Cabletron Systems Netlink FRX8000, User Manual

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7-8 FRX8000 3. 0 User G uide, Rev 02
receives an I-frame for transmission, the acknowledgment will be sent with it, and the
delay timer will be reset.
T3 Link Assurance Period
is X.25 timer T3, the length of time after which the logical DCE will poll its coun-
terpart if there is no data transfer. The value should be sufficiently larger than the
DCE's T1 timer (Retransmission Period), to assure that the link is not operational
before a poll is sent.
Propagation Delay
tells the software how long it will take a signal to travel from one point to another (e.g.,
from a satellite dish to a satellite). This helps the FRX8000 determine the fastest
routing. The value to be specified is normally determined by the signal carrier.
Logical DCE
Selecting
N
defines the port as logical DTE. The other end of the connection must be
the opposite of this port. Logical DCE/DTE is independent of physical—either can be
either. A node connecting a subscriber device into a network should normally be con-
figured as logical DCE.
Generate Clock
If this port is a physical DCE (determined by LP jumpers and/or cable/converter
interface), specify
Y
, since DCE generates clock. If the port is DTE, specify
N
.
Rcv Clock (TT) from DTE
allows the clock to be looped back from the DTE using the TT (Terminal Timing)
signal, which can be helpful on high-speed ports.
Extra CRC
provides a second cyclical redundancy check (CRC), in addition to the two-byte CRC
included in the frame check sequence in a standard X.25 frame. Each CRC is a calcu-
lation that is placed in the field by the transmitting device, then recalculated at the
receiving device to determine whether errors occurred. On a noisy line the single CRC
can miss errors, but a second CRC greatly improves the chances of catching errors.
Line Setup Retries
is the number of times the node will attempt to initialize the V.25 modem on this port
if the node does not receive an OK after sending a modem initialization string. (See
"
V.25bis Modem Operations" on page 7-10.)
Remote Telephone Number
is used by the V.25bis dialer to call the other end of the connection.
Modem INI String Name
identifies a string of data that will be sent to the modem each time the connection is
initialized. The actual data is specified in the Modem Initialization file (described on
page 7-10 ).