PC Routers

[James Knott]

CLIFFORD ILKAY wrote:
> On 12/21/2011 10:19 PM, James Knott wrote:
>> CLIFFORD ILKAY wrote:
>>> I thought so, too, until I upgraded to a gigabit switch. It comes in
>>> handy when copying large files on the LAN.
>>
>> There's no reason why the rest of your LAN can't be Gb. The switch takes
>> care of the difference between ports. Unlike the days of coax & hubs,
>> the different devices do not have to be the same speed. You could have
>> 10 Mb, 100 Mb, Gb and 10 Gb (assuming the switch can handle all those
>> speeds) on the same switch and it will all work together.
>
> Sure. That assumes there is another switch on the network. For many 
> people, that isn't the case. They'll just use the switch in the router.
>
> By the way, I found out that just because modern switches can 
> auto-negotiate the connection doesn't mean that it works as you'd 
> expect in all cases. I had installed a consumer-grade D-Link gigabit 
> switch at the colo facility in Toronto where we have some servers so 
> that we could connect multiple servers to one switch port. Even though 
> the colo facility provided a 100Mb/s port, the switch was a gigabit 
> switch, and all the servers had gigabit NICs, the best we could manage 
> on the servers was 10Mb/s. The colo facility's Cisco switch was 
> configured to be 100Mb/s and consumer-grade switches like the D-Link 
> apparently don't auto-negotiate down to 100Mb/s as I thought it would. 
> It fell to the lowest common denominator, 10Mb/s.

That board linked to in a previous article has only 2 Ethernet ports.  
This means a switch will be required, if it is used with more than one 
computer.

As for that D-Link, there may be problems with some devices, but that 
doesn't rule out what I said.  Unlike hubs, switches have a separate 
interface for every port.  This means each port can negotiate (or be 
configured in managed switches) to any speed (actually bandwidth).  The 
switch will then move the data around between the various ports as 
required.  There is no place within the switch, other than on the line 
side of the interfaces where you have speeds such as 100 Mb.  The switch 
bus will have some maximum amount of capacity or bandwidth, with which 
to handle all the traffic.  On some switches, it may be possible to bump 
into that limit.

BTW, why would you use a consumer grade device in a colo site?  It 
likely couldn't handle the load if those servers were busy.

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