数据链路层发送与接收的处理过程及涉及到的模块

ter per frame cycle

1 ... 32

S<4:0>

Binary value minus 1

SCR

Scrambling enabled

0 ... 1

SCR<0>

Binary value

SUBCLASSV

Device Subclass Version 000 – Subclass 0 001 – Subclass 1 010 – Subclass 2

0 … 7

SUBCLASSV

<2:0>

Binary Value

RES1

Reserved field 1

0 ... 255

RES1<7:0>

Binary value

RES2

Reserved field 2

0 ... 255

RES2<7:0>

Binary value

CHKSUM

Checksum Σ(all above fields)mod 256

0 ... 255

FCHK<7:0>

Binary value

*?CF==L?shall always be encoded as 31: control words on all lanes.?CF==31 can only occur when?L==31, see 5.1.3.

Configuration octet no.

Bits

MSB

6

5

4

3

2

1

LSB

0

DID<7:0>

1

ADJCNT<3:0>

BID<3:0>

2

X

ADJDIR<0>

PHADJ<0>

LID<4:0>

3

SCR<0>

X

X

L<4:0>

4

F<7:0>

5

X

X

X

K<4:0>

6

M<7:0>

7

CS<1:0>

X

N<4:0>

8

SUBCLASSV<2:0>

N’<4:0>

9

JESDV<2:0>

S<4:0>

10

HD<0>

X

X

CF<4:0>

11

RES1<7:0> - Set to all X

12

RES2<7:0> - Set to all X

13

FCHK<7:0>

1.4.3 Lane alignment buffering /detection and monitoring

在开始数据帧和通道对齐后，通道将会进入对齐字节检测状态，通道的对齐是通过对齐标志符/A/=/28.3/来决定的，该对齐标志符在复帧的结尾，对于对齐标识符A的插入，可以参考frame alignmentmonitoring。

在一般的情况下，不是所有的通道都会发生同时发生对齐标识符A，但是通道可以通过A在复帧中的位置来检测数据通道的数据是否同步上。

在多个接收通道的情况下，每一个接收器都应该可以从更高层的应用中授权数据链路层对链路中的数据进行从新的动态调整，已完成不同数据通道间的对齐。

 数据通道中发现未对齐

 发现新的对齐字符，但是不在数据复帧的帧尾

 根据对齐字符缓存区中的数据进行从新对齐

 如果连续接在同一个位置上接收到两个有效的A，并且不在数据复帧的结束，并且在两个A之间没有接收到有效或者无效A标识符，通道需要从新的将通道中的数据进行对齐。

 如果在最近的数据帧出现通道间不对齐的可能性很大时，接收器需要将第一个接收到A的位置作为对齐的标准。

1.4.4 Lane alignment detection andmonitoring

通道间的数据检测和对齐处理过程如图27所示，图中变量的具体意思参照表8，具体的操作流程如下:

Variable

Meaning

A_received

Asserted when the current symbol, before possible substitution in frame alignment monitoring, corresponds to control character K28.3

CROSS_COUPLING

Lane misalignment expected because of cross coupling between frame and lane alignment

Fcounter

Counter used to mark the position of the current frame in the multiframe. Frame indexing starts from 0.

K

Number of frames in multiframe.

previous_A_position

Variable into which to store the position in the multiframe of a K28.3 symbol

REPLACE_A

Replace the K28.3 at the decoder output by:

? The data character decoded or used at the same position in the previous frame when scrambling is disabled

? D28.3 when scrambling is enabled

?

However, if the position of the K28.3 is required in subsequent frame alignment monitoring, the K28.3 shall not be replaced or it shall be marked.

RESET_FRAME_COUNTER

Reset frame counter to zero at reception of next frame

INITIATE_SYNC_CHECK

In receivers belonging to a MCDA device class (see clause 9), if authorized via the control interface, initiate a synchronization check between the LMFCs via one of the methods supported by the device class and subclass.

VALID