VSC7440 datasheet(241/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

224

Figure 66 •

Queue Limitation Share

The following table provides descriptions of the queue limitation conditions.

The following table lists the queue limitation registers.

Table 151 •

Queue Limitation Conditions

State

Description

Traffic Condition

Queue is active

The queue size exceeds the

watermark in QLIMIT_QUE_ACT

The queue is not idle. When the

filling gets very high, only non-

active queues are allowed further

enqueing.

Queue looks congested

The queue size exceeds the

watermark in QLIMIT_QUE_CONG

The queue seems to be growing.

When the share filling is high, it can

be chosen to discard further data

into the queue.

Queue consumes too much The queue size exceeds DYN_WM,

which is the QLIMIT_SHR_CTOP

watermark divided by the number of

queues looking congested.

The queue seems to be one of the

reasons for the growing memory

consumption, and further additions

to the queue can be avoided.

Table 152 •

Queue Limitation Registers

Description

QLIMIT_QUEUE

Reads current queue size

QLIMIT_PORT

Assigns ports to shares

QLIMIT_SHR

Configures watermarks for share and monitor filling and dynamic

watermarks

QLIMIT_MON

Reads the status for each of the logical shares.

Discard all

QLIMIT_SHR_TOP

QLIMIT_SHR_ATOP

QLIMIT_SHR_CTOP

QLIMIT_SHR_QLIM

No frame discarding

Discard if queue is active

Discard if queue looks congested

Discard if queue consumes

too much

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