Previously on FUAQ, I spoke about how IP and MAC addresses are used to send data. On this installment, I will cover subnet masks, private address spaces, and network address translation.
First, let’s pick up where we left off with FUAQ Pt. 2: my computer talking to http://www.google.com.
Recap: My computer (220.127.116.11) wants to send something to http://www.google.com (18.104.22.168). My computer will make a letter to 22.214.171.124 and send it to the post office (router). To send something to the router, my computer (F4:5C:89:XX:XX:XX) will use the local address of the router (08:EA:44:XX:XX:XX). So my computer puts the letter to google in an envelope, writes google’s address on it. Then puts that envelope in a box and addresses the box to my router.
A big issue here is that my computer is using one address, and Google is using another. Why is that an issue? There are only 4 billion addresses available in IPv4! There are more than 4 billion devices in the world, though, so how do we handle this? Network Address Translation (NAT) allows multiple computers to use many private network addresses through one public network address.
Example: A grandmother wants to send a letter to her two grandkids that both live in the same house. When she addresses the letters, they are both sent to the same street address, same town, same state. But thanks to their mother’s intelligence, each letter makes it to the right person.
Continue reading “Frequently (Un)Asked Questions – Pt. 3”
Recently, I was teaching a class, and a student asked what 10.0.0.0/255.0.0.0 meant in a firewall policy. I then spent time explaining the tenets of subnets and IP addressing. This wasn’t the first time I have had a student look confused or ask a question on the subject. Therefore, today’s blog will discuss the ideas of IP addresses and MAC addresses.
Scenario: You want to send a letter to your friend in your town. What information do you need? Their street address? Their city? Their state? Their zip code? For something local, you could probably put the street address of your friend, and the post office will get it there.
Continue reading “Frequently (Un)Asked Questions – Pt. 2”
For my job, I teach a class on how to use Aerohive’s Network Management System (NMS). It is a two day class that covers a majority of the knobs and dials in Aerohive’s HiveManager NG. This class assumes that attendees have a knowledge of networking and wireless in general. In fact, a recommended prerequisite is the CWNA certification.
That being said, not many attendees come fully educated on Wi-Fi. It seems that Wi-Fi is still not very extensively studied by the general public (as evidenced by there being fewer than 250 CWNEs worldwide). Therefore, I spend a good part of class going over some basic concepts of Wi-Fi to help explain some of the abilities of the NMS.
What often goes unnoticed, though, is that some attendees are not fully educated on networking basics either. Often times I cover a topic during class (such as the need for a trunk between APs and their switches) and I will be greeted with blank stares because a student doesn’t know what a trunk is, yet they don’t want to ask for fear of sounding stupid.
Thus, I am introducing a series called “Frequently (Un)Asked Questions”. This blog is intended to educate users on the basics of networking and Wi-Fi and will act as a repository for topics I often need to cover but don’t because the questions go unasked. Continue reading “Frequently (Un)Asked Questions – Pt. 1”
Last time, I talked about the need for IPv6. On this installment, I will explain what is included in IPv6 and how it solves the problems from IPv4. Let’s recap:
Internet Protocol version 4 came out in 1981. To identify hosts connected at layer three, IP addresses were used. IPv4’s addressing convention allows for a little over four billion addresses (what seemed like an un-reachable number). In 2011, the world ran out of IPv4 addresses (despite efforts to stall the issue). As such a new version of Internet Protocol was created – IPv6 (further reading: yes, I know it should be IPv5).
How does IPv6 solve this addressing problem? Continue reading “The Future of Network Addressing – IPv6”
Yesterday, my wife asked me about IPv6. “What are the benefits?” and “How is it different from IPv4?” Rather then send her to LMGTFY, like the snarky person I am, I decided to give her the run down on IPv6. Thus I was inspired to share my thoughts about IPv6 here, with you. This week, I will discuss how the need for a new version of Internet Protocol came about.
Let’s dive right in by defining the IPv4 address exhaustion problem. Consider the following:
You are making an address system to help in sending letters. At the time you make your system, there are about 10 houses in your city. As such, you very simply label the houses A, B, C, D, etc. You have used 10 letters of the 26 letter alphabet. This works fine, but eventually, people hear about the amazing landscape in your “town” and start moving in. Within a year, you get five new neighbors. Then five more next year. You can tell, that in two more years, you are going to run out of addresses for the houses in your neighborhood! What do you do?
Continue reading “Why do we need IPv6?”
What does “half-duplex” mean anyway? Simply put, communication can only happen in one direction at a time.
Wi-Fi devices are much like people. We talk by generating noise, with our mouth. We listen to generated noise with our ears. Yet, because we all use the same frequency range for talking, we cannot comprehend if multiple people talk at the same time. Wi-Fi devices work similarly. If two devices try to transmit data at the same time, a collision will occur and neither device will comprehend the other. Continue reading “The IFS of Wi-Fi”
Consider the following scenario:
Two APs can hear each other. AP1 is set to use channel 36+40+44+48 (primary channel 36+40) while AP2 is set to use channel 44+48. Due to the nature of 802.11 and co-channel interference, AP1 cannot transmit while AP2 is transmitting.
In this scenario, the APs will forever dance the dance of CCI, waiting for the other to finish transmitting before taking over the medium itself. Wouldn’t it be better if instead of waiting, they could both transmit at the same time?
This is a scenario brought to you by 802.11ac, an infrequently discussed issue known as: Overlapping BSS (OBSS). OBSS is defines as two BSSs that, well, overlap, because their channel configurations occupy some of the same space. Continue reading “On OBSS Interference”