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Frame Relay—ATM ServiceInterworking—FRF.8 on theCisco MC3810 FRF.8 Frame Relay to Asynchronous Transfer Mode (ATM) Interworking allows connection ofFrame Relay traffic across high-speed ATM trunks using ATM standard Network and ServiceInterworking. This document describes Frame Relay-to-ATM Service Interworking for datatransfer, outlined in Frame Relay Forum implementation agreement FRF.8 and designed for theCisco MC3810 multiservice access concentrator.
This document includes the following sections: • Feature Overview, page 1• Supported Platforms, page 4• Supported Standards, MIBs, and RFCs, page 4• Prerequisites, page 4• Configuration Tasks, page 5• Configuration Example, page 11• Command Reference, page 13• Glossary, page 18 Feature Overview
Service Interworking connects a Frame Relay network to an ATM network while the networksfunction independently. Service Interworking allows bidirectional PVC protocol conversionfunctions and provides a standards-based solution for service providers, enterprises, and end users.
In Service Interworking translation mode, Frame Relay PVCs are mapped to ATM PVCs withoutthe necessity for symmetric topologies—the paths can terminate on the ATM side. TheATM-connected Cisco MC3810 need not be directly linked to a Frame Relay network. Somenetwork devices in a Frame Relay network can evolve to ATM without all network devices doing so.
In Figure 1, customers’ Frame Relay devices are connected to Cisco MC3810 multiservice accessconcentrators, which in turn connect to a service provider’s ATM network and switch.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 1
Feature Overview
Service Interworking Function
This feature supports two modes of operation of the IWF for upper-layer user protocolencapsulation—transparent mode and translation mode—as defined in FRF.8 section 5.3. Themodes are configured at the PVC level. They differ in the following ways: • Translation mode maps between ATM and Frame Relay encapsulation; it also supports interworking of routed and/or bridged protocols.
• Transparent mode does not map encapsulations but sends them unaltered. This mode is used when translation is not practical because encapsulation methods do not conform to the supportedstandards for Service Interworking.
The Service Interworking Function (IWF) in translation mode works like a protocol converter in thefollowing ways: • When Inverse Address-Resolution Protocol (INARP) or static mapping is configured, addresses are resolved one-to-one between Frame Relay and ATM schemes.
• Header function mapping and multiprotocol data unit headers are converted between protocols.
• ATM Adaptation Layer 5 (AAL5) information assists in translating boundary information in both — In the Frame Relay-to-ATM direction, a frame is mapped to an ATM Adaptation Layer 5
— In the ATM-to-Frame Relay direction, the AAL5 information is used to delineate frame
boundaries and insert flags and other information that is stripped from frames in the oppositedirection.
• Discard Eligibility (DE) and Cell Loss Priority (CLP) can be mapped in both directions.
• Mapping can occur between the Frame Relay Forward Explicit Congestion Notification (FECN) and the ATM Explicit Forward Congestion Indicator (EFCI) in both directions, depending uponthe configuration. In some cases, it may be desirable for the mapping to occur, but in many casesit is better to turn the mapping off. This is configurable on each PVC.
• Mapping occurs between the Frame Relay Command Response (C/R) field and the ATM common part convergence sublayer user-to-user least significant bit (CPCS-UU LSB), as definedin FRF.8.
• PVC Management interworking is supported, as defined in FRF.8 section 5.2. The optional asynchronous Local Management Interface (LMI) status message is not implemented.
Benefits
Benefits
In internetworks that include both Frame Relay and ATM networks, Service Interworking makeslinking the two types of networks relatively easy.
If migration from Frame Relay to higher-bandwidth ATM networking is desirable, ServiceInterworking allows a gradual change, linking the two types of networks before the transition iscomplete. The conversion features of Service Interworking mean that interoperability need not beassured across all network nodes.
Expands ATM-Frame Relay Interworking Options Formerly, the Cisco MC3810 directly supported Network Interworking only, as outlined in theFRF.5 Implementation agreement, which allows Frame Relay voice or data traffic to be encapsulatedin Asynchronous Transfer Mode (ATM) cells. Service Interworking could be used on the CiscoMC3810 but only when it was provided by a carrier’s ATM equipment. Now, both ServiceInterworking and Network Interworking are supported on the Cisco MC3810 multiservice accessconcentrator. While Network Interworking requires special configuration on the ATM side in orderto support the link between networks, Service Interworking does not.
Conversion functions between Frame Relay and ATM require minimal configuration and mean thatATM activities need not be performed on the Frame Relay side and Frame Relay activities need notbe performed on the ATM side.
Restrictions
The following functions are not supported in the FRF.8 Cisco MC3810 Frame Relay-to-ATMService Interworking feature: • Fragmentation and Reassembly of RFC 1490, as defined in FRF.8, section 5.3.1.4• Traffic Management• The optional asynchronous LMI status message• Compression• Cisco MC3810 voice encapsulation—only data is supported Related Features and Technologies
There are two types of Frame Relay-ATM interworking, Service Interworking as described in thisdocument, and Network Interworking, which is also supported on the Cisco MC3810 multiserviceaccess concentrator.
Network Interworking allows the transparent tunneling of Frame Relay user traffic and PVCs overATM. This function is often used to link Frame Relay networks over an ATM backbone. The mostdistant nodes must be configured to interoperate with one another—in contrast to ServiceInterworking—because intact Frame Relay frames are sent over the ATM network. The ATMbackbone is used as an alternative to a leased line, and provides cost savings over leased lines. Therecan be a one-to-one relationship between Frame Relay and ATM PVCs, or multiple Frame RelayPVCs can be multiplexed into a single ATM PVC.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 3
Related Documents
In contrast, Service Interworking works to convert the components of the two different transmissionmethods—as described in the “Feature Overview” section on page 1. In addition, there is always aone-to-one relationship between Frame Relay and ATM PVCs.
Related Documents
For information about Frame Relay and ATM IOS configuration for the Cisco MC3810, consult thefollowing Cisco IOS Release 12.0 documents: • Wide-Area Networking Configuration Guide• Wide-Area Networking Command Reference For information about Frame Relay and ATM IOS configuration that is unique to the Cisco MC3810,consult the following Cisco documents: • Cisco MC3810 Multiservice Access Concentrator Software Configuration Guide• Cisco MC3810 Multiservice Access Concentrator Software Command Reference Supported Platforms
The Service Interworking feature is supported on the Cisco MC3810 multiservice accessconcentrator only.
Supported Standards, MIBs, and RFCs
This feature supports the Frame Relay Forum Frame Relay/ATM Service InterworkingImplementation Agreement, document number FRF.8, April 14, 1995.
Prerequisites
Frame Relay-ATM Service Interworking requires specific software, hardware, and preliminaryconfiguration: • Cisco IOS Software Release 12.0(5)XK, 12.0(7)T or later• Configured ATM and Frame Relay networks• One or more Cisco MC3810 multiservice access concentrators (a Cisco MC3810 acts as the Configuring the ATM Interface and PVCs
Configuration Tasks
Perform the following tasks to configure FRF.8 Frame Relay-ATM Service Interworking.
• Configure the ATM interface and PVCs.
• Configure the Frame Relay serial interface and PVCs.
The configuration tasks sections do not include complete configuration information; they assumethat your networks are already set up for Frame Relay and ATM transport modes. Instead, theconfiguration tasks focus on those steps that are necessary or may be important to Frame Relay-ATMService Interworking.
For a complete configuration example, see the “Configuration Example” section on page 11. Formore information about configuring your Cisco MC3810, see the Cisco IOS Release 12.0configuration guides and command references.
Configuring the ATM Interface and PVCs
This section shows the steps for setting global and interface configuration parameters to supportATM interfaces, as well as setting up those interfaces with ATM PVCs that interwork with FrameRelay PVCs.
Note Frame Relay-ATM Service Interworking supports neither Frame Relay nor ATM switched
virtual circuits (SVCs).
Router(config)# configure terminal
Router(config)# controller {T1 | E1} 0
Enter controller configuration mode for controllerT1/E1 0. ATM traffic is supported on controller T1/E1 0only.
Router(config-controller)# framing esf
Set the framing to Extended Superframe (ESF) format, required for ATM on T1. This setting is automatic for T1when the ATM mode is set.
Set the framing to CRC4, required for ATM on E1. This Router(config-controller)# framing crc4
setting is automatic for E1 when the ATM mode is set.
Router(config-controller)# linecode b8zs
Set the line coding to binary zero 0 substitution (B8ZS), required for ATM on T1. This setting is automatic for T1when the ATM mode is set.
Set the line coding to HDB3, required for ATM on E1.
Router(config-controller)# linecode hdb3
This setting is automatic for E1 when the ATM mode isset.
Note When the E1 controller is specified, you must also
configure scrambling on the ATM 0 interface.
Router(config-controller)# mode atm
This allows the controller to support ATM encapsulationand create virtual ATM interface 0 for PVCs. Channelgroups, channel-associated signaling (CAS) groups,Common Channel Signaling (CCS) groups or clearchannels are not allowed on the trunk because ATM trafficoccupies all the DS0s.
Router(config-controller)# interface atm0
Enter interface configuration mode for ATM interface 0,the only available ATM interface for this purpose.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 5
Configuring the ATM Interface and PVCs
Router(config-if)# pvc [name] vpi/vci
Use this form of the pvc command to enter ATM PVC
configuration mode and set up PVCs for Service
Interworking; set up an ATM PVC for each Frame Relay
PVC you are using for Service Interworking.
The optional name is a unique label that can be up to 16characters long.
The ATM network VPI of this PVC is an 8-bit field in theheader of the ATM cell. Valid values are from 0 to 255,but the values from 0 to 31 are usually reserved forparticular services.
The arguments vpi and vci cannot both be set to 0; if oneis 0, the other cannot be 0.
The VCI is a 16-bit field in the header of the ATM cell.
Note There are additional optional keywords for this
command that are not used for Service Interworking
PVCs. For more information, see the Cisco IOS Release
12.0 Wide-Area Networking Command Reference Guide.
Router(config-if-atm-pvc)# oam-pvc [manage] [frequency]
To enable PVC management, you must use this command,which allows the PVC to generate end-to-end OAM(Operation, Administration, and Maintenance) loopbackcells that verify connectivity on the virtual circuit. Theremote end must respond by echoing back such cells. IfOAM response cells are missed (indicating a lack ofconnectivity), the PVC state goes down. If all the PVCson a subinterface go down, the subinterface goes down. Ifthe command is not used, OAM loopback verification isoff.
The manage keyword allows OAM management of the
PVC.
The optional frequency number indicates the intervalbetween transmission of loopback cells and is a value inseconds from 0 to 600. If the command is issued withoutthis parameter, the default value is 10 seconds.
Note To permit PVC management, you must also enable
keepalive on the serial interface. See Step 6 of
“Configuring the Frame Relay Interface and PVCs” on
page 7.
Router(config-if-atm-pvc)# encapsulation aal5mux
Use this form of the ATM encapsulation command to set fr-atm-srv
the PVC for Frame Relay-to-ATM Service Interworking.
The fr-atm-srv keyword specifies the interworking
function.
Note The command encapsulation aal5mux
frame-relay specifies FRF.5 Frame Relay-to-ATM
Network Interworking.
Verifying ATM Interface and PVC Configuration
Verifying ATM Interface and PVC Configuration
Follow the steps below to verify configuration of ATM interface 0 and the PVCs you have created.
Use the show interface atm0 command to verify configuration of the ATM interface.
Important information appears in bold. Note that the total count of configured virtual
circuits (VCs) is shown.
router# show interface atm0
MTU 3000 bytes, sub MTU 3000, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ATM, loopback not set
Encapsulation(s):, PVC mode
1024 maximum active VCs, 11 current VCCs
Last input never, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/0/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 1000 bits/sec, 1 packets/sec 2838 packets input, 971318 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 201591 packets output, 16783240 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out Use the show atm pvc command to verify the PVCs you created. Note that in this
example, PVC 10 is set up for Network Interworking; the other PVCs are configured for
Service Interworking.
router# show atm pvc
Interface Name VPI VCI Type Encaps SC Kbps Kbps Cells Sts Configuring the Frame Relay Interface and PVCs
The steps below show how to configure the Frame Relay interface for Service Interworking and setup Frame Relay PVCs to work with ATM PVCs. Some preliminary global configuration commandsare also included. For more information about setting up Frame Relay on the Cisco MC3810, see theCisco MC3810 Multiservice Access Concentrator Software Configuration Guide.
To configure the Frame Relay interface and PVCs, follow the steps below.
Router# configure terminal
Router(config)# network-clock base-rate {56k | 64k}
Configure the network clock base rate for serial ports; thedefault setting is 56 kbps.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 7
Configuring the Frame Relay Interface and PVCs
Router(config)# frame-relay switching
Enables PVC switching on the serial interfaces.
Router(config)# interface serial {0 | 1}
Specify a serial interface for Frame Relay PVCs and enterinterface configuration mode.
Router(config-if)# encapsulation frame-relay [cisco |
Specify the Frame Relay encapsulation on the interface.
To allow FRF.8 communications in translation mode, youmust use the Internet Engineering Task Force (IETF) formof Frame Relay encapsulation, which allowsinteroperability among devices from different vendors.
Use the default cisco option when Cisco devices are
communicating in transparent mode. This method uses a
4-byte header, with 2 bytes to identify the data-link
connection identifier (DLCI) and 2 bytes to identify the
packet type.
Router(config-if)# keepalive [number]
To enable the keepalive timer and allow PVC
management in FRF.8 communications, enter the
keepalive command.
The optional number is and integer value for the keepaliveinterval, which is the frequency at which the Cisco IOSsoftware sends messages to the other end to ensure that anetwork interface is alive. The interval is adjustable in1-second increments down to 1 second. An interface isdeclared down after three update intervals have passedwithout receiving a keepalive packet. The default settingis 10 seconds.
Router(config-if)# frame-relay intf-type [dce | dte |
(Optional) This command sets the switch type.
dce indicates a router that functions as a switch connected
to a router.
dte is used when the Cisco MC3810 is connected to a
Frame Relay network. This is the default.
The nni option specifies a switch connected to a switch,
Network-to-Network Interface (NNI) connections.
Router(config-if)# frame-relay lmi-type {ansi | cisco |
(Optional) Unless this command is set, Local Management Interface (LMI) autosensing automaticallyselects a method for addressing the LMI. If you connect tothe public data network (PDN), the LMI type must matchthe type used on the PDN. Otherwise, you can specify aparameter that suits your private network’s needs.
ansi specifies Annex D defined by American National
Standards Institute (ANSI) standard T1.617.
cisco sets an LMI type defined jointly by Cisco and three
other companies.
q933a sets a type defined by ITU-T Q.933 Annex A.
Configuring the Frame Relay Interface and PVCs
Router(config-if)# frame-relay pvc dlci service
This command sets up Frame Relay PVCs for Frame {transparent | translation} [clp-bit {0 | 1 |
Relay-ATM Service Interworking. Repeat this step for map-de}][de-bit {0 | 1 | map-clp}][efci-bit {0 | 1 |
each PVC that you wish to set up. Corresponding ATM map-fecn}]interface atm0 {vpi/vci | vcd}
PVCs are configured in “Configuring the ATM Interfaceand PVCs” section on page 5.
dlci sets the data-link connection identifier (DLCI), avalue ranging from 16 to 1007 for the PVC. This label isused when you associate a Frame Relay PVC with anATM PVC.
The service setting configures Service Interworking in
transparent mode, where encapsulations are sent
unaltered, or in translation mode, where mapping and
translation take place. There is no default.
The clp-bit parameter configures the discard eligible (DE)
and cell loss priority (CLP) mapping in the Frame
Relay-to-ATM direction according to Mode 1 or 2 as
specified in FRF.8, section 4. The selections are as
follows:
• The default keyword, map-de, adheres to Mode 1 and
maps the DE field in the frame to the ATM CLP fieldgenerated by each cell during AAL5 segmentation.
• Rather than mapping, 0 or 1 adheres to Mode 2 and sets
a constant value (of 0 or 1) for the ATM CLP of eachATM cell that the AAL5 segmentation processgenerates.
The de-bit parameter configures the cell loss priority
(CLP) and discard eligibility (DE) mapping in the
ATM-to-Frame Relay direction according to Mode 1 or 2
as specified in FRF.8, section 4. The selections are as
follows:
• The default keyword, map-clp, adheres to Mode 1 and
sets the DE field in the frame if one or more cells in aframe have a CLP field set.
• 0 or 1 adheres to Mode 2 and sets a constant value (of 0
The efci-bit parameter sets the mode of Forward Explicit
Congestion Notification (FECN) and the ATM Explicit
Forward Congestion Indicator (EFCI) in the Frame
Relay-to-ATM direction.
The default map-fecn adheres to Mode 1 and maps the
FECN indicators to EFCI indicators.
0 sets a constant value rather than mapping, as does 1.
The last part of the command maps the Frame Relay PVCto an ATM PVC by specifying the ATM interface (0 is theonly value), and either the ATM virtual circuit descriptor(VCD), or the virtual path identifier-virtual channelidentifier (VPI-VCI) pair for the PVC.
Router(config-if)# exit
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 9
Verifying Frame Relay Interface and PVC Configuration
Verifying Frame Relay Interface and PVC Configuration
Use the show interface serial command to confirm serial interface configuration for
Frame Relay. Note that some important text appears in bold, as follows:
• Encapsulation is set to IETF, and the default keepalive is in effect. These settings allow translation mode and management of PVCs respectively.
• The LMI type of CCITT was specified with the q933a keyword, as ITU-T is the
successor to CCITT and the type is set to ITU-T Q.933 Annex A.
• The Frame Relay switch type is DCE.
router# show interface serial0
MTU 5000 bytes, BW 1544 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY IETF, crc 16, loopback not set
LMI enq sent 0, LMI stat recvd 0, LMI upd recvd 0 LMI enq recvd 36108, LMI stat sent 36108, LMI upd sent 0, DCE LMI up LMI type is CCITT
frame relay DCE
Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0 Last input 00:00:02, output 00:00:02, output hang never Last clearing of "show interface" counters 4d04h Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 54846 packets input, 7038195 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 8 giants, 0 throttles 9 input errors, 0 CRC, 1 frame, 0 overrun, 0 ignored, 0 abort 36436 packets output, 1599185 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out Hardware config: V.35; DTE; DSR = UP DTR = UP RTS = UP CTS = UP DCD = Note For a description of each output display field, refer to the show interface serial
command reference page in the Cisco IOS Release 12.0 Interface Command Reference.
Verifying Frame Relay Interface and PVC Configuration
Use the show frame-relay pvc [type number [dlci]] command to see status and traffic
information about Frame Relay PVCs that you have configured. The type, number, and
dlci arguments are optional and allow you to specify the switch type of the interface, an
interface number, and a DLCI number.
Router# show frame-relay pvc dce
PVC Statistics for interface Serial0 (Frame Relay DCE) DLCI = 100, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial0 input pkts 4936 output pkts 62 in bytes 989118 out bytes 63676 dropped pkts 4 in FECN pkts 8 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 pvc create time 1d16h, last time pvc status changed 1d16h Configuration Example
This section provides a configuration example where both sides of the Frame Relay-ATM ServiceInterworking function are performed on the same Cisco MC3810 multiservice access concentrator,which is acting as a gateway to mediate traffic between the two transport methods.
A serial interface is configured for Frame Relay with Frame Relay PVCs, and an ATM interface isconfigured on the same Cisco MC3810.
This command enables Frame-Relay switching on the serial interfaces of the Cisco MC3810: The mode atm command is required for ATM service.
The frame-relay pvc commands below set up Frame Relay PVCs that correspond to ATM PVCs.
Although one uses translation mode and one transparent mode, Cell Loss Priority (CLP) and Discard
Eligibility (DE) bits are mapped in both directions, corresponding to Mode 1 of the FRF.8 agreement
for these parameters.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 11
Configuration Example
In the Frame Relay-to-ATM direction, Forward Explicit Congestion Notification (FECN) and theATM Explicit Forward Congestion Indicator (EFCI) are mapped to one another.
Finally, the command points to the ATM PVC that corresponds to the Frame Relay PVC, using theATM interface number (0) and the virtual path identifier-virtual channel identifier (VPI/VCI) pair asidentification.
frame-relay pvc 44 service transparent clp-bit map-de de-bit map-clp efci-bit map-fecn frame-relay pvc 120 service translation clp-bit map-de de-bit map-clp efci-bit The frame-relay lmi-type command is set to the type defined by ITU-T Q.933 Annex A.
The frame-relay intf-type command designates digital communications equipment (DCE), because
the Cisco MC3810 is acting as a switch connected to a router rather than being connected directly
to a Frame Relay network.
The ATM PVCs are created on interface ATM 0, the only available interface for this purpose. The
oam-pvc setting provides for loopback testing and PVC management on PVC 44/44.
Note that these PVCs are specified in the frame-relay pvc commands that are configured on serial
interface 0. Encapsulation is set for Service Interworking.
Because the interworking function is used for data transfer, unspecified bit rate (UBR) can beconfigured as the QoS class for a PVC, as in PVC 44/44. The peak cell rate for output is set at56 Kbps.
The balance of the configuration does not bear on Frame Relay-to-ATM interworking.
Verifying Frame Relay Interface and PVC Configuration
Command Reference
This section documents new or modified commands. All other commands used with this feature aredocumented in the Cisco IOS Release 12.0 command references.
• encapsulation
• frame-relay pvc
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 13
encapsulation
encapsulation
To configure the ATM adaptation layer (AAL) and encapsulation type for an ATM PVC class, use
the encapsulation ATM virtual circuit. Use the no form of this command to remove an
encapsulation from a PVC.
encapsulation aal-encap
no encapsulation aal-encap
ATM adaptation layer (AAL) and encapsulation type. When
aal5mux is specified, a protocol is required. Possible values for
aal-encap are as follows:
• aal5mux frame-relay---For a MUX-type virtual circuit for
FRF.5 Frame Relay-ATM Network Interworking on theCisco MC3810.
• aal5mux fr-atm-srv---For a MUX-type virtual circuit for
FRF.8 Frame Relay-ATM Service Interworking on the CiscoMC3810.
• aal5mux voice---For a MUX-type virtual circuit for Voice
• aal5snap---The only encapsulation supported for Inverse
ARP. Logical Link Control/Subnetwork Access Protocol(LLC/SNAP) precedes the protocol datagram. This keywordis used for data.
The global default encapsulation is aal5snap. See the "Usage Guidelines" section for other default
characteristics.
Interface-ATM-VC configuration mode (for an ATM PVC or SVC) encapsulation
Modification
This command superseded the encapsulation atm command on the
Cisco MC3810, and the aal5mux frame and aal5mux voice
suboptions appeared.
The aal5mux fr-atm-srv suboption appeared for the Cisco MC3810.
Use one of the aal5mux encapsulation options to dedicate the specified PVC to a single protocol; use
the aal5snap encapsulation option to multiplex two or more protocols over the same PVC. Whether
you select aal5mux or aal5snap encapsulation might depend on practical considerations, such as
the type of network and the pricing offered by the network. If the network's pricing depends on the
number of PVCs set up, aal5snap might be the appropriate choice. If pricing depends on the number
of bytes transmitted, aal5mux might be the appropriate choice because it has slightly less overhead.
If you specify virtual template parameters after the ATM PVC is configured, you should issue a
shutdown command followed by a no shutdown command on the ATM subinterface to restart the
interface, causing the newly configured parameters (such as an IP address) to take effect.
The following example configures a PVC to support encapsulation for Voice over ATM on the CiscoMC3810: The following example configures a PVC to support encapsulation for Frame Relay-ATM NetworkInterworking on the Cisco MC3810: The following example configures a PVC to support encapsulation for Frame Relay-ATM ServiceInterworking on the Cisco MC3810: Description
This interface command creates an ATM PVC for FRF.8 ServiceInterworking with a corresponding Frame Relay PVC.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 15
frame-relay pvc
frame-relay pvc
To configure Frame Relay PVCs for FRF.8 Frame Relay-ATM Service Interworking, use the
frame-relay pvc interface configuration command. The no form of the command removes the PVC.
frame-relay pvc dlci service {transparent | translation} [clp-bit {0 | 1 | map-de}][de-bit {0 |
1 | map-clp}][efci-bit {0 | 1 | map-fecn}] interface atm0 {vpi/vci | vcd}
no frame-relay pvc dlci service {transparent | translation} [clp-bit {0 | 1 | map-de}][de-bit
{0 | 1 | map-clp}][efci-bit {0 | 1 | map-fecn}] interface atm0 {vpi/vci | vcd}
(Required) A value ranging from 16 to 1007 for the PVC’sdata-link connection identifier (DLCI). Use this label when youassociate a Frame Relay PVC with an ATM PVC.
service {transparent |
(Required) In the transparent mode of Service Interworking,
translation}
encapsulations are sent unaltered. In translation mode,
mapping and translation take place. There is no default.
clp-bit {0 | 1 | map-de}
(Optional) Sets the mode of DE/CLP mapping in Frame Relay
to the ATM direction. The default is map-de.
• map-de—Specifies Mode 1, which is described in 4.2.1 of
FRF.8. The DE field in the Q.922 core frame is mapped tothe ATM CLP field of every cell generated by thesegmentation process of the AAL5 PDU containing theinformation of that frame.
• 0 or 1—Specifies Mode 2 described in 4.2.1 of FRF.8. The
ATM CLP of each ATM cell generated by the segmentationprocess of the AAL5 PDU containing the information of thatframe is set to a constant value (either 0 or 1).
de-bit {0 | 1 | map-clp}
(Optional) Sets the mode of DE/CLP mapping in the
ATM-to-Frame Relay direction. The default is map-clp.
• map-clp—Specifies Mode 1, which is described in 4.2.2 of
FRF.8. If one or more cells in a frame has its CLP field set,the Service Interworking function sets the DE field of theQ.922 core frame.
• 0 or 1—Specifies Mode 2 described in 4.2.2 of FRF.8. The
DE field is set to a constant value (either 0 or 1).
efci-bit {0 | 1 | map-fecn}
(Optional) This part of the command sets the mode of Forward
Explicit Congestion Notification (FECN) and the ATM Explicit
Forward Congestion Indicator (EFCI) in the Frame
Relay-to-ATM direction. map-fecn is the default.
• 0—Sets a constant value rather than mapping.
• 1—Sets a constant value rather than mapping.
• map-fecn—Adheres to Mode 1 and maps the FECN
frame-relay pvc
interface atm0 {vpi/vci | vcd}
(Required) This part of the command maps the Frame RelayPVC to an ATM PVC specified by slot number (0 is the onlyoption for ATM on the Cisco MC3810) and either one of thefollowing labels: • vpi/vci—The virtual path identifier-virtual channel identifier • vcd—The ATM virtual circuit descriptor (VCD) for the ATM Modification
Use this command to create Frame Relay PVCs for association with ATM PVCs when you areconfiguring FRF.8 Frame Relay-ATM Service Interworking on the Cisco MC3810 multiserviceaccess concentrator.
In the example below, two Frame Relay PVCs are configured on a serial interface of aCisco MC3810.
frame-relay pvc 222 service translation clp-bit map-de de-bit map-clp efci-bit frame-relay pvc 925 service transparent clp-bit map-de de-bit map-clp efci-bit Description
ATM interface configuration command to create ATM PVCs thatcorrespond to Frame Relay PVCs for FRF.8 Service Interworking.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 17
Glossary
Glossary
AAL—ATM Adaptation Layer. Service-dependent sublayer of the data link layer. The AAL accepts
data from different applications and presents it to the ATM layer in the form of 48-byte ATM
payload segments. AALs consist of two sublayers: convergence sublayer (CS) and segmentation and
reassembly (SAR). AALs differ on the basis of the source-destination timing used, whether they use
constant bit rate (CBR) or variable bit rate (VBR), and whether they are used for connection-oriented
or connectionless mode data transfer. At present, the four types of AAL recommended by the ITU-T
are AAL1, AAL2, AAL3/4, and AAL5.
AAL1—ATM adaptation layer 1. One of four AALs recommended by the ITU-T. AAL1 is used for
connection-oriented, delay-sensitive services requiring constant bit rates, such as uncompressed
voice.
ATM—Asynchronous Transfer Mode. International standard for cell relay in which multiple service
types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells
allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take
advantage of high-speed transmission media such as E3, SONET, and T3.
B8ZS—binary 8-zero substitution. Line-code type, used on T1 and E1 circuits, in which a special
code is substituted whenever 8 consecutive zeros are sent over the link. This code is then interpreted
at the remote end of the connection. This technique guarantees ones density independent of the data
stream.
BECN—backward explicit congestion notification. Bit set by a Frame Relay network in frames
traveling in the opposite direction of frames encountering a congested path. DTE receiving frames
with the BECN bit set can request that higher-level protocols take flow control action as appropriate.
CBR—constant bit rate. QoS class defined by the ATM Forum for ATM networks. CBR is used for
connections that depend on precise clocking to ensure undistorted delivery.
CPCS—common part convergence sublayer. One of the two sublayers of any AAL. The CPCS is
service-independent and is further divided into the CS and the SAR sublayers. The CPCS is
responsible for preparing data for transport across the ATM network, including the creation of the
48-byte payload cells that are passed to the ATM layer.
CS— convergence sublayer. One of the two sublayers of the AAL CPCS, which is responsible for
padding and error checking. PDUs passed from the SSCS are appended with an 8-byte trailer (for
error checking and other control information) and padded, if necessary, so that the length of the
resulting PDU is divisible by 48. These PDUs are then passed to the SAR sublayer of the CPCS for
further processing.
DLCI— data-link connection identifier. Value that specifies a PVC or SVC in a Frame Relay
network. In the basic Frame Relay specification, DLCIs are locally significant (connected devices
might use different values to specify the same connection). In the LMI extended specification,
DLCIs are globally significant (DLCIs specify individual end devices).
E1—European digital carrier facility used for transmitting data through the telephone hierarchy. The
transmission rate for E1 is 2.048 megabits per second (Mbps).
EFCI—Explicit Forward Congestion Indication. In ATM, one of the congestion feedback modes
allowed by ABR service. A network element in an impending congestion state or in a congested state
can set the EFCI. The destination end-system can implement a protocol that adaptively lowers the
cell rate of the connection based on the value of the EFCI.
ESF—Extended Superframe. Framing type used on T1 circuits that consists of 24 frames of 192 bits
each, with the 193rd bit providing timing and other functions. ESF is an enhanced version of
Superframe format.
frame-relay pvc
FECN—forward explicit congestion notification. Bit set by a Frame Relay network to inform DTE
receiving the frame that congestion was experienced in the path from source to destination. DTE
receiving frames with the FECN bit set can request that higher-level protocols take flow-control
action as appropriate.
FRF.5—Frame Relay Forum implementation agreement for Frame Relay-to-ATM Network
Interworking.
FRF.8—Frame Relay Forum implementation agreement for Frame Relay-to-ATM Service
Interworking.
IETF—Internet Engineering Task Force
ILMI—Interim Local Management Interface. Specification developed by the ATM Forum for
incorporating network-management capabilities into the ATM User-Network Interface (UNI).
ISDN—Integrated Services Digital Network. Communication protocol, offered by telephone
companies, that permits telephone networks to carry data, voice, and other source traffic.
IWF—Interworking Function.
LMI—Local Management Interface
Network Interworking—FRF.5 Frame Relay-to-ATM Network Interworking, where Frame Relay
user traffic and PVCs are tunneled transparently over ATM. This function is often used to link Frame
Relay networks over an ATM backbone.
NNI—Network-to-Network Interface. ATM Forum standard that defines the interface between two
ATM switches that are both located in a private network or are both located in a public network. The
interface between a public switch and private one is defined by the UNI standard. Also, the standard
interface between two Frame Relay switches meeting the same criteria.
OAM cell—Operation, Administration, and Maintenance cell. ATM Forum specification for cells
used to monitor virtual circuits. OAM cells provide a virtual circuit-level loopback in which a router
responds to the cells, demonstrating that the circuit is up, and the router is operational.
PDU—protocol data unit
PVC—permanent virtual circuit. Virtual circuit that is permanently established. PVCs save
bandwidth associated with circuit establishment and tear down in situations where certain virtual
circuits must exist all the time. In ATM terminology, called a permanent virtual connection.
QoS—quality of service. Measure of performance for a transmission system that reflects its
transmission quality and service availability.
SAR—segmentation and reassembly. One of the two sublayers of the AAL CPCS, responsible for
dividing (at the source) and reassembling (at the destination) the PDUs passed from the CS. The
SAR sublayer takes the PDUs processed by the CS and, after dividing them into 48-byte pieces of
payload data, passes them to the ATM layer for further processing.
Service Interworking—FRF.8 Frame Relay-to-ATM Service Interworking, where Frame Relay
PVCs are mapped to ATM PVCs bidirectionally through protocol conversion functions. This
function is often used to migrate Frame Relay network devices or networks selectively or gradually
to ATM.
SONET—Synchronous Optical Network. High-speed (up to 2.5 Gbps) synchronous network
specification developed by Bellcore and designed to run on optical fiber. STS-1 is the basic building
block of SONET.
SVC—switched virtual circuit. Virtual circuit that is dynamically established on demand and is torn
down when transmission is complete. SVCs are used in situations where data transmission is
sporadic. Called a switched virtual connection in ATM terminology.
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 19
Glossary
T1—Digital WAN carrier facility. T1 transmits DS-1-formatted data at 1.544 Mbps through the
telephone switching network, using alternate mark inversion or B8ZS coding.
UNI—User-Network Interface. ATM Forum specification that defines an interoperability standard
for the interface between ATM-based products (a router or an ATM switch) located in a private
network and the ATM switches located within the public carrier networks. Also used to describe
similar connections in Frame Relay networks.
UBR—unspecified bit rate. QoS class defined by the ATM Forum for ATM networks. UBR allows
any amount of data up to a specified maximum to be sent across the network, but there are no
guarantees in terms of cell loss rate and delay.
VC—virtual circuit. Logical circuit created to ensure reliable communication between two network
devices. A virtual circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or
switched (SVC). Virtual circuits are used in Frame Relay and X.25. In ATM, a virtual circuit is
sometimes called a virtual channel.
VCI—virtual channel identifier. 16-bit field in the header of an ATM cell. The VCI, together with
the virtual path identifier (VPI), is used to identify the next destination of a cell as it passes through
a series of ATM switches on its way to its destination. ATM switches use the VPI/VCI fields to
identify the next network virtual channel link (VCL) that a cell needs to transit on its way to its final
destination.
VCL—virtual channel link. Connection between two ATM devices. A VCC is made up of one or
more VCLs.
VPI—virtual path identifier. 8-bit field in the header of an ATM cell. The VPI, together with the
VCI, is used to identify the next destination of a cell as it passes through a series of ATM switches
on its way to its destination. ATM switches use the VPI/VCI fields to identify the next VCL that a
cell needs to transit on its way to its final destination.
frame-relay pvc
Frame Relay—ATM Service Interworking—FRF.8 on the Cisco MC3810 21
Glossary

Source: http://docs.tpu.ru/docs/cisco/ios120/120newft/120t/120t7/frf8_t6.pdf