Page 1252 - 5G Basics - Core Network Aspects

2 Transport aspects

Input client Flag 512-bit (64-Octet) field
characters bit
All data block 0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 DB8
7 data block 1 0 AAA aaaa DB1 DB2 DB3 DB4 DB5 DB6 DB7
1 control block CB1
6 data block 1 AAA aaaa 0 BBB bbbb
2 control block 1 CB1 CB2 DB1 DB2 DB3 DB4 DB5 DB6
5 data block 1 AAA aaaa 1 BBB bbbb 0 CCC cccc
3 control block 1 CB1 CB2 CB3 DB1 DB2 DB3 DB4 DB5
4 data block 1 AAA aaaa 1 BBB bbbb 1 CCC cccc 0 DDD dddd
4 control block 1 CB1 CB2 CB3 CB4 DB1 DB2 DB3 DB4
3 data block 1 AAA aaaa 1 BBB bbbb 1 CCC cccc 1 DDD dddd 0 EEE eeee
5 control block 1 CB1 CB2 CB3 CB4 CB5 DB1 DB2 DB3
2 data block 1 AAA aaaa 1 BBB bbbb 1 CCC cccc 1 DDD dddd 1 EEE eeee 0 FFF ffff
6 control block 1 CB1 CB2 CB3 CB4 CB5 CB6 DB1 DB2
1 data block 1 AAA aaaa 1 BBB bbbb 1 CCC cccc 1 DDD dddd 1 EEE eeee 1 FFF ffff 0 GGG gggg
7 control block 1 CB1 CB2 CB3 CB4 CB5 CB6 CB7 DB1
1 AAA aaaa 1 BBB bbbb 1 CCC cccc 1 DDD dddd 1 EEE eeee 1 FFF ffff 1 GGG gggg 0 HHH hhhh
8 control block 1 CB1 CB2 CB3 CB4 CB5 CB6 CB7 CB8
- Leading bit in a 66B control block FC = 1 if there are more than 66Bcontrol block and = 0 if this payload contains the last control
block in that 513B block
- AAA = 3-bit representation of the first control code's original position (First control code loca tor: POS)
- BBB = 3-bit representation of the second control code's original position (Second control code lo cator: POS)
.....
- HHH = 3-bit representation of the eighth control code's original position (Eighth control code lo cator: POS)
- aaa = 4-bit representation of the first control code's type (first control block type: CB TYPE)
- bbb = 4-bit representation of the second control code's type (Second control block type: CB TYPE)
.....
-hhh = 4-bit representation of the eighth control code's type (Eighth control block type: CB TYPE)
- CBi = 56-bit representation of the i-th control code caracters
- DBi = 64-bit representation of the i-th data value in order of transmission
G.709-Y.1331(12)_FB.5

Figure B.5 – 513B code block components

B.3.1 Errors detected before 512B/513B encoder
A set of errors might be detected at the 64B/66B PCS receive process which, in addition to appropriate
alarming, needs to send the appropriate signal downstream.

Errors encountered before the encoder, such as loss of client signal, will result in the insertion of an
Ethernet LF sequence ordered set prior to this process, which will be transcoded as any other control block.
The same action should be taken as a result of failure to achieve 66B block lock on an input signal.
An invalid 66B block will be converted to an error control block before transcoding and the OTN BIP-8
calculation as described in clause E.4.1. An invalid 66B block is one which does not have a sync header of
"01" or "10", or one which has a sync header of "10" and a control block type field which does not appear in
Figure B.2. An error control block has sync bits of "10", a block type code of 0x1E, and 8 seven-bit/E/error
control characters. This will prevent the Ethernet receiver from interpreting a sequence of bits containing
this error as a valid packet.

B.3.2 Errors detected by 512B/513B decoder
Several mechanisms will be employed to reduce the probability that the decoder constructs erroneous
64B/66B encoded data at the egress if bit errors have corrupted. Since detectable corruption normally
means that the proper order of 66B blocks to construct at the decoder cannot be reliably determined, if
any of these checks fail, the decoder will transmit eight 66B error control blocks (sync="10", control block
type=0x1e, and eight 7-bit/E/control characters).
Mechanisms for improving the robustness and for 513B block lock are discussed in Annex F.

B.4 Link fault signalling
In-band link fault signalling in the client 64B/66B code (e.g., if a local fault or remote fault sequence
ordered set is being transmitted between Ethernet equipments) is carried transparently according to this
transcoding.

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