[kyle01]

I have created a network design and worked out all the information for a fixed-length subnet mask, but I am not sure if it is correct, could someone give the once over and provide some help if there are any errors? Thanks

on the far left there is 2 PC's connected to a switch then to a router, then through a leased WAN line it connects to the middle router, then to the far right router. The middle is 4 workgroups, they all connect to a router, then to a local backbone then to 2 servers. while the far right has 2 workgroups that connect to a router. Also another question I have is, at the bottom i have wrote 10 subnets, I have excluded the servers, do they need to be counted too?

The network address is: 136.15.224.0

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The Calculations I have made:

Max. number of hosts: 100
Num. of host bits needed: 7
Subnet mask: 255.255.255.128
Num. of subnets: 10 (7 LAN, 1 backbone, 2 leased lines)
Num of subnet bits needed: 4
supernet mask: /21

Attached image(s)

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[kyle01]

I have this network that I am trying to calculate.
I have a max host # of 100
The host_bits i need is 7
The subnet mask is 255.255.255.128, where the largest subnet is 100
number of subnets is 10
the subnet_bits needed is 4

when i calculate the supernet mask it comes up with /21, but if i use a subnet calculator, I get /25. Am i doing something wrong here?

[kyle01]

I have made progress, and got the following:

I have a network address of 136.14.224.0, it is using a fixed-length sub-net mask. which i have managed to work out to be 255.255.255.128/25. The working out I have done to come to this is the following:

Working out:
Maximum number of hosts: 100

Number of host bits needed:7

Subnet Mask: 11111111.11111111.11111111.10000000
Largest subnet is 100 PC (101 including router NIC)
Requires 7 host_id bits (upto 128 addresses – 126 usable)

Number of subnets: 10

Number of subnet bits needed: 4

Supernet Mask:
Supernet Mask is /21
Subnet Mask: 11111111.11111111.11111111.10000000
Supernet Mask: 11111111.11111111.11111000.00000000


Could someone help me in making sure this is correct, and if not where I am going wrong?

[modi123_1]

Please do not create duplicate topics. Merging.

[kyle01]

I have a network address of 136.15.224.0/21 and I have 3 subnetworks (shown in picture). I know that 3 cannot be used for subnet's for I have to increment by 1 to make it 4. So that would make my CIDR /23. I have made a table with the network address, mask, usable IP range and Broadcasts. (shown in the attached picture). This would be for the subnetworks themselves.


In my first subnetwork I only have 1 router, which is fine.

But in my second subnetwork I have 4 router's and then 2 server's that all 4 router's connect to, then a main router that connects to the other 2 subnetworks.

When making the table with network addresses. would i have to split my network address into 8? or would i also have to change my first subnetwork to 8 subnets instead of 4? Or would I have have to also then change my first subnetwork into 8 instead of 4 too?

Thanks for any answers, and if you need anymore detail, please ask.