Cabletron Systems SPECTRUM 1800, User Manual

Page: 137 / 232

Configuring SNA Ports 7-13
SNA Status and Configuration
If the T1 Timer expires and acknowledgments or responses are still outstanding,
the link station will send one of the following, then restart the T1 Timer:
¥ A Supervisory LPDU with the P bit set to BÕ1Õ to solicit remote link station
status
¥ Any Unnumbered LPDUs that were not responded to the Þrst time they were
sent.
If acknowledgments or responses are still outstanding after the number of tries
speciÞed in the
N2-Max LPDUs parameter (see below), the link station will
declare the link inoperative.
The value speciÞed for the T1 LLC2 Reply Timer should allow for any delays
introduced by the MAC sublayer (e.g., queuing). The value is the amount of time
in 100 millisecond units; the default value is 10.
T2-Rcv Ack Timer
This 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 acknowledgment is sent, it must be sent as soon as
possible. The value is the amount of time in milliseconds; the default value is 100.
The value must be less than the value for the
T1-LLC2 Reply Timer (see above) to
ensure that the remote link station will receive the delayed acknowledgment
before the T1 Timer expires.
N2-Max LPDUs
This is the maximum number of times that an LPDU (including Information
LPDUs resent after a checkpoint operation) will be sent following the expiration
of the T1 Timer. The default value for this parameter is 8.
N3-Max Info LPDUs
This is the number of Information LPDUs that will be received by the local station
before it sends an acknowledgment. This parameter is used in conjunction with
the
T2-Rcv Ack Timer to allow stations to reduce trafÞc. A counter is initialized to
the value speciÞed, and is decremented by one each time a valid sequential
Information LPDU is received. When the counter reaches 0, an acknowledgment
is sent. The counter is reset whenever an Information or Supervisory
acknowledgment LPDU is sent by the local station. The default value for this
parameter is 1.
Tw-Max Out LPDUs
This is the maximum number of sequentially numbered Information LPDUs that
the link station can have outstanding. The default value for this parameter is 1.
Bandwidth Allocation Group
This parameter assigns the LLC2 host to one of 16 Bandwidth Allocation Groups
(BAG). The default value for this parameter is 0.