P-660R-Tx Series Support Note s
ADSL FAQ
1. How does ADSL compare to Cable modems?
ADSL provides a dedicated service over a single telephone line; cable modems
offer a dedicated service over a shared media. While cable modems have
greater downstream bandwidth capabilities (up to 30 Mbps), that bandwidth is
shared among all users on a line, and will therefore vary, perhaps dramatically,
as more users in a neighborhood get online at the same time. Cable modem
upstream traffic will in many cases be slower than ADSL, either because the
particular cable modem is inherently slower, or because o f rate reductions
caused by contention for upstream bandwidth slots. The big difference between
ADSL and cable modems, however, is the number of lines available to each.
There are no more than 12 million homes passed today that can support
two-way cable modem transmissions, and while the figure also grows steadily, it
will not catch up with telephone lines for many years. Additionally, many of the
older cable networks are not capable of offering a return channel; consequently,
such networks will need significant upgrading before they can offer high
bandwidth services.
2. What is the micro-filter or splitter used for?
Generally, the voice band uses the lower frequency ranging from 0 to 4KHz,
while ADSL data transmission uses the higher frequency. The micro filter acts as
a low-pass filter for your telephone set to ensure that ADSL transmissions do not
interfere with your voice transmissions. For the details about how to connect the
micro filter please refer to the user's manual.
3. How do I know the ADSL line is up?
You can see the DSL LED Green on the P-660R-Tx's front panel is on when the
ADSL physical layer is up.
4. Does the VC-based multiplexing perform better than the LLC-based
multiplexing?
Though the LLC-based multiplexing can carry multiple protocols over a single VC,
it requires extra header information to identify the protocol being carried on the
virtual circuit (VC). The VC -based multiplexing needs a separate VC for carrying
each protocol but it does not need the extra headers. Therefore, the VC-based
multiplexing is more efficient.
We can choose one of them on the web configuration page:
Interface Setup
->
Internet ->Dynamic IP ->Encapsulation:
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