Aastra OpenCom 510 User Manual page 106

Configuration Examples
notified of the new e-mail on his system terminal. OpenPhone 6x/OpenPhone 7x
and OpenPhone 2x system terminals can also display information such as the
sender or the subject of the e-mail.
9.6.4 NAT
Network address translation (NAT) is activated on accessing the Internet (ISP). You
require this feature in order to translate internal IP addresses to valid external IP
addresses. This has three important consequences for Internet access:
■
Several workstations can share a single Internet access. You do not require a
LAN access, only a single account with the Internet service provider.
■
The IP addresses used in the LAN are translated into IP addresses valid
worldwide. So you require no such addresses for your LAN.
■
Only IP connections triggered from a workstation can be established. Conse-
quently, while you can call up Web pages from a workstation, you cannot
install a Web server visible in the Internet on a workstation.
Certain protocols cannot be used when NAT is being used. This affects protocols
with the following properties:
■
IP addresses are transported in the useful load, e.g. NetBIOS over IP or SIP.
■
The protocol requires an active, inward-directed connection establishment,
e.g. ICQ.
■
The protocol will function without TCP/UDP port numbers, e.g. ICMP or IGMP.
The OpenCom 510 NAT has suitable processes for ensuring the functions of many
important protocols affected by these rules. These are the protocols FTP (in
"active" mode), CuSeeMe ("videoconferencing"), IRC ("chat"), ICMP errors
("traceroute") and ICMP echo ("ping").
Depending on the internet telephony protocol (VoIP, SIP) the required NAT
extension ("Full Cone NAT") or RTP-Proxy is activated on the Media Gateway Card.
Protocols which require inward-directed connection establishment can be con-
figured in the Net Configuration: Port Access menu. For further information,
refer to the online help of this menu.
104
Useful Information on Internet Access