3Com MSR 50 Series Configuration Manual page 747

Introduction to Terminal Access 747
Terminal buffer parameter configuration
You can set the parameters of terminal buffer, including whether to clear the
buffer before receiving data, receive buffer size, transmit buffer threshold, and the
maximum size of data to be sent to the terminal at one time.
Threshold for VTY switching failure times
When an RTC client needs to initiate a connection to an RTC server, it first initiates
a connection to the RTC server that corresponds to the VTY with the lowest
number. If the number of connection failures exceeds the threshold configured,
the RTC client will initiate a connection to the RTC server that corresponds to the
VTY with the second lowest number.
Receiver VTY switching rules
If the RTC server is configured to switch between VTYs based on priority (the
lower the VTY number, the higher the priority) and the VTY number corresponding
to a new connection request is less than the VTY number corresponding to the
existing connection, the RTC server tears down the existing connection and begins
to use the new connection for communication. If the RTC server is not configured
to perform VTY switching based on priority and a connection is already
established, the RTC server will ignore any new connection request.
RTC terminal authentication
In terminal access, the RTC server can perform password authentication for RTC
clients to enhance security. Authentication succeeds only when the passwords
configured on the RTC server and the RTC client are the same.
Terminal access multi-instance
Terminal access multi-instance means that terminal access supports VPN
multi-instance. That is, some of the terminals connected to the router can be
grouped in one VPN domain and some other in another VPN domain. This allows a
terminal to access the FEP or remote router that is in the same VPN domain as the
terminal.
Server connection authentication
In practice, some users need to use the FEP to perform necessary authentication
on the connected router to enhance data security. At present, two authentication
modes are supported: character string-based authentication and MAC-based
authentication.
In character string-based authentication, which is similar to password
authentication, the same authentication character string is configured on the FEP
and the router. To establish a connection with the FEP, the router sends the
authentication character string to the FEP, and the FEP checks whether the
authentication character string is correct. If yes, the authentication succeeds; if
not, the authentication fails and the connection attempt fails.
The difference between MAC-based authentication and character string-based
authentication is that the MAC addresses configured on the FEP and the router are
the same. This MAC address is the MAC address of an interface on the router (You
can specify this MAC address with a command).