VSC7511 datasheet(116/324 Pages) MICROSEMI

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Functional Descriptions

VMDS-10488 VSC7511 Datasheet Revision 4.2

101

A new command must not be set up until after the VCAP_UPDATE_CTRL.VCAP_UPDATE_SHOT field

is automatically cleared neither must the cache be written to before VCAP_UPDATE_SHOT is cleared.

3.9

Analyzer

The analyzer module is responsible for a number of tasks:

•

Determining the set of destination ports, also known as the forwarding decision, for frames received

by port modules. This includes Layer-2 forwarding, CPU-forwarding, mirroring, and SFlow sampling.

•

Keeping track of network stations and their MAC addresses through MAC address learning and

aging.

•

Holding VLAN membership information (configured by CPU) and applying this to the forwarding

decision.

The analyzer consists of the following main blocks.

•MAC table

•

VLAN table

•

Forwarding Engine

The MAC and VLAN tables are the main databases used by the forwarding engine. The forwarding

engine determines the forwarding decision and initiates learning in the MAC table when appropriate.

The analyzer operates on analyzer requests initiated by the port modules. For each received frame, the

port module requests the analyzer to determine the forwarding decision. Initially, the analyzer request is

directed to the VCAP. The result from the VCAP (the IS2 action) is forwarded to the analyzer along with

the original analyzer request. For more information about VCAP, see VCAP, page 60.

The analyzer request contains the following frame information.

•

Destination and source MAC addresses.

•

Physical port number where the frame was received (referred to as PPORT).

•

Logical port number where the frame was received (referred to as LPORT).

By default, LPORT and PPORT are the same. However, when using link aggregation, multiple

physical ports map to the same logical port. The LPORT value is configured in

ANA:PORT:PORT_CFG.PORTID_VAL in the analyzer.

•

Frame properties derived by the classifier and VCAP IS1:

•

Classified VID

•

Link aggregation code

•

Basic CPU forwarding

•

CPU forwarding for special frame types determined by the classifier

Based on this information, the analyzer determines an analyzer reply, which is returned to the ingress

port modules. The analyzer reply contains:

•

The forwarding decision (referred to as DEST). This mask contains 11 bits, 1 bit for each front port.

DEST does not include the CPU port. The CPU port receives a copy of the frame if the CPU

extraction queue mask, CPUQ, has any bits set.

•

The CPU extraction queue mask (referred to as CPUQ). This mask contains 8 bits, 1 bit for each

CPU extraction queue.

The terms PPORT, LPORT, DEST and CPUQ, as previously defined, are used throughout the remainder

of this section.

3.9.1

MAC Table

This section provides information about the MAC table block in the analyzer. The following table lists the

registers associated with MAC table access.

Table 73 •

MAC Table Access

Description

Replication

MACHDATA

MAC address and VID when accessing the MAC table.

None

MACLDATA

MAC address when accessing the MAC table.

None

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