Telos Zephyr Xstream - Manual (Page 332)

USER’S MANUAL
Appendix 6 – Special Operational Modes 320
Port forwarding is basically telling the router that when it receives packets from
the Wide Area Network on a given port, from those packets should be
forwarded transparently to the specified address on the Local Area Network.
NAT (Network Address Translation)
This is a scheme by which a private network can make connections into a public
network (such as the Internet) using only one address on the public net. An
example is having 3 computers behind a router/firewall on a residential DSL line.
The three computers have separate addresses on the local network, but only
the Router's WAN IP is visible on the outer network.
NAT works because the router knows the format of TCP/IP packets. It can
substitute its own IP into the packets that are outbound, then reinsert the
proper LAN IP when a packet comes inbound from the WAN. This works
because TCP is connection‐based, so the router knows that all traffic on a given
connection is destined for the machine that initiated it.
THE ZEPHYR XSTREAM BEHIND A FIREWALL
In our world, we will always have a studio codec and a remote codec so there are always two
Xstreams to consider. For this discussion, we'll assume that the remote Zephyr Xstream is
properly configured already. That way, we only need to discuss the considerations for the local
machine. If each operator does this, both codecs will end up being configured properly.
To begin, for all of the scenarios presented below, the following procedure should be followed:
• Give the Zephyr a fixed IP address on the LAN. Usually, this is done by simply picking an
unused address.
• Set the LAN subnet mask (usually 255.255.255.0 ‐ get these numbers from the IT
administrator)
• Set the gateway to the LAN address of the router
• Set the DNS to the server specified in the WAN/DHCP area of the router's information
pages (optional).
HTTP Mode Not recommended for use over the public network. If it's behind a router, it
really shouldn't be used.
RTP Mode
Sending
After configuring the Xstream as above, there are no special settings required to send an
RTP stream only. Take the IP address given to you by the person you're calling. Press
Dial. Enter the IP address. Press Dial again.