Date printed: 5/11/2017 USGMII Functional Specification: EDCS-1155168
Copyright 2015 Cisco Systems 1 Cisco Confidential ---- Controlled Access
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Document Number
EDCS-1155168
Based on
Template
EDCS-189229 Rev 20
Created By
Amrik Bains
USGMII Specification
The Universal Serial Gigabit Media Independent Interface (USGMII) is an extension of current
SGMII and QSGMII. USGMII provides flexibility to add new features while maintaining
backward compatibility. Previous definition/implementations cover single (SGMII) and quad
(QSGMII) options. This specification define USGMII option to support 4x1GE/8 x1GE network
ports and 5G/10G PHY/MAC SERDES speed respectively:
• Convey 4 to 8 ports of network data and port speed between a 10/100/1000
PHY and a MAC with significantly less signal pins than required for GMII &
SGMII.
• Utilize a 8B/10B PCS to maintain compatibility with SGMII/QSGMII
• USGMII interface operates as Full Duplex, while network interface supports
both half and full duplex modes.
• Ability to send Packet Channel Header to support programmable information
exchange between PH and MAC, for example PTP time stamp from PHY to
MAC to improve accuracy/jitter on encrypted PTP packet and MACSec is in the
ASIC
• Can be configured to support backward compatibility with SGMII and
QSGMII
Modification History
Revision
Date
Originator
Comments
3.0
11/12/2015
Amrik Bains
First general release
3.1
05/12/2016
Amrik Bains
Typo Fix
3.2
09/19/2016
Amrik Bains
Typo fix for Q-USGMII speed from 10G to 5G
3.3
11/02/2016
Amrik Bains
Typo correction for Extesnion Field Type to:
01: Extension Field contains Tag/Signature associated
with for time-stamp to be taken by the PHY
4.0
02/10/2017
Amrik Bains
Added Pre-emption Features – PCH changes
4.1
05/11/2017
Amrik Bains
With pre-emption, additional PTP enable is required on
egress – see table 5