Subnetting question

I'm working on my subnetting and I'm trying to use the way Jeremy from CBTNuggets does it.

I have an IP of 192.168.1.0 /24.

I need two networks, one with 50 host and the other with 40 host.

128 64 32 16 8 4 2 1
0 0 1 1 0 0 1 0 = 50
0 0 1 0 1 0 0 0 = 40

Both of those require 6 bits for the host, right? so my subnet mask would be 255.255.255.192? giving me increments of 64.

192.168.1.0 - 192.168.1.63
192.168.1.64 - 192.168.1.127

When I put this in the packet tracer lab and hit check it tells me I have the incorrect IPs. Can anyone tell me what I missed?

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Comments

Monkerz

What specifically are you inputting in PT? And where?

networker050184

Maybe it wants you to put in the usable hosts only? I'm not very familiar with Packet Tracer though so not sure.

BobbyDC

Its a lab with a network already setup. I just need to input the IPs, subnets, and gateways.

zrockstar

Your network bits need to be contiguous. To support either 50 or 40 hosts, you are going to need 6 host bits, or 2^6, that gives you a total of 64 IP address, or 63 usable (take out one for broadcast, one for network). That means the other two bits go to your network. Think of it like this, you are starting with a nnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh. You leave 6 bits for hosts and give the rest to the network since you need more than one network and end up with a nnnnnnnn.nnnnnnnn.nnnnnnnn.nnhhhhhh. That would be a 255.255.255.192 network mask. Your first network would be 192.168.1.0 then 192.168.1.64 then 192.168.1.128 then 192.168.1.192. Watch the packet tracer because sometimes they tell you assign the first valid subnet, in this case that would be subnet 0. Sometimes they will say something to the effect of assuming the first subnet is invalid... then your first usable would be .64.

SharkDiver

My first thought was what Networker said.

Try putting in 192.168.1.1 - 192.168.1.62 and 192.168.1.65 - 192.168.1.126 and see what happens.

Also, maybe they are looking for the IPs of the hosts which would only be 192.168.1.1 to 192.168.1.50 and 192.168.1.65 to 192.168.1.104.

zrockstar

Can you post the name of the PT exercise, I can see if I have it and try it out?

Ola_CISCO

Sorry to butt in BobbyDC, but I also have a subnetting question, and I didnt want to start another thread because its on the same topic:

Could someone help me with this question please

Which command successfully pings an individual IP address, assume a mask of 255.255.255.0?

Router> ping 192.5.5.0
Router# ping 192.5.5.30
Router> ping 192.5.5.256
Router# ping 192.5.5.255

zrockstar

Ola_CISCO wrote: »

Sorry to butt in BobbyDC, but I also have a subnetting question, and I didnt want to start another thread because its on the same topic:

Could someone help me with this question please

Which command successfully pings an individual IP address, assume a mask of 255.255.255.0?

Router> ping 192.5.5.0
Router# ping 192.5.5.30
Router> ping 192.5.5.256
Router# ping 192.5.5.255

Ola, there is only one answer here 192.5.5.30. The key to the question is INDIVIDUAL IP ADDRESS. In a 255.255.255.0 network, .0 is always going to be a network address, and .255 is going to be a broadcast. Since .256 is out of range, the only individual IP address is .30.

Ola_CISCO

Thanks for your help zrockstar

, I was stuck on this for a while!

zrockstar

Ola_CISCO wrote: »

Thanks for your help zrockstar , I was stuck on this for a while!

No prob!

Monkerz

BobbyDC wrote: »

Its a lab with a network already setup. I just need to input the IPs, subnets, and gateways.

Ok, but you still haven't answered my question. Are you just filling in a spreadsheet or are you setting the IP, Netmask and DefGate on a PC/Server.

zrockstar

Monkerz wrote: »

Ok, but you still haven't answered my question. Are you just filling in a spreadsheet or are you setting the IP, Netmask and DefGate on a PC/Server.

Monkerz, depending on where he is in his studies, he's either inputting it in to the router through a GUI or CLI. At any rate, it always requires subnet mask for IPs and default gateway for hosts.

Monkerz

He said the network was already setup. If he is setting up hosts and giving them the wrong gateway that could be a problem. Just trying to find out what exactly he is doing with the IPs.

zrockstar

Monkerz wrote: »

He said the network was already setup. If he is setting up hosts and giving them the wrong gateway that could be a problem. Just trying to find out what exactly he is doing with the IPs.

With PT a lot of the times they give you a setup physical topology, and require that you go in there and setup your addressing scheme. But you're right, a lot of the time the problem lies in host configuration. Actually, we could be getting a lot more information here, packet tracer will actually tell you which ip of which piece of equipment is wrong. But given the lack of feedback, I am assuming he already figured it out.

BobbyDC

Sorry, I was busy. Its 4.1.3.5: Implementing an IP Addressing Scheme.

In this activity, you will subnet the private address space 192.168.1.0/24 to provide enough host addresses for the two LANs attached to the router. You will then assign valid host addresses to the appropriate devices and interfaces. Finally, you will test connectivity to verify your IP address implementation.[h=4]Step 1: Subnet an address space based on the host requirements.[/h]

You are given the private address space 192.168.1.0/24. Subnet this address space based on the following requirements:
- LAN-A needs enough addresses for 50 hosts.
- LAN-B needs enough addresses for 40 hosts.

PT.jpg

Monkerz

Ok, check the router (customer router) to see if you see 'ip subnet-zero' or 'no ip subnet-zero' command is issued.

If 'ip subnet-zero' is issued:

Configure the router port connecting to HostA with 192.168.1.1 255.255.255.192
Configure HostA with IP=192.168.1.2 NetMask=255.255.255.192 DefGate=192.168.1.1

Configure the router port connecting to HostB with 192.168.1.65 255.255.255.192
Configure HostB with IP=192.168.1.66 NetMask=255.255.255.192 DefGate=192.168.1.65

If 'no ip subnet-zero' is issued:

Configure the router port connecting to HostA with 192.168.1.65 255.255.255.192
Configure HostA with IP=192.168.1.66 NetMask=255.255.255.192 DefGate=192.168.1.65

Configure the router port connecting to HostB with 192.168.1.129 255.255.255.192
Configure HostB with IP=192.168.1.130 NetMask=255.255.255.192 DefGate=192.168.1.129

See if that works, and let know.

BobbyDC

The IPs it wanted was.

HostA IP=192.168.1.62 NetMask=255.255.255.192 DG=192.168.1.1
HostB IP=192.168.1.126 NetMask=255.255.255.192 DG=192.168.1.65

I'm an idiot and missed the part where it ask for the last host IP in the subnet.