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ALC1224 User’s Guide
3-2
ADSL Port Setup
Profiles allow you to configure ADSL ports efficiently. You can configure all of the ADSL ports with the same
profile, thus removing the need to configure the ADSL ports one-by-one. You can also change an individual ADSL
port by assigning it a different profile.
For example, you could set up different profiles for different kinds of accounts (for example, economy, standard
and premium). Assign the appropriate profile to an ADSL port and it takes care of a large part of the port’s
configuration maximum and minimum transfer rates. You still get to individually enable or disable each port, as
well as configure its channels and operational mode. See later in this chapter for how to configure profiles.
3.5 Interleave Delay
Interleave delay is the wait (in milliseconds) that determines the size of a single block of data to be interleaved
(assembled) and then transmitted. Interleave delay is used when transmission error correction (Reed- Solomon) is
necessary due to a less than ideal telephone line. The bigger the delay, the bigger the data block size, allowing
better error correction to be performed.
Reed-Solomon codes are block-based error correcting codes with a wide range of applications. The Reed-Solomon
encoder takes a block of digital data and adds extra "redundant" bits. The Reed-Solomon decoder processes each
block and attempts to correct errors and recover the original data.
3.5.1 Fast
Mode
Fast mode means no interleaving takes place and transmission is faster (a “fast channel”). This would be suitable if
you have a good line where little error correction is necessary.
3.6 Configured Versus Actual Rate
You configure the maximum rate of an individual ADSL port by modifying its profile (see the
ALC Edit Profile
screen) or assigning the port to a different profile (see the
ALC Edit Port Setup
screen). However, due to noise
and other factors on the line, the actual rate may not reach the maximum that you specify.
Even though you can specify arbitrary numbers using the
ALC Edit Profile
screen, the actual rate is always a
multiple of 32 Kbps. If you enter a rate that is not a multiple of 32 Kbps, the actual rate will be the next lower
multiple of 32Kbps. For instance, if you specify 60 Kbps for a port, the actual rate for that port will not exceed 32
Kbps, and if you specify 66 Kbps, the actual rate will not be over 64Kbps.
Regardless of a profile’s configured upstream and downstream rates, the ALC1224 automatically limits the actual
rates for each individual port to the maximum speeds supported by the port’s ADSL operational mode. For
example, if you configure a profile with a maximum downstream rate of 25000 Kbps, and apply it to a port set to
use G.dmt, the ALC1224 automatically uses a maximum downstream rate of 8160 Kbps. This means that if you
configure a profile with very high rates, you can still use it with any port. See
Table 3-1
for a list of the maximum
rates supported by the different ADSL standards.
Summary of Contents for ALC1224
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Page 38: ...ALC1224 User s Guide 2 6 Web Configurator Introduction Figure 2 6 ALC Edit Port Setup...
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Page 129: ...Index V Part V Index This part provides an index of important terms...
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