Miscellaneous

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== WDS == == WDS ==
-Wireless Distribution System. A method of bridging two or more access points wirelessly. The access point function still operates on both units but that's not a requirement of WDS but a common feature.+Wireless Distribution System. A method of bridging two or more access points wirelessly. The access point function still operates on both units but that's not a requirement of WDS but a common feature. It effectively creates the same as running a CAT5 LAN cable between the switch side of the wrt54g units. However the wireless range of WDS is not nearly as great as that of a Client talking to an Access Point which is the other way of linking. The advantage of WDS over AP to Client is that MAC addresses are handled correctly which is important with respect to accessing the Internet. As with most things wireless, if you can run a cable then perhaps you should.
== WISP == == WISP ==

Revision as of 18:35, 15 October 2006

Contents

Glossary

The glossary is a long list of terms and DD-WRT features with definitions and fairly extensive explantions.


802.11b

Channels 1 to 14 (depending on country) in the 2.4GHz range. Operates up to 11Mbits speed. Actual data speed typically 4Mbits, fastest 6Mbits. Further distance than 802.11g

802.11g

Same channels and frequency of 802.11b but with speeds up to 54Mbits, typically actual data speeds are 18Mbits. G equipment is newer and tends to have a better reciever and can be operated as a B only radio. Each channel tends to spread out by a couple of channels ether side. If a foreign channel is as strong as your signal then you need to leave a couple of channels gap.

802.11a

This is the 5.8GHz standard and is subject to more licencing restrictions than the above. The WRT54G is not capable of this, however since dd-wrt is available on hardware with mini-PCI slots these radios could be slotted in.

Bricked

Oh dear, you turned your high tech Linksys into nothing more technical than a brick. You broke it. It may be possible to de-brick your unit and make it work again.

Client Mode

dd-wrt this is where the wrt54g is wirelessly connected to an access point and provides a routing firewall and NAT function.

Client Bridged

dd-wrt this is where the wrt54g is wirelessly connected to an access point and provides a non-routed connection on the same subnet. There is a problem with this mode in that hosts on the LAN side do not have their MAC addresses carried across properly. This means that they are not properly accessable to hosts on the wireless side. WDS mode is often suggested as a way round this.

ESSID

Sometimes called SSID. It's the tag broadcast by your access point and the one seen on site survey at the clients. It's what you have to associate with. As a rule you can only have one ESSID per Access Point, however it would be cool to have more than one, it would then look like you had several Access Points. See dd-wrt V24.

Firmware

This is just Software but it runs on your Hardware. It's usually delivered as a binary ROM image that has to be copied down onto your hardware (wrt54g) over a cable. The cable is usually an ethernet patch lead but could be a JTAG serial cable or doe some devices an RS232 cable. In the good old days we would burn an EPROM or FLASH chip in a programmer and then insert the chip phyically into a socket. Hence the term Firmware being software you can touch in the form of a chip.

MAC Address

Media Access Control. Every network device, wired and wireless, has a 12 digit globally unique HEX number. The number is used by the lowest level of the network stack to communicate locally instead of using IP addresses, the number does not cross over into the Internet, only IP addreses can do this. A typical wrt54g MAC address looks like 00-16-b6-bc-49-d6, however a wrt54g has three addresses in sequence, one for WLAN, WAN,LAN.

MAC Filtering

A very efficent way of either including or excluding wireless clients on your Access Point. However the main weakness is MAC cloning where a bandit would set their equipment to match one of your allowed MAC addresses. You are not supposed to be able to do this but you can.

M.A.C number

Migration Authorisation Code number. Not to be confused with MAC Address. This is the number your ADSL ISP gives you when you want to switch to another ISP without a long wait whilst the phone company sends out engineers to move the wires. As you can imagine, this number can be held to ransom until you pay the old ISP bill, which is ofcourse a contravention of the Ofcom guidelines.

Source Code

This is the software before cross compliation into Firmware. For Firmware this is usually written in 'C'. For dd-wrt the source can be downloaded and cross compiled on the PC to produce firmware which is ready to be downloaded onto the wrt54g. This is not something most people need to do since the binary firmware is provided for download from the site.

QOS

Quality Of Service setting. This is a method by which some services (usually by port number) can be given higher priority when they go through the WAN port than others. Even on Broadband the WAN is a limited resource, you may for instance give high priority to your VoIP traffic and low prority to your P2P traffic. It's actually pretty hard to traffic shape P2P trffic.

Sveasoft

Alternative firmware company people here prefer not to use.

VoIP

Voice over Internet Protocol. This is a cool new technology for making phonecalls using your Internet. Skype is an example of VoIP but so is Vonage which allows you to use a real phone directly plugged into your wrt54g rather than needing to fire up your PC.

VPN

Virtual Private Network. You can securely connect two LANs together over the Internet using a virtual cable, or VPN. You have PPTP, IPSec, OpenVPN. Mostly dd-wrt is not too good at doing this but will allow these service to operate as a pass-through. Hence the term VPN-Passthrough.

VPN Passthough

The router allows you to run a VPN service on your network. Not particularly amazing. The VPN version of dd-wrt has this.

VPN server

This is where the router actually creates a VPN connection to another VPN server. This is the one you really want for VPN. The VPN version of dd-wrt does not seem to do this.


WDS

Wireless Distribution System. A method of bridging two or more access points wirelessly. The access point function still operates on both units but that's not a requirement of WDS but a common feature. It effectively creates the same as running a CAT5 LAN cable between the switch side of the wrt54g units. However the wireless range of WDS is not nearly as great as that of a Client talking to an Access Point which is the other way of linking. The advantage of WDS over AP to Client is that MAC addresses are handled correctly which is important with respect to accessing the Internet. As with most things wireless, if you can run a cable then perhaps you should.

WISP

Wireless Internet Service Provider. A company using wireless gear such as WRT54G and dd-wrt to deliver Broadband Internet into peoples homes without using their phone line.