Conferencing With EchoLink
Conferencing refers to EchoLink's ability to be connected to more than one station at a time
over the Internet. Each such station becomes a participant in a conference. It is conventional for
participants in a conference to take turns transmitting, in roundtable fashion. When connected in this fashion, each
member of the conference can hear each other member's comments. Text Chat messages are also sent to all single-user
participants.
EchoLink supports conferencing as an option, in either the Single-User or Sysop modes. Conferencing
is disabled by default. To enable conferencing, change the settings on the Connections tab of the Preferences window.
Conferencing is not recommended if you are connected to the Internet over a slow connection, such as a dial-up
modem. Even with high-speed connections, be judicious about setting the connection limit, since each additional
station in the conference requires about 17 kbps of upstream bandwidth. For example, a typical cable-modem connection provides
only 128kbps upstream, which would support a maximum of about 7 or 8 stations in a conference. For more information,
see
Low-Bandwidth Indicator below.
Note that when conferencing is enabled, you can assemble a conference by establishing connections to other
stations yourself, or by waiting for them to connect to you. An interesting feature in Sysop mode is the ability to
assemble a conference by entering commands into EchoLink's built-in Web server from some remote location on the Internet.
Please use discretion when assembling a conference. It is considered poor operating practice to "conference-in"
a station to an existing conversation, unless you are certain the new station will welcome it.
Multi-Conferencing
Multi-conferencing is the connection of one conference to another. Previous versions of EchoLink
included safeguards to prevent multi-conferencing, since there was no reliable way to detect and prevent conference loops,
in which more than one path is established between conferencees.
Support for multi-conferencing is now available as an option in EchoLink version 1.7 and above. Multi-conferencing
is disabled by default. To enable it, check the Allow multi-conferencing box on the Connections tab
of the Preferences window.
When multi-conferencing is enabled, the software will allow you to host a conference consisting
of any type of station, including conferences and conference servers.
When multi-conferencing is disabled, EchoLink enforces the following rules:
- If a station is already connected, EchoLink will not connect to a conference server.
- If a station is already connected, EchoLink will not connect to an EchoLink station to which a station
is already connected (if both stations are using EchoLink version 1.1 or above).
- If already connected to a conference server, no additional stations may connect.
- If EchoLink is already connected to an EchoLink conference which is running EchoLink version 1.1 or above,
no additional stations may connect.
Low-Bandwidth Indicator
EchoLink includes a feature that displays a warning indicator whenever the available Internet bandwidth is not sufficient
to handle the rate of data being sent by EchoLink. Typically, this can occur when Conferencing is enabled, and the Internet
connection does not have enough capacity to support the number of conferencees who are connected. This can easily occur over
a dial-up connection if two or more stations have joined the conference. (For this reason, enabling Conferencing is not recommended
for EchoLink stations on a dial-up connection.)
Remember that for each station joining a conference, the station hosting the conference needs an additional 17 kbps of
upstream Internet bandwidth. If two stations have joined the conference, each transmission from the host station must be sent
to both conferencees, requiring a minimum of 34 kbps. Thus, despite its name, a perfect "56k" dial-up connection provides
only 33.6 kbps upstream, which is insufficient for conferencing.
A low-bandwidth situation can also occur over a normal, one-to-one connection if an Internet connection slower than 28.8
kbps is in use, for example, if a 14.4 kbps modem is being used to connect to the Internet.
A "low bandwidth indicator" will appear in the bottom right-hand corner of the screen when insufficient
Internet bandwidth is available. The indicator is a yellow triangle with an exclamation mark: . When this happens, the program
will continue to work normally, but stations at the other end will probably hear drop-outs or gaps in the audio. The indicator
will disappear once sufficient bandwidth is restored.
