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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

180

3.22.6

Source Check and Automated Learning

This section describes hardware (or automated) learning related to source checking. The following table

lists the applicable registers.

The device learns addresses from each received frame’s SMAC field, so that subsequently forwarded

frames whose destination addresses have been learned can be used to restrict transmission to the port

or ports necessary to reach their destination.

The analyzer performs source lookup of the received {SMAC, IFID} in the MAC table to determine if the

source station is known or unknown. For more information, see Figure 39, page 181. If the source station

is known, a port move detection is performed by checking that the frame was received at the expected

port as specified by the ADDR_TYPE and ADDR stored in the source entry. The expected port can be a

logical port (represented as UPSID, UPSPN), an MC_IDX, or a global aggregated port (represented as

GLAGID). Failing source checks can trigger a number of associated actions:

•

Secure forwarding. Disable forwarding from unknown or moved stations. This action can be

triggered by two configurations:

•

VLAN-based Secure forwarding controlled per VLAN

(ANA_L3:VLAN:VLAN_CFG.VLAN_SEC_FWD_ENA).

•

Port-based secure forwarding controlled per port (ANA_L2::LRN_SECUR_CFG).

•

Secure forwarding from locked entries. Disable forwarding from known but moved stations with

locked MAC table entry (ANA_L2:COMMON:LRN_SECUR_LOCKED_CFG).

•

Automatic learning enabled per port (ANA_L2::AUTO_LRN_CFG). Automatic learning of traffic

received from an unknown source station will cause the MAC table to be updated with a new entry.

Traffic received from a known source station with changed port will cause the known MAC table

entry ADDR_TYPE and ADDR to be updated.

•

CPU copy enabled per port (ANA_L2::LRN_COPY_CFG and ANA_L2::LRN_CFG.CPU_LRN_QU).

A learn copy is sent to CPU.

Table 114 •

Hardware-Based Learning

Target::Register.Field

Description

Replication

ANA_L2::AUTO_LRN_CFG

Configures automatic learning per port

ANA_L2::LRN_SECUR_CFG

Configures secure forwarding per port

ANA_L2::LRN_SECUR_LOCKED_CF

Configures secure forwarding for static locked entries per

port.

ANA_L2::LRN_COPY_CFG

Configures CPU copy of learn frames per port.

ANA_L2::MOVELOG_STICKY

Identifies ports with moved stations.

ANA_L2::LRN_CFG

Configures common learning properties.

ANA_L3:VLAN:VLAN_CFG.VLAN_FID Configures filtering identifier (FID) to be used for learning.

Per VLAN

LRN::AUTO_LRN_CFG

Configures automatic learning options.

LRN::EVENT_STICKY

Signal various sticky learning events.

ANA_L2:PORT_LIMIT:PORT_LIMIT_

CTRL

Controls automatic learn limits per logical port and GLAG.

per port and

GLAG (11+8

instances)

ANA_L2:PORT_LIMIT:PORT_LIMIT_

STATUS

Status for port limits.

per port and

GLAG (11+8

instances)

ANA_L2:LRN_LIMIT:FID_LIMIT_CTRL Controls automatic learn limits per FID.

per FID (4,224

instances)

ANA_L2:LRN_LIMIT:FID_LIMIT_

STATUS

Status for FID limits.

per FID (4,224

instances)

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