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Using a Loopback to register Voice GW to CallManager

rrobles007
Level 1
Level 1

Hello Cisco experts,

I had a question about how to use a loopback address as the IP address that is used for registering the GW to the CallManager.

Right now the GW uses the ip address of the LAN interface but that will be changing soon and the new LAN IP is not going to be reachable by the CallManager so I want to use a Loopback and give it the existing IP of the LAN interface (currently reachable from CM)

Can someone please help??

1 Accepted Solution

Accepted Solutions

Hi,

You are spot on hear.

You should always use a bound  loopback address when you have multiple ip addressed interfaces.

Add this to your config

!

mgcp bind media source interface loopback0

mgcp bind signal source interface loopback0

mgcp

!

Make sure you advertise the loopback via your BGP or OSPF and test that it has connectivity throughout your voip network as your CUCM, phones and other gateways will need 2 way comms for RTP streams etc. TTest this before you implement the config change.

HTH

Alex

Regards, Alex. Please rate useful posts.

View solution in original post

4 Replies 4

rrobles007
Level 1
Level 1

Sorry.. additional detail.. this is an MGCP configuration.

vamer-laframet1-1394743#show run

Building configuration...

Current configuration : 3702 bytes

!

! Last configuration change at 17:20:04 GMT Wed Oct 12 2011 by admin

! NVRAM config last updated at 17:22:49 GMT Wed Oct 12 2011 by admin

!

version 12.4

service timestamps debug datetime msec localtime

service timestamps log datetime localtime

service password-encryption

!

hostname vamer-laframet1-1394743

!

boot-start-marker

boot-end-marker

!

logging buffered 4096 debugging

enable secret 5 $1$UoZ4$6c5p8qLCGSk9at0fhVp8Y/

!

aaa new-model

!

!

!

aaa session-id common

clock timezone GMT 0

clock calendar-valid

network-clock-participate wic 2

!

!

ip cef

!

!

no ip bootp server

no ip domain lookup

ip domain name virginam.com

isdn switch-type primary-ni

!

voice-card 0

no dspfarm

!

!

!

!

!

!

!

!        

!

!

!

!

!

!

username GNOuser password 7 110D325C1634202406

username admin password 7 13061E010803

!

!

controller T1 0/2/0

framing esf

linecode b8zs

channel-group 0 timeslots 1-24

!

controller T1 0/2/1

framing esf

linecode b8zs

pri-group timeslots 1-24 service mgcp

!

ip ftp source-interface Loopback0

ip tftp source-interface Loopback0

!        

!

!

interface GigabitEthernet0/0

ip address 172.19.4.4 255.255.255.0

duplex full

speed auto

!

interface GigabitEthernet0/1

ip address 10.16.0.42 255.255.255.252

duplex auto

speed auto

!

interface Serial0/2/0:0

ip address 10.14.0.42 255.255.255.252

fair-queue

!

interface Serial0/2/1:23

no ip address

encapsulation hdlc

isdn switch-type primary-ni

isdn incoming-voice voice

isdn bind-l3 ccm-manager

no cdp enable

!

interface Serial0/3/0

no ip address

encapsulation frame-relay IETF

shutdown

no fair-queue

frame-relay lmi-type cisco

!

router ospf 1

log-adjacency-changes

redistribute bgp 65012 subnets

network 10.16.0.40 0.0.0.3 area 0

default-information originate

!

router bgp 65012

no synchronization

bgp router-id 10.14.0.42

bgp log-neighbor-changes

network 10.14.0.40 mask 255.255.255.252

network 10.17.4.0 mask 255.255.255.0

network 10.18.4.0 mask 255.255.255.0

network 10.19.4.0 mask 255.255.255.0

network 172.19.1.0 mask 255.255.255.0

network 172.19.4.0 mask 255.255.255.0

redistribute ospf 1

neighbor 10.14.0.41 remote-as 1803

no auto-summary

!

ip forward-protocol nd

!

ip as-path access-list 1 permit ^$

!

no ip http server

no ip http secure-server

!

!

!

!

control-plane

ccm-manager redundant-host 172.20.9.200

ccm-manager mgcp

ccm-manager music-on-hold

ccm-manager config server 172.20.9.200 

ccm-manager config

!

mgcp

mgcp call-agent 172.20.9.201 2427 service-type mgcp version 0.1

mgcp dtmf-relay voip codec all mode out-of-band

mgcp rtp unreachable timeout 1000 action notify

mgcp modem passthrough voip mode nse

mgcp package-capability rtp-package

mgcp package-capability sst-package

mgcp package-capability pre-package

no mgcp package-capability res-package

no mgcp package-capability fxr-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp fax t38 inhibit

mgcp rtp payload-type g726r16 static

!

mgcp profile default

!

!

!

!

privilege exec level 0 traceroute

privilege exec level 1 ping ip

privilege exec level 0 ping

privilege exec level 0 send

privilege exec level 0 show configuration

privilege exec level 0 show

!

line con 0

exec-timeout 30 0

password 7 13013C4B0A2A2F0229

stopbits 1

line aux 0

exec-timeout 30 0

password 7 121D2E4E132D272C28

no exec

stopbits 1

line vty 0 4

exec-timeout 30 0

password 7 045F205F0E0767660B

transport input telnet

!

scheduler allocate 20000 1000

ntp clock-period 17180293

ntp source Loopback0

ntp update-calendar

ntp server 146.170.64.132 prefer

ntp server 146.170.124.133

!

end      

Hi,

You are spot on hear.

You should always use a bound  loopback address when you have multiple ip addressed interfaces.

Add this to your config

!

mgcp bind media source interface loopback0

mgcp bind signal source interface loopback0

mgcp

!

Make sure you advertise the loopback via your BGP or OSPF and test that it has connectivity throughout your voip network as your CUCM, phones and other gateways will need 2 way comms for RTP streams etc. TTest this before you implement the config change.

HTH

Alex

Regards, Alex. Please rate useful posts.

thank you very much!!! thats what i was leaning towards doing and you just confirmed.. thank you!!!!!!

There is a known defect in IOS that can cause the MGCP GW to register with another address then the one used in the bind statements. This only happens the first time the MGCP GW registers after the bind statements have been issued. The defect causes the GW to use the address of the interface closest to the CM. To check if this has happened look at the IP address that the GW have registered with in CM.

If this happens use the below commands.

no mgcp
no mgcp bind media source interface loopback0
no mgcp bind signal source interface loopback0

mgcp bind media source interface loopback0
mgcp bind signal source interface loopback0
mgcp



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