(s) and
non-shortest paths and follow paths that meet constraints which are
specific to the given class. It also allows each class to select the
proper protection/restoration mechanism(s) that satisfy its
survivability requirements in a cost effective manner.
Besides the set of parameters defined for the general aggregate TE
[TE-REQ], a new set of per-class parameters needs to be provided at
each LSR interface and propagated via extensions to the IGP
(ISIS/OSPF) [TEWG-FW]. Furthermore, the per-class parameters can be
aggregated into per-Class-Type parameters. The main motivation for
grouping a set of classes into a Class-Type is to improve the
scalability of the IGP link state advertisements by propagating
information on a per-Class-Type basis instead of on a per-class
basis. This approach also has the benefit of allowing better
bandwidth sharing between classes in the same Class-Type.
A Class-Type [TEWG-FW] is defined as a set of classes that satisfy
the following two conditions:
1) Classes in the same Class-Type possess common aggregate maximum
and minimum bandwidth requirements to guarantee the required
performance level.
2) There is no maximum or minimum bandwidth requirement to be
enforced at the level of an individual class within the Class-
Type. One can still implement some "priority" policies for
classes within the same Class-Type in terms of accessing the
Class-Type bandwidth (e.g. via the use of preemption
priorities).
An example of Class-Type comprising multiple Diff-Serv classes is a
low-loss Class-Type that includes both AF1-based and AF2-based
Ordering Aggregates.
Note that with per Class-Type TE, Constraint-Based Routing is
performed with bandwidth constraints on a per Class-Type basis but
LSPs may carry a single Diff-Serv class (Ordered Aggregate) with
Diff-Serv scheduling (i.e. PHB) performed separately for each class.
Diff-Serv scheduling parameters for a given class within a Class-
Type may be automatically adjusted by the LSRs based on the
bandwidth of all LSPs currently established for each class within
the Class-Type.
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Extensions for Diff-Serv Traffic Engineering July 2000
In this document, we will only discuss "per Class-Type TE" because
"per Class TE" can be viewed as a special case of per Class-Type TE
(where each Class-Type is degenerated into a single Diff-Serv
class).
This document focuses on intra-domain operations. Inter-domain
operations is for further study.
A companion document [DIFF-TE-REQTS] defines the requirements for
support of MPLS Traffic Engineering on a per-Class-Type basis. The
following sections propose detailed extensions to OSPF, ISIS, RSVP
and CR-LDP that meet those requirements.
2. OSPF Extensions
In this section we propose extensions to OSPF for support of Diff-
Serv Traffic Engineering on a per-Class-Type basis which meet the
requirements defined in [DIFF-TE-REQTS]. These extensions are in
addition to the extensions already defined for support of
(aggregate) MPLS Traffic Engineering [OSPF-TE].
2.1. Existing TE Sub-TLVs
[OSPF-TE] defines a new LSA for support of (aggregate) Traffic
Engineering, which is referred to as the Traffic Engineering LSA.
This LSA contains a Link TLV (Type 2) comprising a number of sub-
TLVs.
In this document we refer to the sub-TLV 7 (maximum reservable
bandwidth) of the Link TLV (as defined in [OSPF-TE]) as the "Maximum
Reservable Aggregate Bandwidth".
We also refer to the sub-TLV 8 (unreserved bandwidth) of the Link
TLV (as defined in [OSPF-TE]) as the "Unreserved Bandwidth for
Class-Type 0".
2.2. New Sub-TLVs
The following additional sub-TLVs are defined for the Link TLV of
the Traffic Engineering LSA (sub-TLV numbers to be allocated)
TBD - Unreserved Bandwidth for Class-Type 1 (32 octets)
TBD+1 - Unreserved Bandwidth for Class-Type 2 (32 octets)
TBD+2 - Unreserved Bandwidth for Class-Type 3 (32 octets)
Each sub-TLV may occur only once. Unrecognized types are ignored.
Unlike the sub-TLVs defined for the Link TLV in [OSPF-TE], the
additional sub-TLVs defined above are optional.
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Extensions for Diff-Serv Traffic Engineering July 2000
The Link TLV may include the sub-TLVs for any subset of the three
additional Class-Types. In other words, the Link TLV may contain
none of the three sub-TLVs defined above, any one of those, any two
of those, or the three sub-TLVs. Where a Class-Type is not
effectively used in a network, it is recommended that the
corresponding sub-TLV is not included in the Link TLV. For instance,
a Network Administrator may elect to use Diff-Serv Traffic
Engineering in order to compute separate routes for data traffic and
voice traffic (and apply different bandwidth constraints to the
route computation for those). In that case, the IGP would only
advertise the sub-TLV for one additional Class-Type (i.e. the Link
TLV would contain sub-TLV 7 for the Maximum Reservable Aggregate
Bandwidth, sub-TLV 8 for the Unreserved Bandwidth for Class-Type 0
and sub-TLV TBD for Unreserved Bandwidth for Class-Type 1).
An LSR which supports Class-Type N and receiving a Link TLV without
the sub-TLV corresponding to Class-Type N, interprets this as
meaning that the corresponding link does not support Class-Type N.
For Constraint Based Routing purposes, the LSR may consider this
equivalent to the case where the Link TLV contains an Unreserved
Bandwidth for Class-Type N sub-TLV set to zero.
2.3. Sub-TLV Details
The Unreserved Bandwidth for Class-Type N (N= 1,2,3) sub-TLV
specifies the amount of bandwidth not yet reserved at each of the
eight preemption priority levels for Class-Type N, in IEEE floating
point format. Each value will be less than or equal to the Maximum
Reservable Bandwidth for Class-Type N. The units are bytes per
second. The values correspond to the bandwidth that can be reserved
with a holding priority of 0 through 7, arranged in increasing order
with priority 0 occurring at the start of the sub-TLV, and priority
7 at the end of the sub-TLV.
The Unreserved Bandwidth for Class-Type N sub-TLV is TLV type
(TBD-1+N) , and is 32 octets in length.
3. ISIS Extensions
In this section we describe extensions to IS-IS for support of Diff-
Serv Traffic Engineering on a per-Class-Type basis which meet the
requirements defined in [DIFF-TE-REQTS]. These extensions are in
addition to the extensions required to support (aggregate) MPLS
Traffic Engineering [ISIS-TE].
3.1. Existing TE sub-TLVs
[ISIS-TE] defines new extended TLVs for support of (aggregate)
Traffic Engineering. One of these extended TLV is referred to as the
extended IS reachability TLV (TLV type 22). This TLV contains a
number of new sub-TLVs.
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Extensions for Diff-Serv Traffic Engineering July 2000
In this document we refer to the sub-TLV 10 (maximum reservable
bandwidth) of the extended IS reachability TLV (as defined in [ISIS-
TE]) as the "Maximum Reservable Aggregate Bandwidth".
We also refer to the sub-TLV 11 (unreserved bandwidth) of the
extended IS reachability TLV (as defined in [ISIS-TE]) as the
"Unreserved Bandwidth for Class-Type 0".
3.2. New Sub-TLVs
The following additional sub-TLVs are defined for the extended IS
reachability TLV (sub-TLV numbers to be allocated):
TBD - Unreserved bandwidth for Class-Type 1 (32 octets)
TBD+1 - Unreserved bandwidth for Class-Type 2 (32 octets)
TBD+2 - Unreserved bandwidth for Class-Type 3 (32 octets)
Each sub-TLV may occur only once. Unrecognized types are ignored.
The additional sub-TLVs defined above are optional so that they may
or may not be included in the extended IS reachability TLV.
The extended IS reachability TLV may include the sub-TLVs for any
subset of the three additional Class-Types. In other words, the IS
reachability TLV may contain none of the three sub-TLVs defined
above, any one of those, any two of those, or the three sub-TLVs.
Where a Class-Type is not effectively used in a network, it is
recommended that the corresponding sub-TLV is not included in the IS
reachability TLV. For instance, a Network Administrator may elect to
use Diff-Serv Traffic Engineering in order to compute separate
routes for data traffic and voice traffic (and apply different
bandwidth constraints to the route computation for those). In that
case, the IGP would only advertise the sub-TLV for one additional
Class-Type (i.e. the extended IS reachability TLV would contain sub-
TLV 10 for the Maximum Reservable Aggregate Bandwidth, sub-TLV 11
for the Unreserved Bandwidth for Class-Type 0 and sub-TLV TBD for
Unreserved Bandwidth for Class-Type 1).
An LSR which supports Class-Type N and receiving an extended IS
reachability TLV without the sub-TLV corresponding to Class-Type N,
interprets this as meaning that the corresponding link does not
support Class-Type N. For Constraint Based Routing purposes, the LSR
may consider this equivalent to the case where the extended IS
reachability TLV contains an Unreserved Bandwidth Class-Type N sub-
TLV set to zero.
3.3. Sub-TLV Details
The Unreserved Bandwidth for Class-Type N (N= 1,2,3) sub-TLVs
specifies the amount of bandwidth not yet reserved at each of the
eight preemption priority levels for Class-Type N, in IEEE floating
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Extensions for Diff-Serv Traffic Engineering July 2000
point format. Each value will be less than or equal to the Maximum
Reservable Bandwidth for Class-Type N. The units are bytes per
second. The values correspond to the bandwidth that can be reserved
with a holding priority of 0 through 7, arranged in increasing order
with priority 0 occurring at the start of the sub-TLV, and priority
7 at the end of the sub-TLV.
The Unreserved Bandwidth for Class-Type N sub-TLV is TLV type
(TBD-1+N), and is 32 octets in length.
4. RSVP Extensions
In this section we describe extensions to RSVP for support of
Diff-Serv Traffic Engineering on a per-Class-Type basis which meet
the requirements defined in [DIFF-TE-REQTS]. These extensions are in
addition to the extensions to RSVP defined in [RSVP-TE] for support
of (aggregate) MPLS Traffic Engineering and to the extensions to
RSVP defined in [DIFF-MPLS] for support of Diff-Serv over MPLS.
4.1. Diff-Serv related RSVP Messages Format
One new RSVP Object is defined in this document: the CLASSTYPE
Object. Detailed description of this Object is provided below. This
new Object is applicable to Path messages. This specification only
defines the use of the CLASSTYPE Object in Path messages used to
establish LSP Tunnels in accordance with [RSVP-TE] and thus
containing a Session Object with a C-Type equal to LSP_TUNNEL_IPv4
and containing a LABEL_REQUEST object.
Restrictions defined in [RSVP-TE] for support of establishment of
LSP Tunnels via RSVP are also applicable to the establishment of LSP
Tunnels supporting Diff-Serv Traffic Engineering. For instance, only
unicast LSPs are supported and Multicast LSPs are for further study.
This new CLASSTYPE object is optional with respect to RSVP so that
general RSVP implementations not concerned with MPLS LSP set up do
not have to support this object.
An LSR supporting Diff-Serv Traffic Engineering on a per-Class-Type
basis in compliance with this specification MUST support the
CLASSTYPE Object. It MUST support Class-Type value 1, and MAY
support other Class-Type values.
4.1.1. Path Message Format
The format of the Path message is as follows:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <EXPLICIT_ROUTE> ]
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<LABEL_REQUEST>
[ <SESSION_ATTRIBUTE> ]
[ <DIFFSERV> ]
[ <CLASSTYPE> ]
[ <POLICY_DATA> ... ]
[ <sender descriptor> ]
<sender descriptor> ::= <SENDER_TEMPLATE> [ <SENDER_TSPEC> ]
[ <ADSPEC> ]
[ <RECORD_ROUTE> ]
4.2. CLASSTYPE Object
The CLASSTYPE object format is shown below.
4.2.1. CLASSTYPE object
class = TBD, C_Type = 1 (need to get an official class num from the
IANA with the form 0bbbbbbb)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |CT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved : 30 bits
This field is reserved. It must be set to zero on transmission
and must be ignored on receipt.
CT : 2 bits
Indicates the Class-Type. Values currently allowed are 1, 2 and
3.
4.3. Handling CLASSTYPE Object
To establish an LSP tunnel with RSVP, the sender LSR creates a Path
message with a session type of LSP_Tunnel_IPv4 and with a
LABEL_REQUEST object as per [RSVP-TE]. The sender LSR may also
include the DIFFSERV object as per [DIFF-MPLS].
If the LSP is associated with Class-Type 0, the sender LSR must not
include the CLASSTYPE object in the Path message.
If the LSP is associated with Class-Type N (N=1,2,3), the sender LSR
must include the CLASSTYPE object in the Path message with the
Class-Type (CT) field set to N.
[Editor's Note: additional options whereby the Class-Type could be
determined by the LSR without explicit Class-Type signaling are
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Extensions for Diff-Serv Traffic Engineering July 2000
investigated. For example, the Class-Type could be determined from
Diff-Serv information already signaled such as the PSC for an L-LSP
and using a PSC<-->Class-Type mapping locally configured ]
If a path message contains multiple CLASSTYPE objects, only the
first one is meaningful; subsequent CLASSTYPE object(s) must be
ignored and not forwarded.
Each LSR along the path records the CLASSTYPE object, when present,
in its path state block.
If the CLASSTYPE object is not present in the Path message, the LSR
must associate the Class-Type 0 to the LSP.
The destination LSR responds to the Path message by sending a Resv
message without a CLASSTYPE object (whether the Path message
contained a CLASSTYPE object or not).
During establishment of an LSP corresponding to the Class-Type N,
the LSR performs admission control over the bandwidth available for
that particular Class-Type, which is computed using the smallest of:
- the Class-Type N bandwidth currently unreserved (i.e. the
difference between the Maximum Reservable Bandwidth for Class-
Type N and the bandwidth reserved by existing Class-Type N
LSPs).
- the aggregate bandwidth currently unreserved (i.e. the
difference between the Maximum Reservable Aggregate Bandwidth
and the bandwidth reserved by existing LSPs of all Class-Types).
In order to accurately apportion the resources associated with a
Class-Type among the classes comprised in this Class-Type, the LSR
may automatically adjust Diff-Serv scheduling parameters associated
with a class within a Class-Type based on the bandwidth currently
reserved by LSPs currently established in that class.
An LSR that recognizes the CLASSTYPE object and receives a path
message which contains the CLASSTYPE object but which does not
contain a LABEL_REQUEST object or which does not have a session type
of LSP_Tunnel_IPv4, must send a PathErr towards the sender with the
error code `Diff-Serv TE Error' and an error value of `Unexpected
CLASSTYPE object'. Those are defined below in section 4.5.
An LSR receiving a Path message with the CLASSTYPE object, which
recognizes the CLASSTYPE object but does not support the particular
Class-Type, must send a PathErr towards the sender with the error
code `Diff-Serv TE Error' and an error value of `Unsupported Class-
Type'. Those are defined below in section 4.5.
An LSR receiving a Path message with the CLASSTYPE object, which
recognizes the CLASSTYPE object but determines that the Class-Type
value is not valid (i.e. Class-Type value 0), must send a PathErr
towards the sender with the error code `Diff-Serv TE Error' and an
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Extensions for Diff-Serv Traffic Engineering July 2000
error value of `Invalid Class-Type value'. Those are defined below
in section 4.5.
An LSR MUST handle the situations where the LSP can not be accepted
for other reasons than those already discussed in this section, in
accordance with [RSVP-TE] and [DIFF-MPLS] (e.g. a reservation is
rejected by admission control, a label can not be associated).
4.4. Non-support of the CLASSTYPE Object
An LSR that does not recognize the CLASSTYPE object Class-Num must
behave in accordance with the procedures specified in [RSVP] for an
unknown Class-Num whose format is 0bbbbbbb (i.e. it must send a
PathErr with the error code `Unknown object class' toward the
sender).
An LSR that recognizes the CLASSTYPE object Class-Num but does not
recognize the CLASSTYPE object C-Type, must behave in accordance
with the procedures specified in [RSVP] for an unknown C-type (i.e.
it must send a PathErr with the error code `Unknown object C-Type'
toward the sender).
In both situations, this causes the path set-up to fail. The sender
should notify management that a LSP cannot be established and
possibly might take action to retry reservation establishment
without the CLASSTYPE object.
4.5. Error Codes For Diff-Serv TE
In the procedures described above, certain errors must be reported
as a `Diff-Serv TE Error'. The value of the `Diff-Serv TE Error'
error code is (TBD).
The following defines error values for the Diff-Serv TE Error:
Value Error
1 Unexpected CLASSTYPE object
2 Unsupported Class-Type
3 Invalid Class-Type value
5. CR-LDP Extensions
CR-LDP, defined in [CR-LDP], is an extension to LDP, defined in
[LDP], for support of (aggregate) MPLS Traffic Engineering. In this
section we describe extensions to CR-LDP for support of Diff-Serv
Traffic Engineering on a per-Class-Type basis which meet the
requirements defined in [DIFF-TE-REQTS]. These extensions are in
addition to the extensions to LDP defined in [DIFF-MPLS] for support
of Diff-Serv over MPLS. They closely resemble the extensions to RSVP
defined in the previous section.
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Extensions for Diff-Serv Traffic Engineering July 2000
Note that extensions of this section for support of Diff-Serv
Traffic Engineering are not applicable to LDP due to the fact that
LDP does not support MPLS Traffic Engineering and bandwidth
reservation in particular.
5.1. Diff-Serv related CR-LDP Messages Encoding
One new CR-LDP TLV is defined in this document: the Class Type TLV.
Detailed description of this TLV is provided below. This new TLV is
applicable to Label Request messages.
Restrictions defined in [CR-LDP] for support of establishment of
LSPs via CR-LDP are also applicable to the establishment of LSPs
supporting Diff-Serv Traffic Engineering: for instance, only unicast
LSPs are supported and multicast LSPs are for further study.
This new Class Type TLV is optional with respect to CR-LDP so that
general CR-LDP implementations not concerned with per-Class-Type
Diff-Serv Traffic Engineering do not have to support this TLV.
An LSR supporting Diff-Serv Traffic Engineering on a per-Class-Type
basis in compliance with this specification MUST support the Class
Type TLV. It MUST support Class-Type value 1, and MAY support other
Class-Type values.
5.1.1. Label Request Message Encoding
The encoding for the CR-LDP Label Request message is extended as
follows, to optionally include the Class Type 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Label Request (0x0401) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Diff-Serv TLV (LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Class Type TLV (CR-LDP optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Other CR-LDP TLVs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The extension is based on a related LDP extension, defined in [DIFF-
MPLS], for support of Diff-Serv TLV but further extended for CR-LDP
with CR-LDP TLVs.
5.2. Class Type TLV
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Extensions for Diff-Serv Traffic Engineering July 2000
The Class Type TLV has the following form:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Class Type TLV | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |CT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved : 30 bits
This field is reserved. It must be set to zero on transmission
and must be ignored on receipt.
CT : 2 bits
Indicates the Class-Type. Values currently allowed are 1, 2 and
3.
5.3. Handling Class Type TLV
To establish an LSP using CR-LDP, an ingress LSR generates a Label
Request message as per [CR-LDP]. This Label Request may optionally
include the Diff-Serv TLV as defined in [DIFF-MPLS] for LDP but
extended to CR-LDP.
If the LSP is associated with Class-Type 0, the ingress LSR must not
include the Class Type TLV in the Label Request message.
If the LSP is associated with Class-Type N (N=1,2,3), the ingress
LSR must include the Class Type TLV in the Label Request message
with the Class-Type (CT) field set to N.
[Editor's Note: additional options whereby the Class-Type could be
determined by the LSR without explicit Class-Type signaling are
investigated. For example, the Class-Type could be determined from
Diff-Serv information already signaled such as the PSC for an L-LSP
and using a PSC<-->Class-Type mapping locally configured ]
If a Label Request message contains multiple Class Type TLVs, only
the first one is meaningful; subsequent Class Type TLV(s) must be
ignored and not forwarded.
If the Class Type TLV is not present in the Label Request message,
an LSR must associate the Class-Type 0 to the LSP.
A downstream LSR sending a Label Mapping message in response to a
Label Request message must not include the Class-Type TLV (whether
the Class-Type TLV was included in the Label Request message or
not).
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Extensions for Diff-Serv Traffic Engineering July 2000
During establishment of an LSP corresponding to the Class-Type N, an
LSR performs admission control over the bandwidth available for that
particular Class-Type, which is computed using the smallest of:
- the Class-Type N bandwidth currently unreserved (i.e. the
difference between the Maximum Reservable Bandwidth for Class-
Type N and the bandwidth reserved by existing Class-Type N
LSPs).
- the aggregate bandwidth currently unreserved (i.e. the
difference between the Maximum Reservable Aggregate Bandwidth
and the bandwidth reserved by existing LSPs of all Class-Types).
In order to accurately apportion the resources associated with a
Class-Type among the classes comprised in this Class-Type, an LSR
may automatically adjust Diff-Serv scheduling parameters associated
with a class within a Class-Type based on the bandwidth currently
reserved by LSPs currently established in that class.
An LSR that recognizes the Class Type TLV and receives a Label
Request message which contains the Class Type TLV but which does not
contain any of the CR-LDP TLVs, must reject the label request by
sending upstream a Notification message which includes the Status
TLV with a Status Code of 'Unexpected Class-Type TLV'. This is
defined below in section 5.4. This error can only occur when an LDP
LSP as opposed to CR-LDP LSP is being established. As was already
mentioned, Class Type TLV extension for Diff-Serv Traffic
Engineering is not applicable to LDP.
An LSR receiving a Label Request message with the Class Type TLV,
which recognizes the Class Type TLV but does not support the
particular Class-Type, must reject the label request by sending
upstream a Notification message which includes the Status TLV with a
Status Code of 'Unsupported Class-Type'. This is defined below in
section 5.4.
An LSR receiving a Label Request message with the Class Type TLV,
which recognizes the Class Type TLV but determines that the Class-
Type value is not valid (i.e. Class-Type value 0), must reject the
label request by sending upstream a Notification message which
includes the Status TLV with a Status Code of 'Invalid Class-Type
value'. This is defined below in section 5.4.
An LSR MUST handle the situations where the LSP can not be accepted
for other reasons than those already discussed in this section, in
accordance with [CR-LDP], [LDP] and [DIFF-MPLS] (e.g. reservation
rejected by admission control, a label can not be associated).
5.4. Status Code Values for Diff-Serv TE
In the procedures described above, certain errors must be reported.
The following values are defined for the Status Code field of the
Status TLV:
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Extensions for Diff-Serv Traffic Engineering July 2000
Status Code E Status Data
Unexpected Class Type TLV 0 TBD
Unsupported Class-Type 0 TBD
Invalid Class-Type value 0 TBD
6. Security Considerations
This document raises no new security issues for IS-IS, OSPF, RSVP or
CR-LDP. The security mechanisms already proposed for these
technologies may be used.
7. Acknowledgments
This document has benefited from discussions with Carol Iturralde
and Rob Goguen.
References
[TE-REQ] Awduche et al, Requirements for Traffic Engineering over
MPLS, RFC2702, September 1999.
[TEWG-FW] Awduche et al, A Framework for Internet Traffic
Engineering, draft-ietf-tewg-framework-01.txt, May 2000.
[DIFF-TE-REQTS] Le Faucheur et al, Requirements for support of
Diff-Serv-aware MPLS Traffic Engineering, draft-lefaucheur-diff-te-
reqts-00.txt, July 2000.
[OSPF-TE] Katz, Yeung, Traffic Engineering Extensions to OSPF,
draft-katz-yeung-ospf-traffic-01.txt, April 2000.
[ISIS-TE] Smit, Li, IS-IS extensions for Traffic Engineering, draft-
ietf-isis-traffic-01.txt, May 1999.
[RSVP-TE] Awduche et al, "Extensions to RSVP for LSP Tunnels",
draft-ietf-mpls-rsvp-lsp-tunnel-05.txt, February 2000.
[DIFF-MPLS] Le Faucheur et al, "MPLS Support of Diff-Serv", draft-
ietf-mpls-diff-ext-05.txt, June 2000
[LDP] Andersson et al., "LDP Specification", draft-ietf-mpls-ldp-
06.txt, October 1999
[CR-LDP] Jamoussi et al., "Constraint-Based LSP Setup using LDP",
draft-ietf-mpls-cr-ldp-03.txt, October 1999
Authors' Address:
Le Faucheur et. al 13
Extensions for Diff-Serv Traffic Engineering July 2000
Francois Le Faucheur
Cisco Systems, Inc.
Petra B - Les Lucioles - 291, rue Albert Caquot - 06560 Valbonne -
France
Phone: +33 4 92 96 75 64
Email: flefauch@cisco.com
Angela Chiu
AT&T Labs
Rm 4-204,100 Schulz Dr., Red Bank, NJ 07701
USA
Phone: +1 (732) 345-3441
Email: alchiu@att.com
William Townsend
Tenor Networks
100 Nagog Park
Acton, MA 01720
Phone: +1-978-264-4900
Email: btownsend@tenornetworks.com
Thomas D. Nadeau
Cisco Systems, Inc.
250 Apollo Drive
Chelmsford, MA 01824
Phone: +1-978-244-3051
Email: tnadeau@cisco.com
Darek Skalecki
Nortel Networks
3500 Carling Ave,
Nepean K2H 8E9
Phone: +1-613-765-2252
Email: dareks@nortelnetworks.com
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