Need some advice on learning networking

[BillyCarpenter]

Re: Need some advice on learning networking

Learning wireless has been an eye opening experience. For me, even learning the basics was an experience. I already knew how RF signals worked from my study of Industrial Electronics back in the day.


You don't want 2 access points interfering with each other by being on the same frequency. But if you look at the 2.4GHz channel, you'll notice that it's not just that one frequency. It's a range of frequencies that are divided up into 13-channels. If you look closer, only 3 channels don't overlap. This is why 2.4GHz isn't preferred. All of the same principles apply to the 5GHz range but you have many more channels that don't overlap.


With that in mind, if you're installing 100 access points, it's gonna be an enormous job to put all of them on the correct channel so that they don't interfere with each other. Thank goodness that the Wireless Lan Controller does all of that for us.

[BillyCarpenter]

Re: Need some advice on learning networking

By the way, I think I have all of this down in my head. The hardest part will be configuring the Layer 3 switch. That's where the real work is at. There is some configuring of the WLC, too. DHCP option 43 could be a challenge as the IP address must be entered in HEX and there are codes for the different vendors (Cisco in my case) that must be entered. But I think I have that down, also.

[BillyCarpenter]

Re: Need some advice on learning networking

Thought I'd follow up on the wireless access points. I have not received my Cisco gear as of yet. The last of it will arrive on Friday.


But I wanted to give an update on something else. As I said, I already had 2 Aruba Instant On Access Points. I installed them a couple of years ago when I knew zero about networking. They are very easy to set up. In fact they are plug and play.

Now that I know what I'm doing, I wanted to find out what goes on behind the scene and if the Instant On AP's would be a viable opition. I must say that I am very impressed.


Here's what I did.


I downloaded an app on my laptop called Wifi Analyzer. I plugged in one Access Point to my switch. It received a DHCP address and I went to the GUI via the IP address. I gave it an SSID name and password and we were off to the races with wifi transmitting from the access point.

Next I grabbed my laptop and pulled up the Wifi Analyzer app and started walking until I got far enough away that the signal from the first AP was weak. I then placed the 2nd AP in that spot and plugged it in to the switch.


There's a master/slave relationship between multiple AP's. The first AP that's plugged in becomes the master and every subsequent AP is a slave and gets it's configuration from the master AP.

Once both AP were transmitting a radio, I would walk back and forth between zone 1 and 2 and the Wifi Analyzer App would show me when my laptop would switch from one AP to the other via Mac Address of the AP's.


It worked flawlessly. There was a few seconds of lag time when switching from one AP to the other. You wouldn't want to make wifi phone call and walk around the building because it would be dropped. You'd need a Wireless LAN controller to make that work.

I do highly recommend the Aruba Instant On AP's for a small/medium office.

PS - It did take me a minute to figure out how to limit the Guest Network to internet only with no access to the LAN. They could have made that easier.

I'll give an update on the Cisco System when it gets here and I've figured it out.

[BillyCarpenter]

Re: Need some advice on learning networking

My Cisco access points arrived yesterday along with my Wireless Access Controller. My Layer 3 switch will arrive today. I'm super excited about getting it configured and I also plan to implement a Triple A server for authentication.

To this point, I have mostly used Packet Tracer or one of the other emulator programs to learn how to configure routers, switches, ect., but nothing takes the place of the real thing. There's just something about plugging into the console port of a router and using Putty to pull up the CLI.

[rthonpm]

Re: Need some advice on learning networking

My Cisco access points arrived yesterday along with my Wireless Access Controller. My Layer 3 switch will arrive today. I'm super excited about getting it configured and I also plan to implement a Triple A server for authentication.

To this point, I have mostly used Packet Tracer or one of the other emulator programs to learn how to configure routers, switches, ect., but nothing takes the place of the real thing. There's just something about plugging into the console port of a router and using Putty to pull up the CLI.

Pro tip: for any Windows machine, you can get a built-in ssh client by either enabling the Windows Subsystem for Linux or by installing PowerShell 7. With the former enabled, you can just enter ssh at a command prompt and it works, with the latter just open PowerShell and enter the same command. PuTTY is a great tool, but it's showing its age.

[BillyCarpenter]

Re: Need some advice on learning networking

Pro tip: for any Windows machine, you can get a built-in ssh client by either enabling the Windows Subsystem for Linux or by installing PowerShell 7. With the former enabled, you can just enter ssh at a command prompt and it works, with the latter just open PowerShell and enter the same command. PuTTY is a great tool, but it's showing its age.

You're on another level, dude. How long have you been doing this?

Once again, thanks for sharing the knowledge. I'll give it a try.

[BillyCarpenter]

Re: Need some advice on learning networking

Welp, my Layer 3 switch did not arrive on Friday as scheduled. That damn FedEx.


But since I had the WLC and the access points, I decided to see what I could do with it.


This turned out to be an incredibly frustrating experience. For starters, every piece of info I read or watched said the best way to configure the Wireless Lan Controller was via GUI. This should have been a snap, right? Wrong.

Before you can access the GUI there's some settings that must be configured in the CLI. I'm very adapt at working with the CLI in Cisco. But the Lan Controller is running a different IOS and the syntax is completely different. Also, before I could even make those changes, I had to wipe the old configuration and reset to factory default. This took a couple of hours to figure out.

Once I was able to access the GUI, I thought that I was home free. Wrong. The Access Points wouldn't join the Controller and I wasn't sure why. My first thought was that it had something to do with DHCP Option 43 but after double checking, I focused my troubleshooting elsewhere.

I did a factory reset of the Access Point. Still didn't work. So I consoled into the AP and ran a couple of tests and found out that the security certs were expired. I correct that and finally I got it up and running.


I gained valuable experience but that was tough sledding. When the Layer 3 switch arrives, I'll do the more advanced configuration.

[slimslob]

Re: Need some advice on learning networking

So I consoled into the AP and ran a couple of tests and found out that the security certs were expired.

I have encountered that with Ricoh's when they suddenly stop being able to send email.

[rthonpm]

Re: Need some advice on learning networking

I have encountered that with Ricoh's when they suddenly stop being able to send email.

Managing TLS certificates can be a job in and of itself. Even in my very small office we have at around 35 TLS certs. They're all tied to an internal authority so there's no real troubleshooting needed if they expire, but scale that to an enterprise organisation and things get really ugly really fast when a mission critical system goes down because of an expired cert. At least at that scale there are ways to automate alerts for certs.

Sent from my BlackBerry using Tapatalk

[slimslob]

Re: Need some advice on learning networking

Managing TLS certificates can be a job in and of itself. Even in my very small office we have at around 35 TLS certs. They're all tied to an internal authority so there's no real troubleshooting needed if they expire, but scale that to an enterprise organisation and things get really ugly really fast when a mission critical system goes down because of an expired cert. At least at that scale there are ways to automate alerts for certs.

Sent from my BlackBerry using Tapatalk

Many internet SMTP require a device certificate issued by an approved certificate authority. Luckily when scan to email started being used, Ricoh published a Knowledge Base article explaining how export one from Internet Explorer and Firefox to you HDD and then install it on the MFP. The Authority and specific recommended have changed over the years but the installing to the MFP is still pretty much the same.

[BillyCarpenter]

Re: Need some advice on learning networking

A quick note: I now have 3 Lightweight Access Points connected to the WLC. There's a couple of advantages that I see right off the bat.


1. The WLC automatically adjusts the power of the radio signal for each AP. Example: I have 2 AP's sitting on a table about a foot away from each other. The first AP is running at 87% radio and the other at 7%. The 3rd AP is on the other end of the building and it's at 11%.

These Cisco AP's are twice the size of the Aruba AP's and MUCH more powerful. I walked out in the parking lot and went about 150 yards away and could still access the internet.

2. Another difference is that the signal never drops when switching from 1 AP to the next.


This is definitely the way to go.

[BillyCarpenter]

Re: Need some advice on learning networking

PS - All of the Access Points were automatically placed on different channels with absolutely no overlap. It's the cleanest looking wireless setup that I've seen and the controller did much of the work.

[BillyCarpenter]

Re: Need some advice on learning networking

Now that my head is clear this morning after a frustrating day before, I have some random thoughts I'd like to share.


My journey into networking has led me in many different directions and the jobs are getting more and more complex. For me personally, I'm so glad that I'm learning the CCNA for routers and switches. Without knowing this, a networker would be extremely limited in what he can do.

On the other hand, CCNA teaches next to nothing about Windows 10, Linux, Windows Server or any other operating system and thus that has severely limited what I can do in that area.

It's clear to me that when I'm finished with the CCNA that I'm gonna have to learn more about operating systems/Servers.


Other random thoughts.

For the first time, I ran into a problem with security certs. I don't really understand them. I was able to resolve my issue by using google, but still don't understand them they way I should. I'll correct that at some point.


Lastly, I thought I understood DHCP. I found out that I understood the basics but there was much more to learn.

With Cisco's wireless lan controller it uses DHCP in a little different way. DHCP has "options." Google "DHCP OPTIONS" and you'll see what I mean.

You have DHCP option 43 that is used to help Cisco Access Points discover the Wireless LAN controller. And there are MANY other options.


PS - I have a question if anyone wants to jump in.

Let's say that I have a single Windows server. Good or bad idea to use that for DHCP? If it goes down, then what? Just wondering.

[rthonpm]

Re: Need some advice on learning networking

Most servers now are virtual so spinning up new servers is fairly trivial as long as you have available licenses (Windows and RHEL only). That said, I have several customers with only a single DHCP server and issues have been very rare. The key with servers is to keep their roles as separate as possible so that a failed server doesn't take down everything. DHCP is also easy to configure so that a secondary server is available if the primary isn't responding.

A basic Windows network could look something like:

Domain Controller/DNS/DHCP

Domain Controller/DNS (domain controllers will always also be your internal DNS servers)

File/Print

Web (IIS, Apache, etc)

Database (SQL, etc)

Any other appliances


In terms of licensing, the basics of Windows are:

Server Standard allows you either a physical install and two virtual machines as long as the physical server is only used for the Hyper-V role, or just two virtual machines if another OS is managing the physical hardware.

Server Datacenter allows you an unlimited number of virtual machines for any supported versions of Windows Server, so Server 2022 will let you install virtual machines for any version back to Server 2012. The cost is significantly higher, and your point where it becomes more cost effective is around more than 16 virtual machines on a single host.

You can also download evaluation versions of Windows Server which are good for 180 days. You can extend the period past that several times so that your evaluation copies can give you close to three years of use by reloading the activation every 180 days.

Server 2019 and earlier also offered a free version called Hyper-V Server which could only serve as a platform to host virtual machines. This is great for lab environments or for failover and replication servers since it doesn't require any licenses and can host as many VM's as you like, again as long as you have the appropriate licenses.

The norm for at least the last decade or so has been to virtualise everything as much as possible. Of the piles of servers we manage for ourselves or customers, the only physical servers are either hypervisors or servers that require a direct physical connection to some other piece of hardware, like a tape drive or other special equipment.

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[BillyCarpenter]

Re: Need some advice on learning networking

If my Layer 3 switch ever arrives, I'm gonna set up Wireless and spread it out over different VLANS. It's important for me to learn how to do this because, let's say that we have 100 AP's and let's say that each AP has 20 users on each one at the same time. That's 2000 users on the same vlan. Not good.

I've been studying this for several days and it's been fucking confusing. At times I think I understand the concept but then doubt starts to creep in. Finally, I had that "light bulb" moment and now I understand.

Basically I need need to create several different ssid's and assign them to a different vlan. That is done via logical interfaces on the Wireless LAN Controller. The WCL then applies a vlan tag and sends the packet to the switch where it is routed to the correct vlan and final destination.



There are other steps involved but I wanted to simplify in order to explain it.


PS - In future posts, I will be referring to Access Points as LAP's - "Light Weight Access Points". That just means that the WLC handles much of the work that is normally done by an autonomous AP.