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Cable Modems

Configuring Cable Modem Voice Using H323v2 Static Mapping

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Document ID: 12191


Contents

Introduction
Before You Begin
      Conventions
      Prerequisites
      Components Used
      VoIP Summary
Configure
      Network Diagram
      Configurations
Verify
      show Commands
      debug Commands
Troubleshoot
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Introduction

This document is a sample configuration for Voice over IP (VoIP) between two cable modems connected through the same Cable Modem Terminal System (CMTS). The call is established end to end without going through the Public Switched Telephone Network (PSTN). The cable modems are configured in bridging mode, however, they can be equally configured for routing mode without changing any of the VoIP configurations. This document provides a basic VoIP setup in a lab configuration

Before You Begin

Conventions

For more information on document conventions, see the Cisco Technical Tips Conventions.

Prerequisites

You shold be familiar with a basic understanding of the Data-over-Cable Service Interface Specifications (DOCSIS) and H323 protocols.

Components Used

This document is not restricted to specific software and hardware versions.

VoIP Summary

VoIP allows normal telephony-style voice to be carried over an IP-based internet with Plain Old Telephone Service (POTS)-like functionality, reliability, and voice quality. Using a voice supported Cisco uBR92x series router such as the uBR924 or the CVA 122, packets are transmitted and received in a digitized form over an IP network. Voice traffic is supported in both the DOCSIS-bridging and routing modes.

Note: When the cable modem router is acting in DOCSIS-bridging mode, a voice call originating from the router's Ethernet interface cannot terminate on another device attached to that same Ethernet interface; it must terminate on a device that is reached through the cable interface. To allow calls to both originate and terminate on the Ethernet interface, the router must be configured in routing mode.

Voice signals are packetized and transported in compliance with the following protocols:

  • H.323v2: second version of an International Telecommunications Union (ITU) standard that specifies call signaling and control protocols for an IP data network. Supported on Cisco IOS® Software Release 12.0(4)XI and later voice images.

  • Simple Gateway Control Protocol (SGCP) Version 1.1: a signaling protocol under review by the Internet Engineering Task Force (IETF). Supported on Cisco IOS Software Release 12.0(7)T and later voice images.

  • Media Gateway Control Protocol (MGCP) Version 0.1: a proposed IETF voice control protocol intended to eventually supersede the existing SCGP 1.1 protocol. Supported on Cisco IOS Software Release 12.1(3)T and later voice images.

Note: If using SGCP or MGCP, the Cisco cable modem router acts as the residential gateway that forwards the voice packets to the CMTS, which then connects to the external call agent (SGCP or MGCP) or media gateway controller. The call agent or controller determines how to transmit the call across the network to the trunking gateway that will be its ultimate destination.

In this setup, the H.323v2 protocol is used. For more on H.323, refer to H.323 Version 2 Support.

A static voice configuration is used when there are only a few sites calling each other. This setup is simple and does not need a gatekeeper.

Configure

In this section, you are presented with the information to configure the features described in this document.

Note: To find additional information on the commands used in this document, use the Command Lookup Tool ( registered customers only) .

Network Diagram

This document uses the network setup shown in the diagram below. The following hardware was used in this setup:

  • two uBR924 series routers running Cisco IOS 12.1(5)T

  • uBR7223 running Cisco IOS 12.1(5)T

  • two analog phones each connected to the v1+v2 ports on the uBR924

  • Cisco Network Registrar (CNR) acting as DHCP and TFTP servers. In the same server, Time of Day (ToD) is running.

cm_voice_static.gif

Configurations

This document uses the configurations shown below.

  • Psyduck (uBR924)

  • Raichu (uBR924)

  • Sniper (CMTS)

Psyduck (uBR924)

 
Psyduck#wr t
Building configuration...

Current configuration : 1335 bytes
!
! Last configuration change at 13:43:18 - Tue Mar 6 2001
! NVRAM config last updated at 09:38:45 - Tue Mar 6 2001
!
version 12.1
no service single-slot-reload-enable
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Psyduck
!
logging rate-limit console 10 except errors
enable password cisco
!
clock timezone - 0
ip subnet-zero
no ip routing
no ip finger
no ip domain-lookup
!         
ip audit notify log
ip audit po max-events 100
call rsvp-sync
!
!
!
!
!
!
!
!
!
!
interface Ethernet0
 ip address 10.50.50.2 255.255.255.0
 no ip route-cache
 no ip mroute-cache
 bridge-group 59
 bridge-group 59 spanning-disabled
!
interface cable-modem0
 ip address docsis
 no ip route-cache
 no ip mroute-cache
 bridge-group 59
 bridge-group 59 spanning-disabled
!
ip default-gateway 10.50.50.1
ip classless
no ip http server
no ip http cable-monitor
!
snmp-server packetsize 4096
snmp-server manager
!
voice-port 0
 input gain -2
!
voice-port 1
 input gain -2
!
dial-peer voice 1 pots
 destination-pattern 1111          
 

!--- Local phone number. Remote cable modem calls this number.

port 0
!
dial-peer voice 10 voip            
 destination-pattern 3...          


!--- Called number starting with 3 and followed by 3
!--- more digits should be sent 
!--- to gateway with IP address 10.50.50.5. 
!--- In this example, the Raichu cable modem. 

 session target ipv4:10.50.50.5    
!
!
line con 0
 exec-timeout 0 0
 transport input none
line vty 0
 exec-timeout 0 0
 password cisco
 no login
line vty 1 4
 password cisco
 no login
!
end

Raichu (uBR924)

 
Raichu# wr t
Building configuration...

Current configuration : 1143 bytes
!
! Last configuration change at 13:43:13 - Tue Mar 6 2001
! NVRAM config last updated at 09:40:02 - Tue Mar 6 2001
!
version 12.1
no service single-slot-reload-enable
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Raichu
!
logging rate-limit console 10 except errors
!
clock timezone - 0
ip subnet-zero
no ip routing
no ip finger
!
ip audit notify log
ip audit po max-events 100
call rsvp-sync
!
!
!
!
!
!
!
!
!
!
interface Ethernet0
 ip address 10.50.50.5 255.255.255.0
 no ip route-cache
 bridge-group 59
 bridge-group 59 spanning-disabled
!
interface cable-modem0
 ip address docsis
 no ip route-cache
 no ip mroute-cache
 bridge-group 59
 bridge-group 59 spanning-disabled
!
ip classless
no ip http server
no ip http cable-monitor
!
snmp-server packetsize 4096
snmp-server manager
!
voice-port 0
 input gain -2
!
voice-port 1
 input gain -2
!
dial-peer voice 3 pots
 destination-pattern 3333          


!--- Local phone number. Remote cable modem calls this number.

 port 0
!
dial-peer voice 30 voip
 destination-pattern 1...          


 !--- Called number starting with 1 and 
 !--- followed by three additional digits should be sent  
 !--- to gateway with IP address 10.50.50.2. 
 !--- In this example,the Psyduck cable modem.

session target ipv4:10.50.50.2    
!
!         
line con 0
 exec-timeout 0 0
 transport input none
line vty 0 4
 login
!
end

Sniper (CMTS)

 
Sniper#wr t
Building configuration...

Current configuration : 2389 bytes
!
version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers max-servers no-limit
!
hostname Sniper
!
boot system flash slot0:ubr7200-ik1st-mz.121-5.T.bin
logging rate-limit console 10 except errors
enable password cisco
!
no cable qos permission create
no cable qos permission update
cable qos permission modems
cable time-server
ip subnet-zero
no ip finger
no ip domain-lookup
!         
!
!
!
!
interface FastEthernet0/0
 description Connection to lab backbone
 ip address 172.17.110.148 255.255.255.224
 half-duplex
!
interface Ethernet1/0
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/1
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/2
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/3
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/4
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/5
 no ip address
 shutdown
 half-duplex

!
interface Ethernet1/6
 no ip address
 shutdown
 half-duplex
!
interface Ethernet1/7
 no ip address
 shutdown
 half-duplex
!
interface Cable2/0
 ip address 192.168.50.1 255.255.255.0 secondary
 ip address 10.50.50.1 255.255.255.0
 no keepalive
 cable downstream annex B
 cable downstream modulation 64qam
 cable downstream interleave-depth 32
 cable downstream frequency 555000000
 cable upstream 0 frequency 30000000
 cable upstream 0 power-level 0
 no cable upstream 0 shutdown
 cable upstream 1 shutdown
 cable upstream 2 shutdown
 cable upstream 3 shutdown
 cable upstream 4 shutdown
 cable upstream 5 shutdown
 cable dhcp-giaddr policy
 cable helper-address 172.17.110.137
!
interface Cable3/0
 no ip address
 no keepalive
 shutdown
 cable downstream annex B
 cable downstream modulation 64qam
 cable downstream interleave-depth 32
 cable upstream 0 shutdown
 cable upstream 1 shutdown
 cable upstream 2 shutdown
 cable upstream 3 shutdown
 cable upstream 4 shutdown
 cable upstream 5 shutdown
!
ip classless
ip route 0.0.0.0 0.0.0.0 172.17.110.129
no ip http server
!
line con 0
 exec-timeout 0 0
 transport input none
line aux 0
line vty 0 4
 exec-timeout 0 0
 no login
!
end

Verify

Before attempting any of the below debug commands, refer to Important Information on Debug Commands.

show Commands

Certain show commands are supported by the Output Interpreter Tool ( registered customers only) , which allows you to view an analysis of show command output.

The show commands listed below can be run to verify correct operation.

On the uBR924 

Raichu#show voice port summary 
                                  IN      OUT
PORT   CH SIG-TYPE   ADMIN OPER STATUS   STATUS   EC
====== == ========== ===== ==== ======== ======== ==
0      -- fxs-ls     up    up   off-hook idle     y 
1      -- fxs-ls     up    dorm on-hook  idle     y 

Raichu#show dial-peer voice summary 
dial-peer hunt 0
                                                      PASS
  TAG TYPE   ADMIN OPER PREFIX   DEST-PATTERN    PREF THRU SESS-TARGET    PORT
    3 pots   up    up            3333             0                       0
   30 voip   up    up            1...             0   syst ipv4:10.50.50.2

Another useful command is show call active voice brief. At the end of the command output, check for Total call-legs. A sample of the lower portion of the output is shown below. 

Total call-legs: 2
CB   : 8347953hs.1 +141 pid:30 Answer 1111 active
 dur 00:14:50 tx:44601/891991 rx:44530/890571
 IP 10.50.50.2:0 rtt:17ms pl:883120/4360ms lost:0/0/226 delay:26/22/126ms g729r8

CB   : 8347954hs.1 +140 pid:3 Originate 3333 active
 dur 00:14:51 tx:44583/891631 rx:44653/893031
 Tele 0 (65): tx:893140/893050/0ms g729r8 noise:-20 acom:0  i/0:-30/-34 dBm

Other useful commands are show voice port x and show dialplan number ### .

debug Commands

The most commonly used debug commands for VoIP are listed below.

  • debug voip ccapi inout

  • debug cch323 h225

  • debug cch323 h245

For more information, refer to Verify End-to-End VoIP Signaling (VOIP Call-Leg).

On the CMTS 

Sniper#show cable modem 
Interface   Prim Online     Timing Rec    QoS CPE IP address      MAC address
            Sid  State      Offset Power
Cable2/0/U0 1    online     2286    0.25  5   0   10.50.50.4      0050.7366.2223
Cable2/0/U0 2    online     2812    0.00  5   0   10.50.50.5      0001.9659.4449
Cable2/0/U0 3    online     2814    0.00  5   0   10.50.50.2      0001.9659.4477


Sniper#show interfaces cable 2/0 modem 0
SID   Priv bits  Type      State     IP address    method    MAC address
1     00         modem     up        10.50.50.4    dhcp      0050.7366.2223
2     00         modem     up        10.50.50.5    dhcp      0001.9659.4449
3     00         modem     up        10.50.50.2    dhcp      0001.9659.4477

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.

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Related Information

Updated: Jan 18, 2008Document ID: 12191