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Voice Over ATM Services on the VISM

A Cisco MGX 8850 Wide-Area Edge Switch, when equipped with one or more VISM cards, can transport digitized voice signals across a packet network while providing voice quality and reliability equal to the quality expected on the public telephone network. By transporting the voice traffic over ATM packet networks instead of traditional time-division multiplexing (TDM) networks, you realize considerable savings in network bandwidth requirements. Thus, the VISM/MGX 8850 combination provides an interface or voice gateway between conventional voice TDM networks and networks based on packet-switching technology.

The MGX network supports VISM-to-ATM connections. The primary use of this type of connection is to provide interworking with Cisco 3810 voice services.

Figure 22-8 shows an example of VISM and 3810 voice interworking.

Figure 22-8 VISM and Voice Interworking

Follow these steps to create Voice over ATM (VoATM) services in the MGX network on VISM:

Step 1

Type dspvismparam and confirm that the VISM mode is aal2Trunking. If it isn't, type cnfvismmode 2. This outputs the VISM voice mode and changes the voice mode to AAL2 trunking.

Step 2

Type dsplns. This outputs summary information for all lines on the card. Confirm that the line you want to use is enabled and free of alarms.

Step 3

Type dspln <line number> and verify the line signaling type. If you need to change it, use the cnflnsig command. This outputs the line configuration and changes the signaling type.

Step 4

Type dspport. If no port exists, type addport. This outputs the port information and creates a new logical port between the VISM and the PXM1.

Step 5

Type dsprscprtn. If no resource partitions exist, type addrscprtn 1. This outputs the resource partition information and creates a new portable AutoRoute (PAR) resource partition on the port.

Step 6

Type dsplndsp <line number> and review the digital signal processor (DSP) configuration. If you want to make any changes, use the cnfecanenable, cnfecanrec, cnfecantail, or cnfcompvad commands. This outputs the line DSP configuration and changes the line echo cancellation and VAD settings.

Step 7

Type dspendpts to identify an endpoint. If the endpoint you want to use is not listed, use the addendpt or addendpts command to create new endpoints. This outputs a list of all endpoints on the VISM and adds one or more new endpoints.

Step 8

Type dspendpt <endpoint number> and verify that the endpoint is using the appropriate line and timeslot. This outputs the endpoint configuration.

Step 9

To add a local connection, type addcon <local VCI> <preference> <PVC type> <application> <PCR>. Go to Step 11 and note the connection ID.

Step 10

To add a feeder connection, type addcon <local VCI> <preference> <PVC type> <application> <PCR> <mastership> [remote connection ID], specifying the PXM1 trunk in the remote connection ID. This creates a new master connection.

Step 11

Type dspcons and dspcon <channel number> and verify the connection configuration. This outputs the connection status and configuration information.

Step 12

Type addcid <endpoint number> <LCN> <CID number> <codec type> [profile type] [profile number] [VAD] [VAD initialization timer] [echo cancellation] [triple redundancy protection] [CAS transport] [DTMF transport] [ICS] [packet period], specifying the endpoint and connection channel number (LCN) you identified in Step 7 and Step 9 or 10. This creates a CID on the connection.

Step 13

If multiple CIDs are using the same connection, repeat Step 12 for each CID. Specify the same LCN and a different CID and endpoint. This creates additional CIDs.

Step 14

Log into the remote VISM if you are adding a local connection and type cc <card slot>. This transfers the CLI to another card slot.

Step 15

Repeat Steps 1 through 8. This configures the VISM, line, and endpoint(s).

Step 16

If you are adding a local connection, type addcon <local VCI> <preference> <PVC type> <application> <PCR> <mastership> [remote connection ID], specifying the remote connection ID you noted in Step 9. Then go to Step 18. This creates a master connection.

Step 17

If you are adding a feeder connection, type addcon <local VCI> <preference> <PVC type> <application> <PCR> <mastership> [remote connection ID], specifying the PXM1 trunk in the remote connection ID. This creates a master connection.

Step 18

Complete Steps 11 through 13 on this VISM. This adds one or more CIDs.

Step 19

If you have a BPX backbone network, log into the BPX switch attached to one of your MGX switches. Type addcon <local channel> <remote node> <remote channel> <connection class | connection type> [connection parameters] [route avoid] to add an ATM routing connection through the BPX network. Be sure to match the VPI and VCI values in the BPX network with the values you used when you added the MGX connection segments. Use the dspcons and dspcon commands to verify the connection status. Proceed to Step 21.

Step 20

If you have an MGX 8850-PXM45 backbone network, log into the AXSM on the local switch and type addcon <interface number> <vpi> <vci> <service type> 2 [parameters], where 2 indicates the slave endpoint. Be sure to write down the endpoint ID (NSAP address, VPI, and VCI). Log into the AXSM on the remote switch and type addcon <interface number> <vpi> <vci> <service type> 1 <-slave slave endpoint ID> [parameters], where 1 indicates the master endpoint and the slave endpoint ID is as previously noted. This adds a routing connection through the MGX 8850-PXM45 network. Use the dspcons and dspcon commands to verify the connection status.

Step 21

Use the tstcon or tstdelay command to verify connectivity. This tests end-to-end connectivity in the network.

Step 22

Type dspconcnt <channel number> and dspmngcidcnt <CID> and verify that there is traffic. This outputs connection and CID statistics counters.

Step 23

Log into the original VISM and repeat Steps 21 and 22. This confirms that the connection and CID are functioning correctly at the other end.

Step 24

Type bye. This logs you off the CLI.


You have completed the steps necessary to create Voice over ATM (VoATM) services in the MGX network on VISM.

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