Hubs vs Switches
EDTECH Editor-Eiffert
From: Pat Carpenter <pcar...@mickey.esd113.wednet.edu>
My school is in the process of finally building a LAN (hopefully with the
aid of e-rate funds). I don't have much experience with networks and am
getting conflicting advice from two different "experts". One tells me that
we would be much smarter to go with switches rather than hubs; the other
one tells me our network isn't big enough to warrant using switches and
that switches are more trouble becasue they have to be "managed". We
will be starting out with about 25 machines connected to a router and 56k
line, but the WA state k-20 program will provide us with a t-1 line next
year and we will hopefully added more machines on to the network.
Would appreciate advice on this matter as I have to seek bids soon. We
will be getting an 80% discount on the e-rate.
TIA
Pat Carpenter
EDTECH Editor-Beil
From: stan kulikowski ii <stan...@pcola.gulf.net>
>X-From: Pat Carpenter <pcar...@mickey.esd113.wednet.edu>
hubs need management too, but less than bridgeworks.
hubs are clustered repeaters and network switches are advanced bridges.
the hubs will cost a lot less, but are limited in geographical range and
the complexity of the network that can grow with them. for 25 machines, a
switch is an expensive overkill, but you will have room to grow. indeed,
with a switch you generally connect it to three or more hubs each of which
governs a separate lan. lans are what a network switch switches. so if
your school is large enough to eventually contain three or more lans that
need to communicate, then a switch structure may be indicated. if you have
direct lan sharing with sites 5 km or more from your central campus, then a
switch may be indicated (although a network router is more economical).
i suspect your experts are disagreeing over the immediate expense versus
the long range plan. if the funds you have now are not extendable over the
next five years of growth, then the switch proposal may be looking out for
your expansion over that time period. if your funds are fairly adequate
and secure in the future, the hub proposal is to start small and add the
switch collapsed backbone after you install the several lans that will
need it. i must say that if you are bringing in a T1, that is in the
expense range to expect a network switch to make use of that much
bandwidth. the question should be resolved by estimating the data flow
expected. 25 stations just web browsing will not use up the T1, but half a
dozen running full motion video teleconferencing certainly would.
i suspect the hub will be the way you go, especially if your school's
expertese is limited. start simple and learn as you go. you need as
agressive admin to cover the needs of more complexity.
stan
=== god created time so everything would not happen at once
| | god created space so everything would not happen to me
--- -- lament of the overburdened
EDTECH Editor-Eiffert
From: Rick Gilson <rgi...@gppsd.ab.ca>
I would check out 3com's (not a free ad but they've worked well for our
school LAN) switches their ability to adjust load and scale up from 10
to 100 mb depending on the card outway the cost... particularly if you
are able to bring all of your line pulls back to a single center.
Rick Gilson
Pat Carpenter <pcar...@mickey.esd113.wednet.edu> wrote:
> My school is in the process of finally building a LAN (hopefully with the
> aid of e-rate funds). I don't have much experience with networks and am
> getting conflicting advice from two different "experts". One tells me that
> we would be much smarter to go with switches rather than hubs; the other
> one tells me our network isn't big enough to warrant using switches and
> that switches are more trouble becasue they have to be "managed". We
> will be starting out with about 25 machines connected to a router and 56k
> line, but the WA state k-20 program will provide us with a t-1 line next
> year and we will hopefully added more machines on to the network.
> Would appreciate advice on this matter as I have to seek bids soon. We
> will be getting an 80% discount on the e-rate.
Rick Gilson
EDTECH Editor-Eiffert
From: Craig Nansen <cra...@mail.minot.k12.nd.us>
Pat Carpenter <pcar...@mickey.esd113.wednet.edu> wrote:
>getting conflicting advice from two different "experts". One tells me that
>we would be much smarter to go with switches rather than hubs; the other
>one tells me our network isn't big enough to warrant using switches
You don't need a switch until you start getting several IDFs (racks) around
one building. We did not put switches into any of our schools that just had
the one MDF. Schools with one MDF and one or two IDF are marginal for
switches - we went without them but planned for possible upgrades.
>and
>that switches are more trouble becasue they have to be "managed".
This is not "trouble" but preferable. All of our hubs are also "managed"
which helps support a WAN. Our switches have taken 0 hours of support
during the past 12 months other than normal network monitoring.
>We
>will be starting out with about 25 machines connected to a router and 56k
>line, but the WA state k-20 program will provide us with a t-1 line next
>year and we will hopefully added more machines on to the network.
It sounds like a switch is not needed in this case, unless you are planning
for major additions to the network. Do go with managed hubs.
A simple explanation of a switch vrs an MDF that contains more than one
hub. Two 24 port hubs are treated as one big 48 port hub and all the
traffic gets handled as it comes in - a switch segments the two 24 port
segements (assume they are two different labs) and only passes info between
them that is meant for the other lab - reduces traffic and improves network
performance.
Craig Nansen If learning is an act of exploration,
Technology Coordinator then technology equips the explorer
Minot Public Schools for the journey of a lifetime.....
Minot, ND 58701
nan...@sendit.NoDak.edu Technology: opening minds with a
new set of keys
(701) 857-4427
(701) 857-4432 fax
http://minot.com/~nansen
EDTECH Editor-Eiffert
From: "Stephen E. Collins" <edt...@web66.coled.umn.edu>
You can get managed hubs or managed switches, so "management" isn't
really a factor in deciding between the two.
If you buy switches for your network, you're wasting money. Your
network isn't large enough to justify switches. Another use for
switches is to prevent node eavesdropping security breaches, but
I highly doubt your network justifies that either.
First find out if your school district has any plans to
"manage" your network. If they say "yes", ask them what "SNMP"
means. If they can answer that, then ask them to show you a good
hardware inventory that includes MAC addresses. Good intentions
aside, if they can't provide good responses then they aren't really
going to manage the network.
If they are REALLY managing your network, then buy hubs with
management or the ability to install management modules
later (vendor: Hewlett Packard).
Otherwise, buy a cheap hubs. $200 maximum for 24 ports (vendor: D-Link)
For a basic tutorial on setting up a school network, I invite you
to visit the Web66 Network Construction Set: http://web66.umn.edu/
>My school is in the process of finally building a LAN (hopefully with the
>aid of e-rate funds). I don't have much experience with networks and am
>getting conflicting advice from two different "experts". One tells me
that
>we would be much smarter to go with switches rather than hubs; the other
>one tells me our network isn't big enough to warrant using switches and
>that switches are more trouble becasue they have to be "managed". We
>will be starting out with about 25 machines connected to a router and 56k
>line, but the WA state k-20 program will provide us with a t-1 line next
>year and we will hopefully added more machines on to the network.
Stephen E. Collins
http://web66.umn.edu/
s...@web66.umn.edu
EDTECH Editor-Eiffert
From: Charles Kinsella <kins...@cin.net>
With a network of twenty five machines there is no reason to invest in a
switch. As your network grows you might want to look into the purchase of a
switch, but there an unswitched network should be able to run 50 - 60 machines
without a noticable degredation in performance.
I don't think the need for a switch to be "managed" is a good reason to avoid
a switch in the future.
Charlie Kinsella
kins...@cin.net
EDTECH Editor-Eiffert
From: Jake Miller <jmi...@dontsrvr.valverde.edu>
If you have the funds, I would recommend using switches. I will allow
you to build a network with future growth potential.
Hubs and switches embrace different technologies. A hub creates a shared
network. This is like being on a party line. Every computer on the
network has to listen to all other computers on the network talking and
determine if a conversaiton is ment for it. The computer takes up
processing time to "listen" to all of the "conversations" going on. In a
bad case, a computer can be using up 30% or more of its cpu time listing
to the network traffic. For example, if you have 25 computers on your
network and computer A sends a message to computer B, all 24 computers
listen to that message. Twenty three computers discard the message and
only computer B responds to it.
A switch creates an instantaneous private connection for each pair of
computers in a conversation. In the case above, computer A sends a
message to computer B, the switch "knows" to which port on the switch
computer B is connected and routes the message to computer B only. The
other 23 computers never have to deal with the message. At Val Verde we
are in the process of converting to switches from hubs. At some sites we
have over 100 computers on the network and you can imagine what
listening to all those "conversations" is like.
So why is this important? As we get into advanced multimedia being
distributed over the network, you don't want to bog down your network
with multimegabytes of streaming video being sent to every computer on
the network, when only one computer is acutally using the signal.
As far as having to manage switches - this is actually a good thing. You
really don't have to do anything, but the software in a switch or a
managed hub allows you to monitor the traffic on your network and
identify bottlenecks.
Hope this helps some.
Jake Miller
Technology Manager
Val Verde Unified School District
jmi...@valverde.edu
-If we couldn't laugh we would all go insane.
--Jimmy Buffett
EDTECH Editor-Eiffert
From: brian...@redlands.k12.ca.us
Well, I think both "experts" are right. 25 machines on a 56k line
probably do not warrant the added cost and management of a switch. But,
if you only have one-time funds and want to do it right, and have
capacity for future expansion, then get the switch.
If you don't know the difference, a hub splits the 10Mb bandwidth of
Ethernet among all workstations, a switch provides a dedicated 10Mb
circuit to each workstation. In other words, a hub with 25 users, if
each workstation was to send/receive data at the same time, would
provide a maximum of 10/25 Mb bandwidth (about 410Kb). You probably
won't notice a difference accessing the 'net, but sharing data or
downloading large files will make a big difference.
BTW, on't put all your eggs in the e-rate money. Right now, the feds
are not forcing the telecoms to put up all of the money, and even if
they did, by the time 2.5 billion is split between practically every
school in the country (I haven't heard on one school/district that isn't
at least trying for the $) I doubt there is going to be alot to go
around.
Brian Wood
Teacher on Assignment for Technology Staff Development &
Technology Mentor Teacher, Redlands Unified School District
brian...@redlands.k12.ca.us
(909)307-5300 x294 FAX (909)307-5322
EDTECH Editor-Eiffert
From: "Brad A. Nixon" <bni...@cyberdude.com>
With a that small of a network, a 24 port switch at the main distribution
facility would make your network extremely fast. Once a swithc is set up,
there is not much management to be done. You can use hubs in the classrooms
but try not to overdue it. If you have the money for a switch, I would go
for it.
Brad A. Nixon
Teacher on Assignment
California Technology Assistance Project
http://ctap.k12.ca.us