Network Address Ranges?

[GREENGROCER]

How do you determin the address ranges for a given subnet mask?

136.28.92.158 ip address of a machine
136.28.86.63 another
136.28.90.34 another

255.255.240.0 sn mask

so how many subnets and what are the address ranges?

 

[sobak]

Here is the following Statistics on this IP Address Scheme.

Network Address: 136.28.80.0
Subnet Size: 4094
Address Range: 126.28.80.1 to 136.28.95.254

This is a Class A IP Address subnetted to allow 16 subnets. it's using a 20 bit Subnet Mask with 12 bits of Host address. Hosts per subnet are 4094.

Suggest you go to solarwinds.net and download their subnet calculator. you can find it at....

http://solarwinds.net/Tools/Free_tools/Subnet_Calc/download.htm

Although I know how to do subnetting manually, I don't have time to do the conversions unless I'm into pain. This tool does some really cool things as far as printing out your entire subnet and showing you how the subnet mask is divided up. Hope this helps..

david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*

 

[sobak]

Okay I messed up, it's early Friday morning and I already wish it was 5:00. Anyway here is the corrected information....

It's a class "B" Address range not "A" like I said before.

Network Address: 136.28.80.0
Subnet Size: 4094
Address Range: 136.28.80.1 to 136.28.95.254

Time to go get my coffee


david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*

 

[GREENGROCER]

Thank you for that, but how do you determin that it is
80-95 in the third octet?
why not 11-26? or something else
what would the other subnet address ranges be?
Thanks for your time
jonathan

 

[sobak]

Because your current network address is 136.28.80.0. 11-26 are not part of this network, they are part of different networks.

It all boils down to the Subnet Mask. With a subnet mask of 240, I am taking bits from the Host Address and using them as the network address. Using the 255.255.0.0 default Subnet Mask, I would only be able to achieve 1 network with 65534 host on that network. By taking the 4 bits from the host address (255.255.240.0) I can take that 1 network and break it down into 16. Breaking it down into 16 will give me a better way to manage my network. Using Ethernet and having 65534 hosts on the same network (something that can't be done) would cause a network to run slower than carrier pigeon. When you break up a network you break up into separate broadcast domains. You're users will love you for doing it.

Back to your questions. When breaking up 136.28.0.0 into 16 subnets these would be your network address breakdowns..

136.28.0.0 255.255.240.0
136.28.16.0 255.255.240.0
136.28.32.0 255.255.240.0
136.28.48.0 255.255.240.0
136.28.64.0 255.255.240.0
136.28.80.0 255.255.240.0
136.28.96.0 255.255.240.0
136.28.112.0 255.255.240.0
136.28.128.0 255.255.240.0
136.28.144.0 255.255.240.0
136.28.160.0 255.255.240.0
136.28.176.0 255.255.240.0
136.28.192.0 255.255.240.0
136.28.208.0 255.255.240.0
136.28.224.0 255.255.240.0
136.28.240.0 255.255.240.0

For each of the above networks there are two addresses that cannot be used by Workstations. For example...

136.28.112.0 <network address
136.28.127.0 <broadcast address

Each network has these two addresses, the first address in the network is the network address, the last address is the broadcast address.

I would suggest you obtain a book on TCP/IP there is a lot of information that I didn't cover in this that I just couldn't on a forum like this. If I did I could take it and write an entire book. The one that I used (a long time ago) was Teach yourself TCP/IP in 14 Days published by Sams. If you do any network engineering you are going to need to know TCP/IP Subnetting and understand how it works. Sorry I can't be any more descriptive but your question is pretty large to explain in it's entirety.
david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*

 

[GREENGROCER]

Thank you sobak the penny has now dropped. the third octet determins the address ranges ie 240 using increments of 16 248 increments of 8 agree?. I am sure that 255.255.240.0 in this network only allows 14 subnets because you cannot use 0-15 you must start at 16 and also because you cannot go over 240 therefore your last address would be 136.28.239.254.
so the subnet starting 136.28.0.1 and the one 136.28.240.1 are not valid.
Correct me if you think I am wrong
Thanks alot
Jonathan

 

[Jsteve]

You are close
your range useable would be:
136.28.0.1 136.28.15.254
136.28.16.1 136.28.31.254
136.28.32.1 136.28.47.254
136.28.48.1 136.28.63.254
136.28.64.1 136.28.79.254
136.28.80.1 136.28.95.254
136.28.96.1 136.28.111.254
136.28.112.1 136.28.127.254
136.28.128.1 136.28.143.254
136.28.144.1 136.28.159.254
136.28.160.1 136.28.175.254
136.28.176.1 136.28.191.254
136.28.192.1 136.28.207.254
136.28.208.1 136.28.223.254
136.28.224.1 136.28.239.254

136.28.X.0 is reserved for the network number (unless your using subnet zero which is another topic)

136.28.X.255 is reserved for the network broadcast

 

[Jsteve]

Sorry ment, range 136.28.0.1 to 136.28.15.254 is usable if you have subnet zero enabled on the router

 

[sobak]

Jonathan,

Enable IP Subnet-Zero on your router and you can successfully route the 136.28.0.1 to 136.28.15.254 range (as Jsteve pointed out). You are correct that the last range is not a &quot;Valid&quot; subnet but you already knew that. Now if you really want to blow your mind, try to attempt to answer how to subnet with IPV6 in this forum. Remember a good book does wonders and is always there for you when you need it.

Good luck
david e
*end users are just like computers, some you can work with...others just need a simple reBOOTing to fix their problems.*