VSC7440 datasheet(227/444 Pages) MICROSEMI

227 / 444 page

Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

210

modified due to, for instance, routing, MPLS encapsulation, or tagging. The queue system does not

change the original frame data.

An ingress port operates in one of three basic modes: drop mode, port flow control, or priority-based flow

control. The following table lists the modes and flow definitions.

3.24.1

Analyzer Result

The analyzer provides required information for switching frames in the shared queue system. The

following table lists the information provided and a general description of the purpose.

3.24.2

Buffer Control

Frames are stored in a shared packet memory bank, which contains 5,952 words of 176 bytes each. A

memory manager controls which words the packet writer uses to store a frame.

With proper configuration, the packet memory bank always has a free word available for incoming

frames. There are configurable thresholds for triggering pause frame requests on ports enabled for flow

control and for discarding frames due to too large memory use when for instance pause frames are

disobeyed by the link partner.

Table 135 •

Ingress Port Modes

Mode

Flow

Drop mode (DROP)

The link partner is unaware of congestion and all frames received by the port are evaluated

by the congestion control function where copies of the frame can be discarded.

Port flow control (FC)

The link partner is informed through pause frames (full-duplex) or collisions (half-duplex)

that the port cannot accept more data. If the link partner obeys the pause requests, no

incoming data is discarded by the port. If the pause frames are disobeyed by the link

partner, the buffer control function in the queue system discards data before it reaches the

ingress queues.

Priority-based flow

control (PFC)

The link partner is informed about which QoS classes in the queue system are congested

and the link partner should stop scheduling more frames belonging to these QoS classes. If

the pause frames are disobeyed by the link partner, the buffer control function in the queue

system discards data before it reaches the ingress queues.

Table 136 •

Analyzer Result

Group

Field

Function

Destination selection

Destination set

Set of ports to receive a normal switched copy.

Destination selection

CPU queue mask

Set of CPU queues to receive a copy.

Destination selection

Mirror

Requests mirror copy.

Destination selection

Learn all

Requests learn copy to stack ports.

Congestion control

Drop mode

This particular frame can be dropped even if ingress port is setup for

flow control.

Congestion control

Drop precedence level.

Congestion control

Priorities

Ingress resource priority of the frame. Four classified classes are

provided from the analyzer: QoS, PCP, COSID, and TC. All values

between 0 and 7.

Queue mapping

Super priority frame.

Queue mapping

QGRP

Queue group for service-based egress queuing.

Statistics

OAM type

Service counters can be configured to only count certain OAM frame

types.

VSC7440 Datasheet(PDF) 227 Page - Microsemi Corporation

VSC7440 Datasheet(HTML) 227 Page - Microsemi Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL