Network Working Group L. Martini, Ed.

Network Working Group L. Martini, Ed.
Request for Comments: 4619 Cisco Systems, Inc.
Category: Standards Track C. Kawa, Ed.
Oz Communications
A. Malis, Ed.
Tellabs
September 2006

Encapsulation Methods for Transport of Frame Relay over
Multiprotocol Label Switching (MPLS) Networks

Status of This Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2006).

Abstract

A frame relay pseudowire is a mechanism that exists between a
provider's edge network nodes and that supports as faithfully as
possible frame relay services over an MPLS packet switched network
(PSN). This document describes the detailed encapsulation necessary
to transport frame relay packets over an MPLS network.

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Table of Contents

1. Introduction ....................................................2
2. Specification of Requirements ...................................4
3. Co-authors ......................................................4
4. Acronyms and Abbreviations ......................................5
5. Applicability Statement .........................................5
6. General Encapsulation Method ....................................6
7. Frame Relay over MPLS PSN for the One-to-One Mode ...............7
7.1. MPLS PSN Tunnel and PW .....................................7
7.2. Packet Format over MPLS PSN ................................7
7.3. The Control Word ...........................................8
7.4. The Martini Legacy Mode Control Word .......................9
7.5. PW Packet Processing .......................................9
7.5.1. Encapsulation of Frame Relay Frames .................9
7.5.2. Setting the Sequence Number ........................10
7.6. Decapsulation of PW Packets ...............................11
7.6.1. Processing the Sequence Number .....................11
7.6.2. Processing of the Length Field by the Receiver .....11
7.7. MPLS Shim EXP Bit Values ..................................12
7.8. MPLS Shim S Bit Value .....................................12
7.9. Control Plane Details for Frame Relay Service .............12
7.9.1. Frame Relay Specific Interface Parameter Sub-TLV ...12
8. Frame Relay Port Mode ..........................................13
9. Congestion Control .............................................13
10. Security Considerations .......................................14
11. Normative References ..........................................14
12. Informative References ........................................15

1. Introduction

In an MPLS or IP network, it is possible to use control protocols
such as those specified in [RFC4447] to set up "pseudowires" (PWs)
that carry the Protocol Data Units of layer 2 protocols across the
network. A number of these emulated PWs may be carried in a single
tunnel. The main functions required to support frame relay PW by a
Provider Edge (PE) include:

- encapsulation of frame relay specific information in a suitable
pseudowire (PW) packet;

- transfer of a PW packet across an MPLS network for delivery to a
peer PE;

- extraction of frame relay specific information from a PW packet by
the remote peer PE;

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- regeneration of native frame relay frames for forwarding across an
egress port of the remote peer PE; and

- execution of any other operations as required to support frame
relay service.

This document specifies the encapsulation for the emulated frame
relay VC over an MPLS PSN. Although different layer 2 protocols
require different information to be carried in this encapsulation, an
attempt has been made to make the encapsulation as common as possible
for all layer 2 protocols. Other layer 2 protocols are described in
separate documents. [ATM] [RFC4448] [RFC4618]

The following figure describes the reference models that are derived
from [RFC3985] to support the frame relay PW emulated services.

|<-------------- Emulated Service ---------------->|
| |
| |<------- Pseudowire ------->| |
| | | |
| | |<-- PSN Tunnel -->| | |
| PW End V V V V PW End |
V Service +----+ +----+ Service V
+-----+ | | PE1|==================| PE2| | +-----+
| |----------|............PW1.............|----------| |
| CE1 | | | | | | | | CE2 |
| |----------|............PW2.............|----------| |
+-----+ ^ | | |==================| | | ^ +-----+
^ | +----+ +----+ | | ^
| | Provider Edge 1 Provider Edge 2 | |
| | (PE1) (PE2) | |
Customer | | Customer
Edge 1 | | Edge 2
| |
| |
Attachment Circuit (AC) Attachment Circuit (AC)
native frame relay service native frame relay service

Figure 1. PWE3 frame relay PVC interface reference configuration

Two mapping modes can be defined between frame relay VCs and
pseudowires: The first one is called "one-to-one" mapping, because
there is a one-to-one correspondence between a frame relay VC and one
pseudowire. The second mapping is called "many-to-one" mapping or
"port mode" because multiple frame relay VCs assigned to a port are
mapped to one pseudowire. The "port mode" encapsulation is identical
to High-Level Data Link Control (HDLC) pseudowire encapsulation,
which is described in [RFC4618].

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2. Specification of Requirements

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.

Below are the definitions for the terms used throughout the document.
PWE3 definitions can be found in [RFC3916, RFC3985]. This section
defines terms specific to frame relay.

- Forward direction

The forward direction is the direction taken by the frame being
forwarded.

- Backward direction

In frame relay, it is the direction opposite to the direction taken
by a frame being forwarded (see also forward direction).

3. Co-authors

The following are co-authors of this document:

Nasser El-Aawar Level 3 Communications, LLC
Eric C. Rosen Cisco Systems
Daniel Tappan Cisco Systems
Thomas K. Johnson Litchfield Communications
Kireeti Kompella Juniper Networks, Inc.
Steve Vogelsang Laurel Networks, Inc.
Vinai Sirkay Reliance Infocomm
Ravi Bhat Nokia
Nishit Vasavada Nokia
Giles Heron Tellabs
Dimitri Stratton Vlachos Mazu Networks,Inc.
Chris Liljenstolpe Cable & Wireless
Prayson Pate Overture Networks, Inc

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4. Acronyms and Abbreviations

BECN Backward Explicit Congestion Notification
CE Customer Edge
C/R Command/Response
DE Discard Eligibility
DLCI Data Link Connection Identifier
FCS Frame Check Sequence
FECN Forward Explicit Congestion Notification
FR Frame Relay
LSP Label Switched Path
LSR Label Switching Router
MPLS Multiprotocol Label Switching
MTU Maximum Transfer Unit
NNI Network-Network Interface
PE Provider Edge
PSN Packet Switched Network
PW Pseudowire
PWE3 Pseudowire Emulation Edge to Edge
POS Packet over SONET/SDH
PVC Permanent Virtual Circuit
QoS Quality of Service
SVC Switched Virtual Circuit
UNI User-Network Interface
VC Virtual Circuit

5. Applicability Statement

Frame relay over PW service is not intended to emulate the
traditional frame relay service perfectly, but it can be used for
applications that need frame relay transport service.

The following are notable differences between traditional frame relay
service and the protocol described in this document:

- Frame ordering can be preserved using the OPTIONAL sequence field
in the control word; however, implementations are not required to
support this feature.

- The Quality of Service model for traditional frame relay can be
emulated; however, this is outside the scope of this document.

- A Frame relay port mode PW does not process any frame relay status
messages or alarms as described in [Q922] [Q933]

- The frame relay BECN and FECN bit are transparent to the MPLS
network and cannot reflect the status of the MPLS network.

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- Support for frame relay SVC and Switched Permanent Virtual Circuit
(SPVC) is outside the scope of this document.

- Frame relay Local Management Interface (LMI) is terminated locally
in the PE connected to the frame relay attachment circuit.

- The support of PVC link integrity check is outside the scope of
this document.

6. General Encapsulation Method

The general frame relay pseudowire packet format for carrying frame
relay information (user's payload and frame relay control
information) between two PEs is shown in Figure 2.

+-------------------------------+
| |
| MPLS Transport header |
| (As required) |
+-------------------------------+
| Pseudowire (PW) Header |
+-------------------------------+
| Control Word |
+-------------------------------+
| FR Service |
| Payload |
+-------------------------------+

Figure 2. General format of frame relay encapsulation over PSN

The PW packet consists of the following fields: Control word and
Payload, preceded by the MPLS Transport and pseudowire header. The
meaning of the different fields is as follows:

-i. MPLS Transport header is specific to the MPLS network. This
header is used to switch the PW packet through the MPLS core.

-ii. PW header contains an identifier for multiplexing PWs within
an MPLS tunnel.

-iii. Control Word contains protocol control information for
providing a frame relay service. Its structure is provided in
the following sections.

-iv. The content of the frame relay service payload field depends
on the mapping mode. In general it contains the layer 2 frame
relay frame.

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7. Frame Relay over MPLS PSN for the One-to-One Mode

7.1. MPLS PSN Tunnel and PW

MPLS label switched paths (LSPs) called "MPLS Tunnels" are used
between PEs and are used within the MPLS core network to forward PW
packets. An MPLS tunnel corresponds to "PSN Tunnel" of Figure 1.

Several PWs may be nested inside one MPLS tunnel. Each PW carries
the traffic of a single frame relay VC. In this case, the PW header
is an MPLS label called the PW label.

7.2. Packet Format over MPLS PSN

For the one-to-one mapping mode for frame relay over an MPLS network,
the PW packet format is as shown in Figure 3.

+-------------------------------+
| MPLS Tunnel label(s) | n*4 octets (four octets per label)
+-------------------------------+
| PW label | 4 octets
+-------------------------------+
| Control Word |
| (See Figure 4) | 4 octets
+-------------------------------+
| Payload |
| (Frame relay frame |
| information field) | n octets
| |
+-------------------------------+

Figure 3. Frame Relay over MPLS PSN Packet for the
One-to-One Mapping

The meaning of the different fields is as follows:

- MPLS Tunnel label(s)

The MPLS Tunnel label(s) corresponds to the MPLS transport header
of Figure 2. The label(s) is/are used by MPLS LSRs to forward a PW
packet from one PE to the other.

- PW Label

The PW label identifies one PW (i.e., one LSP) assigned to a frame
relay VC in one direction. It corresponds to the PW header of
Figure 2. Together the MPLS Tunnel label(s) and PW label form an
MPLS label stack [RFC3032].

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- Control Word

The Control Word contains protocol control information. Its
structure is shown in Figure 4.

- Payload

The payload field corresponds to X.36/X.76 frame relay frame
information field with the following components removed: bit/byte
stuffing, frame relay header, and FCS. It is RECOMMENDED to
support a frame size of at least 1600 bytes. The maximum length of
the payload field MUST be agreed upon by the two PEs. This can be
achieved by using the MTU interface parameter when the PW is
established. [RFC4447]

7.3. The Control Word

The control word defined below is REQUIRED for frame relay one-to-one
mode. The control word carries certain frame relay specific
information that is necessary to regenerate the frame relay frame on
the egress PE. Additionally, the control word also carries a
sequence number that can be used to preserve sequentiality when
carrying frame relay over an MPLS network. Its structure is as
follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0|F|B|D|C|FRG| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4. Control Word structure for the one-to-one mapping mode

The meaning of the Control Word fields (Figure 4) is as follows (see
also [X36 and X76] for frame relay bits):

- Bits 0 to 3

In the above diagram, the first 4 bits MUST be set to 0 to
indicate PW data.

- F (bit 4) FR FECN (Forward Explicit Congestion Notification) bit.

- B (bit 5) FR BECN (Backward Explicit Congestion Notification) bit.

- D (bit 6) FR DE bit (Discard Eligibility) bit.

- C (bit 7) FR frame C/R (Command/Response) bit.

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- FRG (bits 8 and 9): These bits are defined by [RFC4623].

- Length (bits 10 to 15)

If the PW traverses a network link that requires a minimum frame
size (a notable example is Ethernet), padding is required to reach
its minimum frame size. If the frame's length (defined as the
length of the layer 2 payload plus the length of the control word)
is less than 64 octets, the length field MUST be set to the PW
payload length. Otherwise, the length field MUST be set to zero.
The value of the length field, if non-zero, is used to remove the
padding characters by the egress PE.

- Sequence number (Bit 16 to 31)

Sequence numbers provide one possible mechanism to ensure the
ordered delivery of PW packets. The processing of the sequence
number field is OPTIONAL. The sequence number space is a 16-bit
unsigned circular space. The sequence number value 0 is used to
indicate that the sequence number check algorithm is not used.

7.4. The Martini Legacy Mode Control Word

For backward compatibility to existing implementations, the following
version of the control word is defined as the "martini mode CW" for
frame relay.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0|B|F|D|C|FRG| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 5. Control Word structure for the frame relay martini mode

Note that the "B" and "F" bits are reversed.

This control word format is used for PW type "Frame Relay DLCI (
Martini Mode )"

7.5. PW Packet Processing

7.5.1. Encapsulation of Frame Relay Frames

The encapsulation process of a frame relay frame is initiated when a
PE receives a frame relay frame from one of its frame relay UNI or
NNI [FRF1] [FRF2] interfaces. The PE generates the following fields

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of the control word from the corresponding fields of the frame relay
frame as follows:

- Command/Response (C/R or C) bit: The C bit is copied unchanged in
the PW Control Word.

- The DE bit of the frame relay frame is copied into the D bit field.
However, if the D bit is not already set, it MAY be set as a result
of ingress frame policing. If it is not already set by the copy
operation, setting of this bit by a PE is OPTIONAL. The PE MUST
NOT clear this bit (set it to 0 if it was received with the value
of 1).

- The FECN bit of the frame relay frame is copied into the F bit
field. However, if the F bit is not already set, it MAY be set to
reflect a congestion situation detected by the PE. If it is not
already set by the copy operation, setting of this bit by a PE is
OPTIONAL. The PE MUST NOT clear this bit (set it to 0 if it was
received with the value of 1)

- The BECN bit of the frame relay frame is copied into the B bit
field. However, if the B bit is not already set, it MAY be set to
reflect a congestion situation detected by the PE. If it is not
already set by the copy operation, setting of this bit by a PE is
OPTIONAL. The PE MUST NOT clear this bit (set it to 0 if it was
received with the value of 1).

- If the PW packet length (defined as the length of the payload plus
the length of the control word) is less than 64 octets, the length
field MUST be set to the packet's length. Otherwise, the length
field MUST be set to zero.

- The sequence number field is processed if the PW uses sequence
numbers. [RFC4385]

- The payload of the PW packet is the contents of ITU-T
Recommendations X.36/X.76 [X36] [X76] frame relay frame information
field stripped from any bit or byte stuffing.

7.5.2. Setting the Sequence Number

For a given PW and a pair of routers PE1 and PE2, if PE1 supports
packet sequencing, then the procedures in [RFC4385], Section 4.1,
MUST be followed.

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7.6. Decapsulation of PW Packets

When a PE receives a PW packet, it processes the different fields of
the control word in order to decapsulate the frame relay frame for
transmission to a CE on a frame relay UNI or NNI. The PE performs
the following actions (not necessarily in the order shown):

- It generates the following frame relay frame header fields from the
corresponding fields of the PW packet.

- The C/R bit MUST be copied in the frame relay header.

- The D bit MUST be copied into the frame relay header DE bit.

- The F bit MUST be copied into the frame relay header FECN bit. If
the F bit is set to zero, the FECN bit may be set to one, depending
on the congestion state of the PE device in the forward direction.
Changing the state of this bit by a PE is OPTIONAL.

- The B bit MUST be copied into the frame relay header BECN bit. If
the B bit is set to zero, the BECN bit may be set to one, depending
on the congestion state of the PE device in the backward direction.
Changing the state of this bit by a PE is OPTIONAL.

- It processes the length and sequence field, the details of which
are in the following sub-sections.

- It copies the frame relay information field from the contents of
the PW packet payload after removing any padding.

Once the above fields of a FR frame have been processed, the standard
HDLC operations are performed on the frame relay frame: the HDLC
header is added, any bit or byte stuffing is added as required, and
the FCS is also appended to the frame. The FR frame is then queued
for transmission on the selected frame relay UNI or NNI interface.

7.6.1. Processing the Sequence Number

If a router PE2 supports received sequence number processing, then
the procedures in [RFC4385], Section 4.2, MUST be used.

7.6.2. Processing of the Length Field by the Receiver

Any padding octet, if present, in the payload field of a PW packet
received MUST be removed before forwarding the data.

- If the Length field is set to zero, then there are no padding
octets following the payload field.

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- Otherwise, if the payload is longer, then the length specified in
the control word padding characters are removed according to the
length field.

7.7. MPLS Shim EXP Bit Values

If it is desired to carry Quality of Service information, the Quality
of Service information SHOULD be represented in the Experimental Use
Bits (EXP) field of the PW MPLS label [RFC3032]. If more than one
MPLS label is imposed by the ingress LSR, the EXP field of any labels
higher in the stack SHOULD also carry the same value.

7.8. MPLS Shim S Bit Value

The ingress LSR, PE1, MUST set the S bit of the PW label to a value
of 1 to denote that the PW label is at the bottom of the stack.

7.9. Control Plane Details for Frame Relay Service

The PE MUST provide frame relay PVC status signaling to the frame
relay network. If the PE detects a service-affecting condition for a
particular DLCI, as defined in [Q933] Q.933, Annex A.5, sited in IA
FRF1.1, the PE MUST communicate to the remote PE the status of the PW
that corresponds to the frame relay DLCI status. The Egress PE
SHOULD generate the corresponding errors and alarms as defined in
[Q922] [Q933] on the egress Frame relay PVC.

There are two frame relay flags to control word bit mappings
described below. The legacy bit ordering scheme will be used for a
PW of type 0x0001, "Frame Relay DLCI (Martini Mode)", and the new bit
ordering scheme will be used for a PW of type 0x0019, "Frame Relay
DLCI". The IANA allocation registry of "Pseudowire Type" is defined
in [RFC4446] along with initial allocated values.

7.9.1. Frame Relay Specific Interface Parameter Sub-TLV

A separate document, [RFC4447], describes the PW control and
maintenance protocol in detail, including generic interface parameter
sub-TLVs. The interface parameter information, when applicable, MUST
be used to validate that the PEs and the ingress and egress ports at
the edges of the circuit have the necessary capabilities to
interoperate with each other. The Interface parameter TLV is defined
in [RFC4447], and the IANA registry with initial values for interface
parameter sub-TLV types is defined in [RFC4446], but the frame relay
specific interface parameter sub-TLV types are specified as follows:

- 0x08 Frame Relay Header Length Sub-TLV

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An optional 16-bit value indicating the length of the FR Header,
expressed in octets. This OPTIONAL interface parameter Sub-TLV can
have value of 2, 3, or 4, the default being 2. If this Sub-TLV is
not present, the default value of 2 is assumed.

8. Frame Relay Port Mode

The frame relay port mode PW shares the same encapsulation as the
HDLC PW and is described in the respective document. [RFC4618]

9. Congestion Control

As explained in [RFC3985], the PSN carrying the PW may be subject to
congestion, the characteristics of which depend on PSN type, network
architecture, configuration, and loading. During congestion, the PSN
may exhibit packet loss that will impact the service carried by the
frame relay PW. In addition, since frame relay PWs carry a variety
of services across the PSN, including but not restricted to TCP/IP,
they may or may not behave in a TCP-friendly manner prescribed by
[RFC2914]. In the presence of services that reduce transmission
rate, frame relay PWs may thus consume more than their fair share and
in that case SHOULD be halted.

Whenever possible, frame relay PWs should be run over traffic-
engineered PSNs providing bandwidth allocation and admission control
mechanisms. IntServ-enabled domains providing the Guaranteed Service
(GS) or DiffServ-enabled domains using EF (expedited forwarding) are
examples of traffic-engineered PSNs. Such PSNs will minimize loss
and delay while providing some degree of isolation of the frame relay
PW's effects from neighboring streams.

Note that when transporting frame relay, DiffServ-enabled domains may
use AF (Assured Forwarding) and/or DF (Default Forwarding) instead of
EF, in order to place less burden on the network and to gain
additional statistical multiplexing advantage. In particular, if the
Committed Information Rate (CIR) of a frame relay VC is zero, then it
is equivalent to a best-effort UDP over IP stream regarding
congestion: the network is free to drop frames as necessary. In
this case, the "DF" Per Hop Behavior (PHB) would be appropriate in a
diff-serv-TE domain. Alternatively, if the CIR of a frame relay VC
is nonzero and the DE bit is zero in the FR header, then "AF31" would
be appropriate to be used, and if the CIR of a frame relay VC is
nonzero but the DE bit is on, then "AF32" would be appropriate
[RFC3270].

The PEs SHOULD monitor for congestion (by using explicit congestion
notification, [VCCV], or by measuring packet loss) in order to ensure
that the service using the frame relay PW may be maintained. When a

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PE detects significant congestion while receiving the PW PDUs, the
BECN bits of the frame relay frame transmitted on the same PW SHOULD
be set to notify the remote PE and the remote frame relay switch of
the congestion situation. In addition, the FECN bits SHOULD be set
in the FR frames sent out the attachment circuit, to give the FR DTE
a chance to adjust its transport layer advertised window, if
possible.

If the PW has been set up using the protocol defined in [RFC4447],
then procedures specified in [RFC4447] for status notification can be
used to disable packet transmission on the ingress PE from the egress
PE. The PW may be restarted by manual intervention, or by automatic
means after an appropriate waiting time.

10. Security Considerations

PWE3 provides no means of protecting the contents or delivery of the
PW packets on behalf of the native service. PWE3 may, however,
leverage security mechanisms provided by the MPLS Tunnel Layer. A
more detailed discussion of PW security is given in [RFC3985,
RFC4447, RFC3916].

11. Normative References

[RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
Heron, "Pseudowire Setup and Maintenance Using the Label
Distribution Protocol (LDP)", RFC 4447, April 2006.

[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, February 2006.

[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.

[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446, April 2006.

[RFC4618] Martini, L., Rosen, E., Heron, G., and A. Malis,
"Encapsulation Methods for Transport of Point to Point
Protocol/High-Level Data Link Control (PPP/HDLC) over
Multiprotocol Label Switching (MPLS) Networks", RFC 4618,
September 2006.

[RFC4623] Malis, A. and M. Townsley, "Pseudowire Emulation Edge-to-
Edge (PWE3) Fragmentation and Reassembly", RFC 4623, August
2006.

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12. Informative References

[RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge
(PWE3) Architecture", RFC 3985, March 2005.

[VCCV] Nadeau, T., et al., "Pseudo Wire Virtual Circuit Connection
Verification (VCCV)", Work in Progress, October 2005.

[ATM] Martini, L., et al., "Encapsulation Methods for Transport
of ATM Over MPLS Networks", Work in Progress, April 2005.

[RFC4448] Martini, L., Rosen, E., El-Aawar, N., and G. Heron,
"Encapsulation Methods for Transport of Ethernet over MPLS
Networks", RFC 4448, April 2006.

[FRF1] FRF.1.2, Frame relay PVC UNI Implementation Agreement,
Frame Relay Forum, April 2000.

[FRF2] FRF.2.2, Frame relay PVC UNI Implementation Agreement,
Frame Relay Forum, April 2002

[RFC3916] Xiao, X., McPherson, D., and P. Pate, "Requirements for
Pseudo-Wire Emulation Edge-to-Edge (PWE3)", RFC 3916,
September 2004.

[X36] ITU-T Recommendation X.36, Interface between a DTE and DCE
for public data networks providing frame relay, Geneva,
2000.

[X76] ITU-T Recommendation X.76, Network-to-network interface
between public data networks providing frame relay
services, Geneva,2000

[Q922] ITU-T Recommendation Q.922 Specification for Frame Mode
Basic call control, ITU Geneva 1995

[Q933] ITU-T Recommendation Q.933 Specification for Frame Mode
Basic call control, ITU Geneva 2003

[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, RFC
2914, September 2000.

[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
Protocol Label Switching (MPLS) Support of Differentiated
Services", RFC 3270, May 2002.

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Contributing Author Information

Kireeti Kompella
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089

EMail: [email protected]

Giles Heron
Tellabs
Abbey Place
24-28 Easton Street
High Wycombe
Bucks
HP11 1NT
UK

EMail: [email protected]

Rao Cherukuri
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089

Dimitri Stratton Vlachos
Mazu Networks, Inc.
125 Cambridgepark Drive
Cambridge, MA 02140

EMail: [email protected]

Chris Liljenstolpe
Alcatel
11600 Sallie Mae Dr.
9th Floor
Reston, VA 20193

EMail: [email protected]

Martini & Kawa Standards Track [Page 16]

RFC 4619 Encapsulation for Transport of Frame Relay September 2006

Nasser El-Aawar
Level 3 Communications, LLC.
1025 Eldorado Blvd.
Broomfield, CO, 80021

EMail: [email protected]

Eric C. Rosen
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719

EMail: [email protected]

Dan Tappan
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719

EMail: [email protected]

Prayson Pate
Overture Networks, Inc.
507 Airport Boulevard
Morrisville, NC, USA 27560

EMail: [email protected]

David Sinicrope
Ericsson IPI

EMail: [email protected]

Ravi Bhat
Nokia

EMail: [email protected]

Nishit Vasavada
Nokia

EMail: [email protected]

Martini & Kawa Standards Track [Page 17]

RFC 4619 Encapsulation for Transport of Frame Relay September 2006

Steve Vogelsang
ECI Telecom
Omega Corporate Center
1300 Omega Drive
Pittsburgh, PA 15205

EMail: [email protected]

Vinai Sirkay
Redback Networks
300 Holger Way,
San Jose, CA 95134

EMail: [email protected]

Authors' Addresses

Luca Martini
Cisco Systems, Inc.
9155 East Nichols Avenue, Suite 400
Englewood, CO, 80112

EMail: [email protected]

Claude Kawa
OZ Communications
Windsor Station
1100, de la Gauchetie`re St West
Montreal QC Canada
H3B 2S2

EMail: [email protected]

Andrew G. Malis
Tellabs
1415 West Diehl Road
Naperville, IL 60563

EMail: [email protected]

Martini & Kawa Standards Track [Page 18]

RFC 4619 Encapsulation for Transport of Frame Relay September 2006

Full Copyright Statement

Copyright (C) The Internet Society (2006).

This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.

This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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on the procedures with respect to rights in RFC documents can be
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Acknowledgement

Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).

Martini & Kawa Standards Track [Page 19]