Networking Question

JRowdly2004

Hey y'all, I am currently studyin for the CCNA but I have a little networking question thats to advanced for me right now and was wondering if you could answer it. Its for work,

My boss has a Linksys WRT54G router (I know, it is a small business), which has 4 ports and 1 internet port. Out of that he wants me to hook up 4 different subnets. And i'm thinking that each subnet has to have it's own Ethernet port and ethernet line, so I would really need to buy a bigger and better router.

At first I was thinking that if I just had the address 192.168.1.100 w/ mask 255.255.255.192 I could make 4 subnets, but it would all be on the same ethernet line and the gateway would be of course all the same for all of the 4 networks, which then it wouldn't work. So, am I forced with going out and buying another router or is there an answer to what he wants?

Thanks all! Appreciate it!

markzab

Couple questions. You say it's a small business. Off of the 4 ethernet ports, will there just be one host attached or many? If many, HOW MANY is an important first step for each ethernet port in regards to your addressing scheme. Next, and I doubt it, but does this particular Linksys allow you to assign seperate IP's to each ethernet interface? Or are we talking about the same type of Linksys my brother had in his house?

Let me know how many users per subnet we're talking about and we can move further.

JRowdly2004

There is 3 on one subnet, 4 on the other, 6 on another subnet, and 5 on the other subnet. The linksys won't let you change much. It gives you the default 192.168.1.---, but it will let you choose the subnet you are wanting to work in. I'm sure its the same one your brother had.

tech-airman

JRowdly2004 wrote:

Hey y'all, I am currently studyin for the CCNA but I have a little networking question thats to advanced for me right now and was wondering if you could answer it. Its for work,

My boss has a Linksys WRT54G router (I know, it is a small business), which has 4 ports and 1 internet port. Out of that he wants me to hook up 4 different subnets. And i'm thinking that each subnet has to have it's own Ethernet port and ethernet line, so I would really need to buy a bigger and better router.

At first I was thinking that if I just had the address 192.168.1.100 w/ mask 255.255.255.192 I could make 4 subnets, but it would all be on the same ethernet line and the gateway would be of course all the same for all of the 4 networks, which then it wouldn't work. So, am I forced with going out and buying another router or is there an answer to what he wants?

Thanks all! Appreciate it!

JRowdly2004,

Questions:

1. What's the purpose of 4 subnets?
2. How many hosts per subnet?

JRowdly2004

He said he wanted subnets for different departments, one i know is HR, another is marketing and sales. He just wanted to split up the departments so there would be less traffic. 3 hosts one subnet, 4 on the other, 6 on another subnet, and 5 hosts on the other subnet.

markzab

Ok, so you definitely do need a router to set this up I'd say. As for your scheme, with those numbers of hosts per subnet you could go with an 8 host block across the board. However, if you want to be careful in regards to expension you might want to go with a 16 block because of that one subnet needing 6 hosts already. You'd be maxed on that one with an 8 block.

4 Subnets (not using IP subnet zero):
192.168.10.16 255.255.255.240 (valid hosts 17-30)
192.168.10.32 255.255.255.240 (valid hosts 33-46)
192.168.10.48 255.255.255.240 (valid hosts 49-62)
192.168.10.64 255.255.255.240 (valid hosts 65-7

Doesn't have to be a serious router I wouldn't think. I would suggest getting a switch as well and setting up VLANs. You'll not only create more collision domains that way but with VLANs you'll also break up broadcast domains.

sprkymrk

The 4 ethernet ports on that device are basically just a switch. The only routing the linksys does is between the WAN and those 4 ports, not between each individual port. Think of it like you have a router with a WAN and a single ethernet port, and you hooked up a 4-port switch to the ethernet port. That's what the linksys does.

So yes, you would need to buy a better layer 3 device to make it work the right way. You can either replace the linksys, or just buy a cheap router with 4 Eth ports and place it behind the linksys, but then you would still need a small workgroup switch on each interface unless you bought a good 24 port switch that you could use VLANS on.

tech-airman

JRowdly2004 wrote:

He said he wanted subnets for different departments, one i know is HR, another is marketing and sales. He just wanted to split up the departments so there would be less traffic. 3 hosts one subnet, 4 on the other, 6 on another subnet, and 5 hosts on the other subnet.

JRowdly2004,

Question:

1. Will there be any anticipated growth in any one or more departments in the near future? If so, which department(s) or subnet(s) and by how many?

emsrescue

I doubt a WRT54G supports vlans and inter vlan routing. If you raelly want to use the WRT you may be able to flash it with one of the open source images that support dot1q trunking and attach the router to a switch with 4 vlans setup.

One cheapish way to setup what your talking about with cisco kit is:

1720 router with a second ethernet interface and 2900 switch. Probably loooking at a couple of hundred bucks second hand. I have this setup at home in my lab but does suffer from having all the inter vlan traffic flowing over 1 100mb link. Expensive end of the spectrum = Layer 3 switch.

If your boss is looking at seperate vlans for the organisation he needs to up his IT budget a bit from a wrt.

What are the different departments accessing? Do you have internal servers for each department or is the wrt just acting as a gateway to the internet?

If its just an internet gateway then I cant see how vlans is going to help any.

Jon

ElvisG

Even if the WRT54G could be flashed to support multiple vlans I still don't think a cable or dsl internet connection will support 18 computers.

Eighteen computers plus any future computers that you are going to add is going to suffer when trying to access the internet.

40 Kbps down and 8 Kbps up, per computer, is not good for bandwidth going out the LAN.

If you have a T-1 or better than ignore this post.

emsrescue

Even if the WRT54G could be flashed to support multiple vlans I still don't think a cable or dsl internet connection will support 18 computers.

I work for a cable company and we provide cable modems for SME's with 25+ employees. A 5-10Mb cable modem connection is more than enough depending on how you are using it. If all your employees are browsing the web all day then its got no chance but if its email, some web & the occasional file transfer then its ideal and a hell of a lot cheaper than what we charge for a leased line.

Jon