Hi Enrique,
Found this intresting as generally you receive this error if you already have h323 configured on other interface so I labbed it up for you (weekend fun) and found a work around and some intresting information on this error:
In short you just need to do below:
R1(config-if)#int l1 << re-add loopback1
R1(config-if)#no h323-gateway voip interface << add this command
R1(config-if)#int loop0
R1(config-if)#h323
R1(config-if)#h323-gateway voip int <<< now you will be able to add
R1(config-if)#
R1(config)#no int l1 << remove this loopback1
Detailed Explanation is below:
1) Initially I had a Loopback 1 configured with h323.
R1#sh run int l1
Building configuration...
Current configuration : 134 bytes
!
interface Loopback1
ip address 10.0.0.1 255.255.255.255
h323-gateway voip interface
h323-gateway voip bind srcaddr 10.0.0.1
end
2)
Then I tried to configure H323 on the Loopback 0. Received the same error as you were receiving but you did not had Loopback1. I thought, may be you had a loopback1 interface and somebody might have removed from your router. So I replicated the same, removed Loopback1 see below:
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int l0
R1(config-if)#h323-gate voip int
Duplicate multimedia interface with Loopback1.
R1(config-if)#no int loopback 1
3) Now I am exactly replicating the same error and in same position as you are. I have no interface loopback1, but I am still getting this error, see below output:
R1(config)#do sh run int l1
sh run int l1
^
% Invalid input detected at '^' marker.
R1(config)#do sh run int Loopback1
sh run int Loopback1
^
% Invalid input detected at '^' marker.
4) Also see below I dont have H323 configured on any interface, Then I tried again, but still was getting same error as you are getting, see below output:
R1(config)#do sh run | s h323
R1(config)#int loopback0
R1(config-if)#h323-g voip int
Duplicate multimedia interface with Loopback1.
5) Now the main part, the Work around, easiest way, redefine Loopback 1 interface, and issue the no h323-g voip int. Now loopback 0 accepts all the commands, Please see below:
R1(config-if)#int l1
R1(config-if)#no h323-gateway voip interface
R1(config-if)#int loop0
R1(config-if)#h323
R1(config-if)#h323-gateway voip int
R1(config-if)#
R1(config)#no int l1 << remove this loopback1
To summarize:
I think someone had defined Loopback 1 on the router and removed it before removing the commands. If you remove the loopback without removing the h323-gateway voip interface command, the router somehow keeps on holding this command all other commands are removed. So the work around is recreate loopback 1 and issue no h323-gateway voip interface. Please see the below test results:
R1#sh run int l1
Building configuration...
Current configuration : 134 bytes
!
interface Loopback1
ip address 10.0.0.1 255.255.255.255
h323-gateway voip interface
h323-gateway voip bind srcaddr 10.0.0.1
end
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#no int l1
R1(config)#end
R1#sh run int l1
^
% Invalid input detected at '^' marker.
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int l1
R1(config-if)#do sh run int l1
Building configuration...
Current configuration : 71 bytes
!
interface Loopback1
no ip address
h323-gateway voip interface
end
R1(config-if)#
I hope this is helpful to you. If this resolves your queries please mark this question as answered and rate all helpful posts.
Terry
