Configuring MGCP-Controlled Backhaul of BRI Signaling

Last Updated: December 14, 2011

The MGCP-Controlled Backhaul of Basic Rate Interface (BRI) Signaling in Conjunction with Cisco Unified Communications Manager feature provides MGCP service to remote-office gateways that connect by means of ISDN BRI trunks to a centralized Cisco Unified Communications Manager.

Feature benefits include the following:

  • Centralized call-management architecture, enabling a high degree of network control
  • Short voice cut-through times
  • Graceful evolution to new technology and to AVVID

Only the ETSI BRI basic-net3 switch type is supported.

Feature History for MGCP-Controlled Backhaul of BRI Signaling in Conjunction with Cisco Unified Communications Manager

Release

Modification

12.2(15)ZJ

This feature was introduced for Cisco Communications Manager 3.3(2) (formerly known as Cisco CallManager 3.3(2)).

12.3(2)T

This feature was integrated into Cisco IOS Release 12.3(2)T.

12.3(11)T

Support was added for Cisco Unified Communications Manager 4.1.

12.4(2)T

This feature was implemented on the Cisco 2600XM, Cisco 2691, Cisco 2800 series, Cisco 3700 series, and Cisco 3800 series.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

For more information about this and related Cisco IOS voice features, see the following:

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for MGCP-Controlled Backhaul of BRI Signaling

Cisco Unified Communications Manager

  • Cisco Unified Communications Manager 4.1(1) or a later release

Cisco Voice Gateway

  • 20-MB flash memory
  • 64-MB DRAM
  • One of the supported combinations of BRI voice interface card (VIC) and network module:
    • VIC-2BRI-NT/TE or VIC-2BRI-S/T in NM-1V or NM-2V with Cisco IOS Release 12.3(11)T or a later release
    • VIC2-2BRI-NT/TE in NM-HD-1V, NM-HD-2V, NM-HD-2VE, or NM-HDV2 with Cisco IOS Release 12.4(2)T or a later release
    • EM-4BRI-NT/TE in EVM-HD-8FXS/DID with Cisco IOS Release 12.4(2)T or a later release
  • MGCP enabled globally in a VoIP network
  • MGCP control of dial peers and voice ports
  • MGCP single-point configuration enabled

Note
For MGCP configuration instructions, see "Configuring MGCP Gateway Support for Cisco Unified Communications Manager" on page 23 .

Restrictions for MGCP-Controlled Backhaul of BRI Signaling

  • BRI backhaul uses the enhanced interface numbering support available in Cisco IOS Release 12.3(11)T and later. Previous releases supported only the slot/subslot/port format with the subslot forced to 0 on the Cisco 2600 series, Cisco 3600 series, and Cisco 3700 series. Cisco IOS Release 12.3(11)T and later releases support both the slot/port and slot/subslot/port interface numbering formats for BRI backhaul.
  • Only the ETSI BRI Basic-NET3 switch type is supported.
  • BRI calls are cleared during MGCP gateway fallback and rehome because ISDN BRI L2 must be reinitiated and brought up again by the new L3 task.
  • Do not add the application mgcpapp command to voice dial peers that support BRI backhaul.

Information About MGCP-Controlled Backhaul of BRI Signaling

MGCP-Controlled Backhaul of BRI Signaling

The MGCP-Controlled Backhaul of BRI Signaling feature supports a centralized Cisco Unified Communications Manager architecture with BRI trunks connected to remote branch offices. Transporting signaling information from a branch-office MGCP gateway to a centralized media-gateway controller for processing is called backhaul. D-channel signal information is backhauled to Cisco Unified Communications Manager through a TCP session. All Q.931 messages are passed through the TCP connection between the Cisco MGCP gateway and Cisco Unified Communications Manager. The MGCP gateway neither parses nor has any knowledge of the contents of those messages.

This feature enables you to connect remote ISDN PBXs and key systems to a Cisco ISDN BRI network termination (network side) or PSTN Class 4/5 switch through a Cisco ISDN BRI terminal equipment (as user side) interface. External call-control entities, such as one or more Cisco Unified Communications Manager servers, provide voice service between local and remote branch offices.

The figure below depicts a typical network-side scenario. NT denotes network termination; TE denotes terminal equipment.

Figure 1 Typical ISDN BRI Network-Side Scenario


The figure below shows a typical user-side scenario.

Figure 2 ISDN BRI User-Side Scenario


The following is the sequence of events during normal backhaul:

  1. A call comes in from the PSTN and passes over the BRI trunk to the MGCP gateway.
  2. The MGCP gateway passes signaling information from the call across the WAN to the Cisco Unified Communications Manager at headquarters.
  3. The Cisco Unified Communications Manager instructs the MGCP gateway on how to set up and manage the call.
  4. The call is established.

How to Configure MGCP-Controlled Backhaul of BRI Signaling

Configuring the BRI Interface as an MGCP-BRI Backhaul Endpoint

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface bri slot / port

4.    shutdown

5.    isdn switch-type basic-net3

6.    isdn bind-L3 ccm-manager service mgcp

7.    no shutdown

8.    no mgcp

9.    mgcp

10.    exit


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode on the BRI slot and port.

 
Step 3
interface bri slot / port


Example:

Router(config)# interface bri 1/0

 

Configures the BRI interface as the MGCP-BRI backhaul endpoint.

  • Slot and port syntax is platform-dependent; type ? to determine.
Note    This command is supported only for a user-side ETSI NET3 switch-type.
 
Step 4
shutdown


Example:

Router(config-if)# shutdown

 

(Optional) Clears the interface of any active calls. If there are no active calls, you can skip this step.

 
Step 5
isdn switch-type basic-net3


Example:

Router(config-if)# isdn switch-type basic-net3

 

Sets the central-office switch type on the ISDN interface to basic-net3.

 
Step 6
isdn bind-L3 ccm-manager service mgcp


Example:

Router(config-if)# isdn bind-L3 ccm-manager service mgcp

 

Sets ISDN L3 binding on the BRI interface.

 
Step 7
no shutdown


Example:

Router(config-if)# no shutdown

 

Restarts the interface if it was previously disabled.

 
Step 8
no mgcp


Example:

Router(config-if)# no mgcp

 

Disables all MGCP applications and protocols.

 
Step 9
mgcp


Example:

Router(config-if)# mgcp

 

Restarts MGCP and reregisters the gateway to Cisco Unified Communications Manager.

 
Step 10
exit


Example:

Router(config-if)# end

 

Exits interface-configuration mode.

 

Verifying MGCP-BRI Backhaul Configuration

SUMMARY STEPS

1.    show isdn status

2.    show ccm-manager

3.    show ccm-manager backhaul

4.    show mgcp endpoint


DETAILED STEPS
Step 1   show isdn status

Use the show isdn status command to verify that Layer 2 is established and that Layer 3 is configured as Cisco Unified Communications Manager. This output displays only if TEI negotiation is performed at startup.



Example: 
Router# show isdn status
ISDN BRI1/1 interface
        dsl 1, interface ISDN Switchtype = basic-net3
        L2 Protocol = Q.921  L3 Protocol(s) = CCM-MANAGER
    Layer 1 Status:
        ACTIVE
    Layer 2 Status:
        TEI = 64, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED
Note    Use this command only if TEI negotiation is done at startup. Otherwise, TEI negotiation is done when the first call is placed, so output shows Layer 2 with no TEI negotiated and Layer 3 as down.
Step 2   show ccm-manager

Use the show ccm-manager command to verify your Cisco Unified Communications Manager configuration on the gateway.



Example: 
Router# show ccm-manager
MGCP Domain Name:3845-1.cisco.com
Priority        Status                   Host
============================================================
Primary         Registered               10.3.102.99
First Backup    None
Second Backup   None
Current active Call Manager:   10.3.102.99
Backhaul/Redundant link port:  2428
Failover Interval:             30 seconds
Keepalive Interval:            15 seconds
Last keepalive sent:           20:58:35 UTC Sep 3 2004 (elapsed time:00:00:11)
Last MGCP traffic time:        20:58:35 UTC Sep 3 2004 (elapsed time:00:00:11)
Last failover time:            None
Last switchback time:          None
Switchback mode:               Graceful
MGCP Fallback mode:            Not Selected
Last MGCP Fallback start time: None
Last MGCP Fallback end time:   None
MGCP Download Tones:           Disabled
Configuration Error History:
FAX mode:cisco
Step 3   show ccm-manager backhaul

Use the show ccm-manager backhaul command to display information about the BRI backhaul link.



Example: 
Router# show ccm-manager backhaul
Backhaul Link info:
    Link Protocol:     TCP
    Remote Port Number:2428
    Remote IP Address: 10.3.102.99
    Current Link State:OPEN
    Statistics:
        Packets recvd:  4
        Recv failures:  0
        Packets xmitted:2
        Xmit failures:  0
    BRI Ports being backhauled:
        Slot 0, VIC 0, port 0
        Slot 1, VIC 0, port 0
Step 4   show mgcp endpoint

Use the show mgcp endpoint command to display a list of your MGCP endpoints.



Example: 
Router# show mgcp endpoint
BRI/S1/SU0/P1/1@3745-1
BRI/S1/SU0/P1/2@3745-1

Tips for Troubleshooting MGCP-Controlled Backhaul of BRI Signaling

The table below lists commands that are available for troubleshooting your configuration.

Table 1 Troubleshooting Commands

Command

Purpose

command-type a-law

Enables you to address poor voice quality. If your system uses a-law pulse-code modulation (PCM), use this command in interface-BRI configuration mode to reconfigure the BRI voice port in the gateway for a-law PCM. The system default is mu-law PCM.

debug ccm-manager backhaul packets

Displays debugging information about Cisco Unified Communications Manager backhaul message packets.

debug isdn q931

Displays debugging information about ISDN L3 Q.931 message packets.

debug mgcp packets

Displays debugging information about MGCP message packets.

Configuring SRTP Mode on Cisco IOS MGCP Gateways

SRTP mode provides secure VoIP calls by addressing security requirements for privacy, integrity, and confidentiality of voice conversations. IPsec, a standards-based set of security protocols and algorithms, ensures that signaling information that is sent between the gateway and Cisco Unified Communications Manager are encrypted. Media encryption using standards-based Secure Real-Time Transport Protocol (SRTP) ensures that media streams between supported devices are secure.

Perform this task to configure SRTP mode on the gateway.

Before You Begin

You should first establish an IPsec connection between Cisco Unified Communications Manager and the MGCP gateway before using the MGCP SRTP package. Otherwise, media keys are sent in clear text and your voice call is not considered secure.


SUMMARY STEPS

1.    enable

2.    configure terminal

3.    mgcp package-capability srtp-package

4.    mgcp validate call-agent source-ipaddr

5.    exit


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
mgcp package-capability srtp-package


Example:

Router(config)# mgcp package-capability srtp-package

 

Enables the MGCP gateway capability to process SRTP packages.

 
Step 4
mgcp validate call-agent source-ipaddr


Example:

Router(config)# mgcp validate call-agent source-ipaddr

 

(Optional) Enables the MGCP application validation that packets received are sent by a configured call agent.

 
Step 5
exit


Example:

Router(config)# exit

 

Exits global configuration mode.

 

Configuration Examples for MGCP-Controlled Backhaul of BRI Signaling

MGCP BRI Backhaul on Cisco 3745 Example

Router# show running-config
Building configuration...
Current configuration :3913 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
!
no network-clock-participate slot 1 
no network-clock-participate slot 2 
no network-clock-participate slot 3 
no network-clock-participate slot 4 
no network-clock-participate wic 0 
no network-clock-participate wic 1 
no network-clock-participate wic 2 
no network-clock-participate aim 0 
no network-clock-participate aim 1 
no aaa new-model
ip subnet-zero
ip cef
!
!
!
ip dhcp pool phone1
   host 10.3.102.102 255.255.0.0
   client-identifier 0100.1121.116b.dd
   option 150 ip 10.3.102.99 
   default-router 10.3.102.2 
!
!
ip domain name cisco.com
ip ids po max-events 100
no ftp-server write-enable
isdn switch-type basic-net3
voice-card 1
 no dspfarm
!
voice-card 2
 no dspfarm
!
voice-card 3
 no dspfarm
!
!
!
ccm-manager switchback immediate
ccm-manager fallback-mgcp 
ccm-manager redundant-host 10.3.102.98
ccm-manager mgcp
!
!
!
interface FastEthernet0/0
 ip address 10.3.102.2 255.255.0.0
 duplex auto
 speed auto
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface BRI1/0
 no ip address
 isdn switch-type basic-net3
 isdn incoming-voice voice
 isdn bind-l3 ccm-manager service mgcp
 isdn skipsend-idverify
!
interface BRI1/1
 no ip address
 isdn switch-type basic-net3
 isdn protocol-emulate network
 isdn layer1-emulate network
 isdn incoming-voice voice
 isdn skipsend-idverify
!
interface BRI2/0
 no ip address
 isdn switch-type basic-net3
 isdn incoming-voice voice
 isdn bind-l3 ccm-manager service mgcp
 isdn skipsend-idverify
!
interface BRI2/1
 no ip address
 isdn switch-type basic-net3
 isdn protocol-emulate network
 isdn layer1-emulate network
 isdn incoming-voice voice
 isdn skipsend-idverify
!
interface BRI3/0
 no ip address
 isdn switch-type basic-net3
 isdn incoming-voice voice
 isdn bind-l3 ccm-manager service mgcp
 isdn skipsend-idverify
!
interface BRI3/1
 no ip address
 isdn switch-type basic-net3
 isdn protocol-emulate network
 isdn layer1-emulate network
 isdn incoming-voice voice
 isdn skipsend-idverify
!
!
ip default-gateway 10.3.0.1
ip classless
ip route 0.0.0.0 0.0.0.0 10.3.0.1
!
ip http server
no ip http secure-server
!
!
access-list 10 deny 10.3.102.99 log
access-list 10 permit any
!
!
!
control-plane
!
!
call application alternate DEFAULT
!
!
voice-port 1/1/0
!
voice-port 1/1/1
!
voice-port 2/0/0
!
voice-port 2/0/1
!
voice-port 3/0/0
!
voice-port 3/0/1
!
voice-port 3/1/0
!
voice-port 3/1/1
!
voice-port 3/1/2
!
voice-port 3/1/3
!
!
mgcp
mgcp call-agent 10.3.102.99 service-type mgcp version 0.1
mgcp package-capability srtp-package 
!
mgcp profile default
!
!
!
dial-peer voice 1 pots
 application mgcpapp
 direct-inward-dial
 port 3/0/0
 forward-digits all
!
dial-peer voice 100 voip
 application mgcpapp
 destination-pattern 9...
 session target ipv4:10.3.102.1
 incoming called-number .
!
dial-peer voice 2 pots
 destination-pattern 5001
 port 3/1/0
!
dial-peer voice 4 pots
 destination-pattern 6T
 direct-inward-dial
 port 3/0/1
!
dial-peer voice 3 pots
 destination-pattern 5002
 port 3/1/3
!
dial-peer voice 11 pots
 destination-pattern 2T
 direct-inward-dial
 port 2/0/1
!
dial-peer voice 12 pots
 application mgcpapp
 direct-inward-dial
 port 2/0/0
 forward-digits all
!
!
!
call-manager-fallback
 max-conferences 8
 ip source-address 10.3.102.2 port 2000
 max-ephones 2
 max-dn 4
!
!
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
!
end

MGCP BRI Backhaul on Cisco 3640 Example

version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
no service dhcp
!
hostname 3640
!
!
voice-card 3
!
ip subnet-zero
!
!
ip domain name cisco.com
!
isdn switch-type primary-qsig
!
!
voice call carrier capacity active
!
voice service voip 
 h323
  call start slow
!
!
!
!
mta receive maximum-recipients 0
ccm-manager mgcp
!
controller T1 3/0
 framing esf
 clock source internal
 linecode b8zs
 pri-group timeslots 1-24 service mgcp
!
controller T1 3/1
 framing esf
 linecode b8zs
!
!
!
interface FastEthernet0/0
 ip address 10.15.43.101 255.255.0.0
 duplex auto
 speed auto
 no cdp enable
!
interface Serial0/0
 no ip address
 encapsulation frame-relay
 shutdown
 clockrate 125000
 frame-relay lmi-type ansi
!
interface FastEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0/1
 no ip address
 shutdown
 clockrate 125000
!
interface BRI1/0
 no ip address
 isdn switch-type basic-net3
 isdn incoming-voice voice
 isdn bind-l3 ccm-manager service mgcp
!
interface BRI1/1
 no ip address
 isdn switch-type basic-qsig
!
interface Serial3/0:23
 no ip address
 no logging event link-status
 isdn switch-type primary-qsig
 isdn incoming-voice voice
 no cdp enable
!
ip default-gateway 10.15.10.11
ip classless
ip route 0.0.0.0 0.0.0.0 10.15.10.11
ip http server
!
ip pim bidir-enable
!
!
!
call rsvp-sync
!
voice-port 1/0/0
!
voice-port 1/0/1
!
voice-port 2/0/0
!
voice-port 2/0/1
!
voice-port 2/1/0
!
voice-port 2/1/1
!
voice-port 3/0:23
!
mgcp
mgcp call-agent 10.14.181.10 service-type mgcp version 0.1
mgcp sdp simple
!
mgcp profile default
!
!
!
dial-peer cor custom
!
!
!
dial-peer voice 6000 pots
 application mgcpapp
 port 2/0/0
!
dial-peer voice 4000 pots
 application mgcpapp
 port 2/0/1
!
!
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
!
!
end

Where to Go Next

  • To configure conferencing, transcoding, and MTP support on a Cisco IOS gateway, see "Configuring Enhanced Conferencing and Transcoding for Voice Gateway Routers" on page 67 .
  • To enable MGCP PRI backhaul support, see "Configuring MGCP PRI Backhaul and T1 CAS Support for Cisco Unified Communications Manager" on page 113 .
  • To download region-specific tones and their associated frequencies, amplitudes, and cadences, see "Configuring Tone Download to MGCP Gateways" on page 145 .

Additional References

  • "Overview of Cisco Unified Communications Manager and Cisco IOS Interoperability" on page 13 --Describes basics of underlying technology and lists related documents.
  • " Configuring ISDN BRI" module in the Cisco IOS Dial Technologies Configuration Guide , Release 12.4--Describes how to configure ISDN BRI on the voice gateway.
  • " ISDN Switch Types, Codes, and Values " appendix in the Debug Command Reference , Release 12.4--Describes supported switch types.
  • Cisco Unified Communications Manager documentation --Describes how to install and configure Cisco Unified Communications Manager.
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© 2011 Cisco Systems, Inc. All rights reserved.

© 2011 Cisco Systems, Inc. All rights reserved.