Network Segmentation

[lando09]

I have a single network with my servers connecting to a 3COM switch which inturn connects to a 3Com Fiber Switch. This fiber switch then feeds via fiber 3com hubstacks on 3 different levels of the building. The hubstacks then connect the workstations via UTP cable. These hubstacks are located on both ends of the building on each level therefore having six hubstacks in total, two per level. Can some tell me what would be the best way of segmenting my network? If possible what all would I need to do to make this possible, routers, switches, etc, etc?? I already have a Cisco Router 1800 Series sitting on my desk doing nothing while i'm trying to figure out what's the best way to do this. Help anyone!

Lando

 

[bcastner]

If a network has only switches and no hubs then the collision domains are either reduced to a single link or, if both ends support full duplex, eliminated altogether.



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Users Helping Users

 

[LawnBoy]

If you've got all switches you're already as segmented as you're ever going to get...

What exactly are you trying to accomplish?

 

[lando09]

Well what I was thinking of doing since the oranization is broken into two major setions split my network into two. Having two networks and having these two networks talk to each other. Since the two major sections, one is on the 3rd level and the other is on the 2nd and 1st level then i would segment the network into these two.

 

[LawnBoy]

To give a good answer, I need to know what problem you're trying to solve. Are you running short on bandwidth? Do you want to isolate due to security concerns? Why change what's working?

These 3com "hubstacks" you mention, I don't find anything by that name on 3com's site, can you get a model number off one? Are they truly hubs not switches?

 

[lando09]

Yes bandwidth is one. The 3Com hubs are 3Com SuperStack II Dual Speed Hub 500. They come with 24 ports. These are located in each end of the 3 levels of the building. These feed the workstations via utp cable. Inturn these hubs are connected to a switch in our server room via fiber. Then this fiber switch is connected to another switch which has a 12port connection to our differnet servers.

 

[LawnBoy]

Basically, set a new switch in the server room and connect the level 3 hubs to it. Then place a router between the new switch and the old.

This isn't going to improve your useable bandwidth. Since most traffic is to-and-from your servers, the same number of PCs will be prsenting the same traffic load to the same servers.

If each network had their own servers, or if you increased the connection speed between the hubs and switches, it would increase the available bandwidth.

It would be far simpler to upgrade your hubs and switches.

 

[lando09]

Well I had in mind to change the hubs and switchs from a 100 to 1000 which I guess would increase the bandwidth. So by adding a switch on level 3 would still not improve the useable bandwidth .... i see. What if you divide the servers between the two network? Will this help? Since only the finance and admin dept connect to a server that would be on the level 1&2 network then workstation on level 3 network wouldn't need to cross to the level 1&2 network.

 

[LawnBoy]

Since only the finance and admin dept connect to a server that would be on the level 1&2 network then workstation on level 3 network wouldn't need to cross to the level 1&2 network.

Yes, level 3 having their own server would help considerably.

There is one gotcha, DHCP. A router will not pass DHCP (but it can (usually) be configured to be a DHCP server for the isolated network).

 

[lando09]

So what about having a DHCP server on both sides of the network?

 

[LawnBoy]

That's the easiest way...

 

[lando09]

So it would be best to have two different networks with each one having its own servers and using the router to let both network talk?

 

[LawnBoy]

Best" is a very relative term...

This is one way to increase the available bandwidth. It has the advantage of providing extra security between the user groups.

The simplest way to increase bandwidth would be to simply upgrade your hubs and switches.

 

[lando09]

Well I want to the get the "best' out of the two, increase bandwidth and segment my network, do you have an e-mail address so i can send you a snapshot of what i have and what finally you recommend?

 

[LawnBoy]

Well that depends on whether you can afford my consulting fees...

Seriously, it would be difficult for me to do much specific work without an on-site visit. I recommend that you hire a local consultant for a few hours. His/her report will give you extra confidence and some backing if your mgmt ever wants to know what the !@@#!#! you were thinking.

If you are considering upgrading your switches too I highly recommend HP's Procurve series. Excellent value for the money.