Aastra OpenCom 100 series, Руководство по монтажу и пусконаладке

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Configuration Examples
103
E-Mail
One of the most important services in the Internet is e-mail. E-mails are buffered in
individual e-mail accounts on a mail server. Mail servers are operated by ISPs for
example. With the OpenCom 100 you can set up one or more e-mail accounts for
every user account configured on the OpenCom 100. These e-mail accounts are then
checked at regular intervals.
If there are new e-mails in an e-mail account, and the OpenCom 100 has been con-
figured for this function, the user specified in the OpenCom 100 user account is
notified of the new e-mail on his system terminal. Aastra 677x (OpenPhone 7x) and
Aastra 610d / 620d / 630d system terminals can also display information such as the
sender or the subject of the e-mail.
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 computer can be established.
Consequently, 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 100 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”).