As per Relevance of the word parameter, we have this rfc below:
Network Working Group B. Jamoussi, Editor, Nortel
Request for Comments: 3212 L. Andersson, Utfors
Category: Standards Track R. Callon, Juniper
R. Dantu, Netrake
L. Wu, Cisco
P. Doolan, OTB Consulting Corp
T.
N. Feldman, IBM Corp
A. Fredette, ANF
M. Girish, Atoga
E. Gray,
J. Heinanen, Song Networks, Inc
T. Kilty, Newbridge Networks, Inc
A. Malis, Vivace
January 2002
Constraint-Based LSP Setup using
Status of this
This document specifies an Internet standards track protocol for
Internet community, and requests discussion and suggestions
improvements. Please refer to the current edition of the "
Official Protocol Standards" (STD 1) for the standardization
and status of this protocol. Distribution of this memo is unlimited
Copyright
Copyright (C) The Internet Society (2002). All Rights Reserved
This document specifies mechanisms and TLVs (Type/Length/Value)
support of CR-LSPs (constraint-based routed Label Switched Path
using LDP (Label Distribution Protocol).
This specification proposes an end-to-end setup mechanism of a CR-
initiated by the ingress LSR (Label Switching Router). We
specify mechanisms to provide means for reservation of
using LDP
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
document are to be interpreted as described in RFC 2119 [6].
Jamoussi, et al. Standards Track [Page 1]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
Table of
1. Introduction....................................................3
2. Constraint-based Routing Overview...............................4
2.1 Strict and Loose Explicit Routes...............................5
2.2 Traffic Characteristics........................................5
2.3 Preemption.....................................................5
2.4 Route Pinning..................................................6
2.5 Resource Class.................................................6
3. Solution Overview...............................................6
3.1 Required Messages and TLVs.....................................7
3.2 Label Request Message..........................................7
3.3 Label Mapping Message..........................................9
3.4 Notification Message..........................................10
3.5 Release , Withdraw, and Abort Messages........................11
4. Protocol Specification.........................................11
4.1 Explicit Route TLV (ER-TLV)...................................11
4.2 Explicit Route Hop TLV (ER-Hop TLV)...........................12
4.3 Traffic Parameters TLV........................................13
4.3.1 Semantics...................................................15
4.3.1.1 Frequency.................................................15
4.3.1.2 Peak Rate.................................................16
4.3.1.3 Committed Rate............................................16
4.3.1.4 Excess Burst Size.........................................16
4.3.1.5 Peak Rate Token Bucket....................................16
4.3.1.6 Committed Data Rate Token Bucket..........................17
4.3.1.7 Weight....................................................18
4.3.2 Procedures..................................................18
4.3.2.1 Label Request Message.....................................18
4.3.2.2 Label Mapping Message.....................................18
4.3.2.3 Notification Message......................................19
4.4 Preemption TLV................................................19
4.5 LSPID TLV.....................................................20
4.6 Resource Class (Color) TLV....................................21
4.7 ER-Hop semantics..............................................22
4.7.1. ER-Hop 1: The IPv4 prefix..................................22
4.7.2. ER-Hop 2: The IPv6 address.................................23
4.7.3. ER-Hop 3: The autonomous system number....................24
4.7.4. ER-Hop 4: LSPID............................................24
4.8. Processing of the Explicit Route TLV.........................26
4.8.1. Selection of the next hop..................................26
4.8.2. Adding ER-Hops to the explicit route TLV...................27
4.9 Route Pinning TLV.............................................28
4.10 CR-LSP FEC Element...........................................28
5. IANA Considerations............................................29
5.1 TLV Type Name Space...........................................29
5.2 FEC Type Name Space...........................................30
5.3 Status Code Space.............................................30
Jamoussi, et al. Standards Track [Page 2]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
6. Security Considerations........................................31
7. Acknowledgments................................................31
8. Intellectual Property Consideration............................31
9. References.....................................................32
Appendix A: CR-LSP Establishment Examples.........................33
A.1 Strict Explicit Route Example.................................33
A.2 Node Groups and Specific Nodes Example........................34
Appendix B. QoS Service Examples..................................36
B.1 Service Examples..............................................36
B.2 Establishing CR-LSP Supporting Real-Time Applications.........38
B.3 Establishing CR-LSP Supporting Delay Insensitive Applications.38
Author's Addresses................................................39
Full Copyright Statement..........................................42
1.
Label Distribution Protocol (LDP) is defined in [1] for
of labels inside one MPLS domain. One of the most important
that may be offered using MPLS in general and LDP in particular
support for constraint-based routing of traffic across the
network. Constraint-based routing offers the opportunity to
the information used to setup paths beyond what is available for
routing protocol. For instance, an LSP can be setup based
explicit route constraints, QoS constraints, and other constraints
Constraint-based routing (CR) is a mechanism used to meet
Engineering requirements that have been proposed by, [2] and [3].
These requirements may be met by extending LDP for support
constraint-based routed label switched paths (CR-LSPs). Other
for CR-LSPs include MPLS-based VPNs [4]. More information about
applicability of CR-LDP can be found in [5].
The need for constraint-based routing (CR) in MPLS has been
elsewhere [2], and [3]. Explicit routing is a subset of the
general constraint-based routing function. At the MPLS WG
held during the Washington IETF (December 1997) there was
that LDP should support explicit routing of LSPs with provision
indication of associated (forwarding) priority. In the
meeting (August 1998), a decision was made that support for
path setup in LDP will be moved to a separate document.
document provides that support and it has been accepted as a
document in the Orlando meeting (December 1998).
Jamoussi, et al. Standards Track [Page 3]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
This specification proposes an end-to-end setup mechanism of
constraint-based routed LSP (CR-LSP) initiated by the ingress LSR.
also specify mechanisms to provide means for reservation of
using LDP
This document introduce TLVs and procedures that provide support for
- Strict and Loose Explicit
- Specification of Traffic
- Route
- CR-LSP Preemption though setup/holding
- Handling
-
- Resource
Section 2 introduces the various constraints defined in
specification. Section 3 outlines the CR-LDP solution. Section 4
defines the TLVs and procedures used to setup constraint-based
label switched paths. Appendix A provides several examples of CR-
path setup. Appendix B provides Service Definition Examples
2. Constraint-based Routing
Constraint-based routing is a mechanism that supports the
Engineering requirements defined in [3]. Explicit Routing is
subset of the more general constraint-based routing where
constraint is the explicit route (ER). Other constraints are
to provide a network operator with control over the path taken by
LSP. This section is an overview of the various
supported by this specification
Like any other LSP a CR-LSP is a path through an MPLS network.
difference is that while other paths are setup solely based
information in routing tables or from a management system,
constraint-based route is calculated at one point at the edge
network based on criteria, including but not limited to
information. The intention is that this functionality shall
desired special characteristics to the LSP in order to better
the traffic sent over the LSP. The reason for setting up CR-
might be that one wants to assign certain bandwidth or other
Class characteristics to the LSP, or that one wants to make sure
alternative routes use physically separate paths through the network
Jamoussi, et al. Standards Track [Page 4]
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2.1 Strict and Loose Explicit
An explicit route is represented in a Label Request Message as a
of nodes or groups of nodes along the constraint-based route.
the CR-LSP is established, all or a subset of the nodes in a
may be traversed by the LSP. Certain operations to be
along the path can also be encoded in the constraint-based route
The capability to specify, in addition to specified nodes, groups
nodes, of which a subset will be traversed by the CR-LSP, allows
system a significant amount of local flexibility in fulfilling
request for a constraint-based route. This allows the generator
the constraint-based route to have some degree of
information about the details of the path
The constraint-based route is encoded as a series of ER-
contained in a constraint-based route TLV. Each ER-Hop may
a group of nodes in the constraint-based route. A constraint-
route is then a path including all of the identified groups of
in the order in which they appear in the TLV
To simplify the discussion, we call each group of nodes an "
node". Thus, we can also say that a constraint-based route is a
including all of the abstract nodes, with the specified
occurring along that path
2.2 Traffic
The traffic characteristics of a path are described in the
Parameters TLV in terms of a peak rate, committed rate, and
granularity. The peak and committed rates describe the
constraints of a path while the service granularity can be used
specify a constraint on the delay variation that the CR-LDP
domain may introduce to a path's traffic
2.3
CR-LDP signals the resources required by a path on each hop of
route. If a route with sufficient resources can not be found
existing paths may be rerouted to reallocate resources to the
path. This is the process of path preemption. Setup and
priorities are used to rank existing paths (holding priority) and
new path (setup priority) to determine if the new path can preempt
existing path
The setupPriority of a new CR-LSP and the holdingPriority
of the existing CR-LSP are used to specify priorities. Signaling
higher holding priority express that the path, once it has
Jamoussi, et al. Standards Track [Page 5]
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established, should have a lower chance of being preempted.
a higher setup priority expresses the expectation that, in the
that resource are unavailable, the path is more likely to
other paths. The exact rules determining bumping are an aspect
network policy
The allocation of setup and holding priority values to paths is
aspect of network policy
The setup and holding priority values range from zero (0) to
(7). The value zero (0) is the priority assigned to the
important path. It is referred to as the highest priority.
(7) is the priority for the least important path. The use of
priority values is an aspect of network policy. The
default value is (4).
The setupPriority of a CR-LSP should not be higher (numerically less
than its holdingPriority since it might bump an LSP and be bumped
the next "equivalent" request
2.4 Route
Route pinning is applicable to segments of an LSP that are
routed - i.e. those segments which are specified with a next hop
the "L" bit set or where the next hop is an abstract node. A CR-
may be setup using route pinning if it is undesirable to change
path used by an LSP even when a better next hop becomes available
some LSR along the loosely routed portion of the LSP
2.5 Resource
The network operator may classify network resources in various ways
These classes are also known as "colors" or "administrative groups".
When a CR-LSP is being established, it's necessary to indicate
resource classes the CR-LSP can draw from
3. Solution
CR-LSP over LDP Specification is designed with the following goals
1. Meet the requirements outlined in [3] for performing
engineering and provide a solid foundation for performing
general constraint-based routing
2. Build on already specified functionality that meets
requirements whenever possible. Hence, this specification
based on [1].
Jamoussi, et al. Standards Track [Page 6]
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3. Keep the solution simple
In this document, support for unidirectional point-to-point CR-
is specified. Support for point-to-multipoint, multipoint-to-point
is for further study (FFS).
Support for constraint-based routed LSPs in this
depends on the following minimal LDP behaviors as specified in [1]:
- Use of Basic and/or Extended Discovery Mechanisms
- Use of the Label Request Message defined in [1] in
on demand label advertisement mode with ordered control
- Use of the Label Mapping Message defined in [1] in
on demand mode with ordered control
- Use of the Notification Message defined in [1].
- Use of the Withdraw and Release Messages defined in [1].
- Use of the Loop Detection (in the case of loosely
segments of a CR-LSP) mechanisms defined in [1].
In addition, the following functionality is added to what's
in [1]:
- The Label Request Message used to setup a CR-LSP includes
or more CR-TLVs defined in Section 4. For instance, the
Request Message may include the ER-TLV
- An LSR implicitly infers ordered control from the existence
one or more CR-TLVs in the Label Request Message. This
that the LSR can still be configured for independent
for LSPs established as a result of dynamic routing. However
when a Label Request Message includes one or more of the CR
TLVs, then ordered control is used to setup the CR-LSP.
that this is also true for the loosely routed parts of a CR
LSP
- New status codes are defined to handle error notification
failure of established paths specified in the CR-TLVs. All
the new status codes require that the F bit be set
Optional TLVs MUST be implemented to be compliant with the protocol
However, they are optionally carried in the CR-LDP messages to
certain characteristics of the CR-LSP being established or modified
Examples of CR-LSP establishment are given in Appendix A
illustrate how the mechanisms described in this document work
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3.1 Required Messages and
Any Messages, TLVs, and procedures not defined explicitly in
document are defined in the LDP Specification [1]. The reader
use [7] as an informational document about the state transitions
which relate to CR-LDP messages
The following subsections are meant as a cross-reference to the [1]
document and indication of additional functionality beyond what'
defined in [1] where necessary
Note that use of the Status TLV is not limited to
messages as specified in Section 3.4.6 of [1]. A message other
a Notification message may carry a Status TLV as an
Parameter. When a message other than a Notification carries a
TLV the U-bit of the Status TLV should be set to 1 to indicate
the receiver should silently discard the TLV if unprepared to
it
3.2 Label Request
The Label Request Message is as defined in 3.5.8 of [1] with
following modifications (required only if any of the CR-TLVs
included in the Label Request Message):
- The Label Request Message MUST include a single FEC-
element. The CR-LSP FEC TLV element SHOULD be used. However
the other FEC- TLVs defined in [1] MAY be used instead
certain applications
- The Optional Parameters TLV includes the definition of any
the Constraint-based TLVs specified in Section 4.
- The Procedures to handle the Label Request Message
augmented by the procedures for processing of the CR-TLVs
defined in Section 4.
Jamoussi, et al. Standards Track [Page 8]
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The encoding for the CR-LDP Label Request Message is as follows
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSPID TLV (CR-LDP, mandatory) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Pinning TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Resource Class TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preemption TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.3 Label Mapping
The Label Mapping Message is as defined in 3.5.7 of [1] with
following modifications
- The Label Mapping Message MUST include a single Label-TLV
- The Label Mapping Message Procedures are limited to
on demand ordered control mode
A Mapping message is transmitted by a downstream LSR to an
LSR under one of the following conditions
1. The LSR is the egress end of the CR-LSP and an upstream
has been requested
2. The LSR received a mapping from its downstream next hop LSR
an CR-LSP for which an upstream request is still pending
Jamoussi, et al. Standards Track [Page 9]
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The encoding for the CR-LDP Label Mapping Message is as follows
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 Mapping (0x0400) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FEC TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Request Message ID TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSPID TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic TLV (CR-LDP, optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.4 Notification
The Notification Message is as defined in Section 3.5.1 of [1]
the Status TLV encoding is as defined in Section 3.4.6 of [1].
Establishment of an CR-LSP may fail for a variety of reasons.
such failures are considered advisory conditions and they
signaled by the Notification Message
Notification Messages carry Status TLVs to specify events
signaled. New status codes are defined in Section 4.11 to
error notifications associated with the establishment of a CR-LSP
the processing of the CR-TLV. All of the new status codes
that the F bit be set
The Notification Message MAY carry the LSPID TLV of the
CR-LSP
Notification Messages MUST be forwarded toward the LSR
the Label Request at each hop and at any time that procedures in
specification - or in [1] - specify sending of a Notification
in response to a Label Request Message
Jamoussi, et al. Standards Track [Page 10]
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The encoding of the notification message is as follows
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| Notification (0x0001) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status (TLV) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Optional Parameters |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.5 Release , Withdraw, and Abort
The Label Release , Label Withdraw, and Label Abort Request
are used as specified in [1]. These messages MAY also carry
LSPID TLV
4. Protocol
The Label Request Message defined in [1] MUST carry the LSPID TLV
MAY carry one or more of the optional Constraint-based Routing
(CR-TLVs) defined in this section. If needed, other constraints
be supported later through the definition of new TLVs. In
specification, the following TLVs are defined
- Explicit Route
- Explicit Route Hop
- Traffic Parameters
- Preemption
- LSPID
- Route Pinning
- Resource Class
- CR-LSP FEC
4.1 Explicit Route TLV (ER-TLV
The ER-TLV is an object that specifies the path to be taken by
LSP being established. It is composed of one or more Explicit
Hop TLVs (ER-Hop TLVs) defined in Section 4.2.
Jamoussi, et al. Standards Track [Page 11]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
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| Type = 0x0800 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ............ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ER-Hop TLV n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ER-
Type = 0x0800.
Specifies the length of the value field in bytes
ER-Hop
One or more ER-Hop TLVs defined in Section 4.2.
4.2 Explicit Route Hop TLV (ER-Hop TLV
The contents of an ER-TLV are a series of variable length ER-
TLVs
A node receiving a label request message including an ER-Hop
that is not supported MUST not progress the label request message
the downstream LSR and MUST send back a "No Route"
Message
Each ER-Hop TLV has the 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| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Content // |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Jamoussi, et al. Standards Track [Page 12]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
ER-Hop
A fourteen-bit field carrying the type of the ER-Hop contents
Currently defined values are
Value
------ ------------------------
0x0801 IPv4
0x0802 IPv6
0x0803 Autonomous system
0x0804
Specifies the length of the value field in bytes
L
The L bit in the ER-Hop is a one-bit attribute. If the L
is set, then the value of the attribute is "loose." Otherwise
the value of the attribute is "strict." For brevity, we
that if the value of the ER-Hop attribute is loose then it is
"loose ER-Hop." Otherwise, it's a "strict ER-Hop." Further
we say that the abstract node of a strict or loose ER-Hop is
strict or a loose node, respectively. Loose and strict
are always interpreted relative to their prior abstract nodes
The path between a strict node and its prior node MUST
only network nodes from the strict node and its prior
node
The path between a loose node and its prior node MAY
other network nodes, which are not part of the strict node
its prior abstract node
A variable length field containing a node or abstract
which is one of the consecutive nodes that make up
explicitly routed LSP
4.3 Traffic Parameters
The following sections describe the CR-LSP Traffic Parameters.
required characteristics of a CR-LSP are expressed by the
Parameter values
A Traffic Parameters TLV, is used to signal the Traffic
values. The Traffic Parameters are defined in the
sections
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The Traffic Parameters TLV contains a Flags field, a Frequency,
Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS
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| Type = 0x0810 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Frequency | Reserved | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Data Rate (PDR) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Burst Size (PBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Committed Data Rate (CDR) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Committed Burst Size (CBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excess Burst Size (EBS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the
Parameters TLV Type = 0x0810.
Specifies the length of the value field in bytes = 24.
The Flags field is shown below
+--+--+--+--+--+--+--+--+
| Res |F6|F5|F4|F3|F2|F1|
+--+--+--+--+--+--+--+--+
Res - These bits are reserved
Zero on transmission
Ignored on receipt
F1 - Corresponds to the PDR
F2 - Corresponds to the PBS
F3 - Corresponds to the CDR
F4 - Corresponds to the CBS
F5 - Corresponds to the EBS
F6 - Corresponds to the Weight
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Each flag Fi is a Negotiable Flag corresponding to a
Parameter. The Negotiable Flag value zero
NotNegotiable and value one denotes Negotiable
The Frequency field is coded as an 8 bit unsigned integer
the following code points defined
0-
1-
2-
3-255 -
Reserved - Zero on transmission. Ignored on receipt
An 8 bit unsigned integer indicating the weight of the CR-LSP
Valid weight values are from 1 to 255. The value 0 means
weight is not applicable for the CR-LSP
Traffic
Each Traffic Parameter is encoded as a 32-bit IEEE single
precision floating-point number. A value of positive
is represented as an IEEE single-precision floating-
number with an exponent of all ones (255) and a sign
mantissa of all zeros. The values PDR and CDR are in units
bytes per second. The values PBS, CBS and EBS are in units
bytes
The value of PDR MUST be greater than or equal to the value
CDR in a correctly encoded Traffic Parameters TLV
4.3.1
4.3.1.1
The Frequency specifies at what granularity the CDR allocated to
CR-LSP is made available. The value VeryFrequent means that
available rate should average at least the CDR when measured over
time interval equal to or longer than the shortest packet time at
CDR. The value Frequent means that the available rate should
at least the CDR when measured over any time interval equal to
longer than a small number of shortest packet times at the CDR
The value Unspecified means that the CDR MAY be provided at
granularity
Jamoussi, et al. Standards Track [Page 15]
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4.3.1.2 Peak
The Peak Rate defines the maximum rate at which traffic SHOULD
sent to the CR-LSP. The Peak Rate is useful for the purpose
resource allocation. If resource allocation within the MPLS
depends on the Peak Rate value then it should be enforced at
ingress to the MPLS domain
The Peak Rate is defined in terms of the two Traffic Parameters
and PBS, see section 4.3.1.5 below
4.3.1.3 Committed
The Committed Rate defines the rate that the MPLS domain commits
be available to the CR-LSP
The Committed Rate is defined in terms of the two Traffic
CDR and CBS, see section 4.3.1.6 below
4.3.1.4 Excess Burst
The Excess Burst Size may be used at the edge of an MPLS domain
the purpose of traffic conditioning. The EBS MAY be used to
the extent by which the traffic sent on a CR-LSP exceeds
committed rate
The possible traffic conditioning actions, such as passing,
or dropping, are specific to the MPLS domain
The Excess Burst Size is defined together with the Committed Rate
see section 4.3.1.6 below
4.3.1.5 Peak Rate Token
The Peak Rate of a CR-LSP is specified in terms of a token bucket
with token rate PDR and maximum token bucket size PBS
The token bucket P is initially (at time 0) full, i.e., the
count Tp(0) = PBS. Thereafter, the token count Tp, if less than PBS
is incremented by one PDR times per second. When a packet of size
bytes arrives at time t, the following happens
- If Tp(t)-B >= 0, the packet is not in excess of the peak
and Tp is decremented by B down to the minimum value of 0,
- the packet is in excess of the peak rate and Tp is
decremented
Jamoussi, et al. Standards Track [Page 16]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
Note that according to the above definition, a positive
value of either PDR or PBS implies that arriving packets are never
excess of the peak rate
The actual implementation of an LSR doesn't need to be
according to the above formal token bucket specification
4.3.1.6 Committed Data Rate Token
The committed rate of a CR-LSP is specified in terms of a
bucket C with rate CDR. The extent by which the offered rate
the committed rate MAY be measured in terms of another token
E, which also operates at rate CDR. The maximum size of the
bucket C is CBS and the maximum size of the token bucket E is EBS
The token buckets C and E are initially (at time 0) full, i.e.,
token count Tc(0) = CBS and the token count Te(0) = EBS
Thereafter, the token counts Tc and Te are updated CDR times
second as follows
- If Tc is less than CBS, Tc is incremented by one,
- if Te is less then EBS, Te is incremented by one, else
Tc nor Te is incremented
When a packet of size B bytes arrives at time t, the
happens
- If Tc(t)-B >= 0, the packet is not in excess of the
Rate and Tc is decremented by B down to the minimum value of 0,
- if Te(t)-B >= 0, the packet is in excess of the Committed
but is not in excess of the EBS and Te is decremented by B
to the minimum value of 0,
- the packet is in excess of both the Committed Rate and the
and neither Tc nor Te is decremented
Note that according to the above specification, a CDR value
positive infinity implies that arriving packets are never in
of either the Committed Rate or EBS. A positive infinite value
either CBS or EBS implies that the respective limit cannot
exceeded
The actual implementation of an LSR doesn't need to be
according to the above formal specification
Jamoussi, et al. Standards Track [Page 17]
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4.3.1.7
The weight determines the CR-LSP's relative share of the
excess bandwidth above its committed rate. The definition
"relative share" is MPLS domain specific
4.3.2
4.3.2.1 Label Request
If an LSR receives an incorrectly encoded Traffic Parameters TLV
which the value of PDR is less than the value of CDR then it
send a Notification Message including the Status code "
Parameters Unavailable" to the upstream LSR from which it
the erroneous message
If a Traffic Parameter is indicated as Negotiable in the
Request Message by the corresponding Negotiable Flag then an LSR
replace the Traffic Parameter value with a smaller value
If the Weight is indicated as Negotiable in the Label Request
by the corresponding Negotiable Flag then an LSR may replace
Weight value with a lower value (down to 0).
If, after possible Traffic Parameter negotiation, an LSR can
the CR-LSP Traffic Parameters then the LSR MUST reserve
corresponding resources for the CR-LSP
If, after possible Traffic Parameter negotiation, an LSR
support the CR-LSP Traffic Parameters then the LSR MUST send
Notification Message that contains the "Resource Unavailable"
code
4.3.2.2 Label Mapping
If an LSR receives an incorrectly encoded Traffic Parameters TLV
which the value of PDR is less than the value of CDR then it
send a Label Release message containing the Status code "
Parameters Unavailable" to the LSR from which it received
erroneous message. In addition, the LSP should send a
Message upstream with the status code 'Label Request Aborted'.
If the negotiation flag was set in the label request message,
egress LSR MUST include the (possibly negotiated) Traffic
and Weight in the Label Mapping message
The Traffic Parameters and the Weight in a Label Mapping message
be forwarded unchanged
Jamoussi, et al. Standards Track [Page 18]
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An LSR SHOULD adjust the resources that it reserved for a CR-LSP
it receives a Label Mapping Message if the Traffic Parameters
from those in the corresponding Label Request Message
4.3.2.3 Notification
If an LSR receives a Notification Message for a CR-LSP, it
release any resources that it possibly had reserved for the CR-LSP
In addition, on receiving a Notification Message from a
LSR that is associated with a Label Request from an upstream LSR,
local LSR MUST propagate the Notification message using
procedures in [1]. Further the F bit MUST be set
4.4 Preemption
The default value of the setup and holding priorities should be
the middle of the range (e.g., 4) so that this feature can be
on gradually in an operational network by increasing or
the priority starting at the middle of the range
Since the Preemption TLV is an optional TLV, LSPs that are
without an explicitly signaled preemption TLV SHOULD be treated
LSPs with the default setup and holding priorities (e.g., 4).
When an established LSP is preempted, the LSR that initiates
preemption sends a Withdraw Message upstream and a Release
downstream
When an LSP in the process of being established (outstanding
Request without getting a Label Mapping back) is preempted, the
that initiates the preemption, sends a Notification Message
and an Abort Message downstream
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| Type = 0x0820 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SetPrio | HoldPrio | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the Preemption-
Type = 0x0820.
Specifies the length of the value field in bytes = 4.
Jamoussi, et al. Standards Track [Page 19]
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Zero on transmission. Ignored on receipt
A SetupPriority of value zero (0) is the priority assigned
the most important path. It is referred to as the
priority. Seven (7) is the priority for the least
path. The higher the setup priority, the more paths CR-LDP
bump to set up the path. The default value should be 4.
A HoldingPriority of value zero (0) is the priority assigned
the most important path. It is referred to as the
priority. Seven (7) is the priority for the least
path. The default value should be 4.
The higher the holding priority, the less likely it is for CR
LDP to reallocate its bandwidth to a new path
4.5 LSPID
LSPID is a unique identifier of a CR-LSP within an MPLS network
The LSPID is composed of the ingress LSR Router ID (or any of
own Ipv4 addresses) and a Locally unique CR-LSP ID to that LSR
The LSPID is useful in network management, in CR-LSP repair, and
using an already established CR-LSP as a hop in an ER-TLV
An "action indicator flag" is carried in the LSPID TLV. This "
indicator flag" indicates explicitly the action that should be
if the LSP already exists on the LSR receiving the message
After a CR-LSP is set up, its bandwidth reservation may need to
changed by the network operator, due to the new requirements for
traffic carried on that CR-LSP. The "action indicator flag" is
indicate the need to modify the bandwidth and possibly
parameters of an established CR-LSP without service interruption
This feature has application in dynamic network resources
where traffic of different priorities and service classes
involved
The procedure for the code point "modify" is defined in [8].
procedures for other flags are FFS
Jamoussi, et al. Standards Track [Page 20]
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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| Type = 0x0821 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |ActFlg | Local CR-LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the LSPID-
Type = 0x0821.
Specifies the length of the value field in bytes = 4.
Action Indicator Flag: A 4-bit field that indicates
the action that should be taken if the LSP already exists
the LSR receiving the message. A set of indicator code
is proposed as follows
0000: indicates initial LSP
0001: indicates modify
Zero on transmission. Ignored on receipt
Local CR-LSP
The Local LSP ID is an identifier of the CR-LSP locally
within the Ingress LSR originating the CR-LSP
Ingress LSR Router
An LSR may use any of its own IPv4 addresses in this field
4.6 Resource Class (Color)
The Resource Class as defined in [3] is used to specify which
are acceptable by this CR-LSP. This information allows for
network's topology to be pruned
Jamoussi, et al. Standards Track [Page 21]
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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| Type = 0x0822 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RsCls |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ResCls-
Type = 0x0822.
Specifies the length of the value field in bytes = 4.
The Resource Class bit mask indicating which of the 32
"administrative groups" or "colors" of links the CR-LSP
traverse
4.7 ER-Hop
4.7.1. ER-Hop 1: The IPv4
The abstract node represented by this ER-Hop is the set of nodes
which have an IP address, which lies within this prefix. Note that
prefix length of 32 indicates a single IPv4 node
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| Type = 0x0801 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | PreLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ER-Hop 1, IPv
Address, Type = 0x0801
Specifies the length of the value field in bytes = 8.
L
Set to indicate Loose hop
Cleared to indicate a strict hop
Jamoussi, et al. Standards Track [Page 22]
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Zero on transmission. Ignored on receipt
Prefix Length 1-32
IP
A four-byte field indicating the IP Address
4.7.2. ER-Hop 2: The IPv6
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| 0x0802 | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | PreLen |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPV6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ER-Hop 2, IPv
Address, Type = 0x0802
Specifies the length of the value field in bytes = 20.
L
Set to indicate Loose hop
Cleared to indicate a strict hop
Zero on transmission. Ignored on receipt
Prefix Length 1-128
IPv6
A 128-bit unicast host address
Jamoussi, et al. Standards Track [Page 23]
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4.7.3. ER-Hop 3: The autonomous system
The abstract node represented by this ER-Hop is the set of
belonging to the autonomous system
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| 0x0803 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ER-Hop 3,
Number, Type = 0x0803
Specifies the length of the value field in bytes = 4.
L
Set to indicate Loose hop
Cleared to indicate a strict hop
Zero on transmission. Ignored on receipt
AS
Autonomous System
4.7.4. ER-Hop 4:
The LSPID is used to identify the tunnel ingress point as the
hop in the ER. This ER-Hop allows for stacking new CR-LSPs within
already established CR-LSP. It also allows for splicing the CR-
being established with an existing CR-LSP
If an LSPID Hop is the last ER-Hop in an ER-TLV, than the LSR
splice the CR-LSP of the incoming Label Request to the CR-LSP
currently exists with this LSPID. This is useful, for example,
the point at which a Label Request used for local repair arrives
the next ER-Hop after the loosely specified CR-LSP segment. Use
the LSPID Hop in this scenario eliminates the need for ER-Hops
keep the entire remaining ER-TLV at each LSR that is at
(upstream or downstream) end of a loosely specified CR-LSP segment
part of its state information. This is due to the fact that
Jamoussi, et al. Standards Track [Page 24]
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upstream LSR needs only to keep the next ER-Hop and the LSPID and
downstream LSR needs only to keep the LSPID in order for each end
be able to recognize that the same LSP is being identified
If the LSPID Hop is not the last hop in an ER-TLV, the LSR
remove the LSP-ID Hop and forward the remaining ER-TLV in a
Request message using an LDP session established with the LSR that
the specified CR-LSP's egress. That LSR will continue processing
the CR-LSP Label Request Message. The result is a tunneled,
stacked, CR-LSP
To support labels negotiated for tunneled CR-LSP segments, an
session is required [1] between tunnel end points - possibly
the existing CR-LSP. Use of the existence of the CR-LSP in lieu of
session, or other possible session-less approaches, is FFS
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| 0x0804 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | Local LSPID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the ER-Hop 4, LSPID
Type = 0x0804
Specifies the length of the value field in bytes = 8.
L
Set to indicate Loose hop
Cleared to indicate a strict hop
Zero on transmission. Ignored on receipt
Local
A 2 byte field indicating the LSPID which is unique
reference to its Ingress LSR
Ingress LSR Router
An LSR may use any of its own IPv4 addresses in this field
Jamoussi, et al. Standards Track [Page 25]
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4.8. Processing of the Explicit Route
4.8.1. Selection of the next
A Label Request Message containing an explicit route TLV
determine the next hop for this path. Selection of this next hop
involve a selection from a set of possible alternatives.
mechanism for making a selection from this set is
dependent and is outside of the scope of this specification
Selection of particular paths is also outside of the scope of
specification, but it is assumed that each node will make a
effort attempt to determine a loop-free path. Note that such
efforts may be overridden by local policy
To determine the next hop for the path, a node performs the
steps
1. The node receiving the Label Request Message must
evaluate the first ER-Hop. If the L bit is not set in
first ER-Hop and if the node is not part of the abstract
described by the first ER-Hop, it has received the message
error, and should return a "Bad Initial ER-Hop Error" status
If the L bit is set and the local node is not part of
abstract node described by the first ER-Hop, the node selects
next hop that is along the path to the abstract node
by the first ER-Hop. If there is no first ER-Hop, the
is also in error and the system should return a "Bad
Routing TLV Error" status using a Notification Message
upstream
2. If there is no second ER-Hop, this indicates the end of
explicit route. The explicit route TLV should be removed
the Label Request Message. This node may or may not be the
of the LSP. Processing continues with section 4.8.2, where
new explicit route TLV may be added to the Label
Message
3. If the node is also a part of the abstract node described
the second ER-Hop, then the node deletes the first ER-Hop
continues processing with step 2, above. Note that this
the second ER-Hop into the first ER-Hop of the next iteration
4. The node determines if it is topologically adjacent to
abstract node described by the second ER-Hop. If so, the
selects a particular next hop which is a member of the
node. The node then deletes the first ER-Hop and
processing with section 4.8.2.
Jamoussi, et al. Standards Track [Page 26]
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5. Next, the node selects a next hop within the abstract node
the first ER-Hop that is along the path to the abstract node
the second ER-Hop. If no such path exists then there are
cases
5.a If the second ER-Hop is a strict ER-Hop, then there is
error and the node should return a "Bad Strict Node Error
status
5.b Otherwise, if the second ER-Hop is a loose ER-Hop, then
node selects any next hop that is along the path to
next abstract node. If no path exists within the
domain, then there is an error, and the node should
a "Bad Loose Node Error" status
6. Finally, the node replaces the first ER-Hop with any ER-
that denotes an abstract node containing the next hop. This
necessary so that when the explicit route is received by
next hop, it will be accepted
7. Progress the Label Request Message to the next hop
4.8.2. Adding ER-Hops to the explicit route
After selecting a next hop, the node may alter the explicit route
the following ways
If, as part of executing the algorithm in section 4.8.1, the
route TLV is removed, the node may add a new explicit route TLV
Otherwise, if the node is a member of the abstract node for the
ER-Hop, then a series of ER-Hops may be inserted before the
ER-Hop or may replace the first ER-Hop. Each ER-Hop in this
must denote an abstract node that is a subset of the current
node
Alternately, if the first ER-Hop is a loose ER-Hop, an
series of ER-Hops may be inserted prior to the first ER-Hop
Jamoussi, et al. Standards Track [Page 27]
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4.9 Route Pinning
Section 2.4 describes the use of route pinning. The encoding of
Route Pinning TLV is as follows
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| Type = 0x0823 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the Pinning-
Type = 0x0823
Specifies the length of the value field in bytes = 4.
P
The P bit is set to 1 to indicate that route pinning
requested
The P bit is set to 0 to indicate that route pinning is
Zero on transmission. Ignored on receipt
4.10 CR-LSP FEC
A new FEC element is introduced in this specification to support CR
LSPs. A FEC TLV containing a FEC of Element type CR-LSP (0x04) is
CR-LSP FEC TLV. The CR-LSP FEC Element is an opaque FEC to be
only in Messages of CR-LSPs
A single FEC element MUST be included in the Label Request Message
The FEC Element SHOULD be the CR-LSP FEC Element. However, one
the other FEC elements (Type=0x01, 0x02, 0x03) defined in [1] MAY
in CR-LDP messages instead of the CR-LSP FEC Element for
applications. A FEC TLV containing a FEC of Element type CR-
(0x04) is a CR-LSP FEC TLV
FEC Element Type
Type
CR-LSP 0x04 No value; i.e., 0 value octets
Jamoussi, et al. Standards Track [Page 28]
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The CR-LSP FEC TLV encoding is as follows
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| Type = 0x0100 | Length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CR-LSP (4) |
+-+-+-+-+-+-+-+-+
A fourteen-bit field carrying the value of the FEC
Type = 0x0100
Specifies the length of the value field in bytes = 1.
CR-LSP FEC Element
0x04
5. IANA
CR-LDP defines the following name spaces, which require management
- TLV types
- FEC types
- Status codes
The following sections provide guidelines for managing these
spaces
5.1 TLV Type Name
RFC 3036 [1] defines the LDP TLV name space. This document
subdivides the range of RFC 3036 from that TLV space for
associated with the CR-LDP in the range 0x0800 - 0x08FF
Following the policies outlined in [IANA], TLV types in this
are allocated through an IETF Consensus action
Jamoussi, et al. Standards Track [Page 29]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
Initial values for this range are specified in the following table
TLV
-------------------------------------- ----------
Explicit Route TLV 0x0800
Ipv4 Prefix ER-Hop TLV 0x0801
Ipv6 Prefix ER-Hop TLV 0x0802
Autonomous System Number ER-Hop TLV 0x0803
LSP-ID ER-Hop TLV 0x0804
Traffic Parameters TLV 0x0810
Preemption TLV 0x0820
LSPID TLV 0x0821
Resource Class TLV 0x0822
Route Pinning TLV 0x0823
5.2 FEC Type Name
RFC 3036 defines the FEC Type name space. Further, RFC 3036
assigned values 0x00 through 0x03. FEC types 0 through 127
available for assignment through IETF consensus action.
specification makes the following additional assignment, using
policies outlined in [IANA]:
FEC Element
-------------------------------------- ----------
CR-LSP FEC Element 0x04
5.3 Status Code
RFC 3036 defines the Status Code name space. This document
subdivides the range of RFC 3036 from that TLV space for
associated with the CR-LDP in the range 0x04000000 - 0x040000FF
Following the policies outlined in [IANA], TLV types in this
are allocated through an IETF Consensus action
Jamoussi, et al. Standards Track [Page 30]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
Initial values for this range are specified in the following table
Status Code
-------------------------------------- ----------
Bad Explicit Routing TLV Error 0x04000001
Bad Strict Node Error 0x04000002
Bad Loose Node Error 0x04000003
Bad Initial ER-Hop Error 0x04000004
Resource Unavailable 0x04000005
Traffic Parameters Unavailable 0x04000006
LSP Preempted 0x04000007
Modify Request Not Supported 0x04000008
6. Security
CR-LDP inherits the same security mechanism described in Section 4.0
of [1] to protect against the introduction of spoofed TCP
into LDP session connection streams
7.
The messages used to signal the CR-LSP setup are based on the
done by the LDP [1] design team
The list of authors provided with this document is a reduction of
original list. Currently listed authors wish to acknowledge that
substantial amount was also contributed to this work by
Osama Aboul-Magd, Peter Ashwood-Smith, Joel Halpern
Fiffi Hellstrand, Kenneth Sundell and Pasi Vaananen
The authors would also like to acknowledge the careful review
comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams
Paul Beaubien, Matthew Yuen, Liam Casey, Ankur Anand and
Farrel
8. Intellectual Property
The IETF has been notified of intellectual property rights claimed
regard to some or all of the specification contained in
document. For more information consult the online list of
rights
Jamoussi, et al. Standards Track [Page 31]
RFC 3212 Constraint-Based LSP Setup using LDP January 2002
9.
[1] Andersson, L., Doolan, P., Feldman, N., Fredette, A. and B
Thomas, "Label Distribution Protocol Specification", RFC 3036,
January 2001.
[2] Rosen, E., Viswanathan, A. and R. Callon, "Multiprotocol
Switching Architecture", RFC 3031, January 2001.
[3] Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M. and J. McManus
"Requirements for Traffic Engineering Over MPLS", RFC 2702,
September 1999.
[4] Gleeson, B., Lin, A., Heinanen, Armitage, G. and A. Malis, "
Framework for IP Based Virtual Private Networks", RFC 2764,
February 2000.
[5] Ash, J., Girish, M., Gray, E., Jamoussi, B. and G. Wright
"Applicability Statement for CR-LDP", RFC 3213, January 2002.
[6] Bradner, S., "Key words for use in RFCs to Indicate
Levels", BCP 14, RFC 2119, March 1997.
[7] Boscher, C., Cheval, P., Wu, L. and E. Gray, "LDP State Machine",
RFC 3215, January 2002.
[8] Ash, J., Lee, Y., Ashwood-Smith, P., Jamoussi, B., Fedyk, D.,
Skalecki, D. and L. Li, "LSP Modification Using CR-LDP",
3214, January 2002.
Jamoussi, et al. Standards Track [Page 32]
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Appendix A: CR-LSP Establishment
A.1 Strict Explicit Route
This appendix provides an example for the setup of a strictly
CR-LSP. In this example, a specific node represents each
node
The sample network used here is a four node network with two
LSRs and two core LSRs as follows
LSR1------LSR2------LSR3------LSR
LSR1 generates a Label Request Message as described in Section 3.1
this document and sends it to LSR2. This message includes the CR
TLV
A vector of three ER-Hop TLVs composes the ER-TLV. The ER
Hop TLVs used in this example are of type 0x0801 (IPv4 prefix) with
prefix length of 32. Hence, each ER-Hop TLV identifies a
node as opposed to a group of nodes. At LSR2, the
processing of the ER-TLV per Section 4.8.1 of this document
place
1. The node LSR2 is part of the abstract node described by
first hop . Therefore, the first step passes the test.
to step 2.
2. There is a second ER-Hop, . Go to step 3.
3. LSR2 is not part of the abstract node described by the
ER-Hop . Go to Step 4.
4. LSR2 determines that it is topologically adjacent to
abstract node described by the second ER-Hop . LSR2
a next hop (LSR3) which is the abstract node. LSR2 deletes
first ER-Hop from the ER-TLV, which now becomes .
Processing continues with Section 4.8.2.
At LSR2, the following processing of Section 4.8.2 takes place
Executing algorithm 4.8.1 did not result in the removal of the ER
TLV
Also, LSR2 is not a member of the abstract node described by
first ER-Hop .
Finally, the first ER-Hop is a strict hop
Jamoussi, et al. Standards Track [Page 33]
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Therefore, processing section 4.8.2 does not result in the
of new ER-Hops. The selection of the next hop has been already
is step 4 of Section 4.8.1 and the processing of the ER-TLV
completed at LSR2. In this case, the Label Request Message
the ER-TLV is progressed by LSR2 to LSR3.
At LSR3, a similar processing to the ER-TLV takes place except
the incoming ER-TLV = and the outgoing ER-TLV is .
At LSR4, the following processing of section 4.8.1 takes place
1. The node LSR4 is part of the abstract node described by
first hop . Therefore, the first step passes the test.
to step 2.
2. There is no second ER-Hop, this indicates the end of the CR
LSP. The ER-TLV is removed from the Label Request Message
Processing continues with Section 4.8.2.
At LSR4, the following processing of Section 4.8.2 takes place
Executing algorithm 4.8.1 resulted in the removal of the ER-TLV. LSR
does not add a new ER-TLV
Therefore, processing section 4.8.2 does not result in the
of new ER-Hops. This indicates the end of the CR-LSP and
processing of the ER-TLV is completed at LSR4.
At LSR4, processing of Section 3.2 is invoked. The first
is satisfied (LSR4 is the egress end of the CR-LSP and
mapping has been requested). Therefore, a Label Mapping Message
generated by LSR4 and sent to LSR3.
At LSR3, the processing of Section 3.2 is invoked. The
condition is satisfied (LSR3 received a mapping from its
next hop LSR4 for a CR-LSP for which an upstream request is
pending). Therefore, a Label Mapping Message is generated by LSR
and sent to LSR2.
At LSR2, a similar processing to LSR 3 takes place and a
Mapping Message is sent back to LSR1, which completes the end-to-
CR-LSP setup
A.2 Node Groups and Specific Nodes
A request at ingress LSR to setup a CR-LSP might originate from
management system or an application, the details are
specific
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The ingress LSR uses information provided by the management system
the application and possibly also information from the
database to calculate the explicit route and to create the
Request Message
The Label request message carries together with other
information an ER-TLV defining the explicitly routed path. In
example the list of hops in the ER-Hop TLV is supposed to contain
abstract node representing a group of nodes, an abstract
representing a specific node, another abstract node representing
group of nodes, and an abstract node representing a specific
point
In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B
The ER-TLV contains four ER-Hop TLVs
1. An ER-Hop TLV that specifies a group of LSR valid for the
abstract node representing a group of nodes (Group 1).
2. An ER-Hop TLV that indicates the specific node (Node A).
3. An ER-Hop TLV that specifies a group of LSRs valid for
second abstract node representing a group of nodes (Group 2).
4. An ER-Hop TLV that indicates the specific egress point for
CR-LSP (Node B).
All the ER-Hop TLVs are strictly routed nodes
The setup procedure for this CR-LSP works as follows
1. The ingress node sends the Label Request Message to a
that is a member the group of nodes indicated in the first ER
Hop TLV, following normal routing for the specific node (A).
2. The node that receives the message identifies itself as
of the group indicated in the first ER-Hop TLV, and that it
not the specific node (A) in the second. Further it
that the specific node (A) is not one of its next hops
3. It keeps the ER-Hop TLVs intact and sends a Label
Message to another node that is part of the group indicated
the first ER-Hop TLV (Group 1), following normal routing
the specific node (A).
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RFC 3212 Constraint-Based LSP Setup using LDP January 2002
4. The node that receives the message identifies itself as
of the group 