Apple Wireless Network

11 08 2013

Apple AirPort Extreme is Apple’s router for Internet access. It’s directly connected to a modem and provides wired as well as wireless access for computers, mobile devices like an iPhone or an iPad, printers, and media devices.
Apple offers three different routers (Airport Express, AirPort Extreme, Time Capsule) which can be connected to either a DSL or a Cable modem.

A complete wireless network build with solely Apple products follows the the company’s strategy to provide users with a perfect experience regarding design, setup, and reducing features to those which are necessary. KISS is the motto.

KISS
KISS = Keep it simple, stupid
A design principle noted by the U.S. Navy in 1960 that states that most systems work best if they are kept simple. Unnecessary complexity should be avoided.
Variations of this phrase are:
Keep it simple sir, Keep it simple and straightforward, Keep it short and simple, Keep it simple or be stupid

The hardware …

See this mind map which summarizes all properties of Apple’s hardware for wireless networking with mobile devices. As you can see Apple built it’s own ecosystem where components perfectly work together.

Remark
The router hardware was replaced by new versions on June 10, 2013 on occasion of Apple’s WWDC.

Here are the main features of Apple’s routers summarized in a mind map.

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Feel free to download this map from my Box account.

The alternative file formats have been created with iThoughts HD for iPad (.ITMZ file format). Compatibility to other tools is limited.

Application File format
Adobe Reader PDF
iThoughts ITMZ
MindManager MMAP
XMind XMIND

Please visit

The Apple group on Biggerplate

to see and download all mind maps related to Apple.

This more realistic view shows the kernel with a modem and the router as well as some examples of wirelessly connected hardware components for interactive usage.

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The integration of all you need for a perfect user experience goes along with limitations when using non-Apple hardware. It’s Apple’s strategy to say NO to some features other vendors offer and to say YES to a seamless integration of its hardware with its custom-built software.

Professionals may argue that performance, configuration options, and price is not what should be expected. On the other hand the running system convinces users who see the technology as as a serving and not an experimental environment. So do I after many years with other configurations not following the motto ‘It just works’ or ‘Buy, connect, and use it’ for the tasks you want to use it for.

A complete configuration …

Follow these steps in the order specified.

Step 1 Connect the modem to the multimedia connector with a coaxial cable.

Modem
A modem (modulator-demodulator) is a device used to connect a computer or router to a telephone/cable line to allow the computer to connect to the Internet. It modulates a carrier signal to encode digital information, and also demodulates such a signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.

Step 2 Connect the modem to the power supply.

Wait until the LEDs indicate a functioning connection to your ISP. It may take up to 30 min.

Step 3 Connect the APE to the modem with an Ethernet cable.

Ethernet cable
Ethernet cabling is standardized. If you go to a store you may find a variety of “categories” of cabling. These categories tell you the quality of the cabling. The quality determines, essentially, how much the cable can handle. Recommendation: Cat 6 – works for 10/100/1000Mb.

Step 4 Connect the APE to the power supply.

Here we go.
The configuration with any iOS device and the helper apps Settings and AirPort Utility starts.

Open Settings on your iPhone or iPad and tap on WiFi.
The APE already is sending signals so that your device suggests the set up of a WiFi network.

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Tap on the right-pointing arrow to set up an AirPort basestation.
Enter a name for your network and set a password. Other users like your neighbors, if not too far away, will see this name as an additional WiFi network. Use a strong password for joining this network.

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Tap on Next and that’s all.
Your new WiFi network will connect all your devices with the internet after entering the password you set for your network.

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The utility app …

For controlling the network Apple offers an app called ‘Airport Utility’ which is available for iOS devices, Macs, and Windows PCs.
The slideshow shows the usage of this app when configuring a wireless network with an Airport Extreme router connected to a cable modem.

The most important configuration options can be controlled with the app for iOS devices. For some less important options like adjusting the signal strength Airport Utility for computers must be used.

The benefits …

Apple’s ZEROCONF technique minimizes your efforts to install a usable internet access.

Zero configuration networking (zeroconf)
is a set of techniques that automatically creates a usable Internet Protocol (IP) network without manual operator intervention or special configuration servers.
Zero configuration networking allows devices such as computers and printers to connect to a network automatically. Without zeroconf, a network administrator must set up services, such as Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS), or configure each computer’s network settings manually, which may be difficult and time-consuming.

Apple does not permit the AirPort Extreme to engage in channel bonding on the 2.4GHz frequency band. This is a very neighbor-friendly policy, because only three channels in this band—channels 1, 6, and 11—don’t overlap. A router engaging in 2.4GHz channel bonding can hog more than its share of bandwidth and will likely interfere with other 2.4GHz routers operating nearby.

The AirPort Utility also makes it very easy to update the router’s firmware. The AirPort Extreme is so much easier to set up than any other router of the many competitors.
The reason is that if you stay in Apple’s ecosystem you will benefit from all the efforts Apple did for an easy-to-use experience.

The performance on 802.11n standard transmission technique is high.
The APE is powerful even if thick walls hamper propagation of electromagnetic waves.

Interference …

In physics, interference is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower amplitude. Interference usually refers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency like electromagnetic waves sent from WiFi networks.

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If you get problems with interference or the performance of your network is slow which may be caused by interference follow these guidelines:

Apple about potential sources of interference

Macworld, Troubleshooting Airport Interference

The Airport Utility …

Apple’s ZEROCONF technique minimizes your efforts to install a usable internet access.

Zero configuration networking (zeroconf)
is a set of techniques that automatically creates a usable Internet Protocol (IP) network without manual operator intervention or special configuration servers.
Zero configuration networking allows devices such as computers and printers to connect to a network automatically. Without zeroconf, a network administrator must set up services, such as Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS), or configure each computer’s network settings manually, which may be difficult and time-consuming.

Look at the details to get a deeper understanding of what happened when configuring the network.
To see the details of your own WiFi network go to Settings – WiFi and tap on the right-pointing blue arrow of you network. Go to the bottom and tap on ‘Manage network’. This will open the Airport Utility. Airport Utility can be used to individualize the configuration.

Regarding to my blog Network (1) from April 20 you will now understand the configuration details set by the APE:

  • DHCP ON
    the APE acts as a DHCP server and assigns private IP addresses (10.0.1.x) to all devices joining the WiFi network after entering the password.
  • NAT ON
    the APE does the network address translation that means, NAT converts your private LAN IPs into a external WAN IP
  • Security
    the APE encrypts all WiFi network traffic with WPA2
    (Wi-Fi Protected Access II (WPA2) is a security communication protocol developed by the Wi-Fi Alliance to secure wireless computer networks)

This slideshow shows all settings displayed in Apple’s app AirPort Utility:

This slideshow requires JavaScript.

In addition to the automatic configuration I entered the following settings:

  • Reservations for IP addresses
    the APE reserves an IP address for all devices. Reservations are useful if you want that the DHCP feature of your APE assigns a fixed IP to your devices. Otherwise DHCP is free to assign any free IP address in the range 10.0.1.2 – 10.0.1.200 every time you join your network.
  • 5 GHz network
    The APE works in the 2.4 and 5 GHz frequency band. The iPad is able to connect on the 5 GHz band and I named this (second) network as ‘Apple Airport 5 GHz’.
    If you have interference problems with other WiFi networks you may vary the channel or move over to the 5 GHz network.
  • With the help of Airport Utility for PCs I additionally limited the signal power to 50% which is enough to get connected in all rooms and hampers other WiFi capable devices outside my home to detect my network.

The result is a working internet connection checked by the app Fing which is available at Apple’s App Store.

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The disadvantages …

The AirPort Extreme has only one USB 2.0 port, so it can share either a printer or a storage device over your network. This is in the line with Apple’s strategy that printers should be connected via AirPrint. I miss the support of USB 3.0.

Apple’s design decisions help its product blend into a home’s décor and so the old version of AirPort Extreme was designed to rest flat while the new version was redesigned in June 2013 due to an improved output power. It’s still an eyecatcher.

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Related links …

Airport Extreme Tec Specs

Airport Extreme User Guide

Airport Extreme Easy Setup

Setting up your wireless network

Cisco, 20 Myths of Wi-Fi Interference

Thanks for visiting my blog.
Wireless as well as wired connections are welcome.





Network (1) Addressing

20 04 2013

The articles about networks are written for my readers who are not familiar with the terminology, the functionalities and the cooperation between devices in a network environment.

Part (1) explains the basics of networking. Experts should overlook some verbalization because I want to keep it very simple.

If you want to communicate with other people far away from you, you need an address. It can be a postal address, an E-Mail address or a phone number. In any case the address has to be unique to ensure that your message will be delivered to the person you want to communicate with.

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As you can see I left out the addressing method of the corresponding transmission of a PDF file from one of your devices to a Dropbox cloud storage account.
Addressing we use for letters is not appropriate for a computer network as it can be written in different ways up to the country’s conventions. Furthermore there is no fixed location where data are stored. On a day it can be a webserver in Australia and a day later it possibly can be a webserver in India.
So the device address must be more like a GPS address which is uniquely written all over the world with the additional possibility to forward an existing address to a new address without noticing the users. To do so a complex organizational computer infrastructure has to be established which transmits requests to the right recipients wherever they are actually located.

All network devices around the world use an IP address for identification purposes. It usually consists of 4 numbers separated by a dot (10.0.1.1).

An IP address (Internet Protocol address) is an assigned numerical label that is used to identify devices on computer networks. Think of it like this: An IP address is to a computer what a telephone number is to an iPhone. Each computer can stand alone without its respective IP address. However, if you want to communicate with other computers from yours, you will need an IP address.

  • An IP address is a 32 bit binary number divided into four sections by dots.
  • Each part of an IP address is called on octet.
  • As 255 is the largest number which can be represented with 8 bits each octet can range the range from 0 to 255.
  • For LANs the following IP addresses are reserved by RFC 1918:
    10.0.0.0 – 10.255.255.255
    172.16.0.0 – 172. 31.255.255
    192.168.0.0 – 192.168.255.255

An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: “A name indicates what we seek. An address indicates where it is. A route indicates how to get there.”

Here you can see an example. It’s my small home configuration, a WiFi network with some Apple devices where the boss for addressing all devices is an Apple Airport Extreme router.

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As you can see this network has no connection to the outer world at this time. So this system allows basically the use of any combination of numbers for addressing the devices.

Severe problems would arise if you want to contact a network outside this local area network (LAN) e.g. a webserver in another country which provides a website you are interested in. It cannot be assured that the address of this computer is unique. So your request might wander around the world with uncountable answers.

In my articles about networks you often are confronted with the expression protocol. What is a protocol?

A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications. A protocol may have a formal description. Protocols may include signaling, authentication and error detection and correction capabilities. Communications protocols have to be agreed upon by the parties involved. To reach agreement a protocol may be developed into a technical standard.

Look at the first image of this article.
We can talk about a Postal Protocol where the postal address has to be defined as name, street (or PO box), city, ZIP code and country. It’s just a convention about the way how an address has to be written and what kind of information should be included.

LAN and WAN …

To solve this problem, a LAN (where IP addresses are free to choose) can be connected to other LANs by using a worldwide unique wide area network IP address (WAN IP address). Your Internet Service Provider (ISP) assigns a WAN IP address to your router so that requests from a device inside your LAN is transmitted with this WAN IP and the recipient can answer using your WAN IP as the destination address.

Here is the WAN IP taken for my local area network some weeks ago.

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My ISP is a German Cable Internet Provider. Like most other ISPs the company assigns varying IP addresses to my connection. My IP address is therefore called a Dynamic IP address. It may vary from hour to hour or day to day. So usually I cannot reliably reach any device inside my LAN without looking up the actual IP address. This problem will be discussed later.

Look here for a more detailed view on LAN and WAN IPs and what your devices have to do when you connect to the internet e.g. request for a website.

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You can see that there are several devices with different LAN IPs but only one WAN IP.
So it has to be cleared up how the information requested by a specific device is delivered to this device. NAT (Network Address Translation) does it.

NAT
In computer networking, network address translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across traffic routing devices.

If you enter the address of a website e.g. http://iNotes4You.com you might argue that this format is not the format of an IP address as mentioned above. You are right and some further functionality is needed to convert this human-friendly address into an IP address.
This service is called DNS (Domain Naming System).

Wikipedia
The Domain Name System (DNS)
is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates domain names meaningful for users to the numerical IP addresses needed for the purpose of locating computer services and devices worldwide. By providing a worldwide, distributed keyword-based redirection service, the Domain Name System is an essential component of the functionality of the Internet.
An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name http://www.example.com translates to the addresses 192.0.43.10. Unlike a phone book, the DNS can be quickly updated, allowing a service’s location on the network to change without affecting the end users, who continue to use the same host name. Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and E-Mail addresses without having to know how the computer actually locates the services.

Ports …

You already know that data on the Internet is sent to and from IP addresses. Sending or receiving data is done on ports. Ports are virtual pathways on which Internet data flows.

If we think of an IP address as a telephone number (an identifying number that allows communication between two locations), then we can think of ports as telephone number extensions. Suppose you wanted to make a telephone call to a major corporation like Apple. If Apple only had one simple telephone line it would take a very long time for your call to finally get through. However, by using telephone number extensions, Apple can channel incoming calls to the proper locations and as a result handle many calls on one line as opposed to just one call.
Ports are like telephone number extensions as they allow multiple pieces of data to flow back and forth on a single IP address. In fact, port numbers are appended to the end of IP addresses just as extensions are appended to telephone numbers.

In other words, ports are numerical identifiers that make it possible for you to check your E-Mail and browse the web at the same time. Technically speaking, this is possible because browsing the web traffic generally uses port 80, secure website connections use port 443, and getting your E-Mail generally uses port 110.

Technical Facts
Ports are a 16-bit number can range from 1-65535.
TCP and UDP packets specify the port on which they are to be sent in their packet header.
The ports that a given application uses are generally set by the programmers of that application.the purpose of ports is to uniquely identify different applications or processes running on a single computer and thereby enable them to share a single physical connection to a packet-switched network like the Internet.

The protocols that primarily use ports are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number. The port number, added to a computer’s IP address, completes the destination address for a communications session. That is, data packets are routed across the network to a specific destination IP address, and then, upon reaching the destination computer, are further routed to the specific process bound to the destination port number.
Note that it is the combination of IP address and port number together that must be globally unique. Thus, different IP addresses or protocols may use the same port number for communication; e.g., on a given host or interface UDP and TCP may use the same port number.

Ports in Relation to IP Addresses …

Remember at the top of this page when it was mentioned that ports are appended to the end of IP addresses just as extensions are appended to telephone numbers? There is a specific syntax for appending port numbers to IP addresses and it is as follows:
(IP Address):(Port Number) or.. 10.0.1.5:80

Notice the colon acting as a separator between the IP address and the Port Number. Port Numbers are appended to the end of all IP addresses whenever data is sent.
Why don’t we see a port number appended to the end of web addresses?

There are a few commonly used port numbers. Web traffic uses port 80 and is in fact so common that port 80 is assumed to be appended to the end of a web address by your internet browser and thus can be left off. You can test this by typing google.com:80 into your browser’s address bar. When you press enter, you should go straight to Google. Now, try typing google.com:6060 into your browser’s address bar. When you press enter, you will not be connected to Google.

DHCP …

There is still some information missing. Who assigns IP addresses?

The Dynamic Host Configuration Protocol (DHCP) is a network protocol that is used to configure devices which are connected to a network so that they can communicate on an IP network. The main task of a DHCP server is the assignment of unique IP addresses to all devices within the network. In a typical private LAN, a router is the DHCP server while clients are tablets, computers or printers. The router receives information through a modem from an internet service provider which also operates DHCP servers where the modems are clients. The clients request configuration settings using the DHCP protocol such as an IP address, a default route and one or more DNS server addresses. Once the client implements these settings, the host is able to communicate on that internet.
The DHCP server maintains a database of available IP addresses and configuration information. When the server receives a request from a client, the DHCP server determines the network to which the DHCP client is connected, and then allocates an IP address or prefix that is appropriate for the client, and sends configuration information appropriate for that client.

Summary …

  • IP address
    a number like 10.0.1.1 as an identification of a device within a network
  • LAN
    the local area network
  • WAN
    the wide area network connecting LANs
  • NAT
    the replacing of LAN addresses by WAN addresses
  • DNS
    the renaming of human-friendly addresses into IP addresses and vv.
  • DHCP
    the system which configures devices especially assigns IP addresses
  • Protocol
    a convention how to communicate within a LAN or WAN

Thanks for reading my blog.
If you have any questions don’t hesitate to contact me via my About page or a comment on this article.








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