Need some advice on learning networking

[slimslob]

Just to follow up on my last post....


The problem with learning subnetting is there are several ways to do it. I just watched 4 different ways of subnetting for a Class B network. 3 of them made no sense to me whatsoever. Don't get me wrong, they came up with the right numbers. It's just that I could not wrap my mind around the process that they were using.

On the last video (4th) some country bumkin appears on the screen and there were no fancy white boards or graphics like were used in the other videos. He simply pulls out an 8.5 x11 sheet of paper and proceeded to subnet like a champ. I understood his method perfectly.

His method was much different (and a little more complex) than the 1st method that I had learned. I wasn't complaining because I was just glad to learn a method that I could understand. The method that I had been using didn't really get into the actual "math" that was used, it was just a step-by-step formula. I wasn't really interested in the math anyway. Well, the "country bumkin" went pretty deep into the math and it opened my eyes.

Once I learned the math behind the madness, I was able to use the previous formula that I used for a class C network.

I know this didn't make a damn bit of sense to anyone but me. I apologize for boring everyone with subnetting.


PS - The big takeaway for me is to make sure you get the right teacher. Some of them can confuse you more than they help.

And somewhere out there exist people for whom each of the other 3 ways of doing it made the most sense.

[BillyCarpenter]

And somewhere out there exist people for whom each of the other 3 ways of doing it made the most sense.

That's true.

The thing that threw me off with a Class B network was that I was now working with 2 octets for the hosts. That was no big deal other than when I needed to find the broadcast ID, the numbers work similar to an odometer on a car.



When I need to subtract from the last 2 octets (example: 10.0 - 1) the correct answer is: 9.255. The 0 in the 4th octet rolls back to the highest number. It threw me off big time.

[BillyCarpenter]

I think I'm about donw with subnetting other than making sure I have some numbers committed to memory.

I have a few thoughts now that I'm done.



- Anyone who does networking could benefit greatly from learning about subnetting. It doesn't matter whether or not you'll use it in the real world. The skills I gained in identifying Network ID's, broadcast address, number of host, ect., is invaluable. Moreover, there are many benefits to subnetting. Security is high on the list. Also, you must know a lot of this information if you'll be connecting routers. You can't just willy nilly plug in IP addresses. You also must know how to find the network ID.

Perhaps the most interesting thing is cutting down on broadcast traffic.



A single broadcast packet sends out information that reaches every device connected to that network because each device has an entry point into the network. A large number of entry points, however, can negatively impact internetwork switching device performance, as well as your network’s overall performance.
Another issue with broadcast packets is that they can spam every device within a network, even devices that aren’t relevant to the task at hand, which can strain a network’s capacity and cause it to collapse.
But subnetting enables you to ensure that information remains in the subnetted network or broadcast domain, which allows other subnets to maximize their speed and effectiveness. Subnetting also divides your network’s broadcast domains, enabling you to better control traffic flow, thus increasing network performance!
A word of caution, though. You’re better off limiting traffic to a single subnet instead of letting it move from subnet to subnet. So, you should limit the number of devices on your subnet whenever possible, along with controlling the traffic flow between subnets. Doing this will improve your network’s speed and performance.

[BillyCarpenter]

I had planned to spend the weekend on subnetting. Fortunately, the light came on for me the other day on subnetting and I was able to wrap it up on Friday. So, I moved on to another area that has given me trouble - routing.


I had a fundamental understanding of routing. I knew about routing tables and how they routed packets to individual computers on a network.

But what if we have several networks with each being separated by a router?

Think of it like this: PC's on a single network are like houses on a street. A router can easily communicate with each house. But routers know nothing about streets. Routers can't route traffic from one street to another. Think of streets as separate networks.

Well, there is a way to teach a router how to send packets to a different street. Or multiple streets. There's a few different ways of doing this. Two of the most common are: Static and Dynamic routing.

Static routing is when you go into one router and tell it to forward packets to the next router if the IP address isn't contained in it's routing table. But that only takes care of traffic going one way. We then have to make router 2 aware pf router 1 so that traffic can flow in both directions.

There's also dynamic routing. That's where you set up multiple routers to automatically learn about each other. Haven't gotten into that yet but it's on the list.

[BillyCarpenter]

I wanted to follow up on something. I've been researching the best way to get my CCNA. I knew nothing about it. I thought you had to go to some type of class to get it. False. All you have to do is schedule a time to take the exam and pay the money. So, forget going to school. I ordered the books that I need off Amazon and I'm watching videos which really help. I'm not in a race, so I'll do it at my own pace.

Also, I kind of got into Cisco on accident. CCNA is a Cisco certificate. I didn't know anything about that, either. But I did a lot of research over the weekend and here's what I learned.

Going after your CCNA for your first certificate probably isn't the best idea if you're completely new to networking...which I am. It's also much harder than CompTia. And they just added a bunch more stuff into getting your CCNA. I'm too far into Cisco to turn back now, though.

[slimslob]

I had planned to spend the weekend on subnetting. Fortunately, the light came on for me the other day on subnetting and I was able to wrap it up on Friday. So, I moved on to another area that has given me trouble - routing.


I had a fundamental understanding of routing. I knew about routing tables and how they routed packets to individual computers on a network.

But what if we have several networks with each being separated by a router?

Think of it like this: PC's on a single network are like houses on a street. A router can easily communicate with each house. But routers know nothing about streets. Routers can't route traffic from one street to another. Think of streets as separate networks.

Well, there is a way to teach a router how to send packets to a different street. Or multiple streets. There's a few different ways of doing this. Two of the most common are: Static and Dynamic routing.

Static routing is when you go into one router and tell it to forward packets to the next router if the IP address isn't contained in it's routing table. But that only takes care of traffic going one way. We then have to make router 2 aware pf router 1 so that traffic can flow in both directions.

There's also dynamic routing. That's where you set up multiple routers to automatically learn about each other. Haven't gotten into that yet but it's on the list.

You can also build routing tables on individual PCs. Open a Command Prompt on a Windows PC and enter "route /?" to display the help content for the route command.

[BillyCarpenter]

Oh, by the way, when I was learning subnetting, I finally found out what the term "mask" was referring to. It's simply the imaginary line that divides the network from the hosts.

[BillyCarpenter]

You can also build routing tables on individual PCs. Open a Command Prompt on a Windows PC and enter "route /?" to display the help content for the route command.

I'll check that out. I had no idea.


I spent several hours today working on building routing tables. I hooked up 3 routers together with a PC on the 3 different networks and had to build the routing table for all three networks. That included making sure that traffic could flow in both directions from all networks. It was a lot of damn work. I'm guessing that's not thee way it's done in the real world. But I did learn a lot. I now know all the hops made between the routers and in what order., Also, I learned how to look at the routing table to pinpoint a problem. Hard work.

[BillyCarpenter]

I'm still on routers and by the looks of it, I'm gonna be here for a while. Never in my wildest dreams did I imagine that a router could do so much.

Yesterday I learned how to statically configure the routing table in order to give one network the ability to communicate with another. But this process is tedious and time consuming. It may be okay for a small network but it's out of the question for a production network.

There's another option and that's Dynamic Routing Protocol.


There's a couple of options to choose from when using Dynamic Routing Protocol. The first one has been around for a long time and it's called RIP. RIP stands for Routing Information Protocol. What this does is teach all the routers to gather information from each other and to choose a path based on the least number of "hops." RIP Protocol is kind of dumb because there are other factors that need to be considered to choose the best path. You also have to take into consideration the "cost." Cost is nothing more than the "time" it takes to go from the source to the destination. This protocol has largely been phased out.

What has replaced RIP? There's another protocol called OSPF (Open Shortest Path First. This protocol looks for the path that takes the least amount time. When OSPF is implemented on all of the routers, it does all of the work for you. Fantastic!!!!

Side note: Learning routers has caused me a great deal of discomfort. For one, that's what forced me to learn subnetting.

[BillyCarpenter]

Okay, I just built a network in my lab that has many routers and instead of statically configuring the IP Route, I used RIP. This was MUCH easier but it's not plug-n-play. It still requires some understanding of the router configuration but nothing like STATIC. I hesitate to say that I've mastered these 2 protocols because there's no telling what's around the corner but I will say that I feel "comfortable" with both.

I remember when I started this thread I just wanted to know how to connect 2 routers and form 2 networks.