Internet Draft Don Fedyk, Nortel
Category: Informational Lou Berger, LabN
Expiration Date: August 13, 2009 Loa Andersson, Ericsson AB
February 13, 2009
Generalized Multi-Protocol Label Switching (GMPLS) Ethernet
Label Switching Architecture and Framework
draft-ietf-ccamp-gmpls-ethernet-arch-04.txt
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Abstract
There has been significant recent work in increasing the capabilities
of Ethernet switches and Ethernet forwarding models. As a
consequence, the role of Ethernet is rapidly expanding into
"transport networks" that previously were the domain of other
technologies such as Synchronous Optical Network (SONET)/Synchronous
Digital Hierarchy (SDH), Time-Division Multiplex (TDM) and
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Asynchronous Transfer Mode (ATM). This document defines an
architecture and framework for a Generalized GMPLS based control
plane for Ethernet in this "transport network" capacity. GMPLS has
already been specified for similar technologies. Some additional
extensions to the GMPLS control plane are needed and this document
provides a framework for these extensions.
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Table of Contents
1 Introduction .............................................. 4
1.1 Terminology ............................................... 6
1.1.1 Concepts .................................................. 6
1.1.2 Abbreviations and Acronyms ................................ 7
2 Background ................................................ 8
2.1 Ethernet Switching ........................................ 9
2.2 Operations, Administration, and Maintenance (OAM) ......... 11
2.3 Ethernet Switching Characteristics ........................ 12
3 Framework ................................................. 12
4 GMPLS Routing and Addressing Model ........................ 14
4.1 GMPLS Routing ............................................. 15
4.2 Control Plane Network ..................................... 15
5 GMPLS Signaling .......................................... 15
6 Link Management .......................................... 16
7 Path Computation and Selection ............................ 17
8 Multiple VLANs ............................................ 18
9 Security Considerations ................................... 18
10 IANA Considerations ....................................... 18
11 References ................................................ 18
11.1 Normative References ...................................... 18
11.2 Informative References .................................... 19
12 Acknowledgments ........................................... 20
13 Author's Addresses ........................................ 21
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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 [RFC2119].
1. Introduction
There has been significant recent work in increasing the capabilities
of Ethernet switches. As a consequence, the role of Ethernet is
rapidly expanding into "transport networks" that previously were the
domain of other technologies such as SONET/SDH TDM and ATM. The
evolution and development of Ethernet capabilities in these areas is
a very active and ongoing process.
Multiple organizations have been active in extending Ethernet
technology. This activity has taken place in the Institute of
Electrical and Electronics Engineers (IEEE) 802.1 Working Group, the
International Telecommunication Union (ITU) and the Metro Ethernet
Forum (MEF). These groups have been focusing on Ethernet forwarding,
Ethernet management plane extensions and the Ethernet Spanning Tree
Control Plane, but not on an explicitly routed, constraint based
control plane.
In the forwarding plane context, extensions have been, or are being,
defined to support different Ethernet forwarding models, protection
modes and service interfaces. Examples of such extensions include
[802.1ah], [802.1Qay], [G.8011] and [MEF.6]. These extensions allow
for greater flexibility in the forwarding plane and, in some cases,
the extensions allow for a departure from forwarding based on
Ethernet spanning tree. In the 802.1Qay case, greater flexibility in
forwarding is achieved through the addition of a "provider" address
space.
This document provides a framework for GMPLS Ethernet Label switching
(GELS). It will be followed by technology specific documents. GELS
will likely require more than one switching type, and the GMPLS
procedures that will need to be changed are dependent on switching,
and thus will be covered in the technology specific documents.
In the new provider bridge model developed in the IEEE 802.1ad
project and amended to the IEEE 802.1Q standard [802.1Q], an extra
Virtual Local Area Network (VLAN) identifier (VID) is added. This
VLAN is referred to as the Service VID, (S-VID and is carried in a
Service TAG (S-TAG). In provider backbone bridges (PBB) [802.1ah] a
backbone VID (B-VID) and B-MAC header with a Service Instance (I-TAG)
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encapsulates a customer Ethernet frame or a service Ethernet frame.
An example of Ethernet protection extensions can be found in
[G.8031]. In the IEEE 802.1Q standard the terms Provider Backbone
Bridges (PBB) and Provider Backbone Bridged Network (PBBN) is used in
the context of these extensions.
Ethernet operations, administration, and maintenance (OAM) is another
important area that is being extended to enable provider Ethernet
services. Related extensions can be found in [802.1ag] and [Y.1731].
An Ethernet based service model is also being defined within the
context of the Metro Ethernet Forum (MEF) and International
Telecommunication Union (ITU). [MEF.6] and [G.8011] provide parallel
frameworks for defining network-oriented characteristics of Ethernet
services in transport networks. The framework discusses general
Ethernet connection characteristics, Ethernet User-Network Interfaces
(UNIs) and Ethernet Network-Network Interfaces (NNIs). Within this
framework, [G.8011.1] defines the Ethernet Private Line (EPL) service
and [G.8011.2] defines the Ethernet Virtual Private Line (EVPL)
service. [MEF.6] covers both service types. These activities are
consistent with the types of Ethernet switching defined in [802.1ah].
The Ethernet forwarding and management plane extensions explicitly
allow for the disabling of standard Ethernet spanning tree but do not
define an explicitly routed, constraint based control plane. The
IEEE 802.1, in [802.1Qay], works on an new amendment that explicitly
allows for traffic engineering of Ethernet forwarding paths.
The IETF chartered the GMPLS work to specify a common control plane
for physical path and core tunneling technologies for the Internet
and telecommunication service providers. The GMPLS architecture is
specified in RFC3945 [RFC3945]. The protocols specified for GMPLS
have been used to control "Transport Networks", e.g. Optical and TDM
networks.
This document provides a framework for use of GMPLS to control
"transport" Ethernet. The GMPLS architecture already handles a number
of transport technologies but "transport" Ethernet adds a few new
constraints that must be documented. Some additional extensions to
the GMPLS control plane are needed and this document provides a
framework for these extensions. All extensions to support Eth-LSPs
are also expected to build on the GMPLS Architecture and related
specifications.
This document introduces and explains GMPLS control plane deployment
for Ethernet and the concept of the Ethernet Label Switched Path
(Eth-LSP). The data plane aspects of Eth-LSPs are outside the scope
of this document and IETF activities.
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The intent of this document is to reuse and align with as much of the
GMPLS protocols as possible. For example reusing the IP control
plane addressing allows existing signaling, routing, LMP and path
computation to be used as specified. The GMPLS protocols support a
set of tools for hierarchical LSPs as well as contiguous LSPs. GMPLS
specific protocol mechanisms support a variety of networks from peer
to peer to UNIs and NNIs. Additions to existing GMPLS capabilities
will only be made to accommodate features unique to "transport"
Ethernet.
1.1. Terminology
1.1.1. Concepts
The following are basic Ethernet and GMPLS terms:
o Asymmetric Bandwidth
This term refers to a property of a Bidirectional service
instance may have differing bandwidth allocation in each
direction.
o Bidirectional Congruent LSP
This term refers to the property of a bi-directional LSP that
uses only the same nodes, ports, and links in both directions.
Ethernet data planes are normally bi-directional or reverse path
congruent.
o Contiguous Eth-LSP
A contiguous Eth-LSP is an Eth-LSP that maps one to one with an
another LSP at a VLAN boundary. Stitched LSP are contiguous LSPs.
o Eth-LSP
This term refers to Ethernet switched paths that may be
controlled via GMPLS.
o Hierarchical Eth-LSP
Hierarchical Eth-LSPs aggregate Eth-LSPs by creating a hierarchy
of Eth-LSPs.
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o In-band GMPLS Signaling
In-band GMPLS Signaling is IP based control messages which are
sent on the native Ethernet links encapsulated by a single hop
Ethernet header. Logical links that use a dedicated VID on the
same physical links would be considered In-band signaling.
o Out-of-band GMPLS Signaling
Out-of-band GMPLS Signaling is IP based control messages which
are sent between Ethernet switches that uses some other links
other than the Ethernet data plane links. Out of band signaling
typically shares a different fate from the data links.
o Point-to-point (P2P) Traffic Engineering (TE) Service Instance
An TE service instance made up from two P2P unidirectional Eth-
LSPs.
o Point-to-multipoint (P2MP) Traffic Engineering (TE) Service
Instance
An TE service Instance supported by a set of LSPs which comprises
one P2MP LSP from a root to n leaves plus a Bidirectional
Congruent point-to-point (P2P) LSP from each of the leaves to the
root.
o Shared forwarding
Shared forwarding is a property of a data path where a single
forwarding entry (VID + DMAC) may be used for frames from
multiple sources (SMAC). Shared forwarding does not change any
data plane behavior. Shared forwarding saves forwarding database
(FDB) entries only. Shared forwarding offers similar benefits to
merging in the data plane. However in shared forwarding the
Ethernet data packets are unchanged when using shared forwarding.
With shared forwarding dedicated control plane states for all
Eth-LSP are maintained regardless of shared forwarding entries.
1.1.2. Abbreviations and Acronyms
The following abbreviations and acronyms are used in this document:
CCM Continuity Check Message
CFM Connectivity Fault Management
DMAC Destination MAC Address
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Eth-LSP Ethernet Label Switched Path
I-SID Service Identifier
LMP Link Management Protocol
MAC Media Access Control
MP2MP Multipoint to multipoint
NMS Network Management System
OAM Operations, Administration and Maintenance
PBB Provider Backbone Bridges [802.1ah]
PBB-TE Provider Backbone Bridges Traffic Engineering
[802.1Qay]
P2P Point to Point
P2MP Point to Multipoint
QoS Quality of Service
SMAC Source MAC Address
S-TAG A service TAG defined in the 802.1 Standard
[802.1Q]
TE Traffic Engineering
TAG An Ethernet short form for a TAG Header
TAG Header An extension to an Ethernet frame carrying
priority and other information.
TSpec Traffic specification
VID VLAN Identifier
VLAN Virtual LAN
2. Background
This section provides background to the types of switching and
services that are supported within the defined framework. The former
is particularly important as it identifies the switching functions
that GMPLS will need to represent and control. The intent is for this
document to allow for all standard forms of Ethernet switching and
services.
The material presented in this section is based on both finished and
on-going work taking place in the IEEE 802.1 Working Group, the ITU
and the MEF. This section references and, to some degree, summarizes
that work. This section is not a replacement for, or an
authoritative description of that work.
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2.1. Ethernet Switching
In Ethernet switching terminology, the bridge relay is responsible
for forwarding and replicating the frames. Bridge relays forward
frames based on the Ethernet header fields: Virtual Local Area
Network (VLAN) Identifiers (VID) and Destination Media Access Control
(DMAC) address. PBB [802.1ah] has also introduced a Service Instance
tag (I-TAG). Across all the Ethernet extensions (already referenced
in the Introduction), multiple forwarding functions, or service
interfaces, have been defined using the combination of VIDs, DMACs,
and I-TAGs. PBB [802.1ah] provides a breakdown of the different
types of Ethernet switching services. Figure 1 reproduces this
breakdown.
PBB Network
Service Types
_,,-' | '--.._
_,.-'' | `'--.._
_,.--' | `'--..
Port based S-tagged I-tagged
_,- -.
_.' `.
_,' `.
one-to-one bundled
_.- =.
_.-' ``-.._
_.-' `-..
many-to-one all-to-one
|
|
|
Transparent
Figure 1: Ethernet Switching Service Types
The types are defined in Clause 25 of [802.1ah], and are consistent
with the definitions of Ethernet services supported in [G.8011] and
[MEF.6]. To summarize the definitions:
o Port based
This is a frame based service that supports specific frame types,
no Service VLAN tagging, with MAC address based switching.
o S-tagged
There are multiple Service VLAN tag (S-tag) aware services,
including:
+ one-to-one
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In this service, each VLAN identifier (VID) is mapped into a
different service.
+ Bundled
Bundled S-tagged service supports the mapping of multiple VIDs
into a single service and include:
* many-to-one
In this frame based service, multiple VIDs are mapped into the
same service.
* all-to-one
In this frame based service, all VIDs are mapped into the same
service.
- transparent
This is a special case, all frames are mapped from a single
incoming port to a single destination Ethernet port.
o I-tagged
The edge of a PBBN consists of a combined backbone relay (B-
component relay) and service instance relay (I-component relay).
An I-Tag contains a service identifier (24 bit I-SID) and priority
markings as well as some other fields. An I-Tagged service is
typically between the edges of the PBBN and terminated at each edge
on an I-component that faces a customer port so the service is
often not visible except at the edges. However, since the I-
component relay involves a distinct relay, it is possible to have a
visible I-Tagged Service by separating the I component relay from
the B-component relay. Two examples where it makes sense to do
this are: an I-Tagged service between two PBBNs and as an
attachment to a customer's Provider Instance Port.
In general, the different switching type determines which of the
Ethernet header fields are used in the forwarding/switching function,
e.g. VID only or VID and DMACs. The switching type may also require
the use of additional Ethernet headers or fields. Services defined
for UNIs tend to use the headers on a hop-by-hop basis.
In most bridging cases, the header fields cannot be changed hop-by-
hop, but some translations of VID field values are permitted,
typically at the edges. While not specifically described in
[802.1ah], the Ethernet services being defined in the context of
[MEF.6] and [G.8011] also fall into the types defined in Figure 1.
Across all service types, the Ethernet data plane is bi-directional
congruent. This means that the forward and reverse paths share the
exact same set of nodes, ports and bi-directional links. This
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property is fundamental. The 802.1 group has maintained this bi-
directional congruent property in the definition of Connectivity
Fault Management (CFM) which is part of the overall Operations
Administration and Management (OAM) capability.
2.2. Operations, Administration, and Maintenance (OAM)
Robustness is enhanced with the addition of data plane OAM to provide
both fault and performance management.
Ethernet OAM messages [802.1ag] and [Y.1731], rely on data plane
forwarding for both directions. Determining a broken path or
misdirected packet in this case relies on OAM following the Eth-LSP.
These identifiers are dependent on the data plane so it works equally
well for provisioned or GMPLS controlled paths.
Ethernet OAM currently consists of:
Defined in both [802.1ag & Y.1731]:
- CCM/RDI: Connectivity Check, Remote Defect Indication
- LBM/LBR: Loopback Message, Loopback Reply
- LTM/LTR: Link trace Message, Link trace Reply
- VSM/VSR: Vendor-specific extensions Message/Reply
Additionally defined in [Y.1731]:
- AIS: Alarm Indication Signal
- LCK: Locked Signal
- TST: Test
- LMM/LMR: Loss Measurement Message/Reply
- DM/DMM/DMR: Delay Measurement
- EXM/EXR: Experimental
- APS, MCC: Automatic Protection Switching, Maintenance
Communication Channel
With some Eth-LSP label formats bi-directional transactions (e.g.
LBM/LBR) and reverse direction transactions MAY have a different VID
for each direction. Both Y.1731 & 802.1ag assumes that bi-
directional transactions (e.g., LBM/LBR) use the same VID in both
directions. However in some scenarios, especially with explicitly
routed paths [802.1Qay], it is possible that different VIDs are used
upstream and downstream. In the context of [802.1Qay] work is ongoing
to update [802.1ag] to support such scenarios."
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2.3. Ethernet Switching Characteristics
Ethernet is similar to MPLS it encapsulates many packet and frame
types for data transmission. In Ethernet the encapsulated data is
referred to as MAC client data. The encapsulation is an Ethernet MAC
frame with a header, a source address, destination address, optional
VLAN identifier, Type and length on the front of the MAC client data
with optional padding and a Frame Check Sequence at the end of the
frame.
The type of MAC client data is typically identified by an "Ethertype"
value. This is an explicit type indication but Ethernet also supports
an implicit type indication.
Ethernet bridging switches Ethernet based on the Frame destination
address and VLAN. The VLAN identifies an active topology. The
address is assumed to be unique and invariant within the VLAN. MAC
addresses are often globally unique but this is not necessary for
bridging.
3. Framework
As defined in the GMPLS Architecture [RFC3945], the GMPLS control
plane can be applied to a technology by controlling the data plane
and switching characteristics of that technology. The architecture
includes a clear separation between a control plane and a data plane.
Control plane and data plane separation allows the GMPLS control
plane to remain architecturally and functionally unchanged while
controlling different technologies. The architecture also requires
IP connectivity for the control plane to exchange information, but
does not otherwise require an IP data plane.
All aspects of GMPLS, i.e., addressing, signaling, routing and link
management, may be applied to Ethernet switching. GMPLS can provide
control for traffic engineered and protected Ethernet service paths.
This document defines the term "Eth-LSP" to refer to Ethernet service
paths that are controlled via GMPLS. As is the case with all GMPLS
controlled services, Eth-LSPs can leverage common traffic engineering
attributes such as:
- bandwidth profile;
- forwarding priority level;
- connection preemption characteristics;
- protection/resiliency capability;
- routing policy, such as an explicit route;
- bi-directional service;
- end-to-end and segment protection;
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- hierarchy
The bandwidth profile may be used to set committed information rate,
peak information rate, and policies based on either under-
subscription or over-subscription. Services covered by this
framework MUST use a TSpec that follows the Ethernet Traffic
parameters defined in [ETH-TSPEC].
In applying GMPLS to "transport" Ethernet, GMPLS may be extended to
work with the Ethernet data plane and switching functions. The
definition of GMPLS support for Ethernet is multi-faceted due to the
different forwarding/switching functions inherent in the different
service types discussed in Section 2.1. In general, the header fields
used in the forwarding/switching function, e.g. VID and DMAC, can be
characterized as a data plane label. In some circumstances these
fields will be constant along the path of the Eth-LSP, and in others
they may vary hop-by-hop or at certain interfaces only along the
path. In the case where the "labels" must be forwarded unchanged,
there are a few constraints on the label allocation that are similar
to some other technologies such as lambda labels.
The GMPLS architecture, per [RFC3945], allowed for control of
Ethernet bridges and other layer 2 technologies using the L2SC
switching type. Although, it is worth noting that the control of
Ethernet switching was not explicitly defined in [RFC3471], [RFC4202]
or any other subsequent GMPLS reference document.
The characteristics of the "transport" Ethernet data plane are not
modified in order to apply GMPLS control. For example, consider the
IEEE 802.1Q [802.1Q] data plane: The VID is used as a "filter"
pointing to a particular forwarding table, and if the DMAC is found
in that forwarding table the forwarding decision is taken based on
the DMAC. When forwarding using an Ethernet spanning tree, if the
DMAC is not found the frame is broadcast over all outgoing interfaces
for which that VID is defined. This valid MAC checking and broadcast
supports Ethernet learning. A special case is when a VID is defined
for only two ports on one bridge, effectively resulting in a p2p
forwarding constraint, in this case all frames tagged with that VID
received over one of these ports are forward over the other port
without address learning.
[802.1Qay]allows for turning off learning and hence the broadcast
mechanism providing means to create explicitly routed Ethernet
connections.
This document does not define any specific format for an Eth-LSP
label. Rather, it is expected that service specific documents will
define any signaling and routing extensions needed to support a
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specific Ethernet service. Depending on the requirements of a
service, it may be necessary to define multiple GMPLS protocol
extensions and procedures. It is expected that all such extensions
will be consistent with this document.
It is expected that key a requirement for service specific documents
will be to describe label formats and encodings. It may also be
necessary to provide a mechanism to identify the required Ethernet
service type in signaling and a way to advertise the capabilities of
Ethernet switches in the routing protocols. These mechanisms must
make it possible to distinguish between requests for different
paradigms including new, future, and existing paradigms.
The Switching Type and Interface Switching Capability Descriptor
share a common set of values and are defined in [RFC3945], [RFC3471],
and [RFC4202] as indicators of the type of switching that should
([RFC3471]) and can ([RFC4202]) be performed on a particular link for
an LSP. The L2SC switching type may already be used by
implementations performing layer 2 switching including Ethernet. To
support the continued use of that switching type and those
implementations, a new switching type MUST be defined for each new
Ethernet switching paradigm that is supported.
For discussion purposes, we decompose the problem of applying GMPLS
into the functions of Routing, Signaling, Link Management and Path
Selection. It is possible to use some functions of GMPLS alone or in
partial combinations. In most cases using all functions of GMPLS
leads to less operational overhead than partial combinations.
4. GMPLS Routing and Addressing Model
The GMPLS Routing and Addressing Model is not modified by this
document. GMPLS control for Eth-LSPs uses the Routing and Addressing
Model described in [RFC3945]. Most notably this includes the use of
IP addresses to identify interfaces and LSP end-points. It also
includes support for both numbered and unnumbered interfaces.
In the case where another address family or type of identifier is
required to support an Ethernet service, extensions may be defined to
provide mapping to an IP address. Support of Ethernet MUST strictly
comply to the GMPLS protocol suite addressing as specific in RFC3471,
RFC3473 and related.
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4.1. GMPLS Routing
GMPLS routing as defined in [RFC4202] is IP routing with the opaque
TLV extensions for the purpose of distributing GMPLS related TE
(router and link) information. As is always the case with GMPLS, TE
information is populated with TE resources coordinated with LMP or
from configured information. The bandwidth resources of the links are
tracked as Eth-LSPs are set up. Interfaces supporting the switching
of Eth-LSPs are identified using the appropriate Interface Switching
Capabilities. As mentioned in Section 3, the definition of one or
more new Interface Switching Capabilities to support Eth-LSPs is
expected. The L2SC Interface Switching Capabilities MUST NOT be used
to represent interfaces capable of supporting Eth-LSPs. Interface
Switching Capability specific TE information may be defined as needed
to support the requirements of a specific Ethernet Switching Service
Type.
GMPLS Routing is an optional piece but it is highly valuable in
maintaining topology and distributing the TE database for path
management and dynamic path computation.
4.2. Control Plane Network
In order for a GMPLS control plane to operate, an IP network of
sufficient capacity to handle the information exchange between the
GMPLS routing and signaling protocols is necessary.
One way to implement this is with an IGP that views each switch as a
terminated IP adjacency. In other words, IP traffic and a simple
routing table are available for the control plane but there is no
requirement for a high performance IP data plane.
This IP connectivity can be provided as a separate independent
network (out of band) or integrated with the Ethernet switches (in-
band).
5. GMPLS Signaling
GMPLS signaling, see [RFC3471][RFC3473], is well suited to the
control of Eth-LSPs and Ethernet switches. Signaling enables the
ability to dynamically establish a path from an ingress node to an
egress node. The signaled path may be completely static and not
change for the duration of its lifetime. However, signaling also has
the capability to dynamically adjust the path in a coordinated
fashion after the path has been established. The range of signaling
options from static to dynamic are under operator control.
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Standardized signaling also improves multi-vendor interoperability
over simple management.
GMPLS signaling supports the establishment and control of bi-
directional and unidirectional data paths. Ethernet is bi-directional
by nature and the CFM has been built to leverage this. Prior to CFM
the emulation of a physical wire and the learning requirements also
mandated bi-directional connections. Given this, Eth-LSPs MUST be bi-
directional congruent. Eth-LSPs may be either P2P or P2MP (see
[RFC4875]). GMPLS signaling also allows for full and partial LSP
protection; see [RFC4872] and [RFC4873].
Note that standard GMPLS does not support different bandwidth in each
direction of a bi-directional LSP. See [GMPLS-ASYM] if asymmetric
bandwidth bi-directional LSPs are required.
6. Link Management
Link discovery has been specified for Ethernet in [802.1AB]. However
the 802.1AB capability is an optional feature, is not necessarily
operating before a link is operational, and it primarily supports the
management plane. The benefits of running link discovery in large
systems are significant. Link discovery may reduce configuration and
reduce the possibility of undetected errors in configuration as well
as exposing misconnections.
In the GMPLS context, LMP [RFC4204] has been defined to support link
management and discovery features. LMP also supports the automated
creation of unnumbered interfaces. If LMP is not used there is an
additional configuration requirement to add GMPLS link identifiers.
For large-scale implementations LMP would be beneficial. LMP also has
fault management capabilities that overlap with CFM [802.1ag] and
[Y.1731]. It is the goal of the architecture to allow the selection
of the best tool set for the user needs so full functionality of
Ethernet CFM should be allowed.
LMP and 802.1AB are relatively independent. The LMP capability should
be sufficient to remove the need for 802.1AB but 802.1 AB can be run
in parallel or independently if desired. Figure 2 provides possible
ways of using LMP, 802.1AB and 802.1ag in combination.
Figure 2 illustrates the functional relationship of link management
and OAM schemes. It is intended that LMP would use functions of
link property correlation but that Ethernet mechanisms for OAM such
as CFM, link trace etc would be used for fault management and fault
trace.
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+-------------+ +-------------+
| +---------+ | | +---------+ |
| | | | | | | |GMPLS
| | LMP |-|<------>|-| LMP | |Link Property
| | | | | | | |Correlation
| | (opt) | |IP | | (opt) | |
| | | | | | | | Bundling
| +---------+ | | +---------+ |
| +---------+ | | +---------+ |
| | | | | | | |
| | 802.1AB |-|<------>|-| 802.1AB | |P2P
| | (opt) | |Ethernet| | (opt) | |link identifiers
| | | | | | | |
| +---------+ | | +---------+ |
| +---------+ | | +---------+ |
| | | | | | | |End to End
-----|-| 802.1ag |-|<------>|-| 802.1ag |-|-------
| | Y.1731 | |Ethernet| | Y.1731 | |Fault Management
| | (opt) | | | | (opt) | |Performance
| | | | | | | |Management
| +---------+ | | +---------+ |
+-------------+ +-------------+
Switch 1 link Switch 2
Figure 2: Logical Link Management Options
7. Path Computation and Selection
GMPLS does not specify a specific method for selecting paths or
supporting path computation. GMPLS allows for a wide range of
possibilities supported from very simple path computation to very
elaborate path coordination where a large number of coordinated paths
are required. Path computation can take the form of paths being
computed in a fully distributed fashion, on a management station with
local computation for rerouting, or on more sophisticated path
computation servers.
Eth-LSPs may be supported using any path selection or computation
mechanism. As is the case with any GMPLS path selection function, and
common to all path selection mechanisms, the path selection process
should take into consideration Switching Capabilities and Encoding
advertised for a particular interface. Eth-LSPs may also make use of
the emerging path computation element and selection work; see
[RFC4655]
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8. Multiple VLANs
This document allows for the support the signaling of Ethernet
parameters across multiple VLANs supporting both contiguous Eth-LSP
and Hierarchical Ethernet LSPs. The intention is to reuse GMPLS
hierarchy for the support of Peer to Peer models, UNIs and NNIs.
9. Security Considerations
The architecture for GMPLS controlled "transport" Ethernet assumes
that the network consists of trusted devices, but does not require
that the ports over which a UNI are defined are trusted, nor does
equipment connected to these ports need to be trusted. Access to the
trusted network SHALL only occur through the protocols defined in the
UNI or NNI or through protected management interfaces.
When in-band GMPLS signaling is used for the control plane the
security of the control plane and the data plane may affect each
other. When out-of-band GMPLS signaling is used the control plane
the data plane security is decoupled from the control plane and
therefore the security of the data plane has less impact on overall
security.
Where GMPLS is applied to the control of VLAN only, the commonly
known techniques for mitigation of Ethernet DOS attacks may be
required on UNI ports.
For a more comprehensive discussion on GMPLS security please see the
MPLS and GMPLS Security Framework [SECURITY].
10. IANA Considerations
No new values are specified in this document.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3471] Berger, L. (editor), "Generalized MPLS Signaling
Functional Description", January 2003, RFC3471.
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[RFC3473] Berger, L. (editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
January 2003, RFC3473.
[RFC4202] Kompella, K., Rekhter, Y., "Routing Extensions in
Support of Generalized MPLS", RFC 4202, October 2005
11.2. Informative References
[G.8031] ITU-T Draft Recommendation G.8031, Ethernet Protection
Switching.
[G.8011] ITU-T Draft Recommendation G. 8011, Ethernet over
Transport - Ethernet services framework.
[RFC3945] E. Mannie, Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3495.
[802.1AB] "IEEE Standard for Local and Metropolitan Area
Networks, Station and Media Access Control
Connectivity Discovery" (2004).
[802.1ag] "IEEE Standard for Local and Metropolitan Area
Networks - Virtual Bridged Local Area Networks
- Amendment 5:Connectivity Fault Management",
(2007).
[802.1ah] "IEEE Standard for Local and Metropolitan Area
Networks - Virtual Bridged Local Area Networks
- Amendment 6: Provider Backbone Bridges", (2008)
[802.1Qay] "IEEE standard for Provider Backbone Bridge Traffic
Engineering", work in progress.
[802.1Q] "IEEE standard for Virtual Bridged Local Area Networks
802.1Q-2005", May 19, 2006
[RFC4204] Lang. J. Editor, "Link Management Protocol (LMP)"
RFC4204, October 2005
[MEF.6] The Metro Ethernet Forum MEF 6 (2004), "Ethernet Services
Definitions - Phase I".
[MEF.10] The Metro Ethernet Forum MEF 10 (2004), "Ethernet
Services Attributes Phase 1".
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[RFC4875] Aggarwal, R. Ed., "Extensions to RSVP-TE for Point to
Multipoint TE LSPs", IETF RFC 4875, May 2007
[RFC4655] Farrel, A. et.al., "Path Computation Element (PCE)
Architecture", RCF 4655, August 2006.
[RFC4872] Lang et.al., "RSVP-TE Extensions in support of
End-to-End Generalized Multi-Protocol Label Switching
(GMPLS)-based Recovery ", RFC 4872, May 2007.
[RFC4873] Berger, L. et.al.,"MPLS Segment Recovery", RFC 4873, May
2007.
[Y.1731] ITU-T Draft Recommendation Y.1731(ethoam), " OAM
Functions and Mechanisms for Ethernet based Networks ",
work in progress.
[GMPLS-ASYM] Berger, L. et al., "GMPLS Asymmetric Bandwidth
Bidirectional LSPs", work in progress.
[ETH-TSPEC] Papadimitriou, D., "Ethernet Traffic Parameters", work
in progress.
[SECURITY] Luyuan Fang, Ed., " Security Framework for MPLS
and GMPLS Networks", work in progress.
12. Acknowledgments
There were many people involved in the initiation of this work prior
to this document. The GELS framework draft and the PBB-TE extensions
drafts were two drafts the helped shape and justify this work. We
acknowledge the work of these authors of these initial drafts:
Dimitri Papadimitriou, Nurit Sprecher, Jaihyung Cho, Dave Allan,
Peter Busschbach, Attila Takacs, Thomas Eriksson, Diego Caviglia,
Himanshu Shah, Greg Sunderwood, Alan McGuire, Nabil Bitar.
George Swallow contributed significantly to this document.
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13. Author's Addresses
Don Fedyk
Nortel Networks
600 Technology Park Drive
Billerica, MA, 01821
Phone: +1-978-288-3041
Email: dwfedyk@nortel.com
Lou Berger
LabN Consulting, L.L.C.
Phone: +1-301-468-9228
Email: lberger@labn.net
Loa Andersson
Ericsson AB
Phone:+46 8 632 77 14
Email: loa@pi.nu
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