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

3.1.4.2

LANE 0

LANE 1

LANE 2

LANE 3

S

Dp

D

D

…

D

A

R

K

R

R

Dp

Dp

D

D

…

T

A

R

K

R

R

Dp

Dp

D

D

…

K

A

R

K

R

R

Dp

Ds

D

D

…

K

A

R

K

R

R

The frame format in 1G mode is shown in the next table. The PCS layer

is programmable (bit SP of PCS_CFG) to either expect a strict 8-byte

preamble (bit SP is set to 0) or a variable size preamble (bit SP is set to

1). When configured for supporting a variable size preamble, the PCS

will accept as a valid preamble any starting sequence of 1x|S|,

[0..6]x|Dp|,1x|Ds|).

LANE 0

S

Dp Dp … Dp Ds D D

D

…

D

T

R

I

…

In the SGMII 100Mbps mode, the PCS will search for |S| and then

sample incoming data every 10 cycle. In the 10M, the PCS will sample

incoming data every 100 cycle.

Finally, the PCS supports 4-bit miss-alignment in the data part of the

frame (|DP| to last |D|). This is enabled using the ND option of

PCS_CFG. When this option is enabled, the PCS will accept 0xD5 or

0x5?-0x?D as a valid start of frame and will automatically realign the

frame before sending it to the MAC layer. This is particularly useful

when the SGMII interface is coming from a device that did an MII-

SGMII conversion and the size of the pre-amble on the MII was not a

multiple of 8 bits. This should only be useful in 10M/100M.

In addition to the requirements in these specifications, some optional

enhancements are described as followed.

Local and Remote Faults

The PCS performs the following functions:

• Upon reception of at least four local fault symbols (LFS) within a 128-cycle period,

the PCS enters into a local fault detect state, and exits it when 128 cycles occur

without receiving any LFS. While in local fault, the transmitter sends remote fault

symbols (RFS) to the link partner. MAC data is discarded.

• Upon reception of at least 4 RFS within a 128-cycle period, the PCS enters into a

remote fault detect state, and exits after 128 cycles without receiving any RFS.

While in remote fault, the transmitter sends idle symbols to the link partner. MAC

data is discarded.

• The PCS layer can be configured to transmit RFS when the link goes down

regardless of whether LFS are received.

In the unlikely situation where two faults are received, then the local

faults shall take precedence.

A cycle is 4 bytes.

25

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