[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]
On 14/3/2007, "Neil Stone" <neil@xxxxxxxxxxxxxxx> wrote: >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA1 > >Richard Brown wrote: >> Hi Grant >> >> On 13/03/07, Grant Sewell <dcglug@xxxxxxxxxxxx> wrote: >>> On Sat, 10 Mar 2007 15:07:41 +0000 >>> "Richard Brown" wrote: >>> >>>> Does it make a difference depending on connection speeds. There is a >>>> difference between a hub and a switch. What speeds are your network >>>> cards as well? 10/100 I wouldn't worry but if you have a 1000 then it >>>> could make a difference. Just thought I would add these thoughts and I >>>> don't suppose with two computers networked together it makes a whole >>>> lot of difference. >>> As a point of interest (well, to me)... you *cannot* have a gigabit >>> ethernet hub. Gigabit over copper *must* use switches. 10mbps and >>> 100mbps both support "half duplex" (why it's not called simplex, I do >>> not know) communication where they can either talk, or listen, but do >>> both simultaneously. For "full duplex" communication, the network >>> devices are both talking and listening simultaneously, so in effect a >>> 100mbps connection running at full duplex actually provides you with >>> 200mbps bidirectional throughput. Gigabit ethernet, however, *must* >>> operate at full duplex in order to reach the magic 1000mbps speed. >>> Indeed, where-as on 10/100 networks using Cat5(e) only 2 pairs of >>> cables are used, with 1000mbps networks all 4 pairs are being used >>> simultaneously, in both directions. Each pair of cables on Cat5e has a >>> (current) maximum potential throughput of 125mbps (apparently); 4 pairs >>> of cables @ 125mbps/pair = 500mbps; 500mbps in both directions >>> simultaneously = 1000mbps. Hubs do not support full duplex, >>> whereas switches do; gigabit must use full duplex therefore gigabit >>> cannot use hubs. >>> >> Thanks for pointing that out. Maybe you could add a further >> enlightenment please? What is the difference between managed and >> unmanaged switches (besides the spelling!). >> >> Thanks. > >managed switches are programmed in a particular way, it allows you to >define (as an example) trunks.. which are multiple links from one switch >to another... trust me, all hell it let loose if you plug two unmanaged >switches together with 2 cables in to 2 ports... a trunk will multiply >the available bandwidth from one switch to another.. > >But thats just one thing managed switches can do... there are loads of >other things that they can do too.. > >- -- >Neil Stone A good many of the "better" unmanaged switches will also monitor and use STP, without being managable. As a general rule, a managed switch is configurable - ie in some way you will be able to connect to the switch, either with a webbrowser or a telnet/serial connection, and change the way it behaves. The scope of configuration options available to you varies dramatically depending on the make and model (and version of the operating system). Unmanaged switches will, generally speaking, be unconfigurable... that doesn't mean that they don't use some of the more interesting technologies (such as STP, mentioned above). --Grant -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html