[802.3EEESG] Modified Objectives

[George Zimmerman <gzimmerman@xxxxxxxxxxxxxx>]

I understand that the objectives were modified to read:

 

• Define a mechanism to reduce power consumption during

periods of low link utilization for the following PHYs

– 100BASE-TX

– 1000BASE-T

– 10GBASE-T

– 1000BASE-KX

– 10GBASE-KR

– 10GBASE-KX4

• Define a protocol to coordinate transitions to or from a lower

power consumption state

• The transition time to and from the lower power state should be

transparent to upper layer protocols and applications

• The link status should not change as a result of the transition

• No frames in transit shall be dropped or corrupted during the

transition to and from the lower power state

 

As I read the modified objectives, I see that the objectives would be achieved if we just defined a set of lower power PHYs, without any mechanism to change link speed.  The data presented in the CFI and in contributions (particularly for 100BASE-T and gigabit) suggests that most of the power savings would come from other than the PHY, and would be triggered elsewhere in the system by a change in link speed.

Is this the intent that was considered in the group?

 

The scope of the system over which “lower power state” is considered is not defined.  (from the implication of the first statement, this was about power consumption for the PHY).  If you assume that it is only about the PHY, then we will not achieve significant power savings, and I would say that the 5 critters will be difficult to satisfy at best. (certainly there has been little or no work showing that other than changing link speed there would be savings in power and hence either economic or technical feasibility)

 

I would suggest that at least the first objective be modified to include the mac and controller as follows:

 

Define a mechanism to reduce power consumption of the overall Ethernet system (e.g., MAC/PHY) during periods of low link utilization with the following PHY types:

….

 

It would be better to say for example Controller/PHY, Switch/PHY – but 802.3 doesn’t define these entities – if someone knows better, please help out.

 

Sorry to be wording these things from a remote location…  Please take it as an attempt at constructive work.

 

-george