ADSL (Asymmetric Digital Subscriber
Line)
ADSL as
the name suggests is a digital subscriber line technology which is a data
communications technology that enables faster data transmission over copper
telephone lines. It is permanently switched on, unlike normal dial up
access and is asymmetric in that it uses most of the available bandwidth
downstream. This makes it particularly suitable for applications where
customers expect to receive more data than they transmit such as for Web
browsing, use of corporate intranets, and reception of digital audio-visual
material. The technology also supports analogue connection on the same line,
which enables voice or fax calls to be made simultaneously.
ADSL Max
ADSL MAX
is a faster ADSL technology which improves the speed of bandwidth available to
your business and has typically faster upload and download speeds through ADSL
connection.
Benefits of ADSL MAX
These include:
- Higher upload and download
speeds for business that rely on a high-speed internet connection
- Availability across most of
the UK, even in locations where ADSL is normally slow - lines can reach further
and improve performance
- A leased line alternative
which is often much cheaper
- Flexibility regarding how many
ADSL circuits you decide to bond together
ADSL2+
ADSL2+ extends the capability of basic ADSL by doubling
the number of downstream bits. The data rates can be as high as 24 Mbit/s
downstream and up to 1.4 Mbit/s upstream depending on the distance from the
DSLAM to the customer's premises.
ADSL2+ is capable of doubling the frequency band of typical ADSL
connections from 1.1 MHz to 2.2 MHz. This doubles the downstream data rates of
the previous ADSL2 standard (which was up to 12 Mbit/s), and like the previous
standards will degrade from its peak bitrate after a certain distance.
Also ADSL2+ allows port bonding. This is where multiple ports are
physically provisioned to the end user and the total bandwidth is equal to the
sum of all provisioned ports. So if 2 lines capable of 24 Mbit/s were bonded
the end result would be a connection capable of 48 Mbit/s download and twice
the original upload speed. Not all DSLAM vendors have implemented this
functionality. ADSL2+ port bonding is also known as G.998.x or G.Bond.
SDSL
SDSL (Symmetric Digital Subscriber Line)
is a fixed-speed Internet access service with matching upstream and downstream
data rates. That is, data can be sent to the Internet from the client machine
or received from the Internet with equal bandwidth availability in both
directions. Normally, DSL service is asymmetrical (ADSL), with the bulk of the
bandwidth reserved for receiving data, not sending it.
SDSL
utilises a digital frequency traveling across existing copper telephones lines
to send and receive data. When using the telephone line for this service, phone
and fax services on that line must be suspended. Therefore a dedicated second,
or additional, line is typically needed. This differs from ADSL, which is
capable of connecting standard analogue telephone equipment and the digital
signal equipment to enable both voice and data traffic at the same time.
The SDSL service provided
by BT is gradually being phased out and replaced by FTTC & FTTP. However,
it does give a symmetrical option to those customers where fibre connections
are not yet available