H323 NAT

[juan_cye_ccna]

Hi,

some cisco endpoint have a parameter named H323 NAT, does this field modify h323 payload or something like that? or what is the purpose of this?

Thanks for your help.  

[amehla]

Hi Juan,

The NAT settings in endpoint is used when endpoint IP address is natted to a different IP address.

H323 NAT Mode: ON

The system will signal the configured "NAT Address" in place of its own IP-address within

Q.931 and H.245. The NAT Server Address will be shown in the startup-menu as: "My IP

Address: 10.0.2.1".

H323 NAT Address: ""

Enter the external/global IP-address to the router with NAT support. Packets sent to the router will

then be routed to the system.

In the router, the following ports must be routed to the system's IP-address:

* Port 1720

* Port 5555-5574

* Port 2326-2485

[juan_cye_ccna]

Hi Amit,

It means that parameter only modifies signal information not media, isn't it?
When should i use H323 NAT ? Do you have any example? Currently I have a problem between mxp3000 and sx20 I can not make h323 calls. I viewed mxp configuration and it has configured H323 NAT parameter and I do not usually set this data.

Thanks in advance.

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[amehla]

Hi Juan,

usually endpoints internal to the network are configured to private IP address like 10.0.0.0 - 10.255.255.255,

172.16.0.0 - 172.31.255.255,  192.168.0.0 - 192.168.255.255 and they are convered to  ( NAT ) to public IP address in order to communicate with external public network. in that case, you configure you endpoint for NAT mode and add NAT ip address in endpoint.

however, you dont need NAT if you devices are registered with VCS.

if you can give more details about your MXP 3000 and SX20 unit like registered to VCS or its a direct IP -IP call. i can try to check it.

[juan_cye_ccna]

Hi Amit,

Network topology is mxp - Internet- firewall-VCS- sx20. MXP is not registered to any VCS. If MXP dials out to internal or external test video endpoint calls get stablished but not to sx20. I configured a c40 h323 with direct calls and point to point (c40 not registered in VCS to this test) from mxp to c40 calls fail but if I place a call from c40 to sx20 call is ok video and audio; something strange is happening on mxp I think.
Maybe mxp has software bug or something like that. What do you think about that?

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[amehla]

Hi Juan,

do your MXP has a public IP address or its internal IP is natted to public IP to communicate over internet ?

you MXP should be able to reach VCS, and since your SX 20 is registered to VCS using H323 ID, it should be able to translate the address to H323 ID or alias.

where is your C40 located, is it also on VCS or over public IP ?

[juan_cye_ccna]

Amit,

MXP has a private ip and NAT. I tried to dial out through h323 URI 1234@mydomain.com and I did not made from this device i am only able to place calls to IP address of this way my sx20 receive call but I don't have audio and video

Thanks for your help


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[juan_cye_ccna]

My c40 is not registered with VCS. It is in a private network and gateway is doing NAT to this.

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[amehla]

Hi Juan,

if possible provide us with logs from MXP unit.

• login into the codec using PUTTY and make sure to enable all session output
• xstatus
• xconfig
• syslog 3
• Make a call and keep running until you have recreated the problem
• xstatus, if issue related to video/audio channel status etc.
• Hang up call
• syslog off
• send logs

I am assuming your MXP and C40 are behind same firewall, if not, make sure below ports are opened:

For H.323:

• Gatekeeper Discovery (RAS) – Port 1719 – UDP
• Q.931 call Setup – Port 1720 – TCP
• H.245 – Port Range 5555-5574 – TCP
• Video – Port Range 2326-2485 – UDP
• Audio – Port Range 2326-2485 – UDP
• Data/FECC – Port Range – 2326-2485 – UDP

[amehla]

Hi Juan,

more over, is your VCS is over public IP address ? how can we make reachability to VCS over internet ?