Hello, all! I am trying to get a job in IT fresh out of college (B.S. in Computer Science). The boss for the job wanted someone who knew Linux. I don't, but he decided to give me a chance anyway. To prove that I can learn whatever he needs me to, he gave me this map and told me to go home and figure it out.

http://img155.imageshack.us/img155/6135/assignment.png

The only information he told me is that WALL is the firewall server. The I in the cloud is obviously the internet. eth0, eth1, and eth2 are what I assume to be ethernet cards. He says that there is a reason they are 0, 1, and 2 but the only significance I can think of is that they are three different cards. What do you think?

MPLS, I have found out through my research, is Multiprotocol Label Switching. It allows creation of virtual links between distant nodes, and encapsulates data packets that can then be labeled. What else should I say about MPLS to impress my future boss?

Now, the numbers are obviously IP addresses, but I'm trying to wrap my head around the /21, /23, etc. As far as I can figure out, these are subnet masks that allow that number (21, 23, etc) of bits to be allocated for the network prefix, leaving the remaining bits (32-n, where n is the /n number) reserved for host addressing. What all of that really means, I am truly not sure. I never took a networking class in college. Can anyone fill me in?

Thanks so much for all of your help!

Edit: Also, is there a reason he may be using IP addresses like 10.0.0.0, instead of more traditional ones like the 192.168.42.0?

Hello,

As far as this "diagram" goes, what if the I-variable is a cloud-based service? What if the whole thing is internal to a network? Those are the things that you need to think of. I highly suggest that you get online and learn about TCP/IP stacks, addressing, and general network information too, as then you would know what /24, /16, etc is.

Cheers,

Josh

Hello and Welcome to LinuxQuestions,

Since the assignment is given to you I don't think you'll find anyone giving you all the answers since that would only result in you pretending to be someone you're not. The 0, 1 and 2 in combination with eth do indeed mean three different network cards on the firewall (which is a minimum if you read up about firewalls having one External, one Internal and one DMZ).

About MPLS, don't try to impress your boss by studying things you don't understand. Try to find as much relevant information you can and before trying to memorize it, try to understand what it does, what it means and what it can be used for. Don't be afraid to admit you don't understand something. If you can explain in your own words to your (future) boss what it means you'll make a far better impression then when you would be juggling with terminology you don't grasp. You'll make a bad impression when he asks you a question that might be simple but yet you fail to answer because you don't understand the matter.

The numbers after the IP addresses indicate the subnet indeed. Two networks are Class A, one is Class B. To read about the differences, have a look at this webpage about IP Address Classes. Basically it comes down to how many networks you can have within that range to communicate with each other:
If you want a quick class on TCPIP and subnetting basics, have a look at this website.

Looking forward to your participation in the forums. Have fun with Linux.

Kind regards,

Eric

3 members found this post helpful.

Eric,

Thanks so much for your help! The links you provided are helpful, but I am still a little confused about network classes. As you explained it, this is determined by how many networks you can have on that range. How can you determine an IP address' number of networks, and therefore class, just by looking at it? Also, the code you posted labeled one of the addresses as class C, when in your post you said it was class B. And why wasn't the third address given a class in your code?

I guess Eric forgot about that one

The 10.0.0.0/8 subnet is considered as Single Class A, which is part of the Private Network Class. This is used mainly for small networks, mainly for home use, on LAN's, etc. Read here for more information - https://secure.wikimedia.org/wikiped...rivate_network

Cheers,

Josh

Edit - Just noticed he pointed that out - The 10.1.0.0/24 or /8 class is technically considered the same, so most likely, that is why. The subnet for that class is 10.255.255.255, so there you go Hope that helps to clear that up.

1 members found this post helpful.

"Give a man a fish, and he'll eat for a day."
"Teach a man to fish, and he'll be out there drinking beer for the rest of his life."
"Hit a man with a fish, and he'll go away for good."


Cheers,
Tink

3 members found this post helpful.

Further,

MPLS is not mentioned in the diagram so as others also suggested, forget it. Anyway it is marketed by service providers as a way to integrate hetrogeneous networks in a secure environment once you hit the MPLS touch point (via eth2 in you case).

Presumably ALL traffic to and from the outside world is connected via WALL. There are two types of traffic via etho for the internet and via eth2 to the provider. (presumably to connect to other branches / partner networks).

If MPLS came up in the discussion, it was probably in relation to the provider's touch points (10.0.0.0 and 10.1.0.0).

OK

Hi,

Darn typos. Sorry! Have to re-educate my fingers to type what my mind thinks. Been almost inactive on LQ for too long

Kind regards,

Eric

It's ok, just don't do it again

-Josh

I just use ipcalc.

Sorry guys, when I made the diagram I forgot to label the MPLS, which integrates the 10... IP addresses. So those two are class A? I still would like to be able to explain to my future boss how I arrived at that conclusion. Thanks!

As far as the ethernet cards go, I am guessing eth0 is the external, eth1 is the DMZ, and eth2 is the internal. Would I be correct in this assumption?