Setup guide

IBM Lotus Sametime 7.5 Release Notes Installation, migration, upgrade, and configuration
In both modes, the firewall needs to let the UDP (port 20830) traffic flow in both directions. The direct P2P
connection is used whenever possible, and is the recommended way of using voice chat.
The reflector mode is only used when a specific type of NAT (symmetric NAT) is detected. In that case,
since both clients are unable to guess each other's IP address to establish a P2P connection, the UDP
packets are relayed through the reflector.
This mode is used for compatibility, and performance will not be as good as direct P2P. Consequently,
the user could experience additional delays, and a decrease of quality in the voice chat, depending on the
ST 7.5 reflector availability.
For NAT environments, the reflector will be used. The reflector uses 2 TCP/UDP ports:
- 20831
- 20832
Those ports must be opened for incoming and outgoing UDP and TCP traffic, on the reflector machine. It
is recommended that the reflector machine have a static IP address.
In case the reflector is running on multiple network interfaces, it must be configured with either a
hostname or an IP address, so that clients know which address to use to connect to the reflector.
For example, in the [STReflector] section of the sametime.ini file
STREFLECTOR_SERVER_NAME=reflector.domain.com
or
STREFLECTOR_SERVER_NAME=192.168.1.1
If the reflector is located in an environment with two different subnets, the reflector needs to be accessible
from different networks, hence the property STREFLECTOR_SERVER_NAME should be a fully-qualified
hostname, which resolves to the appropriate addresses in both networks/subnets.
In case the 7.5 client is running against a pre-7.5 server, the voice chat component may not
work correctly in a number of cases:
z
The client has multiple network interfaces (in that case, the 7.5 client might get confused as to
which interface should be used)
z
The client is sitting behind a router/NAT
The symptoms experienced by the client in these cases is that one (or both) of the parties in the voice
chat will not be able to hear each other, even though the chat window will show a "connected" status. To
confirm the problem, the user can increase the log level of the client to FINE, and look in the log for
entries related to "reflector". The IP detection problem will be signaled.
The 7.5 client has the ability to host calls with up to 5 participants, including the host. During such calls,
the host is the creator of the call. The host will mix the audio streams for each participant. Consequently,
the host will have up to 4 incoming/outgoing audio streams, which will multiply the amount of bandwidth
necessary. It is recommended that for multi-party voice chats, the client with the most bandwidth hosts
the call.
Sametime 7.5 is using the iSAC codec for all voice chats. This codec is an adaptive bandwidth codec,
which requires between 10.6 to 28.8 kbits (headers included), depending on the voice activity and the
network quality. For example, during a 3-way call, the host will require twice that amount (between 21.2
and 57.6 kbits), both incoming and outgoing. The other 2 participants, will only require between 10.6 and
28.8 kbit/s.
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