Difference between USGMII and USXGMII and why USGMII is better than SGMII/QSGMII

[Paul Zimmerman]

Difference between USGMII and USXGMII:

• USGMII is used for 8x10M/100M/1GE network ports, with each port maximum speed of 1GE. USXGMII-Single  Port version can be used to support ONE network port with 10M/100M/1G/2.5G/5G/10G data rates
• USGMII is used for 10M/100M/1G network port speeds, while USXGMII support 10M/100M/1G/2.5G/5G/10G. 
• There are two types of USXGMII: USXGMII-Single Port and USXGMII-Multiple Ports.
• USGMII and USXGMII provide the same capabilities using the packet control header.

Why USGMII is better than SGMII/QSGMII:

• SGMII supports a single 10M/100M/1G network port over 1,25Gbps SERDES between MAC and PHY, while QSGMII supports four 10M/100M/1G network ports over 5Gbps SERDES between MAC and PHY. 
• USGMII supports eight 10M/100M/1G network ports over 10Gbps SERDES between MAC and PHY. This is most critical for high density switches and PHY. USGMII also provides packet control header to pass control/status between PHY and MAC. One of the application is Time-Stamp for PTP and 802.1AS.

[youcisco]

Hi Paul,

How can we get the USXGMII specification EDCS-1467841 revision 1.4?

Thanks,

[linusti]

For the latecomers...you need to be a member of this community and go into the ARCHIVED documents section of the network programming- it's no longer, "relevant," but they have thoughtfully archived it under USXGMII there.

It covers, in large, the spec that most care about.  It's kind of shameful that Cisco doesn't do a better job since they fostered the standard in the first place.

[Paul Zimmerman]

Thanks, @linusti ... you are right, the content is still available here:
https://developer.cisco.com/site/usgmii-usxgmii/

But since it is archived, you have to be logged into the developer.cisco.com site.

[linusti]

Yep.  And it needed to be shared.  You kind of need to have this document to understand some of the Specification if you're implementing a system using it between USXGMII so you don't foot-gun yourself with some aspects of it. 

Happy to have helped the community here.  Even if I've now found out that we DID foot-gun ourselves on gear...  X-D

[linusti]

And thanks IS given to Cisco for their keeping it around to able to be found.  Seriously...it's appreciated.

[jkaushik]

May I know if USXGMII-M or USXGMII-4P is the same interface?

Can MAC as USXGMII-M and PHY as USXGMII-4P interface will work?

[fxgang22]

I have a question. xilinx's vivado has qsgmii type ip and qsgmii mode transceiver, but no usgmii mode transceiver. Can I set my qsgmii mode transceiver to 10Gps to use as a usgmii mode transceiver? thank you！