Need some advice on learning networking

[BillyCarpenter]

Re: Need some advice on learning networking

I've been jumping around a lot recently because I needed to take a break from the online CCNA course. I've decided to go back to the organized structure of the online CCNA course after letting my brain rest for a while. But before I do......



....I want to make one last comment on site-to-site VPN's.


The online course I'm taking does teach VPN's but I haven't made it that far and I relied a different source to learn it. Well, today I watched about a 45 minute video on VPN's that's part of the CCNA course that I'm taking and they covered some ground that I hadn't thought about.


For starters, the VPN that I set up in the Packet Tracer Lab is on a very small scale. But what if there's an office in New York that has 20 different networks in the building and we want to set up a VPN to an office in Boston that has 10 different networks?

Think about that for a minute.


Sure we can set up a VPN that connects a single network from New York to Boston but we won't be able to communicate with the other networks at all.

Somehow the New York office needs to learn about all the networks in Boston and vice-versa. But we can't use a dynamic routing protocol because they use multi-casting and IPSEC doesn't support multi-casting. One solution is to use static routes but that's a ton of work to set up.

There are a few solutions to this problem but that's where I'm gonna leave it as I'm gong back to where I left off on the CCNA course and I left off on OSPF, not VPN's.

[BillyCarpenter]

Re: Need some advice on learning networking

I spent several hours today studying the OSPF routing protocol. There are a few different routing protocols that are used in a production network: EIGRP, RIP, & OSPF.

OSPF is an open source protocol and it's supported by all of the vendors unlike the other proprietary routing protocols. OSPF is what is most commonly used by far. It's also the most complex to understand and implement.

One area that I made great progress in was understanding "wildcard masks". Wildcard Masks are used to specify a range of IP addresses and they are always used with OSPF as part of the network statement.





If you're feeling adventurous, here's how it works:


Wildcard masks



Wildcard masks are used to specify a range of network addresses. They are commonly used with routing protocols (like OSPF) and access lists.





Here is an example of using a wildcard mask to include only the desired interfaces in the OSPF routing process:









Router R1 has three networks directly connected. To include only the 10.0.1.0 subnet in the OSPF routing process, the following network command can be used:


R1(config)#router ospf 1
R1(config-router)#network 10.0.1.0 0.0.0.255 area 0



10.0.1.0 = 00001010.00000000.00000001.00000000
0.0.0.255 = 00000000.0000000.00000000.11111111



00001010.00000000.00000001.00000000
00000000.00000000.00000000.11111111



What is we want to match both 10.0.0.0/24 and 10.0.1.0/24? Than we will have to use different wildcard mask. We need to use the wildcard mask of 0.0.1.255. Why is that? Well, we again need to write down the addresses in binary:


00001010.00000000.00000000.00000000 = 10.0.0.0
00001010.00000000.00000001.00000000 = 10.0.1.0
00000000.00000000.00000001.11111111 = 0.0.1.255



NOTE
Wildcard mask of all zeros (0.0.0.0) means that the entire IP address have to match in order for a statement to execute. For example, if we want to match only the IP address of 192.168.0.1, the command used would be 192.168.0.1 0.0.0.0.
A wildcard mask of all ones (255.255.255.255) means that no bits have to match. This basically means that all addresses will be matched.

[BillyCarpenter]

Re: Need some advice on learning networking

I took about a 2 month break from the CCNA course because I had reached burnout. Anyone that's thinking of getting their CCNA should understand that there's more to it than meets the eye. There's a lot of math that must be learned. I'm not talking about Algebra or Trig, I'm talking about Binary. When I say Binary, I'm talking about subnetting, super netting, route summarization and and converting between binary and decimal. It can and will get tricky. I venture to guess that many students give up because of this. You can't run from it, you must embrace it. And you'll have to learn a new language while you're learning all this math. I'm talking about CLI or Cisco syntax.

On top of learning all of that, you're also expected to learn a boatload of protocols. Protocols are simply a shitload of rules that were written by the developers of the software that we must learn to follow in order to get anything to work.


I was sitting here making sure I completely understood a wildcard mask and there was a lot of math involved. Master it or get left behind. That would be my advice.

[BillyCarpenter]

Re: Need some advice on learning networking

PS - The good news is that once you learn all that math, you can really do some amazing things with OSPF. It's an amazing routing protocol, IMHO.

[BillyCarpenter]

Re: Need some advice on learning networking

I've really developed a passion for routers and switches. Maybe that's because things are slowing down for me and I'm on the downside of the learning curve. It's been very rewarding experience thus far. Hard work but rewarding.


It's rewarding to know that I could set up a network with 200 PC's and segment them by VLAN and then set up inter-vlan routing. How do you want to get inter-vlan connectivity? - by router on a stick or use a layer 3 switch?


How about getting connectivity between 20 Wide Area Networks? We can do that with a little help from a dynamic routing protocol - OSPF.


How about setting up an IPSEC VPN? All of that can be done and much, much more.

Back down to earth. I'm only about 50% done with the CCNA course. Back to the grind.

[BillyCarpenter]

Re: Need some advice on learning networking

I'm many hours into learning OSPF. I've learned that when it comes to learning this stuff that time becomes irrelevant. In other words, it takes how ever long it takes.


I've got it down as far as what I need to know to make it work. I'm now working on learning the finer points of OSPF and what makes it tick. Complicated business but I've learned to just relax.

I would explain some of it but I don't think it would make any sense to anyone so that's that.

[BillyCarpenter]

Re: Need some advice on learning networking

One of the great features of OSPF is that it is scalable and works for a small or production network. But things start to change on the routers when we're dealing with a production network. Let me see how I can explain and it still make sense.


Lets compare a production router to the navigation system in our car. If we enter a street that's only a few miles away, there's not that many paths to get there so the CPU doesn't have to work that hard. But if we enter an address that's 3000 miles away, there's a lot more paths that must be computed.

It works the same way for routers. If you have 100 routers, there are many paths to be calculated and it could bog down the processor.

The solution is to segment (logically) the routers into areas thus each router only has to calculate a small number of paths.


That's the simplified explanation.

[BillyCarpenter]

Re: Need some advice on learning networking

I've cleared my schedule for the entire weekend starting right now and I hope to lab up my most challenging network topology ever. This lab will involve setting up 10-15 routers and separating them by zones. This particular topology is common in production networks.

You have the following:

a.) Backbone routers
b.) Area Border Router
c.) Autonomous System Border Router


Each of those 3 types of routers serve a different role in a production network.

If I study around the clock for the next 2 days, I should be able to lab it up and getting to work. We shall see.......

[BillyCarpenter]

Re: Need some advice on learning networking

Several hours have passed since I started this study session. In order to become proficient on routers and switches, it's important to pay attention to the small stuff...better known as best practices. And it's these things that are cumbersome and time consuming. Skip one of these steps and you could get unexpected results.


The other thing that is time consuming is that in order to troubleshoot a problem on a router, we must know how to read the the routing table and other data via the show commands.

The other thing that's worth mentioning is that its necessary to understand all the theory that is being taught.

I just finished learning Metrics. For OSPF the metric that is used is cost.


Cost = reference bandwidth divided by interface bandwidth. (reference bandwidth/interface bandwidth)

[BillyCarpenter]

Re: Need some advice on learning networking

I vastly over-estimated the amount of time it would take to learn OSPF and set up multiple zones. I did the lab and it all worked. I'm done with OSPF. Next up is VLANS and inter-vlans. I already know this because I took another online course when I started and later decided to switch over to the current CCNA course. I'll still go though it, though. Might learn something that I don't know.

[BillyCarpenter]

Re: Need some advice on learning networking

I'm at the half way point in the CCNA course and I decided it was time to review. It's been several months since I looked at a lot of the material. I've kept meticulous notes and I've cataloged related videos that I've found on the web as well as printed material.


I feel very confident in my abilities as far as the stuff that I've covered. The CCNA test is a different matter. There's a lot of useless information on there that must be committed to memory. I'll work on that after I'm completely done with this online course.


Here's an example of some of the useless information:


Question: Who developed the OSI Model?


Answer: The ISO (International Standards Organization)

Who gives a fuck?

[slimslob]

Re: Need some advice on learning networking

I'm at the half way point in the CCNA course and I decided it was time to review. It's been several months since I looked at a lot of the material. I've kept meticulous notes and I've cataloged related videos that I've found on the web as well as printed material.


I feel very confident in my abilities as far as the stuff that I've covered. The CCNA test is a different matter. There's a lot of useless information on there that must be committed to memory. I'll work on that after I'm completely done with this online course.


Here's an example of some of the useless information:


Question: Who developed the OSI Model?


Answer: The ISO (International Standards Organization)

Who gives a fuck?

Attention to details.

[BillyCarpenter]

Re: Need some advice on learning networking

Part of my review included subnetting.

Full disclosure: I've spent countless hours learning subnetting. I have devoted an inordinate amount of time to learning the best way to subnet and there are MANY formulas to get the job done. I worked at it so long that I think I mastered it.


Well, in my review of subnetting I learned that it's kind of like going to the gym....you have to go all the time to stay in shape. If you don't work at it regularly, you're gonna start to lose it.


Today I stumbled upon the greatest video ever for subnetting. Instead of using formulas, this one teaches you how to subnet in your head...no paper needed. I've just started to work on this but already I'm starting to get the hang of it.

[BillyCarpenter]

Re: Need some advice on learning networking

I've been jacking around all day learning how to subnet in my head. This involved committing 3 charts to memory and then doing a lot of practicing. It was a lot of work but once you learn it, it's easier than any other way that I've tried.


Subnetting is a big part of the CCNA test and it doesn't hurt to know this stuff.

[BillyCarpenter]

Re: Need some advice on learning networking

Studying for the CCNN exam is one of the most challenging things I've done in life. It's been extremely frustrating at times. Subnetting is near the top of the list when it comes to frustrating. If you've followed this thread, I've talked a lot about subnetting. There's a reason I talk about it a lot and that's because it's one of those foundational things when it comes to networking.

Subnetting is about more than just the number of usable hosts and IP addresses in a subnet. Understanding all of the 1's and 0's in a subnet mask helps when we have to deal with an Access List or a Wild Card Mask.


I can honestly say that I have mastered subnetting. I just went on a subnetting website that tests subnetting knowledge. I did 100 problems and got every single one right and did each one in 60-seconds or less.


I'll leave the link to the latest method I learned and the site where you can test your subnetting knowledge.



Test your knowledge: subnetting.net - Subnet Questions and Answers



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