< draft-martini-l2circuit-trans-mpls-05.txt   draft-martini-l2circuit-trans-mpls-06.txt >
Network Working Group Luca Martini Network Working Group Luca Martini
Internet Draft Nasser El-Aawar Internet Draft Nasser El-Aawar
Expiration Date: August 2001 Giles Heron Expiration Date: November 2001 Level 3 Communications, LLC.
Level 3 Communications, LLC.
Daniel Tappan Steve Vogelsang Daniel Tappan
Eric C. Rosen John Shirron Eric C. Rosen
Alex Hamilton Toby Smith Alex Hamilton
Jayakumar Jayakumar Laurel Networks, Inc. Jayakumar Jayakumar
Cisco Systems, Inc. Cisco Systems, Inc.
Steve Vogelsang Vasile Radoaca Dimitri Stratton Vlachos
John Shirron Nortel Networks Mazu Networks, Inc.
Toby Smith
Laurel Networks, Inc.
Andrew G. Malis
Vinai Sirkay
Vivace Networks, Inc.
Dimitri Stratton Vlachos Andrew G. Malis Chris Liljenstolpe
Mazu Networks, Inc. Vinai Sirkay Cable & Wireless
Vivace Networks, Inc.
Giles Heron
Gone2 Ltd.
February 2001 May 2001
Transport of Layer 2 Frames Over MPLS Transport of Layer 2 Frames Over MPLS
draft-martini-l2circuit-trans-mpls-05.txt draft-martini-l2circuit-trans-mpls-06.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
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Abstract Abstract
This document describes methods for transporting the Protocol Data This document describes methods for transporting the Protocol Data
Units (PDUs) of layer 2 protocols such as Frame Relay, ATM AAL5, Units (PDUs) of layer 2 protocols such as Frame Relay, ATM AAL5,
Ethernet, and providing a SONET circuit emulation service across an Ethernet, and providing a SONET circuit emulation service across an
MPLS network. MPLS network.
Table of Contents Table of Contents
1 Specification of Requirements .......................... 2 1 Specification of Requirements .......................... 2
2 Introduction ........................................... 3 2 Introduction ........................................... 3
3 Tunnel Labels and VC Labels ............................ 3 3 Tunnel Labels and VC Labels ............................ 3
4 Protocol-Specific Details .............................. 4 4 Protocol-Specific Details .............................. 5
4.1 Frame Relay ............................................ 5 4.1 Frame Relay ............................................ 5
4.2 ATM .................................................... 5 4.2 ATM .................................................... 5
4.2.1 ATM AAL5 VCC Transport ................................. 5 4.2.1 ATM AAL5 VCC Transport ................................. 5
4.2.2 ATM Transparent Cell Transport ......................... 5 4.2.2 ATM Transparent Cell Transport ......................... 5
4.2.3 ATM VCC and VPC Cell Transport ......................... 5 4.2.3 ATM VCC and VPC Cell Transport ......................... 5
4.2.4 OAM Cell Support ....................................... 6 4.2.4 OAM Cell Support ....................................... 6
4.2.5 ILMI Support ........................................... 6 4.2.5 ILMI Support ........................................... 7
4.3 Ethernet VLAN .......................................... 7 4.3 Ethernet VLAN .......................................... 7
4.4 Ethernet ............................................... 7 4.4 Ethernet ............................................... 7
4.5 HDLC ( Cisco ) ......................................... 7 4.5 HDLC ( Cisco ) ......................................... 7
4.6 PPP .................................................... 7 4.6 PPP .................................................... 7
4.7 Static MPLS ............................................ 7
5 LDP .................................................... 8 5 LDP .................................................... 8
5.1 Interface Parameters Field ............................. 9 5.1 Interface Parameters Field ............................. 9
5.2 LDP label Withdrawal procedures ........................ 11
6 IANA Considerations .................................... 11 6 IANA Considerations .................................... 11
7 Security Considerations ................................ 11 7 Security Considerations ................................ 12
8 References ............................................. 11 8 References ............................................. 12
9 Author Information ..................................... 12 9 Author Information ..................................... 12
1. Specification of Requirements 1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119. document are to be interpreted as described in RFC 2119.
2. Introduction 2. Introduction
skipping to change at page 3, line 23 skipping to change at page 3, line 23
An accompanying document [8] also describes a method for transporting An accompanying document [8] also describes a method for transporting
time division multiplexed (TDM) digital signals (TDM circuit time division multiplexed (TDM) digital signals (TDM circuit
emulation) over a packet-oriented MPLS network. The transmission emulation) over a packet-oriented MPLS network. The transmission
system for circuit-oriented TDM signals is the Synchronous Optical system for circuit-oriented TDM signals is the Synchronous Optical
Network (SONET)[5]/Synchronous Digital Hierarchy (SDH) [6]. To Network (SONET)[5]/Synchronous Digital Hierarchy (SDH) [6]. To
support TDM traffic, which includes voice, data, and private leased support TDM traffic, which includes voice, data, and private leased
line service, the MPLS network must emulate the circuit line service, the MPLS network must emulate the circuit
characteristics of SONET/SDH payloads. MPLS labels and a new circuit characteristics of SONET/SDH payloads. MPLS labels and a new circuit
emulation header are used to encapsulate TDM signals and provide the emulation header are used to encapsulate TDM signals and provide the
Circuit Emulation Service over MPLS (CEM). This encapsulation method Circuit Emulation Service over MPLS (CEM).
is described in [8].
3. Tunnel Labels and VC Labels 3. Tunnel Labels and VC Labels
Suppose it is desired to transport layer 2 PDUs from ingress LSR R1 Suppose it is desired to transport layer 2 PDUs from ingress LSR R1
to egress LSR R2, across an intervening MPLS network. We assume that to egress LSR R2, across an intervening MPLS network. We assume that
there is an LSP from R1 to R2. That is, we assume that R1 can cause a there is an LSP from R1 to R2. That is, we assume that R1 can cause a
packet to be delivered to R2 by pushing some label onto the packet packet to be delivered to R2 by pushing some label onto the packet
and sending the result to one of its adjacencies. Call this label the and sending the result to one of its adjacencies. Call this label the
"tunnel label", and the corresponding LSP the "tunnel LSP". "tunnel label", and the corresponding LSP the "tunnel LSP".
skipping to change at page 3, line 51 skipping to change at page 3, line 50
tells R2 how to treat the received packet. Call this label the "VC tells R2 how to treat the received packet. Call this label the "VC
label". label".
So when R1 sends a layer 2 PDU to R2, it first pushes a VC label on So when R1 sends a layer 2 PDU to R2, it first pushes a VC label on
its label stack, and then (if R1 is not adjacent to R2) pushes on a its label stack, and then (if R1 is not adjacent to R2) pushes on a
tunnel label. The tunnel label gets the MPLS packet from R1 to R2; tunnel label. The tunnel label gets the MPLS packet from R1 to R2;
the VC label is not visible until the MPLS packet reaches R2. R2's the VC label is not visible until the MPLS packet reaches R2. R2's
disposition of the packet is based on the VC label. disposition of the packet is based on the VC label.
Note that the tunnel could be a GRE encapsulated MPLS tunnel between Note that the tunnel could be a GRE encapsulated MPLS tunnel between
R1 and R2. In this case R1 would be adjacent to R2 , and only the VC R1 and R2. In this case R1 would be adjacent to R2, and only the VC
label would be used, and the intervening network need only carry IP label would be used, and the intervening network need only carry IP
packets. packets.
If the payload of the MPLS packet is, for example, an ATM AAL5 PDU, If the payload of the MPLS packet is, for example, an ATM AAL5 PDU,
the VC label will generally correspond to a particular ATM VC at R2. the VC label will generally correspond to a particular ATM VC at R2.
That is, R2 needs to be able to infer from the VC label the outgoing That is, R2 needs to be able to infer from the VC label the outgoing
interface and the VPI/VCI value for the AAL5 PDU. If the payload is a interface and the VPI/VCI value for the AAL5 PDU. If the payload is a
Frame Relay PDU, then R2 needs to be able to infer from the VC label Frame Relay PDU, then R2 needs to be able to infer from the VC label
the outgoing interface and the DLCI value. If the payload is an the outgoing interface and the DLCI value. If the payload is an
Ethernet frame, then R2 needs to be able to infer from the VC label Ethernet frame, then R2 needs to be able to infer from the VC label
the outgoing interface, and perhaps the VLAN identifier. This process the outgoing interface, and perhaps the VLAN identifier. This process
is unidirectional, and will be repeated independently for is unidirectional, and will be repeated independently for
bidirectional operation. It is REQUIRED to assign the same VC ID for bidirectional operation. It is REQUIRED to assign the same VC ID, and
a given circuit in both directions. The transported frame MAY be VC type for a given circuit in both directions. The group id MUST NOT
be required to match in both directions. The transported frame MAY be
modified when it reaches the egress router. If the header of the modified when it reaches the egress router. If the header of the
transported layer 2 frame is modified, this MUST be done at the transported layer 2 frame is modified, this MUST be done at the
egress LSR only. Note that the VC label must always be at the bottom egress LSR only.
of the label stack, and the tunnel label, if present, must be
immediately above the VC label. Of course, as the packet is Note that the VC label must always be at the bottom of the label
transported across the MPLS network, additional labels may be pushed stack, and the tunnel label, if present, must be immediately above
on (and then popped off) as needed. Even R1 itself may push on the VC label. Of course, as the packet is transported across the MPLS
additional labels above the tunnel label. If R1 and R2 are directly network, additional labels may be pushed on (and then popped off) as
adjacent LSRs, then it may not be necessary to use a tunnel label at needed. Even R1 itself may push on additional labels above the tunnel
all. label. If R1 and R2 are directly adjacent LSRs, then it may not be
necessary to use a tunnel label at all.
This document does not specify a method for distributing the tunnel This document does not specify a method for distributing the tunnel
label or any other labels that may appear above the VC label on the label or any other labels that may appear above the VC label on the
stack. Any acceptable method of MPLS label distribution will do. stack. Any acceptable method of MPLS label distribution will do.
This document does specify a method for assigning and distributing This document does specify a method for assigning and distributing
the VC label. Static label assignment MAY be used, and the VC label. Static label assignment MAY be used, and
implementations SHOULD provide support for this. If signaling is implementations SHOULD provide support for this. If signaling is
used, the VC label MUST be distributed from R2 to R1 using LDP in the used, the VC label MUST be distributed from R2 to R1 using LDP in the
downstream unsolicited mode; this requires that an LDP connection be downstream unsolicited mode; this requires that an LSP session be
created between R1 and R2. [1] created between R1 and R2. [1] When using LDP to distribute the VC
label, liberal label retention mode SHOULD be used.
Note that this technique allows an unbounded number of layer 2 "VCs" Note that this technique allows an unbounded number of layer 2 "VCs"
to be carried together in a single "tunnel". Thus it scales quite to be carried together in a single "tunnel". Thus it scales quite
well in the network backbone. well in the network backbone.
While this document currently defines the emulation of Frame Relay
and ATM PVC services, it specifically does not preclude future
enhancements to support switched service (SVC and SPVC) emulation.
4. Protocol-Specific Details 4. Protocol-Specific Details
4.1. Frame Relay 4.1. Frame Relay
The Frame Relay PDUs are encapsulated according to the procedures The Frame Relay PDUs are encapsulated according to the procedures
defined in [7]. The MPLS edge LSR MUST provide Frame Relay PVC status defined in [7]. The MPLS edge LSR MUST provide Frame Relay PVC status
signaling to the Frame Relay network. If the MPLS edge LSR detects a signaling to the Frame Relay network. If the MPLS edge LSR detects a
service affecting condition as defined in [2] Q.933 Annex A.5 sited service affecting condition as defined in [2] Q.933 Annex A.5 sited
in IA FRF1.1, it MUST withdraw the label that corresponds to the in IA FRF1.1, it MUST withdraw the label that corresponds to the
frame relay DLCI. The Egress LSR SHOULD generate the corresponding frame relay DLCI. The Egress LSR SHOULD generate the corresponding
errors and alarms as defined in [2] on the Frame relay VC. errors and alarms as defined in [2] on the Frame relay VC.
4.2. ATM 4.2. ATM
4.2.1. ATM AAL5 VCC Transport 4.2.1. ATM AAL5 VCC Transport
ATM AAL5 CSPS-PDUs are encapsulated according to [7] ATM AAL5 CPCS- ATM AAL5 CSPS-PDUs are encapsulated according to [7] ATM AAL5 CPCS-
PDU mode. At the edge LSRs, R1 and R2, if ATM ILMI signaling is PDU mode. This mode allows the transport of ATM AAL5 CSPS-PDUs
supported it SHOULD be connected to VC signaling. This mode allows traveling on a particular ATM PVC across the MPLS network to another
the transport of ATM AAL5 CSPS-PDUs traveling on a particular ATM PVC ATM PVC.
across the mpls network to another ATM PVC.
4.2.2. ATM Transparent Cell Transport 4.2.2. ATM Transparent Cell Transport
This mode is similar to the Ethernet port mode. Every cell that is This mode is similar to the Ethernet port mode. Every cell that is
received at the ingress ATM port on the ingress LSR, R1, is received at the ingress ATM port on the ingress LSR, R1, is
encapsulated according to [7], ATM cell mode, and sent across the LSP encapsulated according to [7], ATM cell mode, and sent across the LSP
to the egress LSR, R2. This mode allows an ATM port to be connected to the egress LSR, R2. This mode allows an ATM port to be connected
to only one other ATM port. [7] allows for grouping of multiple cells to only one other ATM port. [7] allows for grouping of multiple cells
into a single MPLS frame. Grouping of ATM cells is OPTIONAL for into a single MPLS frame. Grouping of ATM cells is OPTIONAL for
transmission at the ingress LSR, R1. If the Egress LSR R2 supports transmission at the ingress LSR, R1. If the Egress LSR R2 supports
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is encapsulated according to [7], ATM cell mode, and sent across the is encapsulated according to [7], ATM cell mode, and sent across the
LSP to the egress LSR R2. Grouping of ATM cells is OPTIONAL for LSP to the egress LSR R2. Grouping of ATM cells is OPTIONAL for
transmission at the ingress LSR, R1. If the Egress LSR R2 supports transmission at the ingress LSR, R1. If the Egress LSR R2 supports
cell concatenation the ingress LSR, R1, MUST only concatenate cells cell concatenation the ingress LSR, R1, MUST only concatenate cells
up to the "Maximum Number of concatenated ATM cells in a frame" up to the "Maximum Number of concatenated ATM cells in a frame"
parameter received as part of the FEC element. parameter received as part of the FEC element.
4.2.4. OAM Cell Support 4.2.4. OAM Cell Support
OAM cells MAY be transported on the VC LSP. When the LSR is operating OAM cells MAY be transported on the VC LSP. When the LSR is operating
in AAL5 PDU transport mode if it does not support transport of ATM in AAL5 CPCS-PDU transport mode if it does not support transport of
cells, the LSR MUST discard incoming MPLS frames on an ATM VC LSP ATM cells, the LSR MUST discard incoming MPLS frames on an ATM VC LSP
that contain a VC label with the T bit set [7]. When operating in that contain a VC label with the T bit set [7]. When operating in
AAL5 PDU transport mode an LSR that supports transport of OAM cells AAL5 PDU transport mode an LSR that supports transport of OAM cells
using the T bit defined in [7], or an LSR operating in any of the using the T bit defined in [7], or an LSR operating in any of the
three cell transport modes MUST follow the procedures outlined in [9] three cell transport modes MUST follow the procedures outlined in [9]
section 8 for mode 0 only, in addition to the applicable procedures section 8 for mode 0 only, in addition to the applicable procedures
specified in [6]. specified in [6].
4.2.4.1. OAM Cell Emulation Mode 4.2.4.1. OAM Cell Emulation Mode
AN LSR that does not support transport of OAM cells across an LSP MAY AN LSR that does not support transport of OAM cells across an LSP MAY
provide OAM support on ATM PVCs using the following procedures: provide OAM support on ATM PVCs using the following procedures:
If an F5 end-to-end OAM cell is received from a ATM VC by an ingress A pair of LSRs may emulate a bidrectional ATM VC by two uni-
LSR or egress LSR, with a loopback indication value of 1 and the LSR directioal LSPs. If an F5 end-to-end OAM cell is received from a ATM
has a label mapping for the ATM VC, the LSR MUST decrement the VC, by either LSR that is transporting this ATM VC, with a loopback
loopback indication value and loop back the cell on the ATM VC. indication value of 1, and the LSR has a label mapping for the ATM
Otherwise the loopback cell MUST be discarded by the LSR. VC, then the LSR MUST decrement the loopback indication value and
loop back the cell on the ATM VC. Otherwise the loopback cell MUST be
discarded by the LSR.
The ingress LSR, R1, may also optionally be configured to The ingress LSR, R1, may also optionally be configured to
periodically generate F5 end-to-end loopback OAM cells on a VC. If periodically generate F5 end-to-end loopback OAM cells on a VC. If
the LSR fails to receive a response to an F5 end-to-end loopback OAM the LSR fails to receive a response to an F5 end-to-end loopback OAM
cell for a pre-defined period of time it MUST withdraw the label cell for a pre-defined period of time it MUST withdraw the label
mapping for the VC. mapping for the VC.
If an ingress LSR, R1, receives an AIS F5 OAM cell, fails to receive If an ingress LSR, R1, receives an AIS F5 OAM cell, fails to receive
a pre-defined number of the End-to-End loop OAM cells, or a physical a pre-defined number of the End-to-End loop OAM cells, or a physical
interface goes down, it MUST withdraw the label mappings for all VCs interface goes down, it MUST withdraw the label mappings for all VCs
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switch has deleted a VC, or if the physical interface goes down, it switch has deleted a VC, or if the physical interface goes down, it
MUST withdraw the label mappings for all VCs associated with the MUST withdraw the label mappings for all VCs associated with the
failure. When a VC label mapping is withdrawn, the egress LSR SHOULD failure. When a VC label mapping is withdrawn, the egress LSR SHOULD
notify its client of this failure by deleting the VC using ILMI. notify its client of this failure by deleting the VC using ILMI.
4.3. Ethernet VLAN 4.3. Ethernet VLAN
The Ethernet frame will be encapsulated according to the procedures The Ethernet frame will be encapsulated according to the procedures
in [7]. It should be noted that if the VLAN identifier is modified in [7]. It should be noted that if the VLAN identifier is modified
by the egress LSR, according to the procedures outlined above, the by the egress LSR, according to the procedures outlined above, the
Ethernet spanning tree protocol might fail to work properly. Ethernet spanning tree protocol might fail to work properly. If the
LSR detects a failure on the Ethernet physical port, or the port is
administratively disabled, it MUST withdraw the label mappings for
all VCs associated with the port.
4.4. Ethernet 4.4. Ethernet
The Ethernet frame will be encapsulated according to the procedures The Ethernet frame will be encapsulated according to the procedures
in [7]. If the LSR detects a failure on the Ethernet physical port, in [7]. If the LSR detects a failure on the Ethernet physical port,
or the port is administratively disabled, the corresponding VC label or the port is administratively disabled, the corresponding VC label
mapping MAY be withdrawn. If the egress LSR, R2, does not have a VC mapping MUST be withdrawn.
label mapping for the corresponding Ethernet port, the Ethernet port
physical layer MAY be disabled.
4.5. HDLC ( Cisco ) 4.5. HDLC ( Cisco )
If the MPLS edge LSR detects that the physical link has failed it HDLC frames are encapsulated according to the procedures in [7]. If
MUST withdraw the label that corresponds to the HDLC link. The Egress the MPLS edge LSR detects that the physical link has failed, or the
LSR SHOULD notify the CE device of this failure by using a physical port is adminstratively disabled, it MUST withdraw the label mapping
layer mechanism to take the link out of service. that corresponds to the HDLC link.
4.6. PPP 4.6. PPP
If the MPLS edge LSR detects that the physical link has failed it PPP frames are encapsulated according to the procedures in [7]. If
MUST withdraw the label that corresponds to the PPP link. The Egress the MPLS edge LSR detects that the physical link has failed, or the
LSR SHOULD notify the CE device of this failure by using a physical port is adminstratively disabled, it MUST withdraw the label mapping
layer mechanism to take the link out of service. that corresponds to the PPP link.
4.7. Static MPLS
The MPLS frames encapsulated according to [3] using any layer 2
technology that is commonly used to transport MPLS can be transported
across the service provider MPLS network using the methods described
in this document. The VC label in this case is the statically
configured label that is accepted at the ingress LSR R1, and
advertised with an associated VC ID in LDP. The VC ID has to match in
both directions on a particular VC. At the egress LSR, R2 a common
MPLS label swap operation will swap the VC label with the label that
is statically configured for this particular VC. This transport mode
can be used to offer packet transport using different kinds of layer
2 access infrastructures.
5. LDP 5. LDP
The VC label bindings are distributed using the LDP downstream The VC label bindings are distributed using the LDP downstream
unsolicited mode described in [1]. The LSRs will establish an LDP unsolicited mode described in [1]. The LSRs will establish an LDP
session using the Extended Discovery mechanism described in [1, session using the Extended Discovery mechanism described in [1,
section 2.4-2.5], for this purpose a new type of FEC element is section 2.4.2 and 2.5], for this purpose a new type of FEC element is
defined. The FEC element type is 128. [note1] defined. The FEC element type is 128. [note1] Note that if the tunnel
label is not available, the VC label MUST NOT be advertized.
The Virtual Circuit FEC element, is defined as follows: The Virtual Circuit FEC element, is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VC tlv |C| VC Type |VC info Length | | VC tlv |C| VC Type |VC info Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group ID | | Group ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 8, line 46 skipping to change at page 8, line 47
0x0001 Frame Relay DLCI 0x0001 Frame Relay DLCI
0x0002 ATM AAL5 VCC transport 0x0002 ATM AAL5 VCC transport
0x0003 ATM transparent cell transport 0x0003 ATM transparent cell transport
0x0004 Ethernet VLAN 0x0004 Ethernet VLAN
0x0005 Ethernet 0x0005 Ethernet
0x0006 HDLC ( Cisco ) 0x0006 HDLC ( Cisco )
0x0007 PPP 0x0007 PPP
0x8008 CEM [8] 0x8008 CEM [8]
0x0009 ATM VCC cell transport 0x0009 ATM VCC cell transport
0x000A ATM VPC cell transport 0x000A ATM VPC cell transport
0x000B MPLS
- Control word bit (C) - Control word bit (C)
The highest order bit (C) of the Vc type is used to flag the The highest order bit (C) of the Vc type is used to flag the
presence of a control word ( defined in [7] ) as follows: presence of a control word ( defined in [7] ) as follows:
bit 15 = 1 control word present on this VC. bit 15 = 1 control word present on this VC.
bit 15 = 0 no control word present on this VC. bit 15 = 0 no control word present on this VC.
- VC information length - VC information length
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- Interface parameters - Interface parameters
This variable length field is used to provide interface specific This variable length field is used to provide interface specific
parameters, such as interface MTU. parameters, such as interface MTU.
5.1. Interface Parameters Field 5.1. Interface Parameters Field
This field specifies edge facing interface specific parameters and This field specifies edge facing interface specific parameters and
SHOULD be used to validate that the LSRs, and the ingress and egress SHOULD be used to validate that the LSRs, and the ingress and egress
ports at the edges of the circuit have the necessary capabilities to ports at the edges of the circuit, have the necessary capabilities to
interoperate with each other. The field structure is defines as interoperate with each other. The field structure is defined as
follows: follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter ID | Length | Variable Length Value | | Parameter ID | Length | Variable Length Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Value | | Variable Length Value |
| " | | " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The parameter ID is defined as follows: The parameter ID is defined as follows:
Parameter ID Length Description Parameter ID Length Description
0x01 4 Interface MTU in octets. 0x01 4 Interface MTU in octets.
0x02 4 Maximum Number of concatenated ATM cells. 0x02 4 Maximum Number of concatenated ATM cells.
0x03 up to 82 Optional Interface Description string. 0x03 up to 82 Optional Interface Description string.
0x04 4 CEM [8] Payload Bytes. 0x04 4 CEM [8] Payload Bytes.
0x05 4 CEM options. 0x05 4 CEM options.
The Length field is defined as the length of the interface parameter The Length field is defined as the length of the interface parameter
including the parameter id and length field itself. including the parameter id and length field itself.
- Interface MTU - Interface MTU
A 2 octet value indicating the MTU in bytes. This is the Maximum A 2 octet value indicating the MTU in octets. This is the Maximum
Transmit Unit of the egress packet interface that will be Transmission Unit, excluding encapsulation overhead, of the
transmitting the decapsulated PDU that is received from the MPLS egress packet interface that will be transmitting the
network. This parameter is REQUIRED, and SHOULD match in both decapsulated PDU that is received from the MPLS network. This
direction of a specific circuit. The MTU is specified in bytes, parameter is applicable only to VC types 1, 2, 4, 5, 6, and 7,
and if it does not match on a specific circuit, that circuit and is REQUIRED for these VC types. If this parameter does not
should not be enabled. This parameter is applicable only to VC match in both directions of a specific VC, that VC MUST NOT be
types 1, 2, 4, 5, 6, 7, and 0x0b. enabled.
- Maximum Number of concatenated ATM cells - Maximum Number of concatenated ATM cells
This 2 octet parameter specifies the maximum number of A 2 octet value specifying the maximum number of concatenated ATM
concatenated ATM cells that can be processed as a single PDU by cells that can be processed as a single PDU by the egress LSR. An
the egress LSR. This parameter does not need to match in both ingress LSR transmitting concatenated cells on this VC can
directions of a specific LSR. This parameter is REQUIRED for the concatenate a number of cells up to the value of this parameter,
following VC types: 3, 9, and 0x0a. An LSR transmitting but MUST NOT exceed it. This parameter is applicable only to VC
concatenated cells on this VC can concatenate a number of cells types 3, 9, and 0x0a, and is REQUIRED for these VC types. This
up to the value of this parameter, but MUST NOT exceed it. parameter does not need to match in both directions of a specific
VC.
- Optional Interface Description string - Optional Interface Description string
This arbitrary, OPTIONAL, interface description string can be This arbitrary, OPTIONAL, interface description string can be
used to send an administrative description text string to the used to send an administrative description text string to the
remote LSR. This parameter is OPTIONAL, and is applicable to all remote LSR. This parameter is OPTIONAL, and is applicable to all
VC types. The interface description parameter length is variable, VC types. The interface description parameter length is variable,
and can be up to 80 octets. and can be up to 80 octets.
- Payload Bytes - Payload Bytes
A 2 octet value indicating the the number of TDM payload octets A 2 octet value indicating the the number of TDM payload octets
contained in all packets on the CEM stream, from 48 to 1,023 contained in all packets on the CEM stream, from 48 to 1,023
octets. All of the packets in a given CEM stream have the same octets. All of the packets in a given CEM stream have the same
number of payload bytes. Note that there is a possibility that number of payload bytes. Note that there is a possibility that
the packet size may exceed the SPE size in the case of an STS-1 the packet size may exceed the SPE size in the case of an STS-1
SPE, which could cause two pointers to be needed in the CEM SPE, which could cause two pointers to be needed in the CEM
header, since the payload may contain two J1 bytes for header, since the payload may contain two J1 bytes for
consecutive SPEs. For this reason, the number of payload bytes consecutive SPEs. For this reason, the number of payload bytes
must be less than or equal to 783 for STS-1 SPEs. must be less than or equal to 783 for STS-1 SPEs.
- CEM Options. An optional 16 Bit value of CEM Flags. Bit 0 is - CEM Options. An optional 16 Bit value of CEM Flags. Bit 0 is
defined being set to indicate CEM-DBA in operation. defined being set to indicate CEM-DBA in operation.
5.2. LDP label Withdrawal procedures
As mentioned above the Group ID field can be used to withdraw all VC
labels associated with a particular group ID. This procedure is
OPTIONAL, and if it is implemented the LDP label withdraw message
should be as follows: the VC information length field is set to 0,
the VC ID field is not present, and the interface paramenters field
is not present.
The interface parameters field MUST NOT be present in any LDP VC
label withdrawal message or release message. A wildcard release
message MUST include only the group ID.
6. IANA Considerations 6. IANA Considerations
As specified in this document, a Virtual Circuit FEC element contains As specified in this document, a Virtual Circuit FEC element contains
the VC Type field. VC Type value 0 is reserved. VC Type values 1 the VC Type field. VC Type value 0 is reserved. VC Type values 1
through 11 are defined in this document. VC Type values 12 through 63 through 10 are defined in this document. VC Type values 11 through 63
are to be assigned by IANA using the "IETF Consensus" policy defined are to be assigned by IANA using the "IETF Consensus" policy defined
in RFC2434. VC Type values 64 through 127 are to be assigned by IANA, in RFC2434. VC Type values 64 through 127 are to be assigned by IANA,
using the "First Come First Served" policy defined in RFC2434. VC using the "First Come First Served" policy defined in RFC2434. VC
Type values 128 through 32767 are vendor-specific, and values in this Type values 128 through 32767 are vendor-specific, and values in this
range are not to be assigned by IANA. range are not to be assigned by IANA.
As specified in this document, a Virtual Circuit FEC element contains As specified in this document, a Virtual Circuit FEC element contains
the Interface Parameters field, which is a list of one or more the Interface Parameters field, which is a list of one or more
parameters, and each parameter is identified by the Parameter ID parameters, and each parameter is identified by the Parameter ID
field. Parameter ID value 0 is reserved. Parameter ID values 1 field. Parameter ID value 0 is reserved. Parameter ID values 1
through 5 are defined in this document. Parameter ID values 6 through 6 are defined in this document. Parameter ID values 7
through 63 are to be assigned by IANA using the "IETF Consensus" through 63 are to be assigned by IANA using the "IETF Consensus"
policy defined in RFC2434. Parameter ID values 64 through 127 are to policy defined in RFC2434. Parameter ID values 64 through 127 are to
be assigned by IANA, using the "First Come First Served" policy be assigned by IANA, using the "First Come First Served" policy
defined in RFC2434. Parameter ID values 128 through 255 are vendor- defined in RFC2434. Parameter ID values 128 through 255 are vendor-
specific, and values in this range are not to be assigned by IANA. specific, and values in this range are not to be assigned by IANA.
7. Security Considerations 7. Security Considerations
This document does not affect the underlying security issues of MPLS. This document does not affect the underlying security issues of MPLS.
skipping to change at page 12, line 12 skipping to change at page 12, line 29
[4] "IEEE 802.3ac-1998" IEEE standard specification. [4] "IEEE 802.3ac-1998" IEEE standard specification.
[5] American National Standards Institute, "Synchronous Optical [5] American National Standards Institute, "Synchronous Optical
Network Formats," ANSI T1.105-1995. Network Formats," ANSI T1.105-1995.
[6] ITU Recommendation G.707, "Network Node Interface For The [6] ITU Recommendation G.707, "Network Node Interface For The
Synchronous Digital Hierarchy", 1996. Synchronous Digital Hierarchy", 1996.
[7] "Encapsulation Methods for Transport of Layer 2 Frames Over [7] "Encapsulation Methods for Transport of Layer 2 Frames Over
MPLS", draft-martini-l2circuit-encap-mpls-01.txt ( Work in progress ) MPLS", draft-martini-l2circuit-encap-mpls-02.txt ( Work in progress )
[8] "SONET/SDH Circuit Emulation Service Over MPLS (CEM) [8] "SONET/SDH Circuit Emulation Service Over MPLS (CEM)
Encapsulation", draft-malis-sonet-ces-mpls-01.txt ( Work in progress Encapsulation", draft-malis-sonet-ces-mpls-04.txt ( Work in progress
) )
[9] "Frame Based ATM over SONET/SDH Transport (FAST)," 2000. [9] "Frame Based ATM over SONET/SDH Transport (FAST)," 2000.
[note1] FEC element type 128 is pending IANA approval. [note1] FEC element type 128 is pending IANA approval.
9. Author Information 9. Author Information
Luca Martini Luca Martini
Level 3 Communications, LLC. Level 3 Communications, LLC.
skipping to change at page 12, line 29 skipping to change at page 13, line 4
[note1] FEC element type 128 is pending IANA approval. [note1] FEC element type 128 is pending IANA approval.
9. Author Information 9. Author Information
Luca Martini Luca Martini
Level 3 Communications, LLC. Level 3 Communications, LLC.
1025 Eldorado Blvd. 1025 Eldorado Blvd.
Broomfield, CO, 80021 Broomfield, CO, 80021
e-mail: luca@level3.net e-mail: luca@level3.net
Nasser El-Aawar Nasser El-Aawar
Level 3 Communications, LLC. Level 3 Communications, LLC.
1025 Eldorado Blvd. 1025 Eldorado Blvd.
Broomfield, CO, 80021 Broomfield, CO, 80021
e-mail: nna@level3.net e-mail: nna@level3.net
Giles Heron Giles Heron
Level 3 Communications Gone2 Ltd.
66 Prescot Street c/o MDP
One Curzon Street
London London
E1 8HG W1J 5HD
United Kingdom United Kingdom
e-mail: giles@level3.net e-mail: giles@goneto.net
Dimitri Stratton Vlachos Dimitri Stratton Vlachos
Mazu Networks, Inc. Mazu Networks, Inc.
125 Cambridgepark Drive 125 Cambridgepark Drive
Cambridge, MA 02140 Cambridge, MA 02140
e-mail: d@mazunetworks.com e-mail: d@mazunetworks.com
Dan Tappan Dan Tappan
Cisco Systems, Inc. Cisco Systems, Inc.
250 Apollo Drive 250 Apollo Drive
Chelmsford, MA, 01824 Chelmsford, MA, 01824
e-mail: tappan@cisco.com e-mail: tappan@cisco.com
Jayakumar Jayakumar, Jayakumar Jayakumar,
Cisco Systems Inc. Cisco Systems Inc.
225, E.Tasman, MS-SJ3/3, 225, E.Tasman, MS-SJ3/3,
San Jose, CA, 95134 San Jose, CA, 95134
skipping to change at page 14, line 4 skipping to change at page 14, line 21
Laurel Networks, Inc. Laurel Networks, Inc.
2607 Nicholson Rd. 2607 Nicholson Rd.
Sewickley, PA 15143 Sewickley, PA 15143
e-mail: sjv@laurelnetworks.com e-mail: sjv@laurelnetworks.com
John Shirron John Shirron
Laurel Networks, Inc. Laurel Networks, Inc.
2607 Nicholson Rd. 2607 Nicholson Rd.
Sewickley, PA 15143 Sewickley, PA 15143
e-mail: jshirron@laurelnetworks.com e-mail: jshirron@laurelnetworks.com
Andrew G. Malis Andrew G. Malis
Vivace Networks, Inc. Vivace Networks, Inc.
2730 Orchard Parkway 2730 Orchard Parkway
San Jose, CA 95134 San Jose, CA 95134
Phone: +1 408 383 7223 Phone: +1 408 383 7223
Email: Andy.Malis@vivacenetworks.com Email: Andy.Malis@vivacenetworks.com
Vinai Sirkay Vinai Sirkay
Vivace Networks, Inc. Vivace Networks, Inc.
2730 Orchard Parkway 2730 Orchard Parkway
San Jose, CA 95134 San Jose, CA 95134
e-mail: vinai.sirkay@vivacenetworks.com e-mail: vinai.sirkay@vivacenetworks.com
Vasile Radoaca
Nortel Networks
600 Technology Park
Billerica MA 01821
e-mail: vasile@nortelnetworks.com
Chris Liljenstolpe
Cable & Wireless
11700 Plaza America Drive
Reston, VA 20190
chris@cw.net
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