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

3.2.7

3.2.7.1

3.2.7.2

3.2.7.3

• TRIG-ID: User defined triggers

• Destination Mask: Bit mask for ports associated with this address. One-hot

encoding for unicast traffic.

The hash function supports address aliasing resolution. The 32-bit CRC

hash function reduces the 60 bit MAC address +VLAN ID to a 16 bit

number. Only 12 bits of this are used as the address to the look-up. The

FM2112 allows any three of four groups of bits to be selected as the

input to the hash function. Performance analysis indicates there is a

very low probability of address aliasing (when multiple distinct MAC

addresses +VLANs point to the same address) of greater than 8 bins

for normal MAC address populations. However, if an address occurrence

happens, and there is an unacceptable level of flooding, then the hash

input may be changed and the table repopulated to resolve the corner

case.

Lookups and Forwarding

Source Address Check

The source address is searched for four reasons:

• Discard and redirection rules

• Security

• Triggers: Can be programmed on source address

• Learning

If all of the features that require a source address check are turned off,

then the check may be disabled to save power. Furthermore, the device

provides a configurable over-provisioned mode in which the source

address search is done on a best-effort basis.

Destination Address

The destination address and VLAN is searched for the following:

• Filtering information (multicast reduced to unicast)

• Traps: Special multicast addresses

• User-defined triggers

VLAN ID

The VLAN ID is searched for the following:

• Ingress and Egress member-list

• Tag processing

• Spanning tree state

• User-defined triggers

• VLAN statistics

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