ADSL Modem/Router Buying Guide

• Fast connections are worth sharing
• Routing is the core of your shared network
• Dedicated devices - the alternatives
• What are the individual functions that make up the device?
• Buying a modem/router/switch
• Buying a device with an Ethernet switch
• Buying a device with wireless networking
• What about security?
• DIY vs ISP?
• Summary of features
• ADSL
• USB or Ethernet?

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If you have multiple computers around the home or office and want to network them together to share an ADSL Internet connection then this guide is for you. In the pages to follow we investigate the main technology required to share broadband Internet - that is the ADSL Modem, router and/or switch - and how to connect it all together. By the end, you will know whether you need a modem, router, access point or all three rolled into one unit. There is also an exhaustive glossary of the terms that you will encounter while choosing the right hardware.

Fast connections are worth sharing

Before the popularisation of broadband, there was little demand for Internet connection sharing. Surfing the Web with a dial-up modem is slow enough when you're not sharing it, let alone when you have two or three computers using it at the same time. Because broadband is more than ten times faster, however, sharing the connection amongst a few computers is not just feasible, it is downright recommended! Consequently, a wide range of routers and combination devices have hit the market making it not only possible, but also easy, to set up broadband connection sharing. Once your connection is shared, all your computers will be able to use the Web, email, instant messaging and any other Internet application you can think of - anytime and all the time.

Routing is the core of your shared network

When you set up a shared connection you are essentially setting up an Ethernet network - wired, wireless, or both - around your home and/or office, with a connection to the Internet attached to that network.

The first thing to understand is that every device on the Ethernet network can connect to any other device. If you have three computers attached to the Ethernet network then they can all connect to each other to share files, access printers or even play multiuser games. [possible pic of an Ethernet network with three computers - no internet connection yet]

If connected together by Ethernet cable, they are connected together through a 'switch'. If connected together by wireless Ethernet, they wirelessly connect to a local Ethernet access point. You may also have a combination of wireless and wired to form your Ethernet network. [pic of a wireless and wired network without an Ethernet connection]

Of course, while you can now connect to all the devices on your network, you still cannot connect to the Internet! To do this you will need a router also attached to the Ethernet network. A router provides the ability to 'route' traffic between one network and another - in our case between our local Ethernet network and the Internet. Because the router is attached to the Ethernet network, all of the devices can see it. Indeed, each of the devices are configured in such a way so they know that if the user wants to access the Internet, they need to direct traffic (data) to the router. Because the router is also attached to the Internet, it will pass the traffic on from the Ethernet network out to the Internet and back again.

A router can be a dedicated hardware device with firmware (software) running, or it can be another computer with the appropriate router software running on the operating system. This buying guide deals with the former - dedicated hardware device solutions - which provide reliability, simplicity and high availability in a cost-effective package.

Dedicated devices - the alternatives

The router must have a connection to each network - Ethernet on one side for your local network, and the broadband interface on the other side. The broadband interface on the other side will depend on your broadband connection type and the hardware you may already have.

Commonly used configurations for ADSL are as follows:

ADSL Modem/Router/Switch (also commonly referred to as ADSL Routers): These devices incorporate an ADSL modem to connect to the Internet, an Ethernet switch to connect your wired local area network devices, and router functionality to hook the two networks together.

ADSL Modem/Router/Switch/Wireless (also commonly referred to as Wireless ADSL Routers): These devices incorporate an ADSL modem to connect to the Internet, an Ethernet switch to connect your wired local area network devices, a wireless access point to connect your wireless local area network devices, and router functionality to hook the three networks together.

ADSL Modem/Router/Wireless (also commonly referred to as Wireless ADSL Routers): These devices incorporate an ADSL modem to connect to the Internet, a wireless access point to connect your wireless local area network devices, and router functionality to hook these networks together.

Router/Switch/Wireless: These devices incorporate an Ethernet port to connect to an ADSL modem (which connects to the Internet), an Ethernet switch to connect your wired local area network devices, a wireless access point to connect your wireless local area network devices, and router functionality to hook the three networks together.

Router/Switch: These devices incorporate an Ethernet port to connect to an ADSL modem (which connects to the Internet), an Ethernet switch to connect your wired local area network devices, and router functionality to hook the two networks together.

You can of course buy each piece of the puzzle - ADSL modem, router, switch, wireless point - separately but it is generally more cost effective to buy a combination device. Indeed, they are generally easier to configure and there is usually more choice available in the combination units than in single function devices.

What are the individual functions that make up the device?

The ADSL modem: An ADSL modem is much like a conventional dial-up modem in that it translates digital information into analogue waveforms that can be transported between computers over a telephone line. ADSL modems use a different modulation technology that allows much higher data rates than regular modems as well as the possibility of sharing a phone line with a conventional telephone service. Consequently, an ADSL modem can be permanently connected to the Internet without interfering with either incoming or outbound telephone calls. The only catch is that an ADSL line filter should be attached to any telephones using the same line as the modem.

The router: The term ADSL router is a bit of a misnomer in that a router doesn't particularly care whether it is connected to an ADSL service or some other network connection. All a router does is 'route' data packets between two networks. On one side you have your local area network (LAN), and on the other side there is the Internet - whether it is connected to the Internet via ADSL, cable or any other method. Subsequently, an ADSL router is a device designed for use with ADSL services, which more often than not means it incorporates an ADSL modem. Because of this confusion in the terminology, it is worth checking whether an ADSL router has an integrated modem or not before you buy it.

The switch: A network infrastructure component to which multiple nodes attach. Unlike hubs, switches typically have internal bandwidth that is a multiple of link bandwidth, and the ability to rapidly switch node connections from one to another. A typical switch can accommodate several simultaneous full link bandwidth transmissions between different pairs of nodes.

The wireless access point: The wireless access point is designed for provide access to local area wireless devices, commonly 802.11a, 802.11b or 802.11g. It is not designed for connecting to wireless Internet, as that requires a special kind of modem.

Buying a modem/router/switch

In most home and small office situations, there is no need to have a separate ADSL modem and router. Consequently, an ADSL modem/router/switch or ADSL modem/router/switch/wireless is a cost-effective way of adding Internet connection sharing to a small network. Certainly if you do not have broadband and are starting from scratch then this is probably the best option.

The downside with modem/router devices is that if you ever want to upgrade either the modem or router capabilities, you are forced to replace both. On the one hand it can be worth paying extra for a device with all the latest features, meaning you won't need to upgrade for some time. Alternatively, you can choose a basic device to get you by now while you wait and see what your needs are in the future.

Don't buy a device with an integrated ADSL modem if you are thinking of switching to cable Internet or wireless Internet later on, however. If you think you might try a few different broadband service types, then a separate modem and router are definitely on the cards. A router/switch combination, however, is always a good investment.

Buying a device with an Ethernet switch

Almost all devices will have wired Ethernet interfaces, and those with built-in switches will have multiple. The benefit of using an Ethernet connection is that the router becomes completely independent of any computer.

The biggest limitation is the number of Ethernet ports available. However, it's worth remembering that if you ever need more you can simply expand by adding a switch. This is a cheap and easy way of expanding the number of computers on the network, without having to buy a router with more ports.

Buying a device with wireless networking

Whether your PCs have wireless already or you plan to add this later, a wireless access point will save you time and money if you want to share your network connection this way. If the wireless router has an integrated ADSL modem, it can only be used to share an ADSL connection.

Three things to be particularly aware of when going wireless are signal strength, speed and security. Most domestic devices have a limited range, especially when one or more brick walls separate the computers from the router. Because of this, in larger properties it may be beneficial to use a separate wireless access point, rather than one that is integrated into an ADSL modem/router. This is because you can determine the best location for the access point by trial and error, without having to worry about the availability of a telephone outlet. A device that uses a separate ADSL modem won't face this challenge, but you will still need to run a cable from the device to the modem.

When it comes to wireless speed, devices that support 802.11g (Wireless-G) which operates 54Mbps should be considered. This is half the speed of conventional wired networking, but ten times faster than most ADSL connections. Some proprietary systems are available that offer 108Mbps, but be sure to get a router and wireless cards for all your computers from the same vendor, or else they will default to a slower connection.

802.11g includes the newer WPA security model to secure your connection against anyone eves dropping within range. WEP is the older security method - you should use it if you have no alternative, however be aware that the encryption scheme has been cracked and tools are freely available online that can be used to rapidly break into WEP networks. The newer WPA standard is only an encryption technology, however, so it requires an authentication process between your wireless access point and the wireless computers. WPA is designed to use a RADIUS server to authenticate users, but as this is beyond the needs and means of most home and small businesses, WPA-PSK authentication is usually available as an alternative. Here the PSK stands for Pre Shared Key and it simply means that you use a password. Consequently, a non-dictionary word with plenty of characters including numbers and punctuation marks is recommended unless you plan on changing it on a regular basis.

What about security?

The router should also include firewall functionality which includes network address translation. Network address translation (NAT) allows you to share the single IP address assigned by your ISP with up to 253 computers on a local network. Each of these local computers has their own IP address which is not visible on the Internet. It is also possible to control the data passing through NAT with filters.

Additionally, routers can offer Virtual Private Networking (VPN) and advanced firewall features such as Stateful Packet Inspection (SPI), Public Key Infrastructure (PKI) and Intrusion Detection Systems (IDS). Although not everyone will need these, it is worth knowing what they are before buying a router without them.

Virtual Private Networking: A virtual private network (VPN) is a combination of security measures that allows authorised users to access resources on a local network via the Internet. Because it utilises encryption technologies such as IPSec, data passing to and from the network is protected from being exposed to unauthenticated users. Some broadband routers will include VPN features that allow you to access your network via the Internet. This is not a feature that everyone needs and, if you aren't going to use it, it should be disabled as it does pose a potential security risk. If using a VPN is something you would like to do but have not previously considered, bear in mind that some routers offer full VPN server capabilities while others only allow VPN pass through. The latter is only useful if you are running VPN software on your network, as it simply permits VPN packets to pass through the router unaffected. An integrated VPN server however can be configured to allow access to the network from the Internet without the need for any software to be installed or configured on your computer.

Stateful Packet Inspection: This is an advanced firewall function that analyses the contents of data packets, allowing filtering to be performed not only according to predefined rules, but to dynamic assessment of the data as well. One example of SPI is to prevent port scanning, a technique often used by hackers to locate security holes in computers by searching for services such as HTTP, FTP, Telnet and peer-to-peer servers. Consequently, SPI provides an extra level of protection required by any permanently connected network, so if you are deciding between two otherwise identical routers, go with the one that supports it.

Public Key Infrastructure: PKI is a means by which two computers can communicate securely without the need for a secure channel over which a shared password must be transmitted. Instead, key pairs are used to encrypt and decrypt data to and from the recipient. The use of PKI in domestic and small business routers is usually limited to the VPN features of the device, which means that passwords are never compromised by being sent over the Internet. Although PKI is an advanced security measure, it will probably not be used by your network unless you configure VPN connections to capitalise on it.

Intrusion Detection Systems: Intrusion detection systems are sometimes built into routers, providing real time analysis of inbound and outbound data packets, looking for suspicious patterns or activity. There are a range of techniques covered by the definition of IDS, although most routers simply detect suspicious events that meet predefined criteria and log them to a file. This is referred to as a passive system, whereas an active system would detect the potential security breach, trigger an alert and possibly ban the source IP address either temporarily or permanently as well.

IPSec: IPSec is an encrypted protocol commonly used by VPN connections. Whereas PKI is used to encrypt information passing between two computers at the data layer, IPSec encrypts the individual data packets at the IP layer. In Tunnel mode, the entire packet is encrypted, including the header information which contains information about the packet. In Transport mode, IPSec encrypts only the data within the packet, leaving the header intact.

PPTP, L2F and L2TP: The Point to Point Tunneling Protocol (PPTP) is a technology developed largely by Microsoft to allow VPN capabilities in Windows operating systems. Layer Two Forwarding (L2F) is a similar protocol developed by Cisco for similar purposes. Layer Two Tunneling Protocol (L2TP) is a more recent VPN technology emerging from the collaboration between Microsoft and Cisco to develop a compatible protocol that integrates the better aspects of both L2F and PPTP.

DIY vs ISP?

Many ISPs offer bundled hardware packages for use with their broadband services. The benefit of going with this option is that you are guaranteed to get devices that are compatible with your provider. Plus, if you do have any difficulties, you will get some level of service, although possibly at a fee. Doing it yourself, however, means you have the flexibility to choose exactly the equipment you need at the best possible price. Compatibility isn't too much of an issue when it comes to Australian ADSL services, as all of them support either PPPoE or PPPoA - and many support both. As long as the modem you buy supports the protocol used by your provider, it should work. Plus, if you build your network yourself, you will have a better idea of how to fix it should you experience any problems.

Summary of features

ADSL2 and/or ADSL2+ support
The newer, faster ADSL standards due to emerge in late 2005 are already supported by some modems, with others having upgradeable firmware for future support.

Antenna (wireless)
A good antenna can help you get better coverage from a standard wireless router. Some devices support antenna upgrades in case you need to expand later.

Bridge/Half-bridge mode
Routers with both bridge and half-bridge modes can be used either as single user modems or for Internet connection sharing, providing extra versatility when it comes to your configuration options.

Cookie blocking
This is a firewall feature that prevents malicious Web sites from storing tracking information on your computer(s) while Web browsing.

QoS
Quality of Service or QoS is a feature that allows the prioritisation of certain types of data. This is particularly useful for real time operations such as video playback and Voice over IP (VoIP) where an uninterrupted stream is important.

DHCP server
A DHCP server is used by a router to automatically configure the IP addresses of local network computers. All routers should have a built in DHCP server, but you can optionally configure IP addresses manually if you prefer.

DDNS support
Dynamic DNS is a feature built into some routers that allows you to use a static Internet sub-domain name (eg: myPC.dyndns.org) even if you don't have a static IP address. This requires the use of a third-party service to work. Although it is a nice feature, the same thing can be achieved using software on any PC without the need for a DDNS compatible router.

"DMZ" facility
A throwback to the days when the military sites formed a significant portion of the Internet, a De-Militarised Zone was a computer or sub-network that was not protected by firewalls and other security measures. In modern day routers, a DMZ simply refers to one or more IP addresses that can be configured to appear "live" on the Internet without going through the firewall.

DoS protection
A Denial of Service attack is when a computer or network is bombarded with requests, usually from hundreds or thousands of different locations. DoS protection is a firewall function that detects such attacks and prevents them from overloading the computer(s) attached to the router.

Ethernet/USB/PCI
A USB connection is easier to configure if you are new to networking, but a router should always have at least one Ethernet interface as well. Alternatively, an internal PCI card ADSL modem can be used if you plan to run routing and/or firewall software on the host machine.

Inbuilt 4 port 10/100 switch
A router with a built-in switch means you won't need to buy a separate device to share your Internet connection with other computers.

Intrusion detection (IDS)
A firewall feature that inspects data traffic for suspicious activity and either logs it, blocks it or does both.

RFC1483 (bridged/routed)
RFC1483 is an encapsulation protocol available in ADSL modems which can be configured to run in bridged Ethernet or routed IP modes on ADSL links. It is rarely used, however, as most modems will need to use PPPoE or PPPoA to connect to ADSL services in Australia.

LAN port rate limiting
This is a router feature that permits you to set bandwidth limits on IP addresses and ports, usually with scheduling. This is handy if you are on an ADSL plan that has peak and off-peak limits, allowing you to limit downloads during peak times, for instance.

Inbuilt firewall
A router performs Network Address Translation (NAT), making it a firewall by definition. Some routers, however, have additional firewall capabilities such as packet filtering, intrusion detection, DoS protection and cookie/URL blocking.

Inbuilt or Free micro-filter
You will need a line filter for every phone connected to the same line as the ADSL modem. If you get one built-in or bundled, that's saving you about $10 or $20.

Java/ActiveX/Javascript blocking
A firewall feature that prevents malicious applications from being downloaded while Web browsing over a shared connection.

MAC address filtering
A firewall feature that only allows network cards with a predefined hardware address to access the network. Every network card has a unique MAC address, but these can be faked by a hacker.

Multiple public IP address binding
Some routers allow you to use multiple IP addresses for your Internet connection. This is mostly useful for businesses running Web servers and VPN connections that require different domain names. It must be supported by the ADSL provider and will incur an additional fee.

NAT
The most fundamental role of a router, Network Address Translation, allows multiple computers to share a single Internet connection.

Packet filter
A firewall feature that inspects data traveling between the Internet and the local network. By comparing each packet to predefined rules, only those that meet certain criteria will be allowed through.

Port forwarding/port range forwarding
This is a useful feature that lets you configure the router to forward all connections on one or more defined ports to a specified IP address on the local network. This is particularly useful for file sharing and peer-to-peer applications running on a shared connection.

RIP-1/RIP-2
Routing information protocol is the method by which routers identify the best pathway for sending data packets. The original RIP-1 has been replaced by RIP-2, which uses much more efficient procedures to perform the same task. Unless you are running multiple networks connected by routers. However, it is unlikely that you will benefit much from version 2 of this technology.

SNTP facility
The Simple Network Time Protocol can be used to synchronise the clocks on all computers in a network. If a router has this feature, it can be used as the source clock which itself is synchronised via the Internet.

SPI
Stateful Packet Inspection is a dynamic firewall function that monitors data traffic passing through a router for common attacks such as port scanning.

Static routing
In home or small business routers, static routing refers to the ability to set predefined routing rules. This is an advanced feature that is useful for redirecting certain types of traffic to nominated IP addresses or network interfaces.

IPoA
IP over ATM is a means of sending Internet Protocol data over an ADSL connection. Some routers will support this low level protocol, although PPPoA and PPPoE are more commonly used.

PPPoE
Point-to-point protocol over Ethernet is a technology for transmitting PPP traffic over an Ethernet connection. PPP is the protocol used to establish conventional dial-up connections with functions such as dynamic IP assignment, authentication and encryption.

PPPoA
Point-to-point protocol over ATM is similar to PPPoE except that it communicates with the ADSL connection mostly at the hardware level, making it slightly faster. Not all ISPs support PPPoA, however, but most modems will provide the option to use either.

Embedded PPPoX login clients
Almost all routers will have the ability to automatically login to the ADSL connection via a built-in or external modem. PPPoX simply means that the login procedure can use either PPPoA or PPPoE.

Parental controls
This is a blanket term for URL blocking, cookie blocking and other content filters that prevent undesirable content from being downloaded through the router's firewall.

Print server inbuilt
Some routers include a 25 pin parallel port interface designed to connect a printer so that it can be shared with multiple computers. A printer does not need to be USB compatible to use this kind of printer server.

Scheduling by time/day of week
Some routers allow you to schedule various features such as bandwidth limiting and content filtering to certain times of the day or week.

USB print server
Some routers include a USB interface designed to connect a printer (or webcam) so that it can be shared with multiple computers.

URL blocking
A firewall feature which can be used to stop malicious or inappropriate Web sites from being accessed while browsing the Web.

UPnP facility
Universal Plug and Play is a protocol developed by Microsoft to allow networked devices to automatically identify and configure themselves. If a router is UPnP compliant, it means that software on your computer(s) can dynamically configure the router to work in their preferred manner. Very few applications actually support this feature, with Windows Messenger and Remote Desktop Connection being two notable examples.

VPN pass through
A router with VPN pass through will let you use the Internet to connect to a VPN server on your network.

Embedded VPN servers
If a router includes an integrated VPN server, you can connect to your network from the Internet without having to run any VPN software on your network.

WEP 64/128/256 bit (wireless security)
WEP is an outmoded wireless encryption standard that should only be used if WPA-PSK is not available on all your wireless equipment.

WPA (wireless security)
A much more reliable encryption standard, WPA can only be used with an authentication server. In most home and small office networks, WPA-PSK is used instead.

WPA-PSK (wireless security)
WPA-PSK stands for Wi-Fi Protected Access with a Pre Shared Key. By using a known password, all wireless devices can make use of the WPA encryption without the need for an authentication server.

Wireless access point
A wireless access point (WAP) is a device that connects a wireless network to a wired one. Some routers have a built-in WAP, making it possible to share an Internet connection with wired and wireless computers simultaneously.

ADSL

What is ADSL: ADSL stands for Asynchronous Digital Subscriber Line, which is a method for transmitting high speed digital information over regular phone lines. It is capable of download speeds up to 9MBps and upload speeds of up to 800kbps, although currently there are very few services available with download speeds of more that 1500kbps due to the limitations of some telephone exchanges. Most home ADSL services offer 256kbps, 512kbps or 1500kbps services, which is usually a measure of their download speed. Occasionally you will see broadband plans listed with two numbers, like 512/256, which indicates a 512kbps downlink (for downloading) and a 256kbps uplink (for uploading).

ADSL2 and ADSL2+: ADSL2 is a more efficient technology than ADSL, permitting downstream speeds of up to 12Mbps using the same telephone lines. It also extends the reach of ADSL services by about 250 metres. ADSL2 adds voice channel capabilities as well as an additional 256kbps upstream capability, making it a viable candidate for digital telephone services. Taking things even further, the newer ADSL2+ standard effectively doubles the frequency of downstream data from 1.1MHz to 2.2MHz, making it capable of speeds up to 25Mbps over phone lines of up to 2km in length. ADSL2 and ADSL2+ are due late 2005, although some modems already have support for these new standards. Others can be upgraded via software to support them, so look out for these features if you want something with maximum longevity.

USB or Ethernet?

Whether you have a separate modem and router or a single device that combines the two, there is still the question of how to connect everything to your computers. The modem will connect to the phone line and, if it is a separate device, it will also connect to the router using a standard network cable. If the router has an integrated hub, each computer you want to access the network and/or Internet will plug directly into the router using network cables. Otherwise, the router will connect to a hub (or switch) with a network cable. This configuration uses the router's Ethernet interface to share the Internet connection, and all broadband routers will support this technique. When connected in this way, the router is configured using a Web browser from any computer connected to it.

In addition to an Ethernet interface, some is installed on the PC. In these models, the USB interface replaces the need for an Ethernet connection altogether, although a Web browser is usually still required to configure the router. Alternatively, some routers may use the USB connection to permit the Internet connection to be configured from the computer's control panel using dial-up networking. Routers will include a USB port. Usually this is used to allow the device to be installed and configured even if there is no Ethernet card.

A USB connection is useful if you don't have a network card installed. Instead, you can use the USB port to connect to ADSL now and, sometime down the track, add computers to the network by connecting them to the router, hub or switch via Ethernet cables or wireless cards. You can always change to the Ethernet interface later if you want to remove the USB connection for some reason. For instance, if you need to move the computer away from the router to a location without a telephone outlet, you can run Ethernet cable or use a wireless connection for much longer distances than USB cables will allow. Overall, however, a USB interface is a good place to start if you are new to networking, and it is an easily configured safety net to fall back on if your computers develop networking problems or can't connect via the Ethernet port.

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