Overall networking issue...

I have the problem that I have to install a server on a larger
professional 100Mbit/s CAT-5 network (with about 100 desktop computers
connected and up to 2-300 more on wireless connections). This network
already has a well-functioning structure, where it is easy to transmit
information at speeds up to 100Mbit/s (the network works). My problem is
that I am not happy with the 100Mbit/s restrictions. The server already
has gigabit network card(s)... And I am wondering how/if it will be
possible to use the gigabit speed without having to change the basic
structure of the network. Because the network is already up and running,
I will get a hard time finding the funds to change everything, and since
100Mbit/s is sufficient in the vast majority of situations, it should
not be necessary.

What would happen if one for instance attached a standard (cheap)
unmanaged gigabit switch (eg. a D-Link DGS-1008D) for such a network.
The server for one port, and the remaining 8 ports connected to the
existing 100Mbit/s network (we can find 8 vacant ports in the existing
structure). Would this give any increase in network speed with the
possibility of 2 (or more) computers at the same time being able to use
the data from the server at speeds closer to the 100Mbit/s. According to
benchmarks the server can read and write the data quite a bit faster
than required by a gigabit connection.

I apologize if this is an absolutely ridiculous question. My hands-on
experience with this aspect of larger networks is unfortunately limited,
and therefore I hope for constructive advice from you.

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.

On Sat, 25 Oct 2008 23:47:25 +0200, Jacob Tranholm rearranged some
electrons to say:

> I have the problem that I have to install a server on a larger
> professional 100Mbit/s CAT-5 network (with about 100 desktop computers
> connected and up to 2-300 more on wireless connections). This network
> already has a well-functioning structure, where it is easy to transmit
> information at speeds up to 100Mbit/s (the network works). My problem is
> that I am not happy with the 100Mbit/s restrictions. The server already
> has gigabit network card(s)... And I am wondering how/if it will be
> possible to use the gigabit speed without having to change the basic
> structure of the network. Because the network is already up and running,
> I will get a hard time finding the funds to change everything, and since
> 100Mbit/s is sufficient in the vast majority of situations, it should
> not be necessary.
>
> What would happen if one for instance attached a standard (cheap)
> unmanaged gigabit switch (eg. a D-Link DGS-1008D) for such a network.
> The server for one port, and the remaining 8 ports connected to the
> existing 100Mbit/s network (we can find 8 vacant ports in the existing
> structure). Would this give any increase in network speed with the
> possibility of 2 (or more) computers at the same time being able to use
> the data from the server at speeds closer to the 100Mbit/s. According to
> benchmarks the server can read and write the data quite a bit faster
> than required by a gigabit connection.
>
> I apologize if this is an absolutely ridiculous question. My hands-on
> experience with this aspect of larger networks is unfortunately limited,
> and therefore I hope for constructive advice from you.

Unless you replace all the client NICs with gigabit-capable units, and
any switches or hubs with gigabit-capable units, nothing will be any
different than it is today.

david wrote:
> Unless you replace all the client NICs with gigabit-capable units, and
> any switches or hubs with gigabit-capable units, nothing will be any
> different than it is today.

That's possibly true... I have more software knowledge than hardware
knowledge regarding networks. And from a software point of view it
should be quite simple to bridge 8 100Mbit/s network-cards into a
gigabit compatible solution. Quite frankly I though this was what a
switch did... In this situation there is however no IP's assigned to the
8 switch-ports connected to the established network, and if I should
make a software solution for this, that might be a minor problem in the
management.

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.

Jacob Tranholm wrote:
>
> In this situation there is however no IP's assigned to the 8
> switch-ports connected to the established network, and if I should
> make a software solution for this, that might be a minor problem in
> the management.
>

A little correction to myself... I have just checked a few of my
previously configured software bridges, and the lack of an IP for each
network-cards will not represent a problem from the bridge point of
view. I don't know if this represents a problem to the hubs of the
established network. - It's late in Denmark and my brain isn't working
at it's peak. Sorry for the mistake in my previous answer.

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.

Jacob Tranholm wrote:

> I have the problem that I have to install a server on a larger
> professional 100Mbit/s CAT-5 network (with about 100 desktop computers
> connected and up to 2-300 more on wireless connections). This network
> already has a well-functioning structure, where it is easy to transmit
> information at speeds up to 100Mbit/s (the network works). My problem is
> that I am not happy with the 100Mbit/s restrictions. The server already
> has gigabit network card(s)... And I am wondering how/if it will be
> possible to use the gigabit speed without having to change the basic
> structure of the network. Because the network is already up and running,
> I will get a hard time finding the funds to change everything, and since
> 100Mbit/s is sufficient in the vast majority of situations, it should
> not be necessary.
>
The 100MBit-Switches, do they have dedicated uplink ports that may be
replaced by GB or optical links?

> What would happen if one for instance attached a standard (cheap)
> unmanaged gigabit switch (eg. a D-Link DGS-1008D) for such a network.
> The server for one port, and the remaining 8 ports connected to the
> existing 100Mbit/s network (we can find 8 vacant ports in the existing
> structure). Would this give any increase in network speed with the
> possibility of 2 (or more) computers at the same time being able to use
> the data from the server at speeds closer to the 100Mbit/s. According to
> benchmarks the server can read and write the data quite a bit faster
> than required by a gigabit connection.
>
You cannot split a single GB output into 2 or 8 100MBit lines - you would
just create loops.

--
vista policy violation: Microsoft optical mouse found penguin patterns
on mousepad. Partition scan in progress to remove offending
incompatible products. Reactivate MS software.
Linux 2.6.24. [LinuxCounter#295241,ICQ#4918962]

Jacob Tranholm wrote:
> I have the problem that I have to install a server on a larger
> professional 100Mbit/s CAT-5 network (with about 100 desktop computers
> connected and up to 2-300 more on wireless connections). This network
> already has a well-functioning structure, where it is easy to transmit
> information at speeds up to 100Mbit/s (the network works). My problem is
> that I am not happy with the 100Mbit/s restrictions. The server already
> has gigabit network card(s)... And I am wondering how/if it will be
> possible to use the gigabit speed without having to change the basic
> structure of the network. Because the network is already up and running,
> I will get a hard time finding the funds to change everything, and since
> 100Mbit/s is sufficient in the vast majority of situations, it should
> not be necessary.
>
> What would happen if one for instance attached a standard (cheap)
> unmanaged gigabit switch (eg. a D-Link DGS-1008D) for such a network.
> The server for one port, and the remaining 8 ports connected to the
> existing 100Mbit/s network (we can find 8 vacant ports in the existing
> structure). Would this give any increase in network speed with the
> possibility of 2 (or more) computers at the same time being able to use
> the data from the server at speeds closer to the 100Mbit/s. According to
> benchmarks the server can read and write the data quite a bit faster
> than required by a gigabit connection.
>
> I apologize if this is an absolutely ridiculous question. My hands-on
> experience with this aspect of larger networks is unfortunately limited,
> and therefore I hope for constructive advice from you.

It all depends on hour network infrastructure. No single client is ever
going to get more than 100 Mbit/s of course, but there might be ways to
increase the aggregate throughput.

If you have a single large switch in the middle of the network, then you
could upgrade the connection between your server and the switch. This
might require new hardware on the switch.

You can do the same thing if your network has several switches at its
core. Are the inter-switch links 100 Mbit/s or 1 Gbit/s? If the former
and management is planning on upgrading them to 1 Gbit/s, are they
planning to upgrade server links as well?

Finally, your cheap 'switch' solution also has the possibility of
getting aggregate speeds up over 100 Mbit/s. It would be simplest to
use a router, not a switch: put the server on its own subnet, and the
other subnets use different links via level 3 routing. If you only use
a level 2 switch, you need to have some way of keeping level 2 loop
avoidance from dropping all but one link. I'm not sure that your dumb
switch can do this.

Walter Mautner wrote:
> The 100MBit-Switches, do they have dedicated uplink ports that may be
> replaced by GB or optical links?

I have to admit that I have not checked this yet... The current Mbit
switches are naturally connected to each other, and I am guessing this
connection is in the gigabit class, and we also have a single switch
that uses a fiber connection to attach an internal network that is
located further away than the standard 100 meter. Quite frankly I have
played enough around with fiber-connections to *not* trust my own
knowledge in this area. And if I have to play around with this part of
the system, I will have to call in assistance from a professional. - And
that may end up being the solution... But I am working within a limited
budget (at a school), and was hoping for a simpler and cheaper solution.
At the moment there is 5 or 6 managed megabit rack-switches each with 48
RJ45 ports to the front and some connection to each other on the back (I
have not checked this part yet, and cannot do it until monday). And
there is also a rack-switch for our internal fiber (mentioned above),
and a rack-router/switch/something which handles our fiber internet
connection. - And then there is a lot of wires...

I spend most of my time in the server-room, and know too little about
our network. I have mostly just checked that the network-cables work,
replaced a few RJ45 plugs and moved a network-cable in case some
computer/server need direct internet-connection instead of going through
the internal network. So my knowledge is limited...

In this case I simply need a faster connection from two servers in the
server-room to the wired computers. First of all I am getting tired of
having to carry the computers to a different location in order to write
new images to the harddisks (the school is using Windows XP, and the
computers collect a lot of garbage and it is easier to clone them at
least every 3 months - every month would be better). At the moment we
are using a separate network for cloning the computers, and I was
thinking that it should be possible to do this using the existing
network and clone the computers at their current location, if we had a
faster connection from the client computers to the cloning-server. This
is ment to happen late in the afternoon when nobody else is using the
network. - Second of all the fileserver is extremely slow from the
client-computers when a lot of people is using it at the same time. This
is quite natural considering everything has to go through a 100Mbit/s
connection and if there is 100 clients...

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.

Allen McIntosh wrote:
>
> It all depends on hour network infrastructure. No single client is ever
> going to get more than 100 Mbit/s of course, but there might be ways to
> increase the aggregate throughput.
>
> If you have a single large switch in the middle of the network, then you
> could upgrade the connection between your server and the switch. This
> might require new hardware on the switch.
>
> You can do the same thing if your network has several switches at its
> core. Are the inter-switch links 100 Mbit/s or 1 Gbit/s? If the former
> and management is planning on upgrading them to 1 Gbit/s, are they
> planning to upgrade server links as well?

There are several switches (5 or 6 48 port rack-switches (they are some
years old, but they still work)), but I have not checked which
connection speed they use internally (between them self). Management
isn't planning anything... This is not a big company we are walking
about, it's a school, and we are working within a limited budget... And
most of our students use their own computers and connect through the
wireless network, where they also have the possibility of accessing the
fileserver. And the stationary computers all use the fileserver for
storing/reading user-files. And the fileserver is the major reason why
we need a faster connection from the server-room to the
switches/hubs/routers/whatevertheyare where every network cable is
connected. - For the clients megabit should be enough.

> Finally, your cheap 'switch' solution also has the possibility of
> getting aggregate speeds up over 100 Mbit/s. It would be simplest to
> use a router, not a switch: put the server on its own subnet, and the
> other subnets use different links via level 3 routing. If you only use
> a level 2 switch, you need to have some way of keeping level 2 loop
> avoidance from dropping all but one link. I'm not sure that your dumb
> switch can do this.

Thanks... This has given me ideas that I will try tomorrow. As for my
"dumb switch" I was actually more worried about that it might bring the
intire network down because it (in my mind) gave an alternate connection
between the existing switches/hubs. And I am not sure they are
configured to ignore this connection and only use their primary internal
connection.

In my previous experiences with this I have left the network unchanged,
and for instance added a network card with 4 ports, connected all 4
ports and have done a software bridging (from Linux or *BSD). But this
was back when gigabit networking was much more expensive... But if I
should use this approach this time, we would have to add more CAT-5
cables between the server-room and the switches, and there is a slight
distance between the two. And this would only solve the problem for one
server...

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.

Jacob Tranholm wrote:

> There are several switches (5 or 6 48 port rack-switches (they are
> some years old, but they still work)), but I have not checked which
> connection speed they use internally (between them self). Management
> isn't planning anything... This is not a big company we are walking
> about, it's a school, and we are working within a limited budget...

Don't forget that the passive infrastructure (cables, wall outlets etc)
might not be suitable for Gbit networking. Replacing these can easily
be much more expensive than buying a few switches.
Here we lost half of our wall outlets because the 1000Base-T needs eight
wires on CAT-5 cables instead of four for fast ethernet.

> And most of our students use their own computers and connect through
> the wireless network, where they also have the possibility of
> accessing the fileserver. And the stationary computers all use the
> fileserver for storing/reading user-files. And the fileserver is the
> major reason why we need a faster connection from the server-room to
> the switches/hubs/routers/whatevertheyare where every network cable is
> connected. - For the clients megabit should be enough.

This should work. All Gbit switches I'm aware of negotiate the standard
with the network card attached to one of the ports. So mixing the two
standards in not a problem and works just fine here.

Günther

Walter Mautner wrote:
>
> The 100MBit-Switches, do they have dedicated uplink ports that may be
> replaced by GB or optical links?
>

No... I have studied the structure a bit closer today. And the fastest
connections used in the rack are 100Mbit/s CAT5 RJ45 cables. At the
moment there is about ten 24-ports 100Mbit/s switches and one
fiber-connection to a remote building. And all of these are connected to
each other using standard 100Mbit/s CAT5 cables. - And we have to make
some changes to get a gigabit connection for our servers. At the moment
I am thinking about buying a new gigabit backbone switch that I can
connect all of the other switches to, and this gigabit switch should
have enough extra ports so that all of the internal servers can connect
here directly (a 24-ports gigabit switch should be enough). That way it
should be possible to get 100Mbit/s from the servers to each of the
older megabit switches. This should give a more acceptable speed for the
clients connection to the fileserver (through the older megabit switches).

At the moment my biggest problem is, that I have to figure out which
24-ports gigabit backbone switch to buy. And the marked for these
switches is so huge that I cannot decide... I am looking for something
with 24 gigabit ports, that auto-negotiates the connection speed (most
switches do). But regarding the management features I am still wondering
which would be better. There should probably be some minor layer 2
management functions, but not too complicated, and it would be easier if
the switch did most of the configuration itself (I am the only
linux-nerd). We also still have a limited budget, so the price is also
an issue. - If you have any suggestions for a good 24-ports gigabit
backbone switch that can handle this task, I will appreciate it.

--
Best regards Jacob Tranholm <http://jtranholm.dk/>
Karl R. Popper: Observation statements and statements of experimental
results are always interpretations of the facts observed.