Understanding NAT and Sametime
Network address translation (NAT) is the method for modifying the IP address information of IP packet headers in transit across a routing device. This is generally done to prevent internal IPs from being viewable to external network devices. Routers manage the translation so that when requests come back, they are translated back to the internal or private IP addresses. Because Sametime client connections, especially those using audio and video, require a client-to-client connection, a technique called NAT transferral is used to maintain connections traversing NAT gateways. The Sametime TURN Server acts as a NAT transversal server and provides this capability so that if your users are attempting to connect to your Media Server outside your NAT'ed network, they will be able to successfully connect. An example of a TURN Server topology can be found at:
http://www.lotus.com/ldd/stwiki.nsf/dx/TURN_Server_topologies_st852
http://tinyurl.com/sametime-c004
We discussed the TURN Server in earlier chapters. However, we provide some additional resources here for understanding how to troubleshoot a TURN Server:
Troubleshooting a Sametime TURN Server:
http://www.lotus.com/ldd/stwiki.nsf/dx/Troubleshooting_a_Sametime_TURN_Server_st852
