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Broadband (ADSL) FAQ

Question

• What is ADSL?
• How does ADSL work?
• What are the different ADSL services available from Aardvark IT?
• What is the difference between NAT and NONAT ADSL connections?
• Do I need an ADSL router or modem?
• What settings do I need to know to setup my ADSL connection to Aardvark IT?
• What is ADSL SS attempt?
• What is a contention ratio?
• Why is the download speed greater than the upload speed?
• What type of phone line is required for ADSL service?
• What is the minimum contract term for ADSL?
• What payment methods are available?
• Do you assign fixed IP addresses?
• What is a microfilter?

Answer

ADSL stands for Asymmetric Digital Subscriber Line. It is a technology for transmitting digital data at high speeds on existing phone lines. The service unlike dialup provides an "always on" connection and allows the simultaneous use of analog (voice) on the same line. Due to the technologies asymmetric nature the upstream is generally 256kb where as the downstream varies between 512kb, 1Mb and 2Mb.

The ADSL service works by splitting the signal found in your existing telephone line into 2 channels. One for voice at a frequency of 0 - 20 kHz and the other for high speed data at a frequency of 25.875 kHz - 1.104 MHz. Where the phone line terminates in the local exchange the data and voice channel are split back into single channels where the ADSL channel is passed in to a DSLAM which is combinded with other ADSL services and is routed on through BT's ATM network untill is reaches Aardvark IT services.

See our range of Broadband services by clicking here.

NAT stands for Network Address Translation, What this means is that you can use mutiple IP address's on your internal network but only need 1 Public IP address. NAT is the best choice for most users. If however you are going to use the ADSL for running a mail server or VPN software etc. you may require NONAT. With NONAT you are provided with a Block of 8 static IP address's (3 of which are used by the ADSL connection). These IP address's are public address's which means some sort of Firewall would be needed for security.

This all depends on what the ADSL is going to be used for. Generaly If you are getting ADSL for home use then an ADSL modem would be more than adequate. This would give access to the internet for one stand alone PC. A router would be used if you intend on sharing the ADSL connection across a network. The Router would most likely plug directly into your existing Hub or Switch. This would allow any PC on your network to access the internet.

The following will be usefull when setting up an ADSL router or modem: VPI = 0 VCI = 38, Encapsulation Mode = PPP over ATM (PPPoA - RFC2364) VC-MUX, Authentication = CHAP, Modulation= set to Auto or if manual use G.DMT or ANSI T1.413

ADSL stands for Asymmetric Digital Subscriber Line
ADSL is a broadband service which uses technology that adds an Internet connection to your telephone line, so you can make or receive calls at the same time as being online*. Better still you dont have to dial up anymore as ADSL is a always on.
*Normal call charges are made for telephone calls made.

Contention ratio refers to the maximum number of users you could be sharing your bandwidth with. There are 2 contention ratios in use by Aardvark IT, 50:1 and 20:1. If you have a 50:1 contention ratio then in theory another 49 users could be competing for the 512kb you have. In practice this very rarely happens and even on the slowest ADSL product users typically see a 10x improvement over a 56k modem.

ADSL is Asymmetric which means it runs at different speeds for upload and download. BT is currently trialling a SDSL (Symmetric Digital Subscriber Line) service which runs at the same speed for both upload and download. Our technical providers are currently working with BT to enable us to be one of the first in the country to offer SDSL.

A standard BT PSTN analogue line is required for ADSL. Certain BT services and/or configurations are NOT compatible with ADSL, these include:-
PBX Switchboard
ISDN 30(PRI)
Surftime
BT Data Stream
BT Video Stream
None BT Telephone Line
Redcare Alarm Monitoring
Pulse Metered Line
Coin/Pay Phone
It is possible to convert a ISDN 2/2e or Business/Highway line into ADSL. This does however mean that the ISDN service is lost as the line has to be converted back to a single analogue line. Certain fax machines will interfere with the ADSL signal so it is not recommended that you use a fax line for ADSL.

The minimum term is 6 months and there is a 1 month notice period to cancel.

You can use credit/debit card to pay the initial installation and first month charges. After that all subsequent charges are payable by direct debit.

Yes, all Aardvark IT ADSL accounts come with fixed IP addresses on both NAT and No-NAT.

A microfilter, sometimes referred to as a 'spliiter', is an adapter that plugs into the telephone socket the ADSL service is provided on. The microfilter seperates the ADSL signal from the voice signal. You plug your phone and your ADSL hardware into the microfilter and the microfilter into the BT phone socket.