| Description | The (conceptual) table containing information
for Switch Threshold Groups. When cells are
queued in the switch for a direction of cell
traffic on an ATM connection (VC or VP), several
functions related to queueing are dictated
by the congestion state (fullness) of the Threshold
Group. Each connection queue is a member of
a Threshold Group.
These functions include:
- The limit on the number of cells that can
be queued. Cells exceeding this limit are
discarded.
- The discard threshold, used for CLP/EPD
discard when the fullness of the queue exceeds
the threshold.
- The marking threshold, used for EFCI marking.
Each Threshold Group has a maximum number of cells
that can be resident in it at any one time. The
number of cells in a Group consists of the number
of cells in all the queues that are a member of
the Group. As the number of cells in a Group
approaches the maximum number for the Group,
the queue limits may be decreased. This limits
the share of buffering available to each
connection as cell-memory is used.
On the Catalyst8540MSR platform, there are a
maximum of 8 switching modules. Each switching
module services a certain group of ports (this
mapping is fixed in hardware). Each module also
has its own cell memory (for per VC queueing),
and hence performs its own congestion control,
independent of any other switching module.
Each switching module has its own set of
Switch Threshold Groups, which are
independently programmable and readable.
This table is supported only on the Catalyst8540MSR
platform. |