4-8 Smart Switch 1800 4. 0 User Guide , Rev 0 1
●An In form a tio n or Sup erv i sory LPDU w ith 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 s tation after the local station has reset
T1, the timer will be restarted if acknowledgments of o r responses to those LPDUs are
outstanding. If no acknowledgments/responses are outstanding, the link station will
start the inactivity timer. (See "Ti" lat e r.)
If T1 expir es and acknowled gme nts/resp onses are stil l outstand ing, 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 tr ie s (see "N2"), 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., qu euin g) .
T2 is the Receiver Acknowledgment Timer, used by the link station to delay sending an
acknowledgment of a received Information LPDU. The timer is started when the
LPDU is received and reset when the acknowledgment is sent. If the timer expires
before the ack no wledg ment i s sent, i t must be sent as s o on as po ssib l e.
Ti is the Inactivity Timer, used by the link station to detect an inoperative condition in
either the remote link station or the tra nsmission medium. The tim er will be started if
T1 has been reset (for one of the reasons listed under "T1"), and additional LPDUs
have been sent by the remote link station, and there are no outstanding acknowledg-
ments or respon ses from the loc al link stat i on .
If the local station does not receive an LPDU before Ti expires, the sta ti on must send
an LPDU with the P bit set to B'1' to solicit the remote station's status. Recovery then
proceeds as described under "T1."
N3 is the number of Information L PDUs that will be received before sending an acknowl-
edgment. This parameter is used in conjunction with T2 to allow stations to reduce
traffic. A counter is initialized to N3, and will be decr emented by one each time a valid
sequential Information LPDU is received. When the counter reaches 0 an acknowl-
edgment is sent.
N3 is reset whenever an Information or S upervi sory acknowledgment LPDU is sent by
the local station.
Tw is the maximum number of sequentially numbered Information LPDUs that the link
station can have outstanding.
N2 is the maximum number of time s that an LPDU (including I nformation LPDUs resent
after a checkpoint operation) will be sent following expiration of T1.