VSC7511 datasheet(130/324 Pages) MICROSEMI

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Functional Descriptions

VMDS-10488 VSC7511 Datasheet Revision 4.2

115

Three different type of learn frames are identified:

•

Normal learn frames. Frames for which an entry for the (SMAC, VID) is not found in the MAC table

or the (SMAC, VID) entry in the MAC table is unlocked and has a DEST_IDX different from LPORT.

In addition, the learn limit for the LPORT must not be exceeded (ENTRYLIM).

•

Learn frames exceeding the learn limit. Same condition as for normal learn frames except that the

learn limit for the LPORT is exceeded (ENTRYLIM)

•

Learn frames triggering a port move of a locked MAC table entry. Frames for which the (SMAC,

VID) entry in the MAC table is locked and has a DEST_IDX different from LPORT.

For all learn frames, the following must apply before learning related processing is applied.

•

Learning is enabled by PORT_CFG.LEARN_ENA.

•

The LRN_DIS flag from previous processing steps must be cleared, which implies the following:

Learning is not disabled due to VLAN ingress filtering

Learning is not disabled due to VCAP IS2 action

Learning is enabled for the VLAN (VLAN_LEARN_DISABLED is cleared in the VLAN table)

In addition, learning must not be disabled due to the ingress policer having policed the frame. For more

information, see Policers, page 118.

If learning is enabled, learn frames are processed according to the setting of the following configuration

parameters.

3.9.3.5.1

Normal Learn Frames

•

Automatic learning. If PORT_CFG.LEARNAUTO is set for PPORT, the (SMAC, VID) entry is

automatically added to the MAC table in the domain being searched.

•

Drop learn frames. If PORT_CFG.LEARNDROP is set for PPORT, DEST is cleared for learn frames.

Therefore, learn frames are not forwarded on any ports. This is used for secure learning, where the

CPU must verify a station before forwarding is allowed.

•

Copy learn frames to the CPU. If PORT_CFG.LEARNCPU is set for PPORT, the CPU port is added

to DEST for learn frames and CPUQ_CFG.CPUQ_LRN is set in CPUQ. This is used for CPU based

learning.

3.9.3.5.2

Learn Frames Exceeding the Learn Limit

•

Drop learn frames. If PORT_CFG.LIMIT_DROP is set for PPORT, DEST is cleared for learn frames.

As a result, learn frames are not forwarded on any ports.

•

Copy learn frames to the CPU – If PORT_CFG.LIMIT_CPU is set for PPORT, the CPU port is added

to DEST and CPUQ_CFG.CPUQ_LRN is set in CPUQ for learn frames.

3.9.3.5.3

Learn Frames Triggering a Port Move of a Locked MAC Table Entry

•

Drop learn frames. If PORT_CFG.LOCKED_PORTMOVE_DROP is set for PPORT, DEST is cleared

for learn frames. Therefore, learn frames are not forwarded on any ports.

PORT_CFG.LEARNDROP

If set for PPORT, the CPU drops or forwards learn

frames.

Per port

PORT_CFG.LIMIT_CPU

If set for PPORT, learn frames for which PPORT

exceeds the port’s limit are copied to the CPU.

Per port

PORT_CFG.LIMIT_DROP

If set for PPORT, learn frames for which PPORT

exceeds the port’s limit are discarded.

Per port

PORT_CFG.LOCKED_PORTMOVE_CPU

If set for PPORT, frames triggering a port move of

a locked entry are copied to the CPU.

Per port

PORT_CFG.LOCKED_PORTMOVE_DROP If set for PPORT, frames triggering a port move of

a locked entry are discarded.

Per port

AGENCTRL.IGNORE_SMAC_FLAGS

Controls the use of the MAC table flags from

(SMAC, VID) entry.

None

Table 89 •

SMAC Learning Registers (continued)

Description

Replication

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