IP addressing

Hi all, I recently started trying to understand how networks are setup, primarily because of a school project I have to make in which I have to simulate the creation of a network from scratch in an enterprise, I don’t need something very elaborate, just basics. I’ve read some useful posts on this forum and I thought I might as well ask something that I have not understand quite well yet. I’m supposed to include at least 200 PCs in the network I’ll simulate, so I’m thinking I should just use a single real ip address from an ISP on a router, then connect this router to five different switches, all of which will have 40 PC’s connected to them, I guess this way the real IP address would be setup on the router and then I would be able to setup virtual addresses to every computer that is connected to a switch. Now my questions are:
1. Is it ok to use a single real IP address for such a high number of computers? The router would only really be connected only to five switches and I’m guessing it should be a very fast connection, like 100mbps or something.
2. Is it ok to setup the network just like that? Or do I need some kind of server or those layer 3 switches I’ve been hearing about?
3. In case I used more than a single real Ip address, how would I connect them? Would they each need a router? And in that case, how would the routers communicate with each other?
Any help would be really appreciated

 

1. Yes, that is how most businesses operate. The router and switches would generally have a 1Gb/s or 10Gb/s connection between them, this is known as the network "backbone" as it is the channel all the data is routed down.

2. You need at least a DHCP server and a DNS server. These may or may not be built into the router, but I would recommend placing these services on a server to reduce load on the router. You will need at least one server anyway for a domain, and maybe more for other functions, so you may as well put DNS and DHCP on there.

3. Only need 1 IP for the company internet router.

BTW, 40 computers on 1 switch is a little unrealistic in terms of load. I would recommend at most 20 computers on 1 switch.

 

If you want to use vlans, youll either need to set up inter-vlan routing on your router or use a layer 3 switch. usually the layer 3 switch would be your core switch, with your other switches trunking to the core.

 

Tnx for the very useful reply, I just have a quick question about the servers you mention that would have to be setup, I'm thinking this kind of servers are setup on a computer with a server OS right? if so, do I connect this computer directly into the router? and do I need a server computer for each service, like one for DNS and one for DHCP, or can a single server handle both?

tnx, one question about that, from what I've read, VLANs are used when I want to group some Ip addresses that are not physically on the same location right? In my case for example If I wanted to have all the PCs connected to two of my switches communicate with each other that's when I'd need a vlan right?

 

no, you dont need vlans to connect switches. vlans can help you manage groups of computers though. say if you have 4 rooms, you can seperate them on your switch by creating a vlan for each room. you can use them for security too. like if your admissions vlan should not have access to your administration vlan, you can create acl's to do that.

you never really "need" vlans, but they can help your manage your switches, manage ACLs according to IP addressing schemes of computers in certain VLANs, provide you with less broadcast traffic through out your network...

If you dont want to use vlans, you dont need a L3 switch.