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Amir, The single pair auto-negotiation does not add substantial time to the startup process. Less than 1ms compared to a target of 100ms to link up. Without autonegotiation
a handshaking scheme is still needed between master and slave to establish the start of link training. Regards, Brett From: Amir Bar-Niv [mailto:Amir.Barniv@xxxxxxxxxxxx]
External Email Question (this is not a suggestion, just a question): is there a need at all for auto-negotiation in this type of environment (automotive)? The biggest disadvantage of auto-negotiation is the additional setup time of the link that is needed to finish the auto-negotiation process, every time we turn
on the power. When you use Ethernet in non-automotive environment/network, then for example when you have a switch that supports multiple speeds (e.g. 10G, 1G and 100M), you
must have auto-negotiation since you never know what speeds are supported by the link partner that is connected to this switch. The auto-negotiation detects the highest common denominator of the switch and the link partner, and set the speed accordingly.
In automotive, once we define the final topology/structure/cables of the in-car network then we know the speed that is required on each link. Even if a PHY supports
multiple speeds we can set it manually to work in the desire speed, and save the extra link setup time of the auto-negotiation.
Regards, Amir From: NATALIE WIENCKOWSKI [mailto:NWIENCKOWSKI@xxxxxxx]
All, As we discuss auto-negotiation and multiple speeds, is it necessary for all of the speeds to use twisted pair to do this? If coax or twinax is chosen for 10 Gbps is it possible for this phy to operate
at and communicate with PHYs at lower speeds that use a form of twisted pair? If auto-negotiation is truly needed by some parties between these speeds we need to ensure that we don't select a cable type that makes this impossible. It would be helpful if PHY vendors could provide contributions on whether this is possible and if end users could provide information on their needs for auto-negotiation. Thanks, Natalie Wienckowski From: Geoff Thompson <thompson@xxxxxxxx> Colleagues |