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Warning: Advanced Topic
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The options available in the default mode should provide good
performance for most users, but in some circumstances it may become
important to fine tune some of the more obscure parameters that make
ACCESS work. By clicking the
Advanced Options
box in the lower left
of the
Profile Settings
screen, the following
Advanced Options
will be
available:
In addition to BRIC Normal and POTS, ACCESS provides the ability to set
up several other channel types. The Advanced menu gives the option to
use a different channel rather than the normal UDP/RTP created in BRIC
Normal mode. Some explanation:
Internet IP packets come in two flavors: TCP and UDP. Most web browsing,
email and other computer-based functions travel over the TCP protocol,
which inherently assures retransmission if a packet is lost, and is therefore
reliable. UDP is optimized for real-time applications, and does not
offer any guarantee of packet delivery. Retransmission typically causes
extra delay in an IP network, and ACCESS is optimized to conceal an
occasional lost packet, so it makes more sense for ACCESS to use UDP for
transmission under most circumstances. But there are occasions where a
network will treat UDP packets poorly. Some examples are:
•Networks with high packet loss (rather than jitter)
•Networks with very high security firewalls
•Networks trying to discourage the use of VOIP functions
In these circumstances it makes more sense to enable a TCP channel. The
result will usually be a more robust audio channel with a delay several
magnitudes higher than an equivalent UDP channel. Channel overhead is
also raised so you will utilize a higher network bandwidth.
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