NCast PR-HD - Manual (Page 38)

NCast Presentation Recorder Reference Manual
administrative boundaries, such as a local LAN, a building, a campus or a region. These are safe addresses
to use in setting up an organization’s multicast network and ideal entries for use in the Channel Table.
Consult with the Network Administrator for the particular address ranges in use on the network hosting the
Presentation Recorder.
All units in one session use the same multicast address. The Video and Audio multicast addresses for a
session can be the same if the Port numbers are different. Units engaged in different sessions should use
different multicast addresses to minimize traffic loading on the network (the multicast routers distribute all
traffic to all points subscribed on a particular multicast address, independent of the port number).
The default settings for a Presentation Recorder use Administratively-Scoped multicast addresses. This
implies that streams created using these addresses will not exit the organization’s network.
If the network is not multicast enabled, point-to-point communications between two Presentation Recorders
is possible by entering the numeric IP address of the remote unit into this field.
5.7.2. Set Video Stream Destination – Port Number
In addition to a multicast address, each media stream requires a unique port to be assigned. Ports must be
even-numbered (the succeeding odd number is used for control purposes and must be available). Port
numbers range from 1024 to 65,535 and this range is divided into two parts: the Registered Ports are those
from 1024 through 49151 and Dynamic and/or Private Ports are those from 49152 through 65535.
In practice, multicast applications assign port numbers in the range of 5002 and up. The port range 1024-
5000 is typically used by a Unix system to assign ports to applications desiring an automatically generated
port number.
Even if different multicast addresses are being used, it is recommended that different port numbers be used
for the different media streams (graphics, audio and collaboration). On some system implementations, use of
the same port number will cause errors.
For multicast traffic to get through a firewall, the even-odd pair defined in this entry must be opened by the
firewall administrator.
5.7.3. Set Video Stream Destination - MTU
The Maximum Transmission Unit (MTU) is the maximum length of a packet and is normally set to 1500. For
some special circuits (satellite links, others) the maximum size may need to be adjusted downward to avoid
packet fragmentation, which leads to inefficiencies and possible packet loss.
5.7.4. Set Audio Stream Destination - Address
An address entered for Audio (the Audio media stream) will be either a valid multicast address, or the
numeric host IP address of the remote unit if a point-to-point connection is being established.
For a discussion of multicast addresses, see the discussion above (Set Video Stream Destination -
Address).
All units in one session use the same multicast address. The Video and Audio multicast addresses for a
session can be the same if the Port numbers are different. Units engaged in different sessions should use
different multicast addresses to minimize traffic loading on the network (the multicast routers distribute all
traffic to all points subscribed on a particular multicast address, independent of the port number).
If the network is not multicast enabled, point-to-point communications between two Presentation Recorders
is possible by entering the numeric IP address of the remote unit into this field.
5.7.5. Set Audio Stream Destination - Port
The port number assigned to the audio media stream.
See the discussion above (Set Video Stream Destination – Port Number) for more detailed information on
ports.
5.7.1. Set Audio Stream Destination – MTU
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