IBM TotalStorage 2109 M12, Инструкция по установке и обслуживанию

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Chapter 4. Installing modems
Note: Throughout this chapter, the term switch refers to the M12.
Each CP card in the switch contains a modem serial port that allows you to connect
to a Hayes-compatible modem. The modem serial port is wired as a standard DTE
port. You do not need any additional software on the switch to use the modems.
The modem serial port has the same command, login capabilities, and operational
behavior as the terminal serial port. However, asynchronous informational
messages and other unsolicited text are not sent to the modem ports.
Connecting a separate modem to each CP card and then connecting both modems
to a shared telephone line ensures the high availability of the modem connection.
This ensures that one telephone line is used to access the active CP card when a
failover occurs. You must log in again if a failover occurs. If both CP cards connect
to a shared telephone line, callers automatically dial into the active CP card. The
active CP card answers on the first ring. If the active CP card cannot answer for
any reason, the standby CP card answers on the seventh ring and allows a login to
proceed.
Note: The switch detects modems only during power on, restart, or a CP card
failover sequence.
After you connect the modems, you can use a Telco system to dial in to the
modems and verify that they answer and dialogue as expected. If a dial-out modem
facility is not available, you can use a terminal emulation program on a computer
workstation (or laptop) that has an attached modem. See “Setting up a remote
modem system (optional)” on page 34 for instructions on how to set up a remote
modem for testing purposes. For security reasons, the modem session is
automatically disconnected if the modem cable is detached while a session is
active.
Figure 19 on page 34 shows two modems that are connected to a switch.
© Copyright IBM Corp. 2004
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