When do you have two different subnet?

david90

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In an office environment, when do you separate the computers into two group and give each group a different subnet?
 
You might consider different subnets if you're looking to keep departments separate ... i.e. accounting, sales, warehouse. Or when you're working with different locations/sites that need to be networked via Terminal Services/VPN over internet ... i.e. Main Site - Seattle (10.1.1.x) Branch Site - New York (10.1.2.x).
 
You might consider different subnets if you're looking to keep departments separate ... i.e. accounting, sales, warehouse. Or when you're working with different locations/sites that need to be networked via Terminal Services/VPN over internet ... i.e. Main Site - Seattle (10.1.1.x) Branch Site - New York (10.1.2.x).

How can you share files between two different subnets using microsoft file share? Is it even possible?
 
... how is 10.1.1.x and 10.1.2.x subnetting? The subnet is 255.255.255.0, 255.255.0.0, or 255.0.0.0... The subnet is what tells the network, how many bytes of the network ip, belongs to which computer, or device on the network...
David - If you are wanting to share between two different subnets, it really doesn't matter, if it is within the same local area (which typically would mean on the same router), you can share with ease... Personally, if you are going to share files, it is best to use ftp, or a web-based system... Though using microsoft, it will not be secure to the least bit... But you can open it up for ftp, vpn, or local area network sharing... Most of the time, the LAN sharing will only broadcast through it's local router, it will not go beyond that unless you set it up to do so (by default it will think that beyond it's router is the internet)... But then you have to go into more then just subnetting for that...
Say for instance you have 10 computers, and 4 routers... You want all the computers running on the same network ip... You want one computer to be close to the modem, while the rest will be running off the other routers in other areas... You then set your primary router to the LAN ip you want, and set it's subnet to 255.255.255.255, you then hook the other three routers to the primary router, setting the routers to the LAN ip and subnets; 255.255.255.0, 255.255.0.0, 255.0.0.0; respectively of course... Using this method, most file sharing software such as Microsoft file share, will broadcast through all the routers because they are all using the same LAN ip, the router will then take care of the subnetting... (or so as to I remember it should)... Also, this means that more then one computer can have the exact same ip address, so long as they have different subnets; or so as I remember it... (it has been a long time since I have done subnetting...)(just so you know, I could be wrong about the same ips, they may still have to have different ips..)
 
just so you know, I could be wrong about the same ips, they may still have to have different ips..)


Hmmm ... yeah I wondered about that too ... hence the need for 10.1.1.x for one subnet, then 10.1.2.x (or whatever you want to do to make it a different unique subnet/network) for another. Guess that's why I suggested that. Your suggestion is definitely an option ... seems limited to just a single location though. When you're trying to communicate over WAN you'd run into issues with firewall/VPN hardware needing different ip address schemes that use the same subnet mask. This is especially true if you're saying that the same ip address can be used on mulitple computers. Wow! That'd make for a headache. Guess that would create job security if you're always having to resolve that problem ... and you would daily. Why would you want to do that?!?

I realize that subnetting may (key word --> may) require subnet mask changes (it isn't always necessary), but in an attempt to possibly make it easier on the O.P. why mess with subnet masking when you can use the default mask of 255.255.255.0 and just change the 3rd octet a little? Just trying to make it a little easier.

If you really want to get down to the nitty gritty then all you'd have to do if using 192.168.1.x put the subnet mask at 255.255.255.128 and that will split that into a 2 subnet network within 192.168.1.1-127 and 192.168.129-255. But for someone who might not have a working knowledge of how to APPLY a subnet mask correctly, this might be too confusing.
 
Well my suggestion wasn't meant to be an option... A subnet is what I explained.
Though Cross, your right it is much easier to just change the third octect and be done with it... Coming from reading some of the CCNA books, that is what they explained subnetting/subnet to be. I just wanted to make sure he knew what the subnet was, not just changing the octets...
 
Didn't really ask about what a subnet was ... just when to use different subnets. Your suggestion of using multiple routers to direct traffic to a single router (I assumed at a single location) seemed a little over the top, but that is what I meant as your suggestion. And now that I'm aware that you're reading CCNA books ... I get where you're coming from. Your suggestion also brings up the need for some serious hardware to make all that play out.
 
Keep in mind, it has been awhile since I have read those CCNA books (since college actually; 5 years).
Well the CCNA books, covers networking for more on commercial, as well as consumer products... Honestly, 4 linksys routers will do that just fine... As well as any consumer product... I would not see that as serious hardware.. Now when you are talking about pix firewalls, or Cisco 36-port gigabit router and firewall (if I remember correctly a 2 million dollar piece of equipment), that would be serious hardware...
 
Hey David
I'm having more questions than answers and just to give you a little food for thought (maybe or maybe not)
Subnet the network: most cases would be better control over network traffic if there is too much going on (traffic). You might want to subnet also just for topography (but not necessary) reasons 1st floor 2nd floor and 5th floor and as already said by CrossCech might want to keep departments isolated from each other accounting, warehouse, terminal services and so on. There is also a company has their own web server and wants to keep it on a separate network from the rest of the companies servers and workstations. But you also brought up about the two networks seeing each other's shares. So I have to ask why are you thinking of sub netting? As far as the MS shares you won't be able to see them on a different subnet, but it can be done.
Things I have to ask. How many routers, switches and clients? How would you implement this, what I mean. Is the network DHCP? How are you going to implement who is on what network? Or would the one network be static addressing (which would be fine). So kind of need to know your hardware situation a little better. A fair amount of ways to go about it.

A few situations, nothing is in stone and other people can have better ideas.
Going to assume there is a router in place for internet (call it R1) and also going to ASSUME it has two interfaces (internet and your place of business) you want 2 networks basically. You could get two more routers (both going to R1) one to address each network (or subnetwork) this can be two fold because it can also take care of addressing for each network since most routers have DHCP.
So I like CrossCech's method let's just change the third octet in 192.168.***.***/24 scheme
R1 interface (1) (internet ***.***.***.*** whatever)
R1 interface (2) (Your office) 192.168.0.1/24 configure this routers DHCP for this network
R2 interface (1) 192.168.0.2/24
R2 interface (2) 192.168.1.1/24 configure this routers DHCP for this network
R3 interface (1) 192.168.0.3/24
R3 interface (2) 192.168.2.1/24 configure this routers DHCP for this network

All routers you would have to enable RIP, once the routers learn of the other networks you can now target any share by IP, but not see it (at least the other network). A WINS server should solve that problem.
The Wins server can be placed on any of the local networks we are dealing with 192.168.0.0 or 192.168.1.0 or 192.168.2.0 but all of the client computers must know where the server is so when configuring the DHCP on the routers for networks 192.168.1.0 and 192.168.2.0 don't forget the WIN's server address.


The above scenario is fairly ideal but like I said depends on your hardware.
In the example I went with three networks instead of two
 
Axegrinder - Granted you are right... Though his question was not when do you sub-network... His question is when do you change subnets... The subnet is the subnet mask... As I said before, the subnet / mask is to tell the network, routers, switches, hubs, ect. ; how many bytes of the ip belong to which device... This way you can use one single ip over multiple routers, or multiple hubs, or multiple switches, ect.; without having to change the ip...
Another example I could give you guys that would explain using subnetting as well as sub-networking...
Ok say you have a static-ip from your ISP, now lets say you have a 300mbps service, but only 1 ip... You could use a switch, router, modem ect. to expand that one single IP over 3 networks, with each network providing service to their own networks...
So you have your modem able to connect 3 routers/firewalls, now you don't want to use different ips cause you want all the networks to have the same IP from your ISP. Now you assign each router the same ip but with different subnets, 255.255.255.255, 255.255.255.0, 255.255.0.0; respectively of course. Now each of these routers/firewalls will have the same Internet IP address, providing service to 3 networks and each network can be networked from there, using the methods of which CrossCech and Axegrinder mentioned...
So you have your one network for say your personal use, one network for say web-hosting, and one network for say business record keeping...
Your personal network router, is going to assign your computers it's own network ips...
So on and so forth, if you wish to segregate farther using different LAN ips you can do so..
 
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