[c-nsp] connection speed at physical layer

[John Gill]

Hi Martin,
I am not sure how you determine you only advertise 10/full, but speed 
detection is not hard, but rather duplex is where it's more necessary.

The interface on the switch is able to operate in 10 or 100 at the phy, 
in this case it knows it can understand the 10Mb/s signaling coming from 
the T60, so it steps down and that is the only way link is established. 
  I have not heard of two phy's operating at different speeds on the 
same link.

John Gill
cisco


On 7/21/11 7:42 AM, Martin T wrote:
> Martin,
> I'm running GNU/Linux(Debian). I set this manually for testing
> purposes. In other words eth0 interface is configured to allow
> autonegotiation, but advertises only 10BASE-T/Full.
>
> So it's clear, that if GE interface is configured to 10BASE-T mode, it
> will send traffic on physical layer at max 10Mbps. Or for example if
> FE interface is set to 10BASE-T mode, it will not send electrical
> signals at rate of 100Mbps, but instead 10 times slower?
>
>
> regards,
> martin
>
>
> 2011/7/21 Martin Barry<marty at supine.com>:
>> $quoted_author = "Martin T" ;
>>>
>>> This might be a bit stupid question, but I have following topology:
>>>
>>> IBM_T60[eth0]<->  [Fa0/2]WS-C2950C-24
>>>
>>> eth0 port is an "Intel Corporation 82573L" GE port and Fa0/2 port in
>>> WS-C2950C-24 switch is of course FE port. I have enabled
>>> autonegotiation on eth0 port, but it advertises only 10BASE-T/Full
>>> mode, so switch port, which is configured to "speed auto" and "duplex
>>> auto", is up with following settings:
>>>
>>> Fa0/2     ->  T60             connected    1          a-full   a-10 10/100BaseTX
>>
>> What operating system are you running on the T60? You need to figure out why
>> it's not offering the full range of speeds during auto-negotiation.
>>
>>
>>> Am I correct, that actual signalling on physical layer is 10BASE-T? Or
>>> is eth0 port actually sending at 1Gbps(1000BASE-T signalling) rate and
>>> Fa0/2(100BASE-TX signalling) is sending at 100Mbps rate on physical
>>> layer?
>>
>> Your first instinct is correct, both sides with be operating at 10/full
>> rather than the 100/full which you would obviously prefer.
>>
>> cheers
>> Marty
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