Switch User Manual

SNA Status and Configuration
7-12 Configuring SNA Ports
IDBLK
This parameter is used in conjunction with the IDNUM parameter (see below) in
generating the Node Þeld in an XID (Exchange IdentiÞcation) frame (format 0 or
3) to establish a link station connection to the host. If both IDBLK and IDNUM are
set to 0, the Node Þeld of the XID frame 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.
IDNUM
This parameter is used in conjunction with the IDBLK parameter (see above) in
generating the Node Þeld in an XID frame (format 0 or 3) to establish a link
station connection to the host. If both IDBLK and IDNUM are set to 0, the Node
Þeld of the XID frame 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.
Ti-Inactivity Timer
This timer 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
the T1-LLC2 Reply Timer has been reset (see below), if additional LLC protocol
data units (LPDUs) have been sent by the remote link station, and if there are no
outstanding acknowledgments or responses from the local link station.
If the local station does not receive an LPDU before the Ti-Inactivity Timer
expires, the station must send an LPDU with the P bit set to BÕ1Õ to solicit the
remote stationÕs status. Recovery then proceeds as described under T1-LLC2
Reply Timer.
The value is the amount of time in seconds; the default value is 30.
T1-LLC2 Reply Timer
The Reply Timer 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 either an Information LPDU or a Command
LPDU with the P bit set to BÕ1Õ. (If the LPDU is sent while the timer is already
running, the link station will reset the timer.)
The link station will reset the T1-LLC2 Reply Timer when it receives one of these:
¥ An REJ (Reject) LPDU, provided a Command LPDU with P bit set to BÕ1Õ is not
outstanding;
¥ A Response LPDU with the F bit set to BÕ1Õ;
¥ An Information or Supervisory LPDU with an N
R
greater than the last N
R
received and less than or equal to the line stationÕs V
S
, provided a Command
LPDU with P bit set to BÕ1Õ is not outstanding.
If additional LPDUs are set from the remote link station after the local station has
reset theT1 timer, 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 Ti Inactivity Timer (see above).