🚀 go-pugleaf

In article <qkBPwGAdA1G3EwDb@howgarth.demon.co.uk>, Jamie Walker
<jamie@howgarth.demon.co.uk> writes
>Can someone clarify this please - do you need an expensive switching hub
>to run some cards at 10mb and others at 100mb or can you do that with a
>hub like that? I was under the impression that if one card is 10mb then
>the hub won't run at 100mb (although I could well have been
>misinformed).

There are basically three types of hub. Passive, switched and dual
speed.

Passive hubs are a single speed (either 10baseT or 100baseTX) and
packets are sent to all ports simultaneously. If there are any hubs like
this that support both 10baseT and 100baseTX, then I expect that they
will run at the speed of the slowest device plugged into them.

Switched hubs learn what Ethernet addresses are present on each port (be
it one, or many), and only sends packets to the appropriate port or
ports. Switched hubs can also take full advantage of full duplex
(10/100Mbps in and out simultaneously rather than 10/100Mbps shared
between in and out). Finally switched hubs split up your network into
many more collision domains, helping reduce the worst cases when the
network is heavily loaded.

Dual speed hubs are like a 100baseT and a 10baseT hub connected by a
single switch. The advantage is cost and flexibility, having only one
big hub rather than two hubs, a 10baseT one and a 100baseT one.

Passive hubs have a bandwidth of 10Mbps or 100Mbps over the whole hub.
Dual speed hubs will have a bandwidth of 100Mbps+10Mbps over the whole
hub. Switched hubs will have a bandwidth of all their combined ports.
I.e. an 8+2 hub (8x 10baseT and 2x 100baseTX ports) will have a
bandwidth of 560Mbps if all of the ports are full duplex (8*20+2*200).

Most switched hubs have lots of 10baseT ports, and a few autosensing
10baseT/100baseTX ports. The idea is that you can connect the hubs to
each other and to servers with the 100Mbps ports and to the workstations
with the 10baseT ports.

For 8/10 port solutions, the costs go approximately:

  1) Passive 10baseT ports             8 ports for  20-30 quid
  2) Passive 100baseTX ports           8 ports for 100-150 quid
  3) Dual speed, 10/100 ports          8 ports for 120-200 quid
  4) Switched, mostly 10baseT ports  8+2 ports for 220-300 quid
  5) Switched, all 10/100 ports        8 ports for 450+ quid

This is all dependant on the brand you chose, where you buy it from etc. 

To be honest, I cant see the point in passive 100baseTX hubs. In a
client server environment switched 10Mbps is only a 5th the speed to
each client, and provides benefits of load sharing, preventing one fast
client from hogging all of the servers bandwidth. In a peer-to-peer
environment, you are still probably better off switched, as again
communications from A to C will only be running at 20Mbps rather than
100Mbps but will no longer be fighting for bandwidth with communications
from B to D and E to F. It all comes down to the usage patterns of your
network.

The optimum seems to be to put servers on the 10/100 ports, and passive
hubs, or workstations on the 10baseT ports.

A very good way to boost performance in a large network with daisy-
chained or stacked passive hubs is to plug all of the uplink ports into
a single 'collapsed backbone' switch rather than into each other. This
can make a huge difference, especially if the servers are plugged into
this switch as well.

I have just installed a system with two rack-mount 8+2 switches, a 5
port 10/100baseTX switch, and two fibre transceivers for 750 quid plus
VAT. The brand is Edimax (www.edimax.com), but I bought them from a
distributor, and I am afraid I don't know where to buy them retail.

Since upgrading I rarely see total utilisation on any of the hubs go
above 5% whereas our old passive hub was usually at around 30-60%. It
gives us quite a margin for expansion.

>Do these new hubs come with BNC connectors too?

Many come with AUI ports onto which you can plug a 10base2 transceiver.
But it is probably cheaper to use a cheapo 8x 10baseT + 10base2 passive
hub to do the conversion (even Cisco sell these at about 30quid), I also
put all of the slow devices (printers and Internet router) onto this
passive hub.

>In article <371b1a09.10133909@gateway1>, Peter Hamilton
><peter@cityc.co.uk> writes
>>Could anyone recommend a reasonable quality 8 port hub? This is for a
>>home network and I need something that can handle 100Mbps.  I'll be
>>using mainly Intel 10/100 cards and occasionally some older 3C509s.


I think that if you want 100Mbps and 8 ports is all you will ever need
then you might as well go for a dual speed, since they are not much more
expensive than a passive 100baseTX hub, and you get the advantage that
you can plug slow devices (like printers) into them without forcing the
computers to run at 10Mbps (I hope someone corrects me if I am wrong
about this).

If you plan on expanding the network, or want to run a server shared
amongst a number of clients, then an 8+2 switch might be a better
choice.

>>Simply do an Intel InBusiness 8xRJ45 100Base-T for ukp114 which sounds
>>good, but presumably because of the mixture of NICs I need the ukp149
>>autosensing version, is this correct?

Be very careful about basing your budget on Simply's advertised prices,
they are frequently wildly inaccurate, especially with regard to
networking products. You could be in for a nasty shock, and many other
suppliers are similarly lax about their adverts.

By the way, auto-sensing might not mean Dual-speed, it might mean 'run
at the speed of the lowest common denominator'. Also note that most
network cards capable of 10/100 are also capable of full duplex (i.e.
20Mbps on a switched 10baseT port), all of my Intel cards are.


Take care, hope this helps,


Mark.........
PS I do not sell any of this stuff, I am only a user.
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