[ S N O M 4 S N A T F I L T E R ]
NAT Filter. Because the NAT Filter itself can be operated in a server farm, you can set up a completely redundant server setup.
Please see also the list of explicit outbound proxies.
4.3.4 Media Ports
The Media Port Begin and Media Port End indicate the range of ports that are used for media relaying. Be sure to have enough ports allocated for the number of calls that you wish to route through the NAT Filter. This is a setting you may have to coordinate with your firewall.
4.3.5 Port Budgets
Because on Windows and Linux systems the number of TCP con- nections is limited, you can define budgets for the different kind of TCP connections.
The Number of Web Connections defines how many sockets for web connections (TCP and TLS) may be used, the Number of SIP Connections defines how many user agents may connect to the SBC at the same time. Please note that the underlying operating system defines the limits.
4.3.6 Media Relay
If you set the Always Relay flag, the filter will always relay media via the filter and will not allow bypassing it by ICE contacts. That means it will remove ICE contacts from the SDP and not insert an addi- tional address for itself. This flag is useful when you want to make sure that all media flows through the filter, e.g. for measurement purposes or because you want to be able to record all calls. However, it will not be pos- sible to do local media path optimization if you turn this flag on.
4.3.7 Controlling Routing
The Loose Routing flag influences the way the NAT Filter inserts routing headers into SIP packets. Loose routing is the routing mechanism proposed in the latest SIP document; however there are devices which are not able to deal properly with these routing headers (the new stan- dard is not backward compatible with the old standard).
4.