Networking -- switches vs hubs ??

Networking -- switches vs hubs ??

Post by Martha H Ada » Wed, 25 Apr 2001 20:46:18



I've just picked up some hardware for making a network, and reading in the
accompanying manuals, I see "switches" and "hubs" in a baseT network are
either same thing for practical purposes -- or different; and I can't guess
which out of the manuals.  The "switch" I have here is a Linksys EZSX55W
5-port switch Version 2.0.  Apparently it's appropriate and I can use it to
network a few desktops and laptops that I have in my home; but I'd like to
be sure.

Can someone advise me on this?

<comment>  My above is really an amazing question.  A few years ago most
people thought it was remarkable if not extravagant, to have *one* computer
in your home.  Here I am thinking about four or more (maybe even a Beowulf
array).  For someone who grew up in the 1930's, this is unexpected and
runaway-velocity change.

Cheers -- Martha Adams

 
 
 

Networking -- switches vs hubs ??

Post by Kwan Low » Wed, 25 Apr 2001 23:09:07



Quote:> I've just picked up some hardware for making a network, and reading in the
> accompanying manuals, I see "switches" and "hubs" in a baseT network are
> either same thing for practical purposes -- or different; and I can't guess
> which out of the manuals.  The "switch" I have here is a Linksys EZSX55W
> 5-port switch Version 2.0.  Apparently it's appropriate and I can use it to
> network a few desktops and laptops that I have in my home; but I'd like to
> be sure.
> Can someone advise me on this?

A switch isolates the connection from one machine to the next. A hub allows
everyone on that network to hear. Because of this, switches have more complex
circuitry and are more expensive than hubs.
In a home network with minimal traffic a hub is all that's needed. In a larger
environment switches make better use of the bandwidth.
Quote:> array).  For someone who grew up in the 1930's, this is unexpected and
> runaway-velocity change.

Impressive... You seem to be a remarkable individual... :)
Quote:> Cheers -- Martha Adams


 
 
 

Networking -- switches vs hubs ??

Post by Eric P. McC » Wed, 25 Apr 2001 23:21:40



Quote:> I've just picked up some hardware for making a network, and reading in the
> accompanying manuals, I see "switches" and "hubs" in a baseT network are
> either same thing for practical purposes -- or different; and I can't guess
> which out of the manuals.

The short answer is that hubs share bandwidth, whereas switches have
dedicated bandwidth for each port.  On a hub, the sum bandwidth of all
ports cannot exceed the port speed - meaning that if one computer is
sending out 8Mb/s, the other can only send at 2Mb/s (on a 10BT hub).
On a switch, each port can operate at maximum speed simultaneously,
assuming the backplane is good enough to handle it.  So on a 10BT
switch, all computers can be pushing out 10Mb/s at once.

The simple reason for this is that hubs broadcast all data, whereas
switches are smarter and only broadcast some.  If you have, say, 8
computers on a hub, any adapter in promiscuous mode can monitor _all_
traffic on the hub, no matter where it's going.  On a switch, this is
(generally) not the case.

--

  "Knowing that a lot of people across the world with Geocities sites
absolutely despise me is about the only thing that can add a positive
spin to this situation."  - Something Awful, 1/11/2001

 
 
 

Networking -- switches vs hubs ??

Post by Joe Pfeiffe » Thu, 26 Apr 2001 08:06:53



Quote:> I've just picked up some hardware for making a network, and reading in the
> accompanying manuals, I see "switches" and "hubs" in a baseT network are
> either same thing for practical purposes -- or different; and I can't guess
> which out of the manuals.  The "switch" I have here is a Linksys EZSX55W
> 5-port switch Version 2.0.  Apparently it's appropriate and I can use it to
> network a few desktops and laptops that I have in my home; but I'd like to
> be sure.

A couple of other people have given correct answers about the
difference; the only thing I'd add is that what it adds up to is that
they work interchangeably in a network, but switches have higher
performance.
--
Joseph J. Pfeiffer, Jr., Ph.D.       Phone -- (505) 646-1605
Department of Computer Science       FAX   -- (505) 646-1002
New Mexico State University          http://www.cs.nmsu.edu/~pfeiffer
SWNMRSEF:  http://www.nmsu.edu/~scifair
 
 
 

Networking -- switches vs hubs ??

Post by Martha H Ada » Thu, 26 Apr 2001 09:58:03


Hi Joseph and others.  Thanks for responses.  Now all I have to do is get
my network set up and get it to *work.*  

My myself-only application for a network in my home is, to have a machine
in a dedicated spot for my fiction writing; another machine there which
runs without keyboard and monitor for some remote-computing work, probably
fractals; two or three machines in my livingroom for general hacking; and
a dedicated machine running a firewall.  ...It wasn't all that long ago,
some Big Name pronounced there *might* be work in this world for three or
four computers.  Well!  Cheers -- Martha Adams

 
 
 

Networking -- switches vs hubs ??

Post by Michael Meissne » Thu, 26 Apr 2001 14:57:46



Quote:> The short answer is that hubs share bandwidth, whereas switches have
> dedicated bandwidth for each port.  On a hub, the sum bandwidth of all
> ports cannot exceed the port speed - meaning that if one computer is
> sending out 8Mb/s, the other can only send at 2Mb/s (on a 10BT hub).
> On a switch, each port can operate at maximum speed simultaneously,
> assuming the backplane is good enough to handle it.  So on a 10BT
> switch, all computers can be pushing out 10Mb/s at once.

Actually for most cards, on a 10Mb/s network, switches can put the card into
full duplex mode, giving you double the bandwidth (the rating is in terms of
the normal half duplex mode where a network card can be receiving or sending,
but not both at the same time).

In theory, switches can also prevent a host from enabling promiscuous mode on
the ethernet card and reading all packets that come over the wire (with a
switch, they would only see the packets destined for their particular ethernet
adapter, or the broadcast packets that everybody sees).

Another place where you need switches is when you have more hubs than you can
connect together and stay within specs.  For example, the spec for 100Mbs
networks is 2 hubs hooked together with a maximum distance between any 2
computers being limited to some value (100 feet?).  At one point, I needed to
have 3 hubs in my house due to having computers spread out, and so I got a 5
port switch to connect the 3 hubs together (each hub plugs into the switch).

--
Michael Meissner, Red Hat, Inc.  (GCC group)
PMB 198, 174 Littleton Road #3, Westford, Massachusetts 01886, USA


 
 
 

Networking -- switches vs hubs ??

Post by Glitc » Thu, 26 Apr 2001 16:59:11





> Another place where you need switches is when you have more hubs than
> you can connect together and stay within specs.  For example, the spec
> for 100Mbs networks is 2 hubs hooked together with a maximum distance
> between any 2 computers being limited to some value (100 feet?).  At

one

The standard length for a segment of 10/100BaseT is 100 meters, so around
310 feet or so, including patch cable length.

Quote:> point, I needed to have 3 hubs in my house due to having computers
> spread out, and so I got a 5 port switch to connect the 3 hubs together
> (each hub plugs into the switch).

 
 
 

Networking -- switches vs hubs ??

Post by Jonadab the Unsightly O » Wed, 09 May 2001 04:48:05



Quote:> I've just picked up some hardware for making a network, and reading in the
> accompanying manuals, I see "switches" and "hubs" in a baseT network are
> either same thing for practical purposes -- or different;

A hub is defined by the fact that it has multiple ports -- more
than two, at any rate, and usually at least five.  A switch is
defined by the fact that it sends packets only where they need
to go, rather than everywhere.  In theory you can have a
standalone switch with only two ports, connecting two segments
of a network.  In practice, I think most switches these days are
also hubs (i.e., have multiple ports).  Sometimes they're called
switching hubs.  

As others have pointed out, a non-switching hub broadcasts
everything because it doesn't know or care where a packet's
destination is connected.  A switch sends the packet just
where it needs to go (according to the MAC address if it's
an ethernet switch).

Then there are routers.  Routers operate at the network
layer (e.g., IP) and know about subnets.  Most hardware
routers (e.g., Cisco routers) also are switching hubs,
but a device can function as a router with as few as two
ports (one for each subnet).  

For example, I have a Linux box in my room that has one
eithernet card and one modem, and it functions as a router
connecting the household LAN (ethernet) to the internet
(via dialup ppp).  It also does IP Masquerading.  The
ethernet card on the router is cabled to a switching
hub, which connects to the other computer (soon to be
computers) on the LAN.

- jonadab

 
 
 

Networking -- switches vs hubs ??

Post by SammyTheSna » Wed, 09 May 2001 19:57:33




>Then there are routers.  Routers operate at the network
>layer (e.g., IP) and know about subnets.  Most hardware
>routers (e.g., Cisco routers) also are switching hubs,
>but a device can function as a router with as few as two
>ports (one for each subnet).  

sorry to add another jargonised word into the fray, but isn't a switch /
router with only two ports more of a gateway?

Cheers & God bless
SammyTheSnake
--

Linux, Hardware & Juggling specialist :-) | job, if you can help, e-mail me :)
Wheels: bike, 'ickle bike, and unicycle.  | /o \/ Working on 5 ball 1/2 shower

 
 
 

1. cheap switch or expensive hub? (switch/hub recommendations)

It seems that you can now get a:

D-Link (D-Link DSS-16 Fast Ethernet Switch 2), Nortel (Nortel NetGear
FS516), or even a Farallon (Farallon Fast Starlet Switch/ 16 PN9160),
or Intel (Intel Express 410T Standalone Switch) unmanaged switch for
the price of a 3com Superstack II 10/100 hub.

Anyone happy using these see success?

Is a cheap switch equal to, or better, then an excellant hub?

Sent via Deja.com http://www.deja.com/
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