Cabletron Systems Netlink FRX8000, User Manual, Page: 165 / 468

Configuring SNA 11-17
IDNUM
is used in conjunction with IDBLK in generating the Node field in an XID frame
(format
0
or
3
) to establish a link station connection to the host. If
0
is specified for
both IDBLK and IDNUM, the Node field of the XID will be provided by the attached
SDLC device. (The node will send an XID command to the remote node to indicate
that the SDLC device should be polled for an XID.)
Reply Timer - T1
is used to detect the failure to receive a required acknowledgment or response from
the remote link station. The link station will start the timer when it transmits one of
these:
●
an Information LPDU (LLC protocol data unit).
●
a Command LPDU with the P bit set to
B‘1.’
(If this LPDU is sent while the timer
is already running, the link station will reset and restart it.)
The link station will reset T1 when it receives one of these:
●
A REJ (Reject) LPDU, provided a Command LPDU with P bit set to
B‘1’
is not
outstanding.
●
A Response LPDU with the F bit set to
B ‘1.’
●
An Information or Supervisory LPDU with an N
(R)
greater than the last N
(R)
received and less than or equal to the line station’s V
(S)
, provided a Command
LPDU with P bit set to
B‘1’
is not outstanding.
If additional LPDUs are set from the remote link station after the local station has reset
T1
, the timer will be restarted if acknowledgments of or responses to those LPDUs are
outstanding. If no acknowledgments/responses are outstanding, the link station will
start the inactivity timer. (See “
Reply Timer - T1
.")
If
T1
expires and acknowledgments/responses are still outstanding, the link station
will send one of the following, then restart
T1
:
●
A Supervisory LPDU with the P bit set to
B‘1’
, to solicit remote link station
status.
●
Any Unnumbered LPDUs that were not responded to the first time they were
sent.
If acknowledgments/responses are still outstanding after
N2
tries (see that entry
on page 11-18 ), the link station will declare the link inoperative.
The value specified for
T1
should allow for any delays introduced by the MAC sub-
layer (e.g., queuing).
Rcv Ack Timer - T2
is used by the link station to delay sending an acknowledgment of a received Infor-
mation LPDU. The timer is started when the LPDU is received and reset when the
acknowledgment is sent. If the timer expires before the acknowledgment is sent, it
must be sent as soon as possible.
Inactivity Timer - Ti
is used by the link station to detect an inoperative condition in either the remote link
station or the transmission medium. The timer will be started if
T1
has been reset (for
one of the reasons listed under “
Reply Timer - T1
”), and additional LPDUs have been