Subnetting Help

[dd1313]

Hi Guys

I have 3 branches:-

Branch one

40 users and another 10 if you include servers and printers etc

Branch two

15 users and 2 more

Branch three

15 users and 2 more

Looking for the best way to subnet these please.

thanks
DD

 

[syntax]

you will need a /26 for the branch one (so 255.255.255.192)
use /27 for branch 2 and 3 (so 255.255.255.224)

so if you have 192.168.0.0/24

Branch 1
192.168.0.0 - 192.168.0.63 (usable from .1 - .62

Branch 2
192.168.0.64 - 192.168.0.95 (usable from .65 - 94)

Branch 3
192.168.0.96 - 192.168.0.127 (usable from .97 to .126)

 

[RoganDawes]

Or just give each of them a private Class C. It's not like you are paying for them

I guess my point is that you haven't given any constraints to suggest that the above is not a valid solution, and is certainly the simplest one.

 

[InvisibleJim]

you will need a /26 for the branch one (so 255.255.255.192)
use /27 for branch 2 and 3 (so 255.255.255.224)

so if you have 192.168.0.0/24

Branch 1
192.168.0.0 - 192.168.0.63 (usable from .1 - .62

Branch 2
192.168.0.64 - 192.168.0.95 (usable from .65 - 94)

Branch 3
192.168.0.96 - 192.168.0.127 (usable from .97 to .126)

I would have gone with something like:

Branch 1: 192.168.0.0/24
Branch 2: 192.168.1.0/24
Branch 3: 192.168.2.0/24

We have a similar arrangement for our company WAN with static routing between the various subnets. Interesting to see someone else take a different approach though.

 

[syntax]

I would have gone with something like:

Branch 1: 192.168.0.0/24
Branch 2: 192.168.1.0/24
Branch 3: 192.168.2.0/24

We have a similar arrangement for our company WAN with static routing between the various subnets. Interesting to see someone else take a different approach though.

I assumed he had a range that he needed to subnet (public or otherwise) and assumed a /24 for it.
If he has no restrictions on what he can use, then sure, just lash out some /24's and you are done.

 

[eCliPSe]

Syntax's suggested subnetting is correct. But truth be told it only makes sense doing this if you want to perhaps segment your "servers" from your users. By having more than one vlan on each branch.

Thus then you would do this

Branch 1 (users) 192.168.0.1 - 192.168.0.62 255.255.255.192 Vlan 20
(servers) 192.168.0.65 - 192.168.0.79 255.255.255.240 Vlan 30

And so on ?

But if you have no real need to subnet just use the class C address as suggested 192.168.0.0 then 192.168.1.0 and so on.

HTH
Daniel

 

[b@nD]

Wasteful

Am I correct in saying that subnetting is actually wasteful of IP addresses ? ( IPv4 )

( Granted everyone cannot use a /24 )

 

[RoganDawes]

Yes, to an extent. For every subnet you create, you "lose" 2 IP addresses, the network address and the broadcast address, which can no longer be assigned to a machine.

 

[syntax]

Am I correct in saying that subnetting is actually wasteful of IP addresses ? ( IPv4 )

( Granted everyone cannot use a /24 )

Well that depends. Subnetting, whilst adding more ip loses as you subnet, actually saves ips in certain scenarios.
For example, when allocating public ip addresses, an ISP does not want to allocate a /24. They also don't want to use /24 between two public routers that is a point to point link.

So subnetting allows more granular ip allocation which can end up saving IP address space that would otherwise have been wasted

 

[eCliPSe]

Subnetting is just segmenting network's broadcast domains. Smaller broadcast domains = better throughput.

 

[ponder]

Subnetting is just segmenting network's broadcast domains. Smaller broadcast domains = better throughput.

In the modern day environment where switches are used that's no longer an issue as each switch port is it's own broadcast domain. In the days of hubs it was an issue though.

The OP does not really supply much info so right now everybody is just taking pot shots

 

[eCliPSe]

In the modern day environment where switches are used that's no longer an issue as each switch port is it's own broadcast domain. In the days of hubs it was an issue though.

I believe you are confusing Collision Domains and Broadcast Domains . Hubs had one broadcast and one collision domain where switches these days have multiple collision domains on a port and a single broadcast domain per vlan. This is extensively covered in the CCNA.

http://en.wikipedia.org/wiki/Collision_domain
http://en.wikipedia.org/wiki/Broadcast_domain

 

[ponder]

I believe you are confusing Collision Domains and Broadcast Domains

Probably those two beers I had at with lunch.