Need some advice on learning networking

**BillyCarpenter** · 06-01-2021

I was able to spend a lot of time on CCNA over the 3-day weekend. I feel that I made a lot of progress. Things seem to be getting easier. That's not to say that they're easy...just easier than what they were.

I made a concerted effort to really learn the fundaments inside and out and that has paid off in spades for me.

Anyway, here's the bottom line for classless vs. classful routing protocols. They work hand in hand with route summarization. Bottom Line: Route Summarization = good. Auto Route Summarization = bad.

Don't let the routers auto summarize the routes for you. It will come back to bite you. Turn auto summarization to off and manually summarize the routes if called for.

**BillyCarpenter** · 06-02-2021

This section on Dynamic Routing Protocols has been a real doozy. I still have to cover OSPF and then I'm done with this topic as far as what's outlined in the curriculum. However, I don't think this online course alone will be enough to pass the test. I need to read about Dynamic Protocols in the official CCNA book and watch some videos from a 3rd party. And then I need spend several hours in the virtual lab.

I see that "Spanning Tree" is about 3 topic away and I hear it's a real bitch to learn.

**BillyCarpenter** · 06-02-2021

Welp, I was at the very end of Dynamic Routing Protocol section and that's when it happened...they threw me a curve ball. What am I talking about? The learning just went to a much deeper understanding.

Here's an example of what I'm talking about. Before I give an example, here's a question for everyone: What's the difference between a broadcast and multicast signal?

Here's another question: What is the IP address for a broadcast and multicast signal?

Were you able to come up with the answer for those questions?

Answer:

A broadcast signal goes out to every host in the subnet (network) and every host must process the packet.
A multicast signal is a method of sending packets to a group of interested receivers in a single transmission.

What is the IP address for broadcast and multicast?

Answer:

Broadcast address: 255.255.255.255
Multicast address: 224.0. 0.0 to 239.255. 255.255

Why is any of this important?

There's one universal truth in networking that I have noticed. BROADCAST TRAFFIC IS BAD.

One of the benefits of VLANs is that it segments broadcast traffic and frees up resources.

How does this any of this relate to Dynamic Routing Protocols?

The answer is complex and I'll attempt to explain:

In order for a Dynamic Routing Protocol to do it's job, it must update it's routing table frequently if there's any changes. For instance, if the connecting router goes down, the next door router must update it's routing table by deleting these routes? But how do routers update their routing tables? Well, RIP v.1 (version 1) sends out a broadcast signal to everyone on the network asking for an update. RIP v. 2 did away with broadcast requests and used multicast.

If you followed all of that, you're doing great.

**BillyCarpenter** · 06-02-2021

I need to make a small correction. I said that broadcast traffic is bad. It would be more accurate to say that broadcast traffic is a "necessary evil." Without using a broadcast signal, IP networking doesn't fly. But it creates problems.

Also, just to clear up any confusion about multicast signals....

Don't let it confuse you. A multicast is simply a communication between different hosts that have signed up for the same application. In this case it's RIP version 2 that is the application. Netflix and YouTube also use multicast signals.

**BillyCarpenter** · 06-02-2021

PS - All of that information led to learning about configuring a passive interface on a router to cut down on broadcast/multicast traffic. It never ends it seems. I'll explain that later.

**blackcat4866** · 06-02-2021

Originally Posted by BillyCarpenter

I need to make a small correction. I said that broadcast traffic is bad. It would be more accurate to say that broadcast traffic is a "necessary evil." Without using a broadcast signal, IP networking doesn't fly. But it creates problems.

Also, just to clear up any confusion about multicast signals....

Don't let it confuse you. A multicast is simply a communication between different hosts that have signed up for the same application. In this case it's RIP version 2 that is the application. Netflix and YouTube also use multicast signals.

Is any of this related to the PostScript error pages collecting on the tray of my endusers Canon? Most of the commands are ecrypted (hearts, smileys, and flowers) But occasionally a line of plain text comes through, vaguely resembling a web address. I figure if it was a wrong print driver of wrong print language, it would be 1000 pages not one or two. And it wouldn't arrive overnight when nobody is in the office. I speculated that maybe some kind of network maintenance is scheduled after hours, like PC updates, or camera downloads. Maybe broadcast traffic?

**BillyCarpenter** · 06-03-2021

Originally Posted by blackcat4866

Is any of this related to the PostScript error pages collecting on the tray of my endusers Canon? Most of the commands are ecrypted (hearts, smileys, and flowers) But occasionally a line of plain text comes through, vaguely resembling a web address. I figure if it was a wrong print driver of wrong print language, it would be 1000 pages not one or two. And it wouldn't arrive overnight when nobody is in the office. I speculated that maybe some kind of network maintenance is scheduled after hours, like PC updates, or camera downloads. Maybe broadcast traffic?

I think I remember you talking about this problem before?

I've done quite a bit of reading on the problems created by too much broadcast traffic.

Because broadcast traffic is sent out to every device on the network, each one has to look at the packet to determine if it was intended for them or not. That's not a big deal if there's only a few broadcast requests every couple of seconds, but that number can get much higher and create problems for devices on the network. Generally the symptoms will be slow response times and missing packets. I can't really say with any certainty whether or not broadcast traffic could cause a printer to print out a bunch of garbage. I can't really wrap my mind around that but that doesn't mean it's not possible.

**rthonpm** · 06-03-2021

Originally Posted by blackcat4866

Is any of this related to the PostScript error pages collecting on the tray of my endusers Canon? Most of the commands are ecrypted (hearts, smileys, and flowers) But occasionally a line of plain text comes through, vaguely resembling a web address. I figure if it was a wrong print driver of wrong print language, it would be 1000 pages not one or two. And it wouldn't arrive overnight when nobody is in the office. I speculated that maybe some kind of network maintenance is scheduled after hours, like PC updates, or camera downloads. Maybe broadcast traffic?

It sounds like the customer has some kind of security scans running at night. Depending on what features are enabled on the Canons, if the scan hits one of the open ports on the machine, the controller sometimes interprets what it's getting as a print job. I had a customer that ran Nessus security scans at night which would cause some of their printers to spit out all kinds of gibberish pages. The quick solution was to disable access to the web interface over port 80 (HTTP) to prove it was the cause, the long-term fix was to have them adjust their scans to bypass the static IP range for their printers.

**BillyCarpenter** · 06-05-2021

There's this restaurant that I go to quite often and the other day the owner has one of the her employees ask me to come to the back office to see her. So, I go back and she show's me her security camera system. Only one of the 8 cameras was working. It was POE system. Standard camera system. I told her that's really not what I do. She kept on until she talked me into giving it a look. Turns out that the system was old and that there was no power going to any of the camera except that one. I told her that she's probably be better off buying a new system considering the age of the current one. I figured that would be that. She then asks me to give her a quote on a system that includes installation. This is a huge restaurant and it's quite the job. I tried to get out of it but she insisted that I do it. lol.

So, I told her I'd get her a quote the next day. I really didn't want to do this job so I gave her an obscenely high quote in order to persuade her to look elsewhere. She accepted the quote. Damn!!

Anyway, there's nothing complicated about installing the system. Or so I thought.

Turns out that setting up a cell phone to view the camera remotely was more complicated than I thought. I've been fucking with my camera system all day. I had to learn about DDNS and port forwarding. Who knew that that shit was so complicated? Or it was to me. I finally got it, though.