Dan87951

I'm working towards my CCNA and have a few questions on subnetting as well as my case study. If anyone can help, let me know or add me to your AIM which my user name is Dan87951, thanks!

Dan

Zero10

I know a bit about it, I almost had my CCNA, but I left the course a little early.
If they're pretty simple questions, I could help, I also have a full set of notes for it at home. (HTML format)

Dan87951

Here’s my question hopefully you can help me out. I’m currently a second semester student as well. I was given a WAN IP address of 192.168.3.0 with a mask of 255.255.255.0 and a LAN IP address of 172.31.0.0. I was told to use the second lowest usable WAN address which is 192.168.3.2 correct? On the local LAN it needed to handle 4000 host address per subnet so I borrowed 4 bits on the LAN address which gave me a subnet mast of 255.255.240.0. On the LAN address I was told to use the 3rd usable subnet which would be 172.31.48.0 correct? I was also told my IGRP AS number is 3? Does this mean when I’m configuring IGRP in global config mode that I just type in "router IGRP 3"?

Here are some of the guidelines for the IP assigning. The production workstations will be assigned the lower-half of the IP address. All network devices and management stations will be assigned the upper half of the IP address numbers and the Ethernet router interface is to be assigned the highest usable address.

Here is what I have.

Network address
172.31.48.0

Range of address for that subnet
172.31.48.1-172.31.63.254

Broadcast
172.31.63.255

Ethernet interface IP
172.31.63.254??

Production host range
172.31.48.1 - 172.31.55.???
How do I figure out what number will be in the last octet? Could it be any number?

Management Host range
172.31.56.???- 172.31.63.254

So one of the production hosts could be:
IP address 172.31.48.1
Subnet mask 255.255.240.0
Default gateway 172.31.63.254

and on of the management hosts could be:
IP address 172.31.56.???
Subnet mast 255.255.240.0
Default gateway 172.31.63.254

My main question does this look correct? I can't figure out the last octet when I divide the address's up, I'm thinking they can be any number?? What would I use my broadcast address for of 172.31.63.255? Do I configure this into the router anywhere?

Thanks for the help I know this is long.

Zero10

Okie dokie,
Forgive me if I am a little rusty, just to get things straight, we are programming a cisco router, correct?

The computer which all my course notes are on is down right now, perhaps I'll get some life out of it tonight. It just keeps overheating, I checked everything out, but it looks like it suffered a painful death via a power surge, popped a capacitor inside the power supply, and for some reason it roasted all the power input buffering capacitors on the mother board. I would just change the capacitors, but I'm sure it also did a lot of hidden damage. I have a spare power supply, and another board I can switch it with, I just need some motivation.

Anyhoo, so I am going from the top of my head.
All of your math in the top half looks good. To me, the subnet 255.255.240.0 should give you 4096 IP addresses (forgive me, the math is in my head as well), which is very close to the 4000 you needed.

Your broadcast address looks correct, the ethernet interface address can be any IP in your subnet. Since you were told to use the 3rd usable subnet, then I would (out of personal preference) pick 172.31.48.1, but I follow the opposite convention of numbering that you do perhaps.

Your range of production host IP addresses should be 172.31.48.1 - 172.31.55.254, I can't give a good explanation of how to get the number in the last octet, except that you are splitting the group of IP addresses in half. so simplifying the numbers a little, if your range was from 0.0.0.1 - 0.0.15.254, the half-way point would be 0.0.7.254, which the way I interpreted it, is what you were looking for.
So, the IP range for the management hosts should be 172.31.56.1 - 172.31.63.254.

Hmm, what would you use the broadcast address for?
The obvious answer is for the client's to receive the broadcast notifications, but if you meant how would you use it, I suppose there would probably be a setting on the computers you're configuring for use on that router. I have started to lose my touch with windows (which I am presuming is the OS of the computers served by the router), but I believe it will automatically determine the broadcast address from the computer's IP, and the subnet mask.

Now, about the IGRP, where did you get the number 3 from? Just curious, I can't even recall what IGRP stands for internal(?) gateway routing protocol?
I believe that number would stand for which group the router is in. If that's the case, then I would use the help commands on the router to determine the exact syntax of setting the IGRP number, I'm a little rusty on syntax.

Hope some of that was either helpful or ego boosting, one or the other should help you out, lol =)

I had to leave the CCNA course due to a conflict with the instructor, I may have modified the settings on all of the computers, and messed with the accounts so that I was an administrator, and only my computer was recognized by the server. I thought it was funny, he did not =(
So, a practical joke cost me my CCNA, after I left the course, I just didn't feel like getting it.

Dan87951

Do you know anything about ACL's?

Zero10

ACL's?..
The acronym is not familliar, so probably not. Although, I may be having a brain fart. What does it stand for?

Dan87951

Access Control Lists.

Zero10

OHH!
I do, I just can't think of it right now. Sorry, I have a really bad cold that's kicking my ***, and I almost got blown up today (was at a house that filled up with gas!!!), so I'm not completely here right now.

Dan87951

LOL alright! Get better!!

Zero10

My my, have I ever been busy, well, I'm better now.
Thanks though =)

I tried to remember, but I can't think up anything on access control lists. I'll try checking my course material once I get home, probably tonight.

Dan87951

Thanks Zero I'd appreciate it.

penfold944

Production host range
172.31.48.1 - 172.31.55.???
How do I figure out what number will be in the last octet? Could it be any number?

Management Host range
172.31.56.???- 172.31.63.254

The highest production host address would be 172.31.55.255 and the lowest management host address will be 172.16.56.0. When you are supernetting, 0 and 255 are only the network adn broadcast addresses at the extreme ends of the entire range.

What do you want to know on ACL's ?

Never knew that being a CCIE was a bonus if your a porsche owner too

Dan87951

I'm doing classful subnetting I'm second semester CCNA. Thanks fro the input i'll keep your user name handy.

Chris_924s

Dan.. Don't do it. Take up knitting, pottery or fishing as a vocation. The IT sector is JUST beginning to recover from 2001 right now.

and you'll enjoy yourself more.

My Creds:
8 years Network Admin.
10 Years NOS break/build/fix Network engineering and Field support.
Throw in a fistfull of alphabet soup of certs including MCSE, MCP, MCSD,MCSA, CNA, CNE, CCNA. I was gonna do CCIE but said screw it.
This dont include Printer, mainframe and Linux certs.
Certified by IBM, HP, Epson, Compaq, Dell, Gateway, buddy.

Now I'm glad to have a help desk gig. I'm FINALLY back in IS/IT after 2 years out.

It's rough in IT/IS unless you have an uncle that's a CIO for Dell or Mr. Softie.
I wish you the best in your future, but unless you wanna you are bilingual in Farsee or Russian you'll be just another fish in a overstocked pond.

Ok, rant over..

IP subnetting and masking? easy. It's a logical sequence. Build yourself an algorithm in Excel and it does the work for you.
OSI layers and IPV6 ? I could talk about it for several hours.

Yeah, I'm a geek.

Zero10

Lol, I was going to come back here with my answer, but this thread has been taken over!

I confess to being a geek as well, but not quite as qualified. Currently in University, working the summer with a couple buddies running their own business. Wireless internet to areas around the city. Really stretching 802.11g =)

IT is going really strong up here in Canada, in Calgary in particular. Not so much programming, but everything else is really booming. I'm sure it will slow down some day though, that's why I'm getting my electrician's ticket, always gives me something to fall back on.