FBFM2112F897CSLJLS View Datasheet(PDF) - Intel

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Description

Manufacturer

FBFM2112F897CSLJLS

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

Intel 

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

3.2.10

3.2.10.1

Link-Aggregation

{Described in registers Table 86 through Table 91}

The FM2112 is fully compliant with the link aggregation spec with IEEE

802.3ad-2000, conversely IEEE 802.3-2002 clause 43.

The FM2112 implements all necessary functionality in hardware for

high performance link aggregation. However, it does require a control

processor to implement the control protocols. LACP and Marker

protocols are trapped to the CPU for processing in software.

There can be up to 12 ports in a trunk group. There are up to 12 trunk

groups in the FM2112. No port may be in multiple trunk groups. These

rules are not enforced in the hardware, it is up to software to follow

them.

A hash distribution function is used to index the physical port in the

trunk group. The input into the hash function is configurable to include

any of the following

• Destination address

• Source address

• Type (If type > 0x600, otherwise this input is zero)

• VLAN-ID

• VLAN-Priority

• Source port - the physical port on which the frame ingressed

The modulus, of the number of ports in the trunk group, is taken of the

result of the hash function, yielding the index to the physical port

within the trunk group. There is an additional renumbering step to

create an arbitrary mapping between the resolved port of the link

aggregate group and the actual physical output port, greatly easing the

constraints of circuit board layout.

Federated Switch Architecture with Link Aggregation

The link aggregation features in conjunction with software support

provided in the FM2112 driver enables federated switch architectures

with standard Ethernet features.

A federated switch is comprised of “line” switches and “fabric” switches

as shown in Figure 8. In a CBB (constant bi-sectional bandwidth)

federated switch architecture (aka “Fat Tree”), the bandwidth and port

count between the network and the line switch (green links) is the

same as the bandwidth between the line switch and the fabric switch

(orange links). There are always twice as many line switches as fabric

switches.

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