Network Working Group K. Shiomoto
Internet Draft NTT
Updates: RFC 3473 R. Papneja
Proposed Category: Standards Track Isocore
Expires: April 2007 R. Rabbat
Fujitsu
October 22, 2006
Use of Addresses in Generalized Multi-Protocol Label Switching
(GMPLS) Networks
draft-ietf-ccamp-gmpls-addressing-05.txt
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Abstract
This document explains and clarifies the use of addresses in
Generalized Multi-Protocol Label Switching (GMPLS) networks. The aim
of this document is to facilitate and ensure better interworking of
GMPLS-capable Label Switching Routers (LSRs) based on experience
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gained in deployments and interoperability testing and proper
interpretation of published RFCs.
The document specifies a proper approach for the interpretation and
choice of address and identifier fields within GMPLS protocols and
references specific control plane usage models. It also examines
some common GMPLS Resource Reservation Protocol-Traffic Engineering
(RSVP-TE) signaling message processing issues and recommends
solutions. Finally, it discusses how to handle IPv6 sources and
destinations in the MPLS and GMPLS TE (Traffic Engineering) MIB
(Management Information Base) modules.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents
1. Introduction...................................................3
2. Changes from draft-ietf-ccamp-gmpls-addressing-04..............4
3. Terminology....................................................4
4. Support of Numbered and Unnumbered Links.......................6
5. Numbered Addressing............................................6
5.1. Addresses in IGPs.........................................6
5.1.1. Router Address.......................................6
5.1.2. Link ID sub-TLV......................................7
5.1.3. Local Interface IP Address...........................7
5.1.4. Remote Interface IP Address..........................7
5.2. Addresses in RSVP-TE......................................7
5.2.1. IP Tunnel End Point Address in Session Object........7
5.2.2. IP Tunnel Sender Address in Sender Template Object...8
5.2.3. IF_ID RSVP_HOP Object for Numbered Interfaces........8
5.2.4. Explicit Route Object (ERO)..........................9
5.2.5. Record Route Object (RRO)............................9
5.2.6. IP Packet Source Address.............................9
5.2.7. IP Packet Destination Address........................9
6. Unnumbered Addressing.........................................10
6.1. Addresses in IGPs........................................11
6.1.1. Link Local/Remote Identifiers in OSPF-TE............11
6.1.2. Link Local/Remote Identifiers in IS-IS/TE...........11
6.2. Addresses in RSVP-TE.....................................12
6.2.1. IF_ID RSVP_HOP Object for Unnumbered Interfaces.....12
6.2.2. Explicit Route Object (ERO).........................12
6.2.3. Record Route Object (RRO)...........................12
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6.2.4. LSP_Tunnel Interface ID Object......................12
7. RSVP-TE Message Content.......................................12
7.1. ERO and RRO Addresses....................................13
7.1.1. Strict Subobject in ERO.............................13
7.1.2. Loose Subobject in ERO..............................14
7.1.3. RRO.................................................14
7.1.4. Label Record subobject in RRO.......................15
7.2. Component Link Identification............................16
7.3. Forwarding Destination of Path Message with ERO..........16
8. Topics Related to the GMPLS Control Plane.....................17
8.1. Control Channel Separation...............................17
8.2. Native and Tunneled Control Plane........................17
8.3. Separation of Control and Data Plane Traffic.............17
9. Addresses in the MPLS and GMPLS TE MIB Modules................17
9.1. Handling IPv6 Source and Destination Addresses...........18
9.1.1. Identifying LSRs....................................18
9.1.2. Configuring GMPLS Tunnels...........................18
9.2. Managing and Monitoring Tunnel Table Entries.............19
10. Security Considerations......................................19
11. IANA Considerations..........................................20
12. Acknowledgments..............................................20
13. Contributors.................................................21
14. References...................................................22
14.1. Normative References....................................22
14.2. Informative References..................................23
Authors' Addresses...............................................24
Intellectual Property Statement..................................24
Disclaimer of Validity...........................................25
Copyright Statement..............................................25
Acknowledgment...................................................25
1. Introduction
This document explains and clarifies the use of addresses in networks
that use GMPLS [RFC3945] as their control plane. GMPLS supports a
control entity that is responsible for one or more data plane
entities, but for the purposes of this document, it is assumed that
there is a one-to-one correspondence between control plane and data
plane entities. That is, each data plane switch has a unique control
plane presence responsible for participating in the GMPLS protocols,
and that each such control plane presence is responsible for a single
data plane switch. The combination of control plane and data plane
entities is referred to as a Label Switching Router (LSR). Various
more complex deployment scenarios exist, but these are out of the
scope of this document.
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The document also covers the handling of IPv6 sources and
destinations in the MPLS and GMPLS TE (Traffic Engineering) MIB
(Management Information Base) modules.
Comments are solicited and should be addressed to the working group's
mailing list at ccamp@ops.ietf.org and/or the author(s).
2. Changes from draft-ietf-ccamp-gmpls-addressing-04
o Fixed section numbering references in RFC 4206
o Removed paragraph about setting IP tunnel sender address for
dynamically set up numbered FAs (end of 5.2.2)
o Removed recommendation about the kind of RRO to prefer
o Updated section 4
3. Terminology
Note that the term 'Router ID' is used in two contexts within GMPLS.
It may refer to an identifier for a participant in a routing
protocol, or it may be an identifier for an LSR that participates in
TE routing. These could be considered as the control plane and data
plane contexts.
In this document, the contexts are distinguished by the following
definitions.
o Loopback address: A loopback address is a stable IP address of the
advertising router that is always reachable if there is any IP
connectivity to it [RFC3477], [RFC3630]. Thus, for example, an
IPv4 127/24 address is excluded from this definition.
o TE Router ID: A stable IP address of an LSR that is always
reachable in the control plane if there is any IP connectivity to
the LSR, e.g., a loopback address. The most important requirement
is that the address does not become unusable if an interface on
the LSR is down [RFC3477], [RFC3630].
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o Router ID: The OSPF protocol version 2 [RFC2328] defines the
Router ID to be a 32-bit network unique number assigned to each
router running OSPF. IS-IS [RFC1195] includes a similar concept
in the System ID. This document describes both concepts as the
"Router ID" of the router running the routing protocol. The
Router ID is not required to be a reachable IP address, although
an operator MAY set it to a reachable IP address on the same
system.
o TE link: "A TE link is a representation in the IS-IS/OSPF Link
State advertisements and in the link state database of certain
physical resources, and their properties, between two GMPLS
nodes." [RFC3945]
o Data plane node: A vertex on the TE graph. It is a data plane
switch or router. Data plane nodes are connected by TE links
which are constructed from physical data links. A data plane node
is controlled through some combination of management and control
plane actions. A data plane node may be under full or partial
control of a control plane node.
o Control plane node: A GMPLS protocol speaker. It may be part of a
data plane switch or may be a separate computer. Control plane
nodes are connected by control channels which are logical
connectionless or connection-oriented paths in the control plane.
A control plane node is responsible for controlling zero, one or
more data plane nodes.
o Interface ID: The Interface ID is defined in [RFC3477] and in
section 9.1 of [RFC3471].
o Data Plane Address: This document refers to a data plane address
in the context of GMPLS. It does not refer to addresses such as
E.164 SAPI in SDH.
o Control Plane Address: An address used to identify a control plane
resource including and restricted to control plane nodes and
control channels.
o IP TTL: The IPv4 TTL field or the IPv6 Hop Limit field, whichever
is applicable.
o TED: Traffic Engineering Database.
o LSR: Label Switching Router.
o FA: Forwarding Adjacency.
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4. Support of Numbered and Unnumbered Links
The links in the control and data planes MAY be numbered or
unnumbered. Implementations have made decisions to support either
numbered or unnumbered addressing. The argument for numbered
addressing is to simplify troubleshooting while the argument for
unnumbered addressing is to save on IP address resources. The end
result is that this leads to lack of interoperability. Given the
importance of having interoperable GMPLS implementations, a control
plane implementation SHOULD support both numbered and unnumbered
links.
A node that receives advertised link information that includes both
numbered and unnumbered addresses SHOULD be able to accept this
advertisement.
Addressing for numbered and unnumbered links is described in sections
5 and 6 of this document respectively.
5. Numbered Addressing
When numbered addressing is used, addresses are assigned to each node
and link in both control and data planes in GMPLS networks.
A numbered link is identified by a network unique identifier (e.g.,
an IP address).
5.1. Addresses in IGPs
In this section we discuss numbered addressing using two Interior
Gateway Protocols (IGPs) that have extensions defined for GMPLS:
OSPF-TE and IS-IS/TE. The routing enhancements for GMPLS are defined
in [RFC3784], [RFC4202], [RFC4203] and [RFC4205].
5.1.1. Router Address
The Router Address is advertised in OSPF-TE using the Router Address
TLV structure of the TE LSA [RFC3630].
In IS-IS/TE, this is referred to as the Traffic Engineering router
ID, which is carried in the advertised Traffic Engineering router ID
TLV [RFC3784].
The IGP protocols use this as a means to advertise the TE Router ID.
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5.1.2. Link ID sub-TLV
The Link ID sub-TLV [RFC3630] advertises the Router ID of the remote
end of the TE link. For point-to-point links, this is the Router ID
of the neighbor. Multi-access links are left for further study.
Note that there is no correspondence in IS-IS to the Link ID sub-TLV
in OSPF-TE. Instead, IS-IS uses the extended IS reachability TLV
[RFC3784] to carry the System ID, which we have defined in section 3
as the Router ID for the purposes of this document.
5.1.3. Local Interface IP Address
The Local Interface IP Address is advertised in:
o the Local Interface IP Address sub-TLV in OSPF-TE
o the IPv4 Interface Address sub-TLV in IS-IS/TE
This is the ID of the local end of the numbered TE link. It MUST be
a network unique number. It does not need to be a routable address
in the control plane.
5.1.4. Remote Interface IP Address
The Remote Interface IP Address is advertised in:
o the Remote Interface IP Address sub-TLV in OSPF-TE
o the IPv4 Neighbor Address sub-TLV in IS-IS/TE
This is the ID of the remote end of the numbered TE link. It MUST be
a network unique number. It does not need to be a routable address
in the control plane.
5.2. Addresses in RSVP-TE
The different subsections describe the use of addresses in the
signaling protocol.
5.2.1. IP Tunnel End Point Address in Session Object
The IP tunnel end point address of the Session Object [RFC3209] is
either an IPv4 or IPv6 address.
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On transmission, the IP tunnel endpoint address in the Session Object
SHOULD be set to the TE Router ID of the egress since the TE Router
ID is a unique routable ID per node.
Alternatively, the tunnel end point address MAY be set to the
destination data plane address (i.e. the Remote Interface IP Address)
if the ingress knows that address.
On reception of the control packet, the IP tunnel endpoint address
could be any address of the remote system, as long as the receiver
knows how to route to it.
5.2.2. IP Tunnel Sender Address in Sender Template Object
The IP tunnel sender address of the Sender Template Object [RFC3209]
is either an IPv4 or IPv6 address.
When an LSP is being set up that will not be used to form an FA, it
is RECOMMENDED that the IP tunnel sender address in the Sender
Template Object specifies the TE Router ID of the ingress LSR since
the TE Router ID is a unique, routable ID per node.
Alternatively, the tunnel sender address MAY be set to the sender
data plane address (i.e. Local Interface IP Address).
5.2.3. IF_ID RSVP_HOP Object for Numbered Interfaces
There are two addresses used in this object:
1. The IPv4/IPv6 Next/Previous Hop Address: The IPv4/IPv6
Next/Previous Hop Address in the IF ID RSVP HOP Object [RFC3473]
in the Path and Resv messages specifies the IP reachable address
of the control plane interface used to send those messages, or the
TE Router ID of the node that is sending those messages.
2. The IPv4/IPv6 address in the Value Field of the Interface_ID TLV:
In both the Path and Resv messages, the IPv4/IPv6 address in the
value field of the Interface ID TLV in the IF ID RSVP HOP Object
[RFC3471] specifies the associated data plane local interface
address of the downstream data channel belonging to the node
sending the Path message and receiving the Resv message.
We describe in section 7.2 the case of a bundled link.
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5.2.4. Explicit Route Object (ERO)
The IPv4/IPv6 address in the ERO provides a data-plane identifier of
an abstract node, TE node or TE link to be part of the signaled LSP.
We describe in section 7 the choice of addresses in the ERO.
5.2.5. Record Route Object (RRO)
The IPv4/IPv6 address in the RRO provides a data-plane identifier of
either a TE node or TE link that is part of the established LSP.
We also describe in section 7 the choice of addresses in the RRO.
5.2.6. IP Packet Source Address
The IP packet source address is either an IPv4 or IPv6 address.
The IPv4 or IPv6 source address of the packet that carries the RSVP-
TE message MUST be a reachable address of the node sending the RSVP-
TE message. It is RECOMMENDED that a stable IPv4 or IPv6 address of
the node be used as a source address of the IP packet.
In case the source address of the received IP packet containing the
Path message is used as the destination address of the Resv message
(see section 5.2.7), setting a stable IPv4 or IPv6 address in the
Path message is beneficial for reliable control-plane transmission.
This allows for robustness when one of control-plane interfaces is
down.
5.2.7. IP Packet Destination Address
The IP packet destination address is either an IPv4 or IPv6 address.
The IP destination address of the packet that carries the RSVP-TE
message is a control-plane reachable address of the next hop or
previous hop node along the LSP.
A Path message is sent to the next hop node. It is RECOMMENDED that
a stable IPv4 or IPv6 address of the next hop node be used as the IP
destination address of the packet that carries the RSVP-TE message.
This address MAY be the TE Router ID of the next hop node or a
reachable next-hop (stable) IPv4 or IPv6 address.
A Resv message is sent to the previous hop node. It is RECOMMENDED
that the IPv4 or IPv6 destination of a Resv message be any of the
following:
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o The IPv4 or IPv6 source address of the received IP packet
containing the Path message,
o A stable IPv4 or IPv6 address of the previous node (found by
consulting the TED and referencing the upstream data plane
interface),
o The value in the received PHOP Object field.
6. Unnumbered Addressing
In this section, we describe unnumbered addressing as used in GMPLS
to refer to different objects and their significance. A TE Router ID
is defined to identify the LSR for TE purposes. An unnumbered link
is identified by the combination of TE Router ID and a node-unique
Interface ID. It is a requirement stated in [RFC3477] that the TE
Router ID MUST be a reachable address in the control plane.
For unnumbered links, an Explicit Route Object (ERO) signaled as a
part of a Label Switched Path (LSP) setup message contains the
desired route of an LSP and may include the identifiers for nodes and
links specified using TE Router IDs and TE link IDs.
Since the LSP setup message must be forwarded within the control
plane, each LSR along the path needs to resolve the next hop in the
ERO into a control plane address of the LSR (signaling controller)
responsible for handling the next hop.
Mandating that TE Router ID be a reachable IP address in the control
plane simplifies the mapping from ERO hop identifiers to LSR control
plane addresses for use as described in section 5.2.7.
If a node is identified in the ERO, the TE Router ID used in the ERO
can be immediately used to address the control plane message.
o If an unnumbered TE link is identified in the ERO, the identifier
includes the TE Router ID and can be immediately used to address
the control plane message. That is, the TE Router ID is used as
the destination for IP packets encapsulating the LSP setup (RSVP
Path) message as described in section 5.2.7.
o If a numbered TE link is identified in the ERO, the correct
control plane address (the TE Router ID) can be found in the IGP
advertisement of the identified TE link - the Router Address TLV
in the OSPF TE LSA, or the Traffic Engineering router ID TLV in
IS-IS (see section 5.1.1).
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An alternative to using the TE Router ID to identify nodes or
unnumbered links in the ERO is to use some other IP-format identifier
unique to the data plane address space. In this case some other
mechanism is required to allow an LSR to map between data plane
identifiers and control plane addresses. Such a mechanism could be
provided through configuration or through LMP [RFC4204].
A physical interface address or a physical interface identifier is
assigned to each physical interface connected to the data plane. An
interface address or an interface identifier is logically assigned to
each TE link end associated with the physical data channel in the
GMPLS domain. A TE link may be installed as a logical interface.
Section 5.1.1 describes how a TE Router ID is advertised. The TE
Router ID is used in addition to the node-unique Interface ID to
identify an unnumbered link in the data plane. In more complex
implementation scenarios (not covered in this draft) where an IGP
router advertises TE link information for more than one LSR, the
Router ID cannot be used to identify the unnumbered link as it does
not uniquely identify the LSR, while on the other hand the TE Router
ID uniquely identifies the LSR.
6.1. Addresses in IGPs
We consider in this section unnumbered addressing using OSPF-TE and
IS-IS/TE.
6.1.1. Link Local/Remote Identifiers in OSPF-TE
Link Local and Link Remote Identifiers are carried in OSPF using a
single sub-TLV of the Link TLV [RFC4203]. They advertise the IDs of
an unnumbered TE link's local and remote ends respectively. Link
Local/Remote Identifiers are numbers unique within the scopes of the
advertising LSR and the LSR managing the remote end of the link
respectively [RFC3477]. Note that these numbers are not network
unique and therefore cannot be used as TE link end addresses on their
own. An unnumbered TE link end network-wide identifier is comprised
of a TE Router ID associated with the link local end, followed by the
link local identifier [RFC3477].
6.1.2. Link Local/Remote Identifiers in IS-IS/TE
The Link Local and Link Remote Identifiers are carried in IS-IS using
a single sub-TLV of the extended IS reachability TLV. Link
identifiers are exchanged in the Extended Local Circuit ID field of
the "Point-to-Point Three-Way Adjacency" IS-IS Option type [RFC4205].
The same discussion in 6.1.1 applies here.
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6.2. Addresses in RSVP-TE
We consider in this section the interface ID fields of objects used
in RSVP-TE in the case of unnumbered addressing.
6.2.1. IF_ID RSVP_HOP Object for Unnumbered Interfaces
The interface ID field in the IF_INDEX TLV specifies the interface of
the data channel for that unnumbered interface.
In both the Path message and the Resv message, the value of the
interface ID in the IF_INDEX TLV specifies the associated local
interface ID of the downstream data channel belonging to the node
sending the Path message and receiving the Resv message.
We describe in section 7.2 the case of a bundled link.
6.2.2. Explicit Route Object (ERO)
For unnumbered interfaces in the ERO, the interface ID is either the
incoming or outgoing interface of the TE link with respect to the
GMPLS-capable LSR.
We describe in section 7 the choice of addresses in the ERO.
6.2.3. Record Route Object (RRO)
For unnumbered interfaces in the RRO, the interface ID is either the
incoming or outgoing interface of the TE link with respect to the
GMPLS-capable LSR.
We also describe in section 7 the choice of addresses in the RRO.
6.2.4. LSP_Tunnel Interface ID Object
The LSP_TUNNEL_INTERFACE_ID Object includes the LSR's Router ID and
Interface ID as described in [RFC3477] to specify an unnumbered
Forward Adjacency Interface ID. The Router ID of the GMPLS-capable
LSR MUST be set to the TE Router ID.
7. RSVP-TE Message Content
We discuss in this section the addresses used in the RSVP-TE
messages, including ERO and RRO addresses as well as component link
identification.
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7.1. ERO and RRO Addresses
We address strict and loose subobjects in ERO separately, then
discuss the RRO.
7.1.1. Strict Subobject in ERO
Implementations making limited assumptions about the content of an
ERO when processing a received Path message may cause
interoperability issues. It is RECOMMENDED that implementations
support the receipt of ERO options applicable to their hardware
capabilities. Note that implementations do not need to support the
options containing Component Link IDs if they do not support link
bundling [RFC4201].
A subobject in the Explicit Route Object (ERO) includes an address
specifying an abstract node (i.e., a group of nodes), a simple
abstract node (i.e., a specific node), or a specific interface of a
TE link in the data plane, depending on the level of control required
[RFC3209].
In case one subobject is strict, any of the following options is
valid:
1. Address or AS number specifying a group of nodes
2. TE Router ID
3. Incoming TE link ID
4. Outgoing TE link ID optionally followed by Component Interface ID
subobject and/or one or two Label subobjects
5. Incoming TE link ID and Outgoing TE link ID optionally followed by
Component Interface ID subobject and/or one or two Label
subobjects
6. TE Router ID and Outgoing TE link ID optionally followed by
Component Interface ID subobject and/or one or two Label
subobjects
7. Incoming TE link ID, TE Router ID and Outgoing TE link ID
optionally followed by Component Interface ID subobject and/or one
or two Label subobjects
The label value that identifies a single unidirectional resource
between two nodes may be different from the perspective of upstream
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and downstream nodes. This is typical in the case of fiber
switching, because the label value is a number indicating the
port/fiber. This is also possible in case of lambda switching,
because the label value is a number indicating the lambda, but may
not be the value directly indicating the wavelength value (e.g., 1550
nm).
The value of a label in RSVP-TE object MUST indicate the value from
the perspective of the sender of the object/TLV [RFC3471]. This rule
MUST be applied to all types of object/TLV.
Therefore, the label field in the Label ERO subobject MUST include
the value of the label for the upstream node's identification of the
resource. ERO processing at region boundaries is done according to
section 6.2 of [RFC4206].
7.1.2. Loose Subobject in ERO
There are two differences between Loose and Strict subobjects.
A subobject marked as a loose hop in an ERO MUST NOT be followed by a
subobject indicating a label value [RFC3473].
A subobject marked as a loose hop in an ERO SHOULD never include an
identifier (i.e., address or ID) of outgoing interface.
There is no way to specify in the ERO whether a subobject is
associated with the incoming or outgoing TE link. This is
unfortunate because the address specified in a loose subobject is
used as a target for the path computation, and there is a big
difference for the path selection process whether the intention is to
reach the target node over the specified link (the case of incoming
TE link) or to reach the node over some other link, so that it would
be possible to continue the path to its final destination over the
specified link (the case of outgoing TE link).
In the case where a subobject in an ERO is marked as a loose hop and
identifies an interface, the subobject SHOULD include the address of
the Incoming interface specifying the TE link in the data plane.
7.1.3. RRO
When a node adds one or more subobjects to an RRO and sends the Path
or the Resv message including the RRO for the purpose of recording
the node's addresses used for an LSP, the subobjects (i.e. number,
each type, and each content) added by the node SHOULD be the same in
the Path RRO and Resv RRO. The intention is that they report the
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path of the LSP, and that the operator can use the results
consistently. At any transit node, it SHOULD be possible to
construct the path of the LSP by joining together the RRO from the
Path and the Resv messages.
It is also important that a whole RRO on a received Resv message can
be used as input to an ERO on a Path message.
Therefore, in case a node adds one or more subobjects to an RRO, any
of the following options are valid:
1. TE Router ID
2. Incoming TE link ID
3. Outgoing TE link ID optionally followed by Component Interface ID
subobject and/or one or two Label subobjects
4. Incoming TE link ID and Outgoing TE link ID optionally followed by
Component Interface ID subobject and/or one or two Label
subobjects
5. TE Router ID and Outgoing TE link ID optionally followed by
Component Interface ID subobject and/or one or two Label
subobjects
6. Incoming TE link ID, TE Router ID and Outgoing TE link ID
optionally followed by Component Interface ID subobject and/or one
or two Label subobjects
An implementation MAY choose any of these options and MUST be
prepared to receive an RRO that contains any of these options.
7.1.4. Label Record subobject in RRO
Routes and labels can be recorded via the RECORD_ROUTE object (RRO)
present in both RSVP Path and Resv messages. When a sender node needs
route and label recording, the Label Recording flag is set in the
SESSION_ATTRIBUTE object and an RRO is included in the Path message
as described in [RFC3209].
As described in [RFC3209] the RRO in a Path message is built up hop
by hop and Label Record subobjects SHOULD be included when requested
and when the label information is available. Also as described in
[RFC3209], for a Resv message "the processing mirrors that of the
Path" and "The only difference is that the RRO in a Resv message
records the path information in the reverse direction." This means
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that when Label Record objects are added to the RRO in a Path message
they SHOULD also be added to the RRO in the corresponding Resv
message.
7.2. Component Link Identification
When using a bundled link [RFC4201] for a data channel, a component
link identifier is specified in the Interface Identification TLV in
the IF_ID RSVP_HOP Object in order to fully specify the resource.
The Interface Identification TLV is IF_INDEX TLV (Type 3) in the case
of an unnumbered component link and IPv4 TLV (Type 1) or IPv6 TLV
(Type 2) in the case of a numbered component link.
A component link for the upstream data channel may differ from that
for the downstream data channel in the case of a bi-directional LSP.
In this case, the Interface Identification TLV specifying a
downstream interface is followed by another Interface Identification
TLV specifying an upstream interface.
Note that identifiers in TLVs for upstream and downstream data
channels in both sent Path and received Resv messages are specified
from the viewpoint of a node sending the Path message and receiving
the Resv message, using the identifiers belonging to the node.
When a bundled link is used, an LSR constructing an ERO SHOULD
include the identifier of the bundled link and MAY choose to not
include an identifier of the component link. This is because
information about the bundled link is flooded but information about
the component links is not. Alternatively, the ERO MAY also include
an identifier of a component link if this identifier is known to the
LSR that constructs the ERO, and if the LSR wishes to constrain the
LSP to a particular component link.
Component links MAY be identified within RROs in addition to the
bundled link. This might provide useful information for fault
diagnosis, and can supply information for the construction of EROs,
for example for pinning.
7.3. Forwarding Destination of Path Message with ERO
The final destination of the Path message is the Egress node that is
specified by the tunnel end point address in the Session object.
The Egress node MUST NOT forward the corresponding Path message
downstream, even if the ERO includes the outgoing interface ID of the
Egress node for Egress control [RFC4003].
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8. Topics Related to the GMPLS Control Plane
8.1. Control Channel Separation
In GMPLS, a control channel can be separated from the data channel
and there is not necessarily a one-to-one association of a control
channel to a data channel. Two adjacent nodes in the data plane may
have multiple IP hops between them in the control plane.
There are two broad types of separated control planes: native and
tunneled. These differ primarily in the nature of encapsulation used
for signaling messages, which also results in slightly different
address handling with respect to the control plane address.
8.2. Native and Tunneled Control Plane
It is suggested that all implementations support a native control
plane to enable better interoperability.
For the case where two adjacent nodes have multiple IP hops between
them in the control plane, then as stated in section 9 of [RFC3945],
implementations SHOULD use the mechanisms of section 6.1.1 of
[RFC4206] whether they use LSP Hierarchy or not. Note that section
6.1.1 of [RFC4206] applies to an "FA-LSP" as stated in that section
but also to a "TE link" for the case where a normal TE link is used.
Note also that a hop MUST NOT decrement the TTL of the received RSVP-
TE message.
For a tunneled control plane, the inner RSVP-TE and IP messages
traverse exactly one IP hop. The IP TTL of the outermost IP header
SHOULD be the same as for any network message sent on that network.
Implementations receiving RSVP-TE messages on the tunnel interface
MUST NOT compare the RSVP-TE TTL to either of the IP TTLs received.
Implementations MAY set the RSVP-TE TTL to be the same as the IP TTL
in the innermost IP header.
8.3. Separation of Control and Data Plane Traffic
Data traffic MUST NOT be transmitted through the control plane. This
is crucial when attempting PSC (Packet-Switching Capable) GMPLS with
separated control and data channels.
9. Addresses in the MPLS and GMPLS TE MIB Modules
This section defines a method of defining or monitoring an LSP tunnel
using the MPLS TE MIB module [RFC3812] and GMPLS TE MIB module
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[GMPLS-TEMIB] where the ingress and/or egress routers are identified
using 128-bit IPv6 addresses. That is, where the
mplsTunnelIngressLSRId and mplsTunnelEgressLSRId objects in the
mplsTunnelTable [RFC3812] cannot be used to carry the tunnel end
point address and Extended Tunnel Id fields from the signaled Session
Object because the IPv6 variant (LSP_TUNNEL_IPv6_SESSION object) is
in use.
9.1. Handling IPv6 Source and Destination Addresses
9.1.1. Identifying LSRs
For this feature to be used, all LSRs in the network MUST advertise a
32-bit value that can be used to identify the LSR. In this document,
this is referred to as the 32-bit LSR ID. The 32-bit LSR ID is the
OSPFv3 router ID [RFC2740] or the ISIS IPv4 TE Router ID [RFC3784].
Note that these are different from TE router ID (See Section 3).
9.1.2. Configuring GMPLS Tunnels
When setting up RSVP TE tunnels, it is common practice to copy the
values of the mplsTunnelIngressLSRId and mplsTunnelEgressLSRId fields
in the MPLS TE MIB mplsTunnelTable [RFC3812] into the Extended Tunnel
ID and IPv4 tunnel end point address fields, respectively, in the
RSVP-TE LSP_TUNNEL_IPv4 SESSION object [RFC3209].
This approach cannot be used when the ingress and egress routers are
identified by 128-bit IPv6 addresses as the mplsTunnelIngressLSRId
and mplsTunnelEgressLSRId fields are defined to be 32-bit values
[RFC3811] and [RFC3812].
Instead, the IPv6 addresses SHOULD be configured in the mplsHopTable
as the first and last hops of the mplsTunnelHopTable entries defining
the explicit route for the tunnel. Note that this implies that a
tunnel with IPv6 source and destination addresses MUST have an
explicit route configured, although it should be noted that the
configuration of an explicit route in this way does not imply that an
explicit route will be signaled.
In more detail, the tunnel is configured at the ingress router as
follows. See [RFC3812] for definitions of MIB table objects and for
default (that is, "normal") behavior.
The mplsTunnelIndex and mplsTunnelInstance fields are set as normal.
The mplsTunnelIngressLSRId and mplsTunnelEgressLSRId fields SHOULD be
set to 32-bit LSR IDs for ingress and egress LSR respectively.
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The mplsTunnelHopTableIndex MUST be set to a non-zero value. That
is, an explicit route MUST be specified.
The first hop of the explicit route MUST have mplsTunnelHopAddrType
field set to ipv6(2) and SHOULD have the mplsTunnelHopIpAddr field
set to a global scope IPv6 address of the ingress router that is
reachable in the control plane.
The last hop of the explicit route MUST have mplsTunnelHopAddrType
field set to ipv6(2) and SHOULD have the mplsTunnelHopIpAddr field
set to a global scope IPv6 address of the egress router that is
reachable in the control plane.
The ingress router SHOULD set the signaled values of the Extended
Tunnel ID and IPv6 tunnel end point address fields, respectively, of
the RSVP-TE LSP_TUNNEL_IPv6 SESSION object [RFC3209] from the
mplsTunnelHopIpAddr object of the first and last hops in the
configured explicit route.
9.2. Managing and Monitoring Tunnel Table Entries
The TE MIB module may be used for managing and monitoring MPLS and
GMPLS TE LSPs, as well as configuring them as described in section
8.2. This function is particularly important at egress and transit
LSRs.
For a tunnel with IPv6 source and destination addresses, an LSR
implementation SHOULD return values in the mplsTunnelTable as follows
(where "normal" behavior is the default taken from [RFC3812]).
The mplsTunnelIndex and mplsTunnelInstance fields are set as normal.
The mplsTunnelIngressLSRId field and mplsTunnelEgressLSRId are set to
32-bit LSR IDs. That is, each transit and egress router maps from
the IPv6 address in the Extended Tunnel ID field to the 32-bit LSR ID
of the ingress LSR. Each transit router also maps from the IPv6
address in the IPv6 tunnel end point address field to the 32-bit LSR
ID of the egress LSR.
10. Security Considerations
In the interoperability testing we conducted, the major issue we
found was the use of control channels for forwarding data. This was
due to the setting of both control and data plane addresses to the
same value in PSC (Packet-Switching Capable) equipment. This
occurred when attempting to test PSC GMPLS with separated control and
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data channels. What resulted instead were parallel interfaces with
the same addresses. This could be avoided simply by keeping the
addresses for the control and data plane separate.
11. IANA Considerations
This document defines no new code points and requires no action from
IANA.
12. Acknowledgments
The authors would like to thank Adrian Farrel for the helpful
discussions and the feedback he gave on the document. In addition,
Arthi Ayyangar, Deborah Brungard, Diego Caviglia, Dimitri
Papadimitriou, Jonathan Sadler, Hidetsugu Sugiyama provided helpful
comments and suggestions.
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13. Contributors
Alan Davey
Data Connection Ltd
Phone: +44 20 8366 1177
Email: Alan.Davey@dataconnection.com
Yumiko Kawashima
NTT Network Service Systems Lab
Japan
Email: kawashima.yumiko@lab.ntt.co.jp
Kaori Shimizu
NTT Network Service Systems Lab
Email: shimizu.kaori@lab.ntt.co.jp
Thomas D. Nadeau
Cisco Systems, Inc.
300 Apollo Drive
Chelmsford, MA 01824
United States of America
Phone: +1-978-244-3051
Email: tnadeau@cisco.com
Ashok Narayanan
Cisco Systems, Inc.
Email: ashokn@cisco.com
Eiji Oki
NTT Network Service Systems Laboratories
Midori 3-9-11
Musashino, Tokyo 180-8585
Japan
Email: oki.eiji@lab.ntt.co.jp
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Lyndon Ong
Ciena Corporation
PO Box 308
Cupertino, CA 95015
United States of America
Phone: +1 408 705 2978
Email: lyong@ciena.com
Vijay Pandian
Sycamore Networks
Email: Vijay.Pandian@sycamorenet.com
Hari Rakotoranto
Cisco Systems
Email: hrakotor@cisco.com
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
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[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September
2003.
[RFC3811] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September
2003.
[RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Traffic Engineering
(TE) Management Information Base (MIB)", RFC 3812,
June 2004.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control",
RFC 4003, February 2005.
[RFC4201] Kompella, K., Rekhter, Y. and L. Berger, "Link Bundling in
MPLS Traffic Engineering (TE)", RFC 4201, October 2005.
[RFC4202] Kompella, K. and Y. Rekhter (Eds.), "Routing Extensions in
Support of Generalized Multi-protocol Label Switching",
RFC 4202, October 2005.
[RFC4203] Kompella, K. and Y. Rekhter (Eds.), "OSPF Extensions in
Support of Generalized Multi-protocol Label Switching",
RFC 4203, October 2005.
[RFC4206] Kompella, K. and Y. Rekhter, "LSP Hierarchy with
Generalized MPLS TE", RFC 4206, October 2005.
14.2. Informative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
RFC 2740, December 1999.
[RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004.
[RFC4204] Lang, J. (Ed.), "Link Management Protocol (LMP)", RFC 4204,
October 2005.
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[RFC4205] Kompella, K. and Y. Rekhter (Eds.), "Intermediate System to
Intermediate System (IS-IS) Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)", RFC
4205, October 2005.
[GMPLS-TEMIB] Nadeau, T. and A. Farrel (Eds.), "Generalized
Multiprotocol Label Switching (GMPLS) Traffic Engineering
Management Information Base", work in progress, draft-ietf-
ccamp-gmpls-te-mib-15.txt, April 2006.
Authors' Addresses
Kohei Shiomoto
NTT Network Service Systems Laboratories
3-9-11 Midori
Musashino, Tokyo 180-8585
Japan
Phone: +81 422 59 4402
Email: shiomoto.kohei@lab.ntt.co.jp
Rajiv Papneja
Isocore Corporation
12359 Sunrise Valley Drive, Suite 100
Reston, Virginia 20191
United States of America
Phone: +1 703-860-9273
Email: rpapneja@isocore.com
Richard Rabbat
Fujitsu Laboratories of America
1240 East Arques Ave, MS 345
Sunnyvale, CA 94085
United States of America
Phone: +1 408-530-4537
Email: rabbat@alum.mit.edu
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