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Re: [STDS-802-3-EPOC] PHY Link frame structure



Duane, 

 

Is anything wrong with CRC32 we have been using for Ethernet frames for
quite some time? I think before we copy solutions from D3.1, a study would
be needed to see whether we could live with CRC8 . 

 

Regards

 

Marek

 

From: Duane Remein [mailto:Duane.Remein@xxxxxxxxxx] 
Sent: Monday, December 16, 2013 11:19 AM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-3-EPOC] PHY Link frame structure

 

All,

Currently in our PHY Link frame structure there is a soft FEC. Unlike a Reed
Solomon FEC, the LDPC FEC does not give a positive indication of an
uncorrectable error. In our MAC data channel we have resolved this with the
placement of a CRC in the FEC codeword. I believe this is also the solution
DOCSIS 3.1 has taken for it's DS PLC where they have defined several types
of message blocks each with it's own CRC. An exception here is the Message
Channel MB the conveys MAC frames which already have a CRC and therefore
don't need additional protection. A summary of the D3.1 MB structure is
shown below (D3.1 folks please correct me if I've misinterpreted anything
here).

I think is it reasonable to resolve this problem in EPoC in a similar
fashion to what has been done in D3.1, my only question is how closely we
want to follow their lead? A thought that has crossed my mind is extending
the "Type" field to create EPoC specific fields. For example we could create
an EPoC PHY Link MB that includes the Opcode, Count, MDIO Add, and MDIO Data
fields with a closing CRC.

Any other thoughts on this idea?

Best Regards,

Duane

 

DOCSIS 3.1 MBs


Msg Block

Field

bits


TS MB
Type=1

Type/R

4/4


Timestamp

64


CRC24D

24


EM MB
Type=2

Type/R

4/4


CM_ID

16


Wake

32


CM_ID

16


Wake

32


CRC24D

24


TR MB
Type=4

Type/R

4/4


Transaction ID

8


Trigger Group

16


Frame Delay

8


Symbol Select

8


CRC24D

24


MC MB
Type=3

Type/R

4/4


Packet Start

16


Frame

512

 

 

FutureWei Technologies Inc.

duane.remein@xxxxxxxxxx

Director, Access R&D

919 418 4741

Raleigh, NC

 

 

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