Cisco IOS Voice Troubleshooting and Monitoring Guide, Release 12.4
Troubleshooting Voice over ATM Interfaces to the IP Network
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Troubleshooting Voice over ATM Interfaces to the IP Network

Table Of Contents

Troubleshooting Voice over ATM Interfaces to the IP Network

Checking the ATM Configuration

Verifying the Voice Connection

Verifying the ATM Interface Configuration

Verifying the VoATM Connection

Troubleshooting Tips


Troubleshooting Voice over ATM Interfaces to the IP Network


Voice over ATM (VoATM) enables a router to carry voice traffic (for example, telephone calls and faxes) over an ATM network. An ATM network is a cell-switching and multiplexing technology that combines the benefits of circuit switching (constant transmission delay and guaranteed capacity) and packet switching (flexibility and efficiency for intermittent traffic).

All traffic to or from an ATM network is prefaced with a virtual path identifier (VPI) and virtual channel identifier (VCI). A VPI-VCI pair is seen as identifying a single virtual circuit. Each virtual circuit is a private connection to another node on the ATM network. Each virtual circuit is treated as a point-to-point mechanism to another router or host and is capable of supporting bidirectional traffic.

Each ATM node establishes a separate connection to every other node in the ATM network with which it must communicate. All such connections are established by means of a permanent virtual circuit (PVC) or a switched virtual circuit (SVC) with an ATM signaling mechanism. This signaling is based on the ATM Forum User-Network Interface (UNI) Specification version 3.0.

Each virtual circuit is considered a complete and separate link to a destination node. Data can be encapsulated as needed across the connection, and the ATM network disregards the contents of the data. The only requirement is that data be sent to the ATM processor card of the router in a manner that follows the specific ATM adaptation layer (AAL) format.

An ATM connection transfers raw bits of information to a destination router or host. The ATM router takes the common part convergence sublayer (CPCS) frame, carves it up into 53-byte cells, and sends the cells to the destination router or host for reassembly. In AAL5 format, 48 bytes of each cell are used for the CPCS data, and the remaining 5 bytes are used for cell routing. The 5-byte cell header contains the destination VPI-VCI pair, payload type, cell loss priority (CLP), and header error control (HEC) information.

To troubleshoot VoATM issues, see the following sections:

Checking the ATM Configuration

Verifying the Voice Connection

Verifying the ATM Interface Configuration

Verifying the VoATM Connection

Checking the ATM Configuration

To check for problems with the ATM configuration, perform the following tasks:

SUMMARY STEPS

1. show dial-peer voice

2. show interface

3. no shutdown

DETAILED STEPS


Step 1 Use the show dial-peer voice command on the local and remote concentrators to verify that the data is configured correctly on both.

Step 2 Use the show interface command to verify that the ATM interface is up.

Step 3 Ensure that the voice port, serial port, and controller T1 0 is set to no shutdown.



Note ATM defaults to Interim Local Management Interface (ILMI). If the carrier is using LMI, be sure to configure LMI support on the router.


Verifying the Voice Connection

To verify that the voice connection is working, perform the following steps:

SUMMARY STEPS

1. Verify dial tone.

2. Verify that a call attempt is successful.

3. show dial-peer voice

4. show voice port

5. show voice call

6. show voice dsp

DETAILED STEPS


Step 1 Pick up the telephone handset and verify that a dial tone is present.

Step 2 Make a call from the local telephone to a configured dial peer and verify that the call attempt is successful.

Step 3 Use the show dial-peer voice command to verify that the configured data is correct.

Step 4 Use the show voice port command to show the status of the voice ports.

Step 5 Use the show voice call command to show the call status for all voice ports.

Step 6 Use the show voice dsp command to show the current status of all DSP voice channels.


Verifying the ATM Interface Configuration

To verify the ATM interface configuration, perform the following tasks:

Enter the privileged EXEC show atm vc command to view the SVC (data only) and PVC set. The following is sample output:

Router# show atm vc

VCD /                                      Peak  Avg/Min Burst
Interface   Name       VPI   VCI  Type   Encaps   SC   Kbps   Kbps   Cells  Sts
0          1            0     5   PVC    SAAL     UBR       0                UP
0          2            0    16   PVC    ILMI     UBR       0                UP
0          379          0    60   SVC    SNAP     UBR       0                UP
0          986          0    84   SVC    SNAP     UBR       0                UP
0          14           0   133   SVC    VOICE    VBR      64     16   10    UP
0          15           0   134   SVC    VOICE    VBR      64     16   10    UP
0          16           0   135   SVC    VOICE    VBR      64     16   10    UP
0          17           0   136   SVC    VOICE    VBR      64     16   10    UP
0          18           0   137   SVC    VOICE    VBR      64     16   10    UP
0          19           0   138   SVC    VOICE    VBR      64     16   10    UP
0          20           0   139   SVC    VOICE    VBR      64     16   10    UP
0          21           0   140   SVC    VOICE    VBR      64     16   10    UP
0          22           0   141   SVC    VOICE    VBR      64     16   10    UP
0          23           0   142   SVC    VOICE    VBR      64     16   10    UP
0          24           0   143   SVC    VOICE    VBR      64     16   10    UP
0          25           0   144   SVC    VOICE    VBR      64     16   10    UP
0          26           0   145   SVC    VOICE    VBR      64     16   10    UP
0          27           0   146   SVC    VOICE    VBR      64     16   10    UP
0          28           0   147   SVC    VOICE    VBR      64     16   10    UP


Note VoATM SVCs are not supported since Cisco IOS Release12.0(7)XK. ATM SVCs for data are still supported.


Enter the show atm pvc command with the VPI/VCI specified to view the PVCs that are set up for ILMI management and Q.SAAL signaling. The following is sample output:

Router# show atm pvc 0/5

ATM0: VCD: 2, VPI: 0, VCI: 5, Connection Name: SAAL
UBR, PeakRate: 56
AAL5-SAAL, etype:0x4, Flags: 0x26, VCmode: 0x0
OAM frequency: 0 second(s), OAM retry frequency: 1 second(s), OAM retry frequenc
y: 1 second(s)
OAM up retry count: 3, OAM down retry count: 5
OAM Loopback status: OAM Disabled
OAM VC state: Not Managed
ILMI VC state: Not Managed
InARP DISABLED
InPkts: 2044, OutPkts: 2064, InBytes: 20412, OutBytes: 20580
InPRoc: 2044, OutPRoc: 2064, Broadcasts: 0
InFast: 0, OutFast: 0, InAS: 0, OutAS: 0
OAM cells received: 0
F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0
F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0
OAM cells sent: 0
F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0
F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0
OAM cell drops: 0
Compress: Disabled
Status: INACTIVE, State: NOT_IN_SERVICE
!
Router# show atm pvc 0/16

ATM0: VCD: 1, VPI: 0, VCI: 16, Connection Name: ILMI
UBR, PeakRate: 56
AAL5-ILMI, etype:0x0, Flags: 0x27, VCmode: 0x0
OAM frequency: 0 second(s), OAM retry frequency: 1 second(s), OAM retry frequenc
y: 1 second(s)
OAM up retry count: 3, OAM down retry count: 5
OAM Loopback status: OAM Disabled
OAM VC state: Not Managed
ILMI VC state: Not Managed
InARP DISABLED
InPkts: 398, OutPkts: 421, InBytes: 30493, OutBytes: 27227
InPRoc: 398, OutPRoc: 421, Broadcasts: 0
InFast: 0, OutFast: 0, InAS: 0, OutAS: 0
OAM cells received: 0
F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0
F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0
OAM cells sent: 0
F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0
F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0
OAM cell drops: 0
Compress: Disabled
Status: INACTIVE, State: NOT_IN_SERVICE

Enter the show atm interface command in privileged EXEC mode and specify ATM 0 to display the ATM interface. The following is sample output from the command:

Router# show interface atm 0

ATM0 is up, line protocol is up
  Hardware is PQUICC Atom1
  Internet address is 9.1.1.6/8
  MTU 1500 bytes, sub MTU 1500, BW 1536 Kbit, DLY 20000 usec,
     reliability 255/255, txload 22/255, rxload 11/255
  NSAP address: 47.0091810000000002F26D4901.000011116666.06
  Encapsulation ATM
  292553397 packets input, -386762809 bytes
  164906758 packets output, 1937663833 bytes
  0 OAM cells input, 0 OAM cells output, loopback not set
  Keepalive not supported
  Encapsulation(s):, PVC mode
  1024 maximum active VCs, 28 current VCCs
  VC idle disconnect time: 300 seconds
  Signalling vc = 1, vpi = 0, vci = 5
  UNI Version = 4.0, Link Side = user
  Last input 00:00:00, output 2d05h, output hang never
  Last clearing of "show interface" counters never
  Input queue: -1902/75/0 (size/max/drops); Total output drops: 205
  Queueing strategy: weighted fair
  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 67000 bits/sec, 273 packets/sec
  5 minute output rate 136000 bits/sec, 548 packets/sec
     76766014 packets input, 936995443 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
     367264676 packets output, 3261882795 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 output buffer failures, 0 output buffers swapped out

Enter the show atm video-voice address privileged EXEC command to display the ATM interface address and confirm the ILMI status (ILMI PVC is set up to enable SVC management). The ATM interface is assigned automatically with the atm voice aesa command. The following is a sample output:

Router# show atm video-voice address

nsap address                                  type         ilmi status
47.0091810000000002F26D4901.00107B4832E1.FE   VOICE_AAL5   Confirmed
47.0091810000000002F26D4901.00107B4832E1.C8   VIDEO_AAL1   Confirmed

Verifying the VoATM Connection

Verify that the voice connection is working by performing the following steps:

SUMMARY STEPS

1. Verify dial tone.

2. Verify that a call attempt is successful.

3. show dial-peer voice

4. show voice port

5. show voice call

6. show voice dsp

DETAILED STEPS


Step 1 Pick up the handset on a telephone connected to the configuration and verify that there is dial tone.

Step 2 Make a call from the local telephone to a configured dial peer to verify the connection.

Step 3 If there are relatively few dial peers configured, use the show dial-peer voice command to verify that the data configured is correct.

Step 4 To show the status of the voice ports, use the show voice port command.

Step 5 To show the call status for all voice ports, use the show voice call command.

Step 6 To show the current status of all DSP voice channels, use the show voice dsp command.


Troubleshooting Tips

If a call does not connect, resolve the problem by performing the following tasks:

Verify dial peer configuration by using the show dial-peer voice command on the local and remote concentrators.

Verify that ATM interface 0 is up by using the show interface command.

Ensure that the voice port, serial port, and controller T1 0 are set to no shutdown.