draft-ietf-mpls-tp-gach-dcn-00.txt   draft-ietf-mpls-tp-gach-dcn-01.txt 
Networking Working Group D. Beller Networking Working Group D. Beller
Internet-Draft Alcatel-Lucent Internet-Draft Alcatel-Lucent
Intended Status: Standards Track A. Farrel Intended Status: Standards Track A. Farrel
Created: March 25, 2009 Old Dog Consulting Created: May 8, 2009 Old Dog Consulting
Expires: September 25, 2009 Expires: November 8, 2009
An Inband Data Communication Network For the MPLS Transport Profile An Inband Data Communication Network For the MPLS Transport Profile
draft-ietf-mpls-tp-gach-dcn-00.txt draft-ietf-mpls-tp-gach-dcn-01.txt
Status of this Memo Status of this Memo
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the provisions of BCP 78 and BCP 79. the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Drafts. Drafts.
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
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Abstract Abstract
A Generic Associated Channel (G-ACH) has been defined as an extension The Generic Associated Channel (G-ACh) has been defined as a
of the pseudowire Associated Channel Header (ACH) to enable the generalization of the pseudowire (PW) associated control channel to
realization of a control/communication channel associated with enable the realization of a control/communication channel associated
Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs), with Multiprotocol Label Switching (MPLS) Label Switched Paths
MPLS pseudowires (PWs), MPLS LSP segments, and MPLS sections between (LSPs), MPLS PWs, MPLS LSP segments, and MPLS sections between
adjacent MPLS-capable devices. adjacent MPLS-capable devices.
The MPLS Transport Profile (MPLS-TP) is a profile of the MPLS The MPLS Transport Profile (MPLS-TP) is a profile of the MPLS
architecture that identifies elements of the MPLS toolkit that may be architecture that identifies elements of the MPLS toolkit that may be
combined to build a carrier grade packet transport network based on combined to build a carrier grade packet transport network based on
MPLS packet switching technology. MPLS packet switching technology.
This document describes how the G-ACH may be used to provide the This document describes how the G-ACh may may be used to provide the
infrastructure that forms part of the Management Communication infrastructure that forms part of the Management Communication
Network (MCN) and a Signaling Communication Network (SCN). Network (MCN) and a Signaling Communication Network (SCN).
Collectively, the MCN and SCN may be referred to as the Data Collectively, the MCN and SCN may be referred to as the Data
Communication Network (DCN). The document explains how MCN and SCN Communication Network (DCN). The document explains how MCN and SCN
packets are encapsulated, carried on the G-ACH, and demultiplexed for packets are encapsulated, carried on the G-ACh, and demultiplexed for
delivery to the management or signaling/routing components on a label delivery to the management or signaling/routing components on a label
switching router (LSR). switching router (LSR).
It should be noted that the use of the G-ACH to provide connectivity It should be noted that the use of the G-ACh to provide connectivity
for the DCN is intended for use only where the MPLS-TP network is not for the DCN is intended for use only where the MPLS-TP network is not
capable encapsulating or delivering native DCN messages. capable encapsulating or delivering native DCN messages.
Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
RFC-2119 [RFC2119]. RFC-2119 [RFC2119].
1. Introduction 1. Introduction
The associated channel header (ACH) is specified in [RFC4385]. It is The associated channel header (ACH) is specified in [RFC4385]. It is
a packet header format for use on pseudowire (PW) packets in order to a packet header format for use on pseudowire (PW) packets in order to
identify packets used for OAM and similar functions. identify packets used for OAM and similar functions.
The ACH is generalized for use on any Multiprotocol Label Switching The use of the ACH is generalized to apply on any Multiprotocol Label
(MPLS) Label Switching Path (LSP) in [GAL-GACH]. The generalized Switching (MPLS) Label Switching Path (LSP) in [GAL-GACH]. The
concept is referred to as the Generic Associated Channel (G-ACH) and generalized concept is referred to as the Generic Associated Channel
is intended to create a control/communication channel associated with (G-ACh) and is intended to create a control/communication channel
the LSP that can be used to carry packets used for OAM and similar associated with the LSP that can be used to carry packets used for
functions (e.g. control plane messages). OAM and similar functions (e.g., control plane messages).
The purpose of a packet carried on the G-ACH is indicated by the The purpose of a packet carried on the G-ACh is indicated by the
value carried by the PW Associated Channel Type field of the G-ACH value carried by the Channel Type field of the ACH and a registry of
and a registry of values is maintained by IANA. values is maintained by IANA [RFC4446].
The MPLS transport profile (MPLS-TP) is described in [MPLS-TP]. The MPLS transport profile (MPLS-TP) is described in [MPLS-TP].
MPLS-TP is the application of MPLS to construct a packet transport MPLS-TP is the application of MPLS to construct a packet transport
network. It constitutes a profile of MPLS that enables operational network. It constitutes a profile of MPLS that enables operational
models typical in transport networks, which includes additional OAM, models typical in transport networks, which includes additional OAM,
survivability and other maintenance functions not previously survivability and other maintenance functions not previously
supported by MPLS. supported by MPLS.
Label Switching Routers in MPLS networks may be operated using Label Switching Routers in MPLS networks may be operated using
management protocols or control plane protocols. Messaging in these management protocols or control plane protocols. Messaging in these
protocols is normally achieved using IP packets exchanged over IP- protocols is normally achieved using IP packets exchanged over IP-
capable interfaces. However, some LSRs in MPLS-TP networks may be capable interfaces. However, some LSRs in MPLS-TP networks may be
constructed without support for direct IP encapsulation on their constructed without support for direct IP encapsulation on their
line-side interfaces and without access to an out-of-fiber data line-side interfaces and without access to an out-of-fiber data
communication network. In order that such LSRs can communicate using communication network. In order that such LSRs can communicate using
management plane or control plane protocols channels must be provided management plane or control plane protocols channels must be provided
and the only available mechanism is to use an MPLS label. and the only available mechanism is to use an MPLS label.
The G-ACH provides a suitable mechanism, and this document defines The G-ACh provides a suitable mechanism, and this document defines
processes and procedures to allow the G-ACH to be used to build a processes and procedures to allow the G-ACh to be used to build a
management communication network (MCN) and a signaling communication management communication network (MCN) and a signaling communication
network (SCN) together known as the data communication network (DCN) network (SCN) together known as the data communication network (DCN)
[G.7712]. [G.7712].
1.1. Requirements 1.1. Requirements
The requirements presented in this section are based on those The requirements presented in this section are based on those
communicated to the IETF by the ITU-T. communicated to the IETF by the ITU-T.
1. A packet encapsulation mechanism must be provided to support the 1. A packet encapsulation mechanism must be provided to support the
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to the related layer 3 process within the management and control to the related layer 3 process within the management and control
plane application, respectively, for further processing. plane application, respectively, for further processing.
6. The G-ACh is not required to provide specific security mechanisms. 6. The G-ACh is not required to provide specific security mechanisms.
However, the management or control plane protocols that operate However, the management or control plane protocols that operate
over the MCC or SCC are required to provide adequate security over the MCC or SCC are required to provide adequate security
mechanisms in order not to be susceptible to security attacks. mechanisms in order not to be susceptible to security attacks.
2. Procedures 2. Procedures
Figure 1 depicts the format of an MCC/SCC packet that is sent over Figure 1 depicts the format of an MCC/SCC packet that is sent on the
the G-ACH. To send an MCC/SCC packet on the G-ACH, the MCC/SCC packet G-ACh. To send an MCC/SCC packet on the G-ACh, the MCC/SCC packet is
is prepended with the extended G-ACH header. This extended G-ACH prepended with the ACH and one or more ACH TLVs [GAL-GACH], and MUST
header is composed of the G-ACH header as defined in [GAL-GACH] and include the ACH Protocol ID TLV [ACH-TLV] to identify the protocol
is extended by four bytes providing an 8-bit protocol identifier type of the MCC or SCC packet.
(PID) field. The remaining 24 bits of the header extension are
reserved.
0 1 2 3 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 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 0 1|Version|A| Reserved | Channel Type | |0 0 0 1|Version| Reserved | Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | PID | | ACH TLV Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACH Protocol ID TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ zero or more other ACH TLVs ~
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MCC/SCC Packet | | MCC/SCC Packet |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: MCC/SCC Packet with Associated Channel Header Figure 1: MCC/SCC Packet with Associated Channel Header
o The Channel Type field determines whether the message is an MCC or o The Channel Type field determines whether the message is an MCC or
an SCC message. See Section 4 for the codepoint assignments. an SCC message. See Section 4 for the codepoint assignments.
o The PID field indicates the PDU type of the MCC/SCC message o The ACH Protocol ID TLV identifies the PDU type of the MCC/SCC
message. The ACH Protocol ID TLV is defined in [ACH-TLV] and uses
The following PID values are defined: the PPP protocol identifiers to distinguish different protocols.
0x00 IPv4
0x01 IPv6
0x02 OSI
0x03-0xFF Reserved
Editor Note: This approach may be changed to use the G-ACH Protocol
Identifier TLV if that work is progressed.
If the PID is OSI, the first octet of the OSI PDU header (Network
Layer Protocol Identifier) as defined in [ISO8473] indicates the
network layer PDU which can be CLNP (0x81), ES-IS (0x82), or IS-IS
(0x83) as specified in [ISO9577].
When the G-ACH sender receives an MCC message from the management When the G-ACh sender receives an MCC message that is to be sent over
application that is supposed to be sent over the MCC, the sender the MCC, the sender creates the G-ACh header, provides an ACH
creates the extended the G-ACH header depending on the MCC layer 3 Protocol ID TLV indicating the MCC layer 3 PDU type, sets the Channel
PDU, sets the Channel Type field to MCC, and prepends the MCC message Type field to MCC, and prepends the MCC message with the G-ACh
with the extended G-ACH header. The same procedure is applied when a header. The same procedure is applied when a control plane message is
control plane message is supposed to be sent over the SCC. In this to be sent over the SCC. In this case, the sender sets the Channel
case, the sender sets the Channel Type field to SCC. Type field to SCC.
If the MPLS section G-ACH is used, the GAL is added to the packet as If the MPLS section G-ACh is used, the GAL is added to the packet as
defined in [GAL-GACH], i.e., the TTL field SHOULD be set to 1, and defined in [GAL-GACH]. The TTL field MUST be set to 1, and the S-bit
the S-bit of the GAL MUST be set to 1. of the GAL MUST be set to 1.
If the G-ACH is associated with an LSP, the GAL is added to the If the G-ACh is associated with an LSP, the GAL is added to the
packet and the LSP label is pushed on top of the GAL as defined in packet and the LSP label is pushed on top of the GAL as defined in
[GAL-GACH], i.e., the TTL field of the GAL SHOULD be set to 1, and [GAL-GACH]. The TTL field of the GAL SHOULD be set to 1, and the
the S-bit of the GAL MUST be set to 1. S-bit of the GAL MUST be set to 1.
It should be noted that the G-ACH MUST NOT be used to carry user data The DCN channel MUST NOT be used to trnasport user traffic and SHALL
and SHALL only be used to carry management or control plane messages. only be used to carry management or control plane messages.
Procedures that ensure this such as e.g. deep packet inspection are Procedures that ensure this such as deep packet inspection are
outside the scope of this specification. outside the scope of this specification.
When a receiver has received a G-ACH packet with the G-ACH Channel When a receiver has received a packet on the G-ACh with the ACH
Type set to MCC or SCC, it SHALL look at the PID field of the Channel Type set to MCC or SCC, it SHALL look at the PID field
extended G-ACH header. If the PID value is known by the receiver it carried in the ACH Protocol ID TLV. If the TLV is absent, the message
SHALL deliver the entire packet including the MCC/SCC message to the SHALL be silently discarded although a local system MAY increment a
appropriate processing entity. If the PID value is unknown, the counter or raise an event log. If the PID value is known by the
receiver SHALL silently discard the received Packet and MAY increment receiver it SHALL deliver the entire packet including the MCC/SCC
a counter that counts discarded packets. message to the appropriate processing entity. If the PID value is
unknown, the receiver SHALL silently discard the received Packet and
MAY increment a counter or raise an event log.
It must be noted that a receiver MUST NOT forward a GAL packet based It must be noted that according to [GAL-GACH] a receiver MUST NOT
on the GAL label as is normally the case for MPLS packets. If the GAL forward a GAL packet based on the GAL label as is normally the case
appears at the bottom of the label stack, it MUST be processed as for MPLS packets. If the GAL appears at the bottom of the label
described in the previous paragraph. stack, it MUST be processed as described in the previous paragraph.
Note that there is no requirement for MPLS-TP devices to support IP Note that there is no requirement for MPLS-TP devices to support IP
or OSI forwarding in the fast or slow paths. Thus, if a message is or OSI forwarding in the fast or slow paths. Thus, if a message is
received on the MCC or SCC and is not targeted to an address of the received on the MCC or SCC and is not targeted to an address of the
receiving LSR, the LSR MAY discard the message as incorrectly receiving LSR, the LSR MAY discard the message as incorrectly
received. received.
3. Security Considerations 3. Security Considerations
The G-ACH provides a virtual link between LSRs and might be used to The G-ACh provides a virtual link between LSRs and might be used to
induce many forms of security attack. Protocols that operate over the induce many forms of security attack. Protocols that operate over the
MCN or SCN are REQUIRED to include adequate security mechanisms and MCN or SCN are REQUIRED to include adequate security mechanisms and
implementations MUST allow operators to configure the use of those implementations MUST allow operators to configure the use of those
mechanisms. mechanisms.
4. IANA Considerations 4. IANA Considerations
Channel Types for the Generic Associated Channel are allocated from Channel Types for the Generic Associated Channel are allocated from
the IANA PW Associated Channel Type registry defined in [RFC4446] and the IANA PW Associated Channel Type registry defined in [RFC4446] and
updated by [GAL-GACH]. updated by [GAL-GACH].
skipping to change at page 6, line 32 skipping to change at page 6, line 21
(PWE3) Control Word for Use over an MPLS PSN", RFC 4385, (PWE3) Control Word for Use over an MPLS PSN", RFC 4385,
February 2006. February 2006.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", RFC 4446, April 2006 . Emulation (PWE3)", RFC 4446, April 2006 .
[GAL-GACH] Vigoureux, M., Bocci, M., Ward, D., Swallow, G., and R. [GAL-GACH] Vigoureux, M., Bocci, M., Ward, D., Swallow, G., and R.
Aggarwal, "MPLS Generic Associated Channel", Aggarwal, "MPLS Generic Associated Channel",
draft-ietf-mpls-tp-gach-gal, work in progress. draft-ietf-mpls-tp-gach-gal, work in progress.
[ACH-TLV] Bryant, S., "Definition of ACH TLVs", draft-bryant-xxxx,
work in progress.
6. Informative References 6. Informative References
[MPLS-TP] Bryant, S., Bocci, M., Lasserre, M., "A Framework for MPLS [MPLS-TP] Bryant, S., Bocci, M., Lasserre, M., "A Framework for MPLS
in Transport Networks", draft-ietf-mpls-tp-framework, work in Transport Networks", draft-ietf-mpls-tp-framework, work
in progress. in progress.
[G.7712] ITU-T Recommendation G.7712, "Architecture and [G.7712] ITU-T Recommendation G.7712, "Architecture and
specification of data communication network", June 2008. specification of data communication network", June 2008.
[ISO8473] ISO/IEC 8473-1, "Protocol for providing the
connectionless-mode network service: Protocol
specification - Part 1: ISO/IEC JTC 1/SC", 1998-11-01.
[ISO9577] ISO/IEC TR 9577, "Protocol identification in the network
layer ISO/IEC JTC 1/SC 6", 1999-12-15.
7. Acknowledgements 7. Acknowledgements
The editors wish to thank Pietro Grandi and Martin Vigoureux for The editors wish to thank Pietro Grandi and Martin Vigoureux for
their contribution to this document. their contribution to this document.
8. Authors' Addresses 8. Authors' Addresses
Dieter Beller Dieter Beller
Alcatel-Lucent Germany Alcatel-Lucent Germany
EMail: dieter.beller@alcatel-lucent.com EMail: dieter.beller@alcatel-lucent.com
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