Table Of Contents
Installing the G.SHDSL ATM WIC on the Cisco 1700 Series Router
Preventing Electrostatic Discharge Damage
Connecting a G.SHDSL Card to the Network
Configuring G.SHDSL on a Cisco Router
Configuring ILMI on the DSLAM Connected to the WIC-1SHDSL Card
Configuring Quality of Service Parameters
Low Latency Queuing (Priority Queuing with Class-Based Weighted Fair Queuing)
Multilink PPP over ATM with Link Fragmentation and Interleaving
Weighted Random Early Detection
ATM per-VC Queuing and VC Bundling
ATM Cell Loss Priority Bit Marking
Configuring the SCC Clock Rate
Configuring FRF.5 and FRF.8 Internetworking Functions
Obtaining Technical Assistance
Installing the G.SHDSL ATM WIC on the Cisco 1700 Series Router
This document describes the multirate symmetric high-speed digital subscriber line (G.SHDSL) one-port wide area network (WAN) interface card (WIC). G.SHDSL is a last-mile access technology, which has a symmetrical data rate over a single copper pair. The G.SHDSL ATM WIC, the WIC-1SHDSL card, is available for, Cisco 1700, 2600, and 3600 series routers and supports ATM AAL5, raw cell, and various classes of quality of service (QoS) for both voice and data service, including the following:
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Constant bit rate (CBR)
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This card is compatible with the Cisco G.SHDSL line card in the Cisco 6015, Cisco 6130, Cisco 6160, or Cisco 6260 digital subscriber line access multiplexer (DSLAM).
This document contains the following sections:
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Related Documentation
Use this document with the following guides:
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These documents are available under Technical Documentation at http://www.cisco.com.
Features
G.SHDSL is an ATM-based, multirate, high-speed (up to 2.32 Mb), symmetric digital subscriber line digital data transfer between a single customer premises equipment (CPE) subscriber and a central office (CO).
The WIC-1SHDSL card is compatible with Cisco 6015, Cisco 6130, Cisco 6160, and Cisco 6260 DSLAMs. The DSLAM must be equipped with G.SHDSL line cards that are compatible with the DSL service to be configured.
The following are features of the WIC-1SHDSL card:
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The following ATM features are supported:
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The following buffering is supported:
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Benefits
The following are benefits of the WIC-1SHDSL card:
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LEDs
Figure 1 shows the WIC-1SHDSL card.
Figure 1 WIC-1SHDSL Card
The WIC-1SHDSL card has three LEDs, which are shown in Figure 1 and are described in Table 1.
Requirements
This section describes the requirements and standards supported for the WIC-1SHDSL card.
Software Requirements
The WIC-1SHDSL card requires Cisco IOS Release 12.2(4)XL or later.
Memory Requirements
The memory requirements for running the full-featured Cisco 1700 router encryption images with the G.SHDSL WIC are as follows:
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Caveats
The following are caveats concerning the use of a WIC-1SHDSL card.
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Data Rate Limitations
The card supports the following data rates (26 AGW) and distances:
Safety Warnings
Safety warnings appear throughout this publication in procedures that can harm you if they are performed incorrectly. A warning symbol precedes each warning statement.
Warning Conventions
Power Supply Warnings
The following warnings apply when you are installing a card or working with the power supply:
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Electrical Warnings
The following warnings apply when you are working with electricity:
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Follow these guidelines when working on equipment powered by electricity:
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If an electrical accident occurs, proceed as follows:
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Preventing Electrostatic Discharge Damage
Electrostatic discharge (ESD) can damage equipment and impair electrical circuitry. It can occur when printed circuit cards are improperly handled and can result in complete or intermittent failures. Always follow ESD prevention procedures when removing and replacing cards. Ensure that the router chassis is electrically connected to earth ground. Wear an ESD-preventive wrist strap, ensuring that it makes good skin contact. Connect the clip to an unpainted surface of the chassis frame to safely channel unwanted ESD voltages to ground. To guard against ESD damage and shocks, the wrist strap and cord must be used properly. If no wrist strap is available, ground yourself by touching the metal part of the chassis.
Caution
Connecting a G.SHDSL Card to the Network
Use a straight-through RJ-11 cable for this connection. The port on this interface card is color-coded lavender.
If you are connecting a DSL card to an RJ-11 wall jack that has the DSL pair wired for pins 2 and 5, you must use an RJ-11 crossover cable (lavender with blue stripe). The RJ-11 crossover cable is orderable separately as a spare.
Complete the following steps to connect a 1-port G.SHDSL card to the network:
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Figure 2 Connecting a G.SHDSL WIC to the Wall Jack
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Configuration Modes
Whenever you install a new card, or if you want to configure an existing card, you must configure the interface. If you replace a card that was already configured, the router recognizes it and brings up the interface by using the existing configuration.
Before you configure an interface, have the following information available:
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Obtain this information from your system administrator or network plan before you begin configuring the router.
You can configure the new interface and other router parameters by using any of the following methods:
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These procedures are explained in the following sections. To change the settings shown in the examples and to obtain further information, refer to the IOS configuration guides and command references. If you have questions or need help, see the "Obtaining Technical Assistance" section in this document.
Command-Line Configuration
You can configure the card by entering IOS commands on the command line. This method provides the greatest power and flexibility. For further information about these commands, refer to the IOS configuration guides and command references. You can display help by entering a question mark (?) at the prompt.
Before you begin, disconnect all WAN cables from the router to prevent it from running the AutoInstall process. The router tries to run AutoInstall whenever you power it on if there is a WAN connection on both ends and if the router does not have a valid configuration file stored in NVRAM (for instance, when you add a new interface). It can take several minutes for the router to determine that AutoInstall is not connected to a remote Transmission Control Protocol/Internet Protocol (TCP/IP) host.
To configure the card by using the command-line interface (CLI), follow this procedure:
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Would you like to enter the initial dialog? [yes]:Step 3
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Router#config terminalRouter(config)#The router enters global configuration mode, shown by the Router(config)# prompt.
If you want to change the router configuration, you can configure global parameters, passwords, network management, and routing protocols. For complete information about global configuration commands, refer to the IOS configuration guides and command references.
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Router(config)#interface Ethernet 0Router(config-if)#The prompt changes again to show that you are in interface configuration mode.
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Router(config-if)#ip address ipaddress subnetmaskRouter(config-if)#ipx network networknumberStep 8
Router(config-if)#no shutdownStep 9
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Router#show running-configStep 11
Router#copy running-config startup-configBuilding configuration. . .[OK]Router#The router automatically copies the startup configuration in NVRAM to the running configuration and executes it whenever the router is powered on or the reload command is entered. To see the configuration stored in NVRAM, enter the show startup-config command:
Router#show startup-config
System Configuration Dialog
You can configure the router by using the system configuration dialog (also called the Setup facility). The system configuration dialog prompts you for each response.
This section shows a sample configuration using the system configuration dialog. You should enter values appropriate for your router and network. To change the settings shown in the examples and to obtain further information, refer to the IOS configuration guides and command references.
Many prompts in the system configuration dialog include default answers, shown in square brackets following the question. Enter your response, or press Return to accept the default answer.
You can request help at any time by entering a question mark (?) at the system configuration dialog prompt.
Before you begin, disconnect all WAN cables from the router to prevent it from running the AutoInstall process. The router tries to run AutoInstall whenever you power it on if there is a WAN connection on both ends, and the router does not have a valid configuration file stored in NVRAM (for instance, when you add a new interface). It can take several minutes for the router to determine that AutoInstall is not connected to a remote TCP/IP host.
Follow these steps to configure the router by using the system configuration dialog:
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If the router does not have a valid startup configuration file, it tries to run AutoInstall. The following prompt appears:
Would you like to enter the initial dialog? [yes]:Step 4
If the startup configuration is valid, the EXEC prompt (Router>) appears.
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Router> enableStep 6
Router# setupStep 7
The following is an example of the process.
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Would you like to enter the initial configuration dialog? [yes/no]: yesAt any point you may enter a question mark '?' for help.Use ctrl-c to abort configuration dialog at any prompt.Default settings are in square brackets '[]'.Basic management setup configures only enough connectivityfor management of the system, extended setup will ask youto configure each interface on the systemb.
Would you like to enter basic management setup? [yes/no]: noFirst, would you like to see the current interface summary? [yes]: noc.
Configuring global parameters:Enter host name [Router]: hostnamed.
The enable secret is a password used to protect access toprivileged EXEC and configuration modes. This password, afterentered, becomes encrypted in the configuration.Enter enable secret: passwordThe enable password is used when you do not specify anenable secret password, with some older software versions, andsome boot images.e.
Enter enable password: passwordf.
The virtual terminal password is used to protectaccess to the router over a network interface.Enter virtual terminal password: passwordg.
Configure SNMP Network Management? [yes]: noConfigure IP? [yes]: yesConfigure IGRP routing? [yes]: yesYour IGRP autonomous system number [1]: 1Configure bridging? [no]: noh.
Configuring interface parameters:Do you want to configure Ethernet0 interface? [yes]: yesConfigure IP on this interface? [yes]: yesIP address for this interface: ipaddressSubnet mask for this interface [255.0.0.0] : netmaskClass X network is x.x.x.x, x subnet bits; mask is /xDo you want to configure FastEthernet0 interface? [yes]: noThe following configuration command script was created:hostname Routerenable secret 5 $1$ANpR$LYOj7mFpk1TE7SSAXDgVA/enable password passwordline vty 0 4password passwordno snmp-server!!ip routingno bridge 1!interface Ethernet0ip address x.x.x.x x.x.x.x!router igrp 1redistribute connectednetwork x.x.x.xnetwork x.x.x.x!endAfter the configuration you entered appears, you are asked if you want to use it.
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Use this configuration? [yes/no]: yesBuilding configuration...Use the enabled mode 'configure' command to modify this configuration.Press RETURN to get started!The configuration is saved.
Enter no if you do not want to save the configuration. The information you entered is discarded, and you can reenter the configuration parameters.
AutoInstall
The AutoInstall process is designed to configure the router automatically after it connects to your WAN. For AutoInstall to work properly, a TCP/IP host on your network must be configured to provide the configuration files. The TCP/IP host can reside anywhere on the network if the following two conditions exist:
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This functionality is coordinated by your system administrator at the TCP/IP host site. You should not try to use AutoInstall unless the required files are installed on the TCP/IP host.
Follow this procedure to prepare your router for the AutoInstall process:
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Router# copy running-config startup-configBuilding configuration. . .[OK]Router#This saves the configuration settings that the AutoInstall process created. If you do not do this, your configuration will be lost the next time you boot the router.
Platform Configuration
See the following sections for configuration tasks for the WIC-1SHDSL:
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Configuring G.SHDSL on a Cisco Router
To configure G.SHDSL service on a Cisco router containing a WIC-1SHDSL card, complete the following steps, beginning in global configuration mode:
Configuring ILMI on the DSLAM Connected to the WIC-1SHDSL Card
The Interim Local Management Interface (ILMI) protocol allows DSLAMs to be used for ATM address registration across an ATM User-Network Interface (UNI). If ILMI is configured on the WIC-1SHDSL card, the ATM PVC must be configured on the DSLAM. All switch-terminating connections use interface 0/0 to connect to the switch CPU.
For information about configuring the DSLAM, refer to the Configuration Guide for Cisco DSLAMs with NI-2.
Verifying ATM Configuration
Use the following commands to verify your configuration:
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Router# sh int atm1/0ATM1/0 is up, line protocol is upHardware is DSLSAR (with Globespan G.SHDSL Module)MTU 4470 bytes, sub MTU 4470, BW 800 Kbit, DLY 2560 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation ATM, loopback not setKeepalive not supportedEncapsulation(s):AAL5 PVC mode24 maximum active VCs, 256 VCs per VP, 2 current VCCsVC idle disconnect time:300 secondsLast input never, output 00:00:01, output hang neverLast clearing of "show interface" counters 03:16:00Queueing strategy:fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 drops30 second input rate 0 bits/sec, 0 packets/sec30 second output rate 0 bits/sec, 0 packets/sec2527 packets input, 57116 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort10798 packets output, 892801 bytes, 0 underruns0 output errors, 0 collisions, 0 interface resets0 output buffer failures, 0 output buffers swapped outRouter# show atm vcVCD / Peak Avg/Min BurstInterface Name VPI VCI Type Encaps SC Kbps Kbps Cells Sts1/0.3 2 9 36 PVC MUX UBR 800 UP1/0.2 1 9 37 PVC SNAP UBR 800 UPRouter# show controllers atm 1/0Interface ATM1/0 is upHardware is DSLSAR (with Globespan G.SHDSL Module)IDB: 62586758 Instance:6258E054 reg_dslsar:3C810000 wic_regs:3C810080PHY Inst:62588490 Ser0Inst:62573074 Ser1Inst: 6257CBD8 us_bwidth:800Slot: 1 Unit: 1 Subunit: 0 pkt Size:4496VCperVP:256 max_vp: 256 max_vc: 65536 total vc:2rct_size:65536 vpivcibit:16 connTblVCI:8 vpi_bits:8vpvc_sel:3 enabled: 0 throttled:0WIC Register Value Notes--------------- ---------- ----------FPGA Dev ID (LB) 0x44 'D'FPGA Dev ID (UB) 0x53 'S'FPGA Revision 0x9DWIC Config Reg 0x45 WIC / VIC select = WIC;CTRLE addr bit 8 = 1;OK LED on;LOOPBACK LED off;CD LED on;WIC Config Reg2 0x07 Gen bus error on bad ADSL accessInt 0 Enable Reg 0x03 ADSL normal interrupt enabledADSL error interrupt enabled•
Output Example
The WIC is configured as CO equipment, and the line is up.
Router# show dsl interface atm 0/0Globespan G.SHDSL Chipset InformationEquipment Type: Central OfficeOperating Mode: G.SHDSLClock Rate Mode: Auto rate selection ModeReset Count: 2Actual rate: 2320 KbpsModem Status: DataNoise Margin: 43 dBLoop Attenuation: 0.0 dBTransmit Power: 13.5 dBReceiver Gain: 204.8000 dBLast Activation Status:No FailureCRC Errors: 0Chipset Version: 1Firmware Version: R1.5Farend Statistics since CO boot-time:CRC Errors: 0Errored Seconds: 0Severly ES: 0Un Available S: 48Loss Of Sync S: 0Output Example
The WIC is configured as CPE, and the line is up.
Router# show dsl interface atm 0/0Globespan G.SHDSL Chipset InformationEquipment Type: Customer PremiseOperating Mode: G.SHDSLClock Rate Mode: Auto rate selection ModeReset Count: 1Actual rate: 2320 KbpsModem Status: DataNoise Margin: 42 dBLoop Attenuation: 0.0 dBTransmit Power: 13.5 dBReceiver Gain: 204.8000 dBLast Activation Status:No FailureCRC Errors: 0Chipset Version: 1Firmware Version: R1.0Configuring Quality of Service Parameters
This section describes QoS parameters that can be configured for Cisco 1700 series routers, using the WIC-1SHDSL card. The following are included:
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Low Latency Queuing (Priority Queuing with Class-Based Weighted Fair Queuing)
Low latency queuing (LLQ) allows strict priority queuing (PQ) to class-based weighted fair queuing (CBWFQ). This priority queuing allows delay-sensitive data such as voice packets to be de-queued and sent before other packet traffic, reducing jitter in voice conversations. To configure LLQ, enter the priority command under the CBWFQ configuration.
Configuration Example
The following example shows a Cisco 1751 router configured with LLQ:
class-map match-all VOIPmatch ip dscp 32class-map CRITICALmatch access-group 100!policy-map 1751_DSLclass CRITICALpriority 48class VOIPbandwidth 64set ip precedence 6!interface Loopback1ip address 10.0.0.10 255.255.255.252!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1 point-to-pointpvc 0/33vbr-rt 320 320 30tx-ring-limit 3protocol ppp Virtual-Template1!interface Virtual-Template1bandwidth 320ip unnumbered Loopback1service-policy output 1751_DSLppp multilinkppp multilink fragment-delay 4ppp multilink interleave!access-list 100 permit udp any any precedence critical!dial-peer voice 201 voipdestination-pattern 3640200session target ipv4:10.0.0.11ip qos dscp cs4 mediaip qos dscp cs4 signallingDiffServ
DiffServ addresses the clear need for relatively simple and coarse methods of categorizing traffic into different classes and applying QoS parameters to those classes. DiffServ supports class-based marking.
Cisco Express Forwarding (CEF) mode is required for DiffServ support. To enable CEF, enter the ip cef command.
Configuration Example
The following example shows a Cisco 1751 router configured with DiffServ:
access-list 102 permit udp host 16.0.0.4 host 15.0.0.5access-list 103 permit udp host 16.0.0.4 host 13.0.0.5ip cefclass-map match-all traffic-INTRAmatch access-group 102class-map match-all traffic-INTERmatch access-group 103class-map match-all traffic-dscp1match ip dscp 1class-map match-any traffic-prec3match ip dscp 24match ip dscp 25match ip dscp 26match ip dscp 27policy-map DSL-outclass traffic-INTRAbandwidth percent 8class traffic-dscp1set ip dscp 5class traffic-prec3set ip precedence 2class traffic-INTERbandwidth percent 8class class-defaultfair-queue!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1 point-to-pointmtu 576ip address 1.0.0.1 255.0.0.0pvc 99/99protocol ip 2.0.0.2 broadcastvbr-nrt 142 142 1tx-ring-limit 3oam-pvc 0oam retry 5 5 1encapsulation aal5snapservice-policy out DSL-out!dial-peer voice 201 voipdestination-pattern 3640200session target ipv4:14.0.0.3ip qos dscp cs4 mediaip qos dscp cs4 signalingCommitted Access Rate
Committed access rate (CAR) allows you to limit bandwidth transmission rates to traffic sources and destinations and allows you to specify policies for handling traffic that conforms to or breaches the specified bandwidth allocations.
CEF mode is required for CAR support. To enable CEF, enter the ip cef command.
To enable CAR, enter the rate-limit command under the atm interface.
Configuration Example
The following example shows a Cisco 1751 router configured with CAR:
ip cefinterface ATM0/0.1 point-to-pointmtu 576ip address 10.0.0.10 255.255.255.0rate-limit output 368000 2000 2000 conform-action set-dscp-transmit 40 exceed-action set- dscp-transmit 48pvc 0/33protocol ip 10.0.0.9 broadcastvbr-nrt 142 142 1encapsulation aal5snap!Multilink PPP over ATM with Link Fragmentation and Interleaving
This feature allows multilink PPP (MLPPP) encapsulation over a single slow link to fragment and interleave (LFI) packets to a small enough size that the delay requirements of delay-sensitive traffic will be met.
Fragment size at the MLPPP bundle can be configured by using the virtual-template interface bandwidth command and the ppp multilink fragment-delay command. The ideal fragment size for MLPPP over ATM should allow the fragments to fit into an exact multiple of ATM cells. These commands calculate fragment size by using the following formula:
fragment size = bandwidth x fragment-delay / 8.
For example, if the MLPPP ATM header is 10 bytes and the AAL5 packet overhead is 8 bytes, the fragment size for MLPPP over ATM can be calculated as follows:
fragment size = 48 x the number of cells - 10 - 8.
In this case, two cells per fragment are desirable, so the fragment size is calculated at 78 bytes.
The total bandwidth usable on this interface is 75 percent of the value declared in the bandwidth command. To change this default value, enter the max-reserved-bandwidth command.
LLQ must be enabled when you configure MLPPP with link fragmentation and interleaving.
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Configuration Example
The following example shows a Cisco 1751 router configuration with MLPPP/LFI:
class-map match-all VOIPmatch ip dscp 32class-map CRITICALmatch access-group 100!policy-map 1751_DSLclass CRITICALpriority 48class VOIPpriority 64set ip precedence 6!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1 point-to-pointpvc 0/33vbr-rt 150 150 30tx-ring-limit 3protocol ppp Virtual-Template1!interface Loopback1ip address 10.0.0.10 255.255.255.255interface Virtual-Template1bandwidth 320ip unnumbered Loopback1service-policy output 1751_DSLppp multilinkppp multilink fragment-delay 4ppp multilink interleave!access-list 100 permit udp any any precedence critical!dial-peer voice 201 voipdestination-pattern 3640200session target ipv4:10.0.0.11ip qos dscp cs4 mediaip qos dscp cs4 signallingWeighted Random Early Detection
You can set a queuing technique on a device's interface to manage how packets are handled when an interface starts to become congested. The queuing technique available for congestion avoidance is called weighted random early detection (WRED).
WRED allows the interface to start dropping packets from selected flows when traffic begins to exceed the interface's traffic thresholds, but before congestion occurs. If the dropped packets are TCP packets, the TCP source recognizes that packets are being dropped, and then lowers its transmission rate. The lowered transmission rate reduces the traffic to the interface, thus avoiding congestion. Because TCP retransmits dropped packets, no actual data loss occurs.
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Configuration Example
The following example shows a Cisco 1751 configured with WRED:
random-detect-group 1751_DSLexponential-weighting-constant 5precedence 2 96 256 100precedence 5 192 256 100!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1 point-to-pointip address 1.0.0.1 255.0.0.0pvc 88/88random-detect attach 1751_DSLprotocol ip 2.0.0.2vbr-rt 320 320 30oam-pvc 40oam retry 3 5 1encapsulation aal5snap!ATM per-VC Queuing and VC Bundling
Parameters can be applied to individual VCs either by using VC classes or by directly applying them to the bundle members. Parameters applied to an individual VC supersede bundle-level parameters. Parameters applied directly to a VC take precedence over the same parameters applied within a class to the VC at the bundle-VC configuration level.
All of the QoS features are supported in per-virtual circuit (VC) and VC bundling mode. The default is per-VC queuing mode.
VC bundling allows individual VCs going to the same destination to be grouped together. Traffic mapping to each VC is based on traffic protocol criteria such as IP precedence. (VC bundling is not supported for MLPPP/LFI.)
To enable VC bundling, enter the bundle command under the ATM interface.
Configuration Example
The following example shows a VC bundling configuration:
vc-class atm atm-bundlebroadcastoam-pvc manage 1oam retry 3 3 1encapsulation aal5snapprotocol ip inarp broadcastoam-bundle manage 1!vc-class atm vipvbr-rt 256 256 20precedence 5-7bump implicitno protect vcno protect group!vc-class atm highvbr-rt 256 256 20precedence 2-4bump implicitno protect vcno protect group!vc-class atm normalvbr-rt 256 256 20precedence 0-1bump explicit 2no protect vcno protect group!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1 point-to-pointip address 2.0.0.2 255.255.0.0bundle 1751_DSLclass-bundle atm-bundlepvc-bundle vip 0/33class-vc vippvc-bundle high 0/34class-vc highpvc-bundle normal 0/35class-vc normalATM Cell Loss Priority Bit Marking
When congestion occurs in an ATM network, ATM cells are discarded. One way to control which cells are discarded is to use the cell loss priority (CLP) bit in the ATM header of each cell. The CLP bit may be set to either 1 or 0. Cells with the CLP bit set to 1 are always discarded before any of the cells with the CLP bit set to 0.
The ATM CLP bit marking feature allows you to control the CLP setting on Cisco routers. The marking of the CLP bit is implemented on a per-packet basis so that the CLP bit of every ATM cell that belongs to a particular packet is set to either 0 or 1.
Configuration Example
The following is an example of enabling ATM CLP Bit Marking using the set atm-clp command and modular QoS command-line interface. In this example, all output packets that have an IP Precedence value of 0 are sent with the CLP set to 1. Note that IP CEF must be on when using ATM CLP bit marking.
ip cefclass-map match-all prec0match ip precedence 0policy-map ATM_OUTclass prec0set atm-clpinterface ATM0/0pvc 0/33service-policy output ATM_OUTCompressed RTP
The Real-Time Transport Protocol (RTP), as described in RFC 1889, is used to carry real-time data for voice and video applications. For a typical Voice over IP (VoIP) application, the payload portion of the packet can be smaller than the header. For instance, using the G.729 codec, the payload is 20 bytes, but the IP, User Data Protocol (UDP), and RTP header is 40 bytes. It is inefficient to send the IP, UDP, and RTP header across a slow link without compressing it. The Compressed Real-Time Transport Protocol (cRTP) feature, as defined in RFC 2508, addresses this inefficiency by making the VoIP packet headers smaller.
The basic premise of cRTP is that although several fields in the IP, UDP, and RTP header change from packet to packet, the differences in these fields from packet to packet are constant. The compression scheme in cRTP is to encode the header to reduce the size of information to be transmitted. With cRTP, a 40-byte IP, UDP, and RTP header of a VoIP packet can be compressed to 2 to 4 bytes per packet, yielding approximately 11.2 kbps of bandwidth for a G.729 codec call with RTP.
cRTP can be applied to an ATM link through cRTP for MLP over ATM, or through cRTP for PPP over ATM.
Configuration Example
The following are examples of cRTP for MLP over ATM, and cRTP for PPP over ATM. The ip rtp header-compression command sets cRTP.
cRTP Using MLP over ATM
interface Loopback1ip address 10.0.0.9 255.255.255.255!interface ATM0/0no ip address!dsl equipment-type CPEdsl operating-mode GSHDSL symmetric annex Adsl linerate AUTO!interface ATM0/0.1 point-to-pointpvc 0/33ip 10.0.0.10vbr-rt 320 320 30tx-ring-limit 3protocol ppp Virtual-Template1!interface Virtual-Template1bandwidth 320ip unnumbered Loopback1ip tcp header-compression iphc-formatservice-policy output ADSL-2ppp multilinkppp multilink fragment-delay 4ppp multilink interleaveip rtp header-compression iphc-formatcRTP Using PPP over ATM
interface Loopback1ip address 10.0.0.9 255.255.255.255!interface ATM0/0no ip address!
dsl equipment-type CPEdsl operating-mode GSHDSL symmetric annex Adsl linerate AUTO!interface ATM0/0.1 point-to-pointpvc 0/33protocol ip 10.0.0.10vbr-rt 320 320 30tx-ring-limit 3protocol ppp Virtual-Template1!interface Virtual-Template1bandwidth 320ip unnumbered Loopback1ip tcp header-compression iphc-formatservice-policy output ADSL-2ip rtp header-compression iphc-formatTunable Transmission Ring
The transmission (tx) ring is the first-in, first-out (FIFO) buffer used to hold frames before transmission at the DSL driver level. The tx ring defines the maximum number of packets that can wait for transmission at Layer 2.
The tx ring complements the ability of LLQ to minimize jitter and latency of voice packets. For maximum voice quality, a low tx ring setting should be used. For maximum data throughput, a high tx ring setting should be used.
You can configure the size of the tx ring for each permanent virtual circuit (PVC). The default value is 60. However, the value of the setting can be from 2 through 60.
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For example, when the tx ring limit is configured as 3 and LLQ is configured on the PVC, the worst-case delay for a voice packet is the time required to transmit three data packets. When the buffering is reduced by configuring the tx ring limit, the delay experienced by voice packets is reduced by a combination of the tx ring and LLQ mechanism.
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Configuration Example
The following example is a configuration of the tx ring limit on an ATM PVC interface. To enable the tx ring limit, enter the tx-ring-limit command.
class-map match-all VOIPmatch ip dscp 32class-map CRITICALmatch access-group 100!policy-map 1751_DSLclass CRITICALpriority 48class VOIPbandwidth 64set ip precedence 6!interface Loopback1ip address 10.0.0.10 255.255.255.252!interface ATM0/0no ip addressno atm ilmi-keepalive!interface ATM0/0.1pvc 0/33vbr-rt 320 320 30tx-ring-limit 3protocol ppp Virtual-Template1!interface Virtual-Template1bandwidth 320ip unnumbered Loopback1ip mroute-cacheservice-policy output 1751_DSLppp multilinkppp multilink fragment-delay 4ppp multilink interleave!access-list 100 permit udp any any precedence critical!dial-peer voice 201 voipdestination-pattern 3640200session target ipv4:10.0.0.11ip qos dscp cs4 mediaip qos dscp cs4 signallingMLP Bundling
Multilink PPP (MLP), standardized in RFC 1990, is similar to load balancing techniques in that it sends packets across the individual links in a round-robin fashion. However, MLP adds three significant capabilities:
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Additionally, when more bandwidth is needed, additional links can be added to the bundle by simply configuring them as members of the bundle. No reconfiguration at the network layer, such as new addressing, is needed. This is also a significant factor when considering the use of advanced router services. For example, a specific QoS can be configured once for the bundle as a whole rather than on each link in the bundle. The trade-off for the increased functionality is that MLP requires greater CPU processing than load-balancing solutions. Packet reordering, fragment reassembly, and the MLP protocol itself increase the CPU load.
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Configuration Example
The following example shows a Cisco 1760 router configured with MLP Bundling:
!interface Multilink1ip address 10.0.0.9 255.255.0.0load-interval 30keepalive 1max-reserved-bandwidth 100service-policy output CISCOno cdp enableppp multilinkppp multilink fragment-delay 10ppp multilink interleavemultilink-group 1!interface ATM0/0no ip addressno atm ilmi-keepalivepvc 0/38vbr-rt 192 192 1000tx-ring-limit 2protocol ppp Virtual-Template1!dsl operating-mode autono shut!!interface ATM1/0no ip addressno atm ilmi-keepalivepvc pvc 6/65vbr-rt 192 192 1000tx-ring-limit 2protocol ppp Virtual-Template1!!dsl operating-mode autono shut!!!interface Virtual-Template1no ip addressload-interval 30keepalive 1ppp multilinkppp multilink multiclassmultilink-group 1!For information on how to verify and troubleshoot MLP Bundling, please refer to Enhanced Voice and QoS for ADSL and G.SHDSL on Cisco 1700 Series, Cisco 2600 Series, and Cisco 3600 Series Routers.
Configuring the SCC Clock Rate
Communciation between a DSL WIC and the host in a router takes place through a device called a serial communications controller (SCC). Whenever the host wants to transmit data or send any control traffic to the DSL WIC, it uses an SCC. Similarly, when a DSL WIC wants to forward incoming data from the line to the host, it also uses an SCC. Each DSL WIC installed in a router uses two SCCs. One SCC, SCC-A, is used for ATM adaptation layer 5 (AAL5) data traffic, while the other, SCC-B, is used for ATM adaptation layer 2 (AAL2) data traffic and for control traffic. The speed at which an SCC transfers data between the host and the WIC depends on the clock rate with which the SCC has been configured. This clock rate is configured by the user, and it is always synchronous. The SCC clock rate is the same whether the WIC is sending or receiving data through the SCC. For an asynchronous DSL (ADSL) WIC, the SCC clock rate should be set slightly higher than the larger of the DSL line rates (upstream or downstream). It is recommended that the SCC clock rate always be set higher than the DSL line rate to accommodate any SCC overhead.
SCC Clock Rate Configuration
The following example is a configuration of SCC clock rates on an ATM interface. Clock rates are set with the clock rate aal5 command and the clock rate aal2 command. On Cisco 1700 series routers, valid clock rates are from 4 Mbps to 8 Mbps. The clock rate values are entered as bits per second, as shown in the example.
interface ATM0/0no ip addressclock rate aal5 5300000clock rate aal2 4000000no atm ilmi-keepalivebundle-enablebundle ama-bundle12!dsl operating-mode autoend
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SCC Clock Rate Verification
To verify the configuration of the SCC clock rate, use the show controller command. SCC-A represents the clock rate for AAL5 while SCC-B represents the clock rate for AAL2.
Router#show controller atm0/0Interface: ATM0/0, Hardware: DSLSAR (with Alcatel ADSL Module), State: upIDB: 82115298 Instance: 82116A4C reg_dslsar:68030000 wic_regs: 68030080PHY Inst:8213862C Ser0Inst: 8210F690 Ser1Inst: 8211281C us_bwidth:864Slot: 0 Unit: 0 Subunit: 0 pkt Size: 4528VCperVP: 256 max_vp: 256 max_vc: 65536 total vc: 1rct_size:65536 vpivcibit:16 connTblVCI:8 vpi_bits: 8vpvc_sel:3 enabled: 0 throttled: 0 cell drops: 0Parallel reads to TCQ:0 tx count reset = 0, periodic safe start = 0Serial idb(AAL5) output_qcount:0 max:40Serial idb(RAW) output_qcount:0, max:40Sar ctrl queue: max depth = 10, current queue depth = 0, drops = 0, urun cnt = 0, total cnt = 99Serial idb tx count: AAL5: 0, RAW: 0, Drop count:AAL5: 0, RAW: 0SCC Clockrates:SCC-A = 5300000SCC-B = 4000000WIC Register Value Notes---- ----------- ---------- ----------FPGA Dev ID (LB) 0x44 'D'FPGA Dev ID (UB) 0x53 'S'FPGA Revision 0x9FWIC Config Reg 0x4D WIC / VIC select = WIC;Configuring FRF.5 and FRF.8 Internetworking Functions
To communicate over WANs, end-user stations and the network cloud typically must use the same type of transmission protocol. This limitation has prevented differing networks such as Frame Relay and ATM from being linked. The Frame Relay-to-ATM Service Interworking feature allows Frame Relay and ATM networks to exchange data despite differing network protocols. The functional requirements for linking Frame Relay and ATM networks are provided by the Frame Relay/ATM PVC Service Interworking Implementation Agreement specified in Frame Relay Forum (FRF) documents FRF.5 and FRF.8. The FRF.5 and FRF.8 interworking functions involve multiplexing PVCs between Frame Relay and ATM networks and mapping the control bits between Frame Relay frame headers and ATM cell headers. FRF.5 and FRF.8 are necessary for ATM-based features to interwork with Frame Relay-based IP class of service (CoS) features.
Configuration Examples
These examples show how to configure a mapping between a Frame Relay data-link connection identifier (To communicate over WANs, end-user stations and the network cloud typically must use the same type of transmission protocol. This limitation has prevented differing networks such as Frame Relay and ATM from being linked. The Frame Relay-to-ATM Service Interworking feature allows Frame Relay and ATM networks to exchange data despite differing network protocols. The functional requirements for linking Frame Relay and ATM networks are provided by the Frame Relay/ATM PVC Service Interworking Implementation Agreement specified in Frame Relay Forum (FRF) documents FRF.5 and FRF.8. The FRF.5 and FRF.8 interworking functions involve multiplexing PVCs between Frame Relay and ATM networks and mapping the control bits between Frame Relay frame headers and ATM cell headers. FRF.5 and FRF.8 are necessary for ATM-based features to interwork with Frame Relay-based IP class of service (CoS) features.
) and an ATM PVC, using the connect command. For a full description of the connect command as used in the FRF.5 and FRF.8 internetworking functions, refer to Enhanced Voice and QoS for ADSL and G.SHDSL on Cisco 1700 Series, Cisco 2600 Series, and Cisco 3600 Series Routers.
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FRF.5
The following example shows how to create an FRF.5 connection, using the network-interworking keyword in the connect command.
interface serial0no ip addressencapsulation frame-relay IETFno fair-queueframe-relay interface-dlci 100 switchedframe-relay intf-type dce!interface atm1no ip addressno atm ilmi-keepalivepvc 0/33encapsulation aal5mux frame-relay!dsl equipment-type CPEdsl operating-mode GSHDSL symmetric annex Adsl linerate AUTO!connect frf5 serial0 100 atm1 0/33 network-interworkingFRF.8
The following example shows how to create an FRF.8 connection, using the service-interworking keyword in the connect command.
interface serial0no ip addressencapsulation frame-relay IETFno fair-queueframe-relay interface-dlci 100 switchedframe-relay intf-type dce!interface atm1no ip addressno atm ilmi-keepalivepvc 0/33encapsulation aal5mux fr-atm-srv!dsl equipment-type CPEdsl operating-mode GSHDSL symmetric annex Adsl linerate AUTO!connect frf8 serial0 100 atm1 0/33 service-interworkingNew or Changed IOS Commands
This section gives the new or changed Cisco IOS commands for configuring the ADSL or G.SHDSL WIC features. All other commands used to configure the ADSL or G.SHDSL WIC features are documented in the following publications:
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Reference information for the following commands is provided in Enhanced Voice and QoS for ADSL and G.SHDSL on Cisco 1700 Series, Cisco 2600 Series, and Cisco 3600 Series Routers.
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Reference information is provided below for configuring the card on the router, using these commands:
dsl equipment-type
To configure the DSL ATM interface to function as central office equipment or customer premises equipment, use the dsl equipment-type ATM interface command.
Use the no form of this command to restore the default equipment type.
dsl equipment-type {co | cpe}
no dsl equipment-type
Syntax Description
co
Configures the DSL ATM interface to function as central office equipment.
cpe
Configures the DSL ATM interface to function as customer premises equipment.
Defaults
The DSL ATM interface functions as customer premises equipment.
Command History
Usage Guidelines
This configuration command applies to a specific ATM interface. You must specify the ATM interface before you enter this command.
The ATM interface must be in the shutdown state before you enter this command.
Examples
The following example configures DSL ATM interface 1/1 to function as central office equipment.
router# conf tEnter configuration commands, one per line. End with CNTL/Z.router(config)# int atm 1/1router(config-if)# dsl equipment-type corouter(config-if)# endrouter# clear interface atm 1/1router#Related Commands
dsl linerate
To specify a line rate for the DSL ATM interface, use the dsl linerate ATM interface command.
Use the no form of this command to restore the default line rate.
dsl linerate {kbps | auto}
no dsl linerate
Syntax Description
Defaults
The DSL ATM interface automatically synchronizes its line rate with the far-end DSLAM or WIC.
Command History
Usage Guidelines
This configuration command applies to a specific ATM interface. You must specify the ATM interface before you enter this command.
The ATM interface must be in the shutdown state before you enter this command.
Examples
The following example configures DSL ATM interface 0/1 to operate at a line rate of 1040 kbps:
router# conf tEnter configuration commands, one per line. End with CNTL/Z.router(config)# int atm 0/1router(config-if)# dsl linerate 1096router(config-if)# endrouter# clear interface atm 0/1router#Related Commands
Configures the DSL ATM interface to function as central office equipment or customer premises equipment.
Obtaining Documentation
These sections explain how to obtain documentation from Cisco Systems.
World Wide Web
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Documentation CD-ROM
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Ordering Documentation
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http://www.cisco.com/go/subscription
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Documentation Feedback
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You can e-mail your comments to bug-doc@cisco.com.
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Obtaining Technical Assistance
Cisco provides Cisco.com as a starting point for all technical assistance. Customers and partners can obtain online documentation, troubleshooting tips, and sample configurations from online tools by using the Cisco Technical Assistance Center (TAC) Web Site. Cisco.com registered users have complete access to the technical support resources on the Cisco TAC Web Site.
Cisco.com
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Cisco.com is a highly integrated Internet application and a powerful, easy-to-use tool that provides a broad range of features and services to help you with these tasks:
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If you want to obtain customized information and service, you can self-register on Cisco.com. To access Cisco.com, go to this URL:
Technical Assistance Center
The Cisco Technical Assistance Center (TAC) is available to all customers who need technical assistance with a Cisco product, technology, or solution. Two levels of support are available: the Cisco TAC Web Site and the Cisco TAC Escalation Center.
Cisco TAC inquiries are categorized according to the urgency of the issue:
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The Cisco TAC resource that you choose is based on the priority of the problem and the conditions of service contracts, when applicable.
Cisco TAC Web Site
You can use the Cisco TAC Web Site to resolve P3 and P4 issues yourself, saving both cost and time. The site provides around-the-clock access to online tools, knowledge bases, and software. To access the Cisco TAC Web Site, go to this URL:
All customers, partners, and resellers who have a valid Cisco service contract have complete access to the technical support resources on the Cisco TAC Web Site. The Cisco TAC Web Site requires a Cisco.com login ID and password. If you have a valid service contract but do not have a login ID or password, go to this URL to register:
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If you are a Cisco.com registered user, and you cannot resolve your technical issues by using the Cisco TAC Web Site, you can open a case online by using the TAC Case Open tool at this URL:
http://www.cisco.com/tac/caseopen
If you have Internet access, we recommend that you open P3 and P4 cases through the Cisco TAC Web Site.
Cisco TAC Escalation Center
The Cisco TAC Escalation Center addresses priority level 1 or priority level 2 issues. These classifications are assigned when severe network degradation significantly impacts business operations. When you contact the TAC Escalation Center with a P1 or P2 problem, a Cisco TAC engineer automatically opens a case.
To obtain a directory of toll-free Cisco TAC telephone numbers for your country, go to this URL:
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Before calling, please check with your network operations center to determine the level of Cisco support services to which your company is entitled: for example, SMARTnet, SMARTnet Onsite, or Network Supported Accounts (NSA). When you call the center, please have available your service agreement number and your product serial number.
This document is to be used in conjunction with the documents listed in the "Related Documentation" section.
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