| VCS Deployment Methods |
45
Parameter
Description
Configuration Method
Route Traversal
Configure the route traversal
type.
•
Auto
—NAT works only
when making a call to a
public address. NAT does not
work when making a call to a
private address.
•
Compulsion
—NAT works
whatever you are making a
call to a public address or
private address.
Default
: auto.
Web user interface
3.
Apply the route traversal settings to the SIP protocol.
For more information, refer to
Enabling Static NAT for SIP Protocol
.
STUN
If you want to use the VCS in the intranet to place calls to the VCS in the extranet, you can use STUN server, as well
as configure ALG on the router or enable static NAT on the system.
STUN is a client/server protocol, which allows the system behind a NAT to discover the NAT presence firstly, and the
mapped public IP address, and then the port number that the NAT has allocated for the UDP flows to remote parties.
Those information is used to establish UDP communication between two system behind the NATs.
The system works as a STUN client, sending exploratory STUN messages to the STUN server. After that, the STUN
server uses those messages to determine the public IP address and the port (which is used to connect the public
network to the intranet), and then informs the client. For more information, refer to
.
Capturing packets after you enable the STUN feature, you can find that the VCS sends Binding Request to the STUN
server, and then the mapped IP address and the port are placed in the Binding Response: Binding Success Response
MAPPED-ADDRESS: 59.61.92.59:19232.
The system will send SIP message using the mapped IP address and the port.
Note:
STUN does not enable the incoming TCP connections through NAT or the incoming UDP packets through
symmetric NATs.
