FBFM2112F897CSLJLS View Datasheet(PDF) - Intel

Part Name

Description

Manufacturer

FBFM2112F897CSLJLS

Intel® FM2112 24-Port 10G/1G Ethernet Switch Chip

Intel 

Intel® FM2112 24-Port 10G/1G Ethernet Switch Chip Data Sheet

3.2.11

3.2.11.1

3.2.11.2

source/destination symmetry function will guarantee that frames from

A to B and frames from B to A travel the same path through a multi-

hop system. This feature enables the use of learning and aging to

maintain the table information in a federated switch architecture.

Table Modification

{Described in registers Table 69 and Table 70}

Table entries are dynamic or static.

Learning and Aging

Each port is independently configurable for learning. If learning is off,

then the only way to add MAC entries to the table is through

management. If learning is on, then the switch will add entries to the

table after performing a source address lookup.

Aging is a global MAC address table configuration controlled by the

SYS_CFG_7 register (see Table 69). If the MAC address is dynamic (the

lock bit is not set) then entries may be aged out of the table. The

configurable times to age the entire table are limited to:

• 32,000 CPU clock periods < Age Time < 6.87 x 1013 CPU clock periods

• Don't age

When a learning or an aging event occurs, the change in the MAC

address Table is made available to the CPU and a maskable interrupt is

raised. There is a 64-deep queue of MAC address change information.

If a burst of learning events happen more quickly then the CPU can

service the interrupts, then this FIFO will overflow. In which case, the

software image of the table may be resynchronized by reading the

hardware table.

If the FM2112 is operated above its guaranteed maximum fully

provisioned frame rate, but below its “best effort” maximum frame

rate, then the source address look-up rate may be reduced through the

best-effort look-up feature. The best effort look-up feature reduces the

source address look-up rate when the frame rate is sufficiently high

that the look-up would otherwise begin to drop frames. In this rare

case, learning becomes statistical.

Static Configuration

The switch does not modify static entries in the MAC Table.

The manager may make an entry static, by setting the lock bit.

42

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