Digi PortServer II, User Manual

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Page 8 Introduction 90030500B
Each PVC is identified by a unique number called a DLCI (Data Link Channel Identi-
fier), which is used in Frame Relay “cloud” packets for routing.
Frame Relay allows network devices to exchange status information using the LMI
(Local Management Interface). DLCI lists may also be “learned” from the LMI.
SNMP
SNMP (Simple Network Management Protocol) allows a server or PC (the SNMP
Manager) to gather data and event records from devices connected to the network. The
SNMP Manager may also set thresholds and alarms on network devices. PortServer II
includes an SNMP agent that allows it to interact with the SNMP Manager. PortServer
II maintains several MIBs (Management Information Bases) which are databases of
the functions and events that it tracks for the SNMP Manager.
RealPort protocol
RealPort™ is a protocol developed by Digi International that permits the ports on the
PortServer II to be controlled by a host server. RealPort provides “real” TTY access,
and allows the terminal users seamless access to server-resident applications and data.
The server can change port parameters such as baud rate and flow control. It is also
possible for more than one server to control ports on the PortServer II; for example,
one server may use the odd numbered ports, while another server may use the even
numbered ports. RealPort can also provide access for printers and modems. It is also
possible to share the same ports with different servers running RealPort drivers.
Note: The appropriate Digi device driver software must be installed on each server
to implement RealPort.
Authentication and security
In addition to the authentication features provided for dial-up connections by
PAP/CHAP and RADIUS described previously, PortServer II provides two levels of
access security, based on passwords. Supervisory access is available using the root
login and permits the configurations and functions of the PortServer II to be changed.
Normal user logins provide transparent access to applications, and do not allow access
to PortServer II configuration data. If maintaining security is not critical, users may
be configured to permit logging in without a password or for automatic login.