Wireless STM-1 link

Kevin Loch kloch at kl.net
Thu Sep 10 15:33:14 UTC 2009

Brian Reichert wrote:
> On Thu, Sep 10, 2009 at 11:55:40AM +0200, Rens wrote:
>> All the interfaces are forced to 1Gbps and full duplex.
> I thought that with 1000T, you need to keep autonegotiation in place:
>   http://etherealmind.com/2008/07/15/ethernet-autonegotiation-works-why-how-standard-should-be-set/
>     "A major problem is that many people are also hard setting
>     Gigabit Ethernet , and this is causing major problems. Gigabit
>     Ethernet must have auto-negotiation ENABLED to allow negotiation
>     of master / slave PHY relationship for clocking at the physical
>     layer.  Without negotiation the line clock will not establish
>     correctly and physical layers problems can result."
> Further:
>   http://en.wikipedia.org/wiki/Autonegotiation
>     "The debatable portions of the autonegotiation specifications were
>     eliminated by the 1998 version of IEEE 802.3. In 1999, the negotiation
>     protocol was significantly extended by IEEE 802.3ab, which specified the
>     protocol for gigabit Ethernet, making autonegotiation mandatory for
>     1000BASE-T gigabit Ethernet over copper."
> Note the 'mandatory'...

I'm in the "it's not 1996 anymore, let autonegotiation do it's
job" camp.  I occasionally see folks who religiously "lock down"
all ports only to create the very duplex mismatches they are trying
to avoid.  Engineers, equipment, port positions and operating systems
can change over time defeating even the best laid plans for total
port control.

- Kevin

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