Evolution of 100G Host to Module
IEEE CEI-28G VSR AdHoc
Ali Ghiasi
Broadcom Corporation
1
Overview
    Short term need has given rise to VSR application
model with 4” host PCB
Longer term 100 GbE applications, FC, and IB need
longer PCB traces 10” instead of 4”
QSFP2 PD may not allow any retiming
How do we make sure we don’t end up with twice
or 4 times as many interfaces!
IEEE CEI-28G VSR AdHoc
2
100 Gig CFP Module (Gen I) “Market
Enabler”
 Robust but too big and we all agree!
CFP Module
LR4/ER4
TX
CMOS
8404
ASIC/SerDes
25G
10:4 Gearbox
CAUI
LR4/
ER4
RX
Common Electrical Interface
IEEE CEI-28G VSR AdHoc
3
Possible 28G Applications Model
 Application model emerging
CFP2/QSFP2
CMOS
ASIC/SerDes
8404
CAUI
25G
10:4 Gearbox
Retimer*
LR4/ER4
TX
Retimer*
LR4/
ER4
RX
VSR
CFP2/QSFP2
CMOS
ASIC/SerDes
Retimer#
LR4/ER4
TX
Retimer#
LR4/
ER4
RX
28G-SR
*Full retiming my not be required
#Full retiming likely required but PD will exceed QSFP2 limit IEEE CEI-28G VSR AdHoc
4
28G Applications Model Cont.
QSFP2
LR4/ER4
TX
Retimer*
CMOS
ASIC/SerDes
28G-SR
VSR
Retimer*
LR4/
ER4
RX
*Assuming in the case of QSFP2 the retimers are external it solves the
power issue and distance IEEE CEI-28G VSR AdHoc
5
Option Moving Forward
 QSFP2 likely has to be unretimed/half retimed due to PD and
CFP2 could be retimed fully, option on how to proceed?
• • • • •  Define 4” full retime
Define 10” retime
Define unretime/half retime
Define 4” full/half retime
If we do not create a super-set then we can end up with 4
plausible interfaces!
Propose to have two interfaces
• • Phase I- nAUI like interface to support 4” host PCB without
back channel and 10” with back channel
Phase II- nPPI like interface to support 4” of host PCB
IEEE CEI-28G VSR AdHoc