[802.3AZ] EEE - Negotiation clarification
Hi,
I have a few doubt's when it comes to the Negotiation part as in the
802.3az 0.9 draft.
Would be grateful for any clarifications provided.
1.) It is proposed that the systems exchange Tq/Tr supported in AN,
and the lowest is settled for;
For ex;
A ------ B
Tq/Tr(A) best case advertised is 'lowest energy' -> i.e. (Tq >> Tr)
Tq/Tr(B) best case advertised is 'reduced energy' -> i.e. (Tq > Tr)
And they both settle for Tq/Tr(B) , "to ensure lowest common value to
ensure robust and quality link" .
Now as the Tq/Tr parameters are useful only for the peer link partner,
what is the benefit in making my peer choose
a ratio which is not as energy efficient as what I may best support,
just on the basis that my own Tq/Tr ratio cannot be
as good as my peers.
How does that effect "robustness" & "link quality"??
In my opinion considering the asymettric nature of EEE ( ie only the
TX triggers it not depending on the peer TX), it only effects
the timers running on my side for the benefit of the peer. And gives
an overall more efficient system rather than what would come
by ensuring "lowest common value"
2.) In the LLDP negotiation, we resolve the Transmit Tw ( section
93.4.2.3 ) , to be the "minimum" of local Transmit Tw and the
received(from the link partner) Receive Tw. And the local device shall
wait for the time indicated by the Resolved time after deasserting
from LPI and sending data packets.
For ex:
A - Transmit Tw - 10 ms, Receive Tw - 20 ms
B - Transmit Tw - 10 ms, Receive Tw - 20 ms
( These values exchanged are default values for the given PHY)
Now post LLDP exchange;
On A;
Resolved Tw, cannot be 10ms, as the peer Tw is at least 20ms, which is
contrary to the statement of being minimum.
Thanks,
-Sujay