Restructure the Network

[Aelara]

Hello, We operate a network of 420 workstations and 30 servers. There are also a number of network decvices eg Switches, Printers, IP cams etc which require IP addresses. We have maxed the 512 IP address range and need to change the subneting setup to accommodate another 150 workstations due to expansion. Total required capacity on the network is 800 including spare IP's and future expansion.

How do I go about it? Is it as simple as working out the new IP range and systematically changing workstation/server/printer IP's? What about the 3 DNS servers? We are currently on fixed IP's throughout the domain but would entertain moving to DHCP. There are reasons why we decided to go static but that's a tail for another day.

What's the best way to approach this?

Regards, Aelara.

 

[58sniper]

You should absolutely go to DHCP. For everything except servers, switches, and routers. You can assign reserved IP addresses to things like printers.

But you also have to consider what having that many devices in one subnet will do. It might make more sense to have separate subnets to keep chatter down.

If you do keep them on one subnet, you're going to miss things. You have to touch every device. EVERY DEVICE. Printers, switches, routers, servers, workstations, wireless access points, etc.

You also have to touch things like email servers that allow relaying, applications that talk to other devices, etc.

Not a plan for the faint of heart. Proper planning will mean everything.

Pat Richard
Microsoft Exchange MVP
Contributing author Microsoft Exchange Server 2007: The Complete Reference

 

[Dublin73]

Hi, DHCP is the way to go alright. I don't know what type of network gear you have, what layer switches they are, how many routers you have etc., but a few things to consider from a network point of view are....

when your clients are shouting out (sending a network broadcast) for an IP address, this communication doesn't take place between the client and DHCP server only, it takes place across multiple places on the network and will hit multiple switches, thus (temporarily) adding to the traffic across the network.

These DHCP broadcasts cannot pass through routers to get to DHCP servers by default (with Cisco gear this can be catered for by the use of an ip helper.. more info on google)

Broadcasts also do not pass through VLANs on the network

Based on the two points above, it's quite common practice to segment a large network into VLANS. This way, any network broadcasts that are sent out, remain on the local VLAN and don't spill over onto the rest of the network

Regarding your actual DHCP servers. With a few hundred clients, you want to cater for real time failover, should one DHCP server go down. A "100 100" failover scenario is good here, see link...

http://searchwincomputing.techtarget.com/tip/0,289483,sid68_gci1197499,00.html

good luck with it

 

[Aelara]

Thanks Guys, Going on the assumption that we decide to change the subneting and touch every device on the network during implementation what do I need to worry about? What effect would it have on the current setup if i changed the IP's on all the servers to the new range? The workstation would be set to get Dynamics IP's and obviously I'd reserve IP's for printers, switches etc.

I guess my question is this, On the assumption that its all planned for will anything get screwed up if we simply changes IP range? DNS servers would be changed to also reflect the change.

Thanks, Aelara

 

[Aelara]

If we were to decide to create seperate subnets on the network and break it up into 3 networks for example what is the method used for getting all workstations accessing the same set of servers? If I were to break up the 420 workstation into 3 new subnets of 140 workstations how do I go about ensuring they all authenticate against and connect to the 30 servers which are required. DNS? How will that work?

Forgive my ignorance but subnetting has always been cause of many headaches.

 

[58sniper]

Connectivity between subnets is routing. It has nothing to do, really, with what servers you can authenticate to. You just need to make sure that all subnets are properly configured in Active Directory Sites and Services.

As long as their is routing between the subnets, you're fine.

Pat Richard
Microsoft Exchange MVP
Contributing author Microsoft Exchange Server 2007: The Complete Reference

 

[Aelara]

Thanks Sniper, My concern though is latency. Will there be a delay when a user request crosses subnets to reach the Servers?

How do I also deal with stand alone IP printers(Not listed in AD) if there is a need to get 2 subnets printing to it?

Many Thanks, Aelara.

 

[58sniper]

The latency is imposed by your equipment. There shouldn't be any noticeable latency if all of the subnets are local.

How you layout your printers is up to you. You could have a subnet or VLAN for them.

Pat Richard
Microsoft Exchange MVP
Contributing author Microsoft Exchange Server 2007: The Complete Reference

 

[Aelara]

I'm sorry to keep asking, But I would appreciate a bit more info on the segmentation of the existing setup.

At present the IT dept run on the following network IP range:

192.168.100.1 to 192.168.101.254 using submask 255.255.254.0 providing the 512 hosts. Can you give me an idea of the IP ranges required if we decided to break the network into 4 segmants with the ability to cope with the projected 800 hosts.

As mentioned before, I am strugliong to get my head round this one. What I'd like to do is separate the 4 main areas of the business but ensure interconectivity via the 3com infrastructure.

Kind Regards, Aelara.

 

[Dublin73]

Aelara, I'd recommend getting an IT Consulting company in to help you since you're in the early learning stages of TCP/IP and networks etc... you can really mess things up if you're not really sure of what you're doing

having said all that, here's a bit more info for you....

The number of hosts that a subnet can have depends on the mask. See link

http://www.google.ie/search?client=...subnetting+explained&meta=&btnG=Google+Search

you need to pick network IDs that are private, not in use on the internet, 192.168....... for example. You can look on google for more info on this as well.

If you have two different subnets (or 3 or 4 or 5 etc.), computers and devices that are on one subnet, can't talk to computers on other subnets without some form of routing between them. This routing is done by either a router or a switch with Layer 3 capabilities

for your situation, it'd be a good idea to draw out a map, with all of your network hardware and figure out how you're going to split things up. Again, keeping in mind the stuff about broadcasts etc..

 

[dearingkr]

I would strongly recommend no more that 150-200 devices per subnet.
Try to segment your network logically; by departments, geographically, etc.
It is also a good practice to put your servers in their own subnet.


MCSE CCNA CCDA

 

[Aelara]

Many Thanks guys, I'm 21 and new to the networking world. My Boss knowns his stuff inside out but has no time to explain things. At least now I'll be able to assist him as I have taken your helpful comments inboard.

Many thanks, Aelara