Extron Electronics SME 100 User Guide - Manual (Page 173)

Subnet Mask
The subnet mask is a 32-bit binary number used to "mask" certain bits of the IP address.
and extends the number of network options available for the IP address. The subnet mask
does this by allowing part of the host identifier to be used as a subnetwork identifier.
It is important that the correct value is used for the subnet mask. The value of the
subnet mask is dependent on the IP address class being used. Use the table below and
the table in the "
What is an IP Address? " section on page 166 to select the subnet mask
class that matches the IP address class.
Class Subnet Mask
Class A 255.0.0.0
Class B 255.255.0.0
Class C 255.255.255.0
Port Number
A port number is combined with the IP address to create an application-specific or
process-specific address. The port number can uniquely identify an application or process
on a computer and thereby enable the computer to share a single ethernet connection
for multiple requirements. A port number is always associated with the IP address of the
computer, as well as the type of protocol used for network communication.
The SME 100 uses specific ports, but can be configured to meet most requirements. In
addition to the default ports, any port in the available range (1024 to 65535) can be used.
NOTE: Ports previously assigned and currently in use by the SME 100 cannot be used
again.
All streaming methods (except TS/UDP push) use multiple port numbers. The following table
shows the number of ports used by each streaming method.
RTSP (Pull) TS/UDP (Push) TS/RTP (Push) ES/RTP (Push)
Unicast (per stream) 4* 1 2 4 *
Multicast 4 * 1 2 4 *
* 4 ports for "Audio/Video", or 2 ports for "Video only"
When the SME 100 ports are configured, only the initial port is entered by the user. The
SME 100 firmware then assigns the multiple port numbers based on the initial port number.
Choosing IP Addresses
If the SME 100 and other devices are connected via an independent network, then follow
the guidelines below when choosing IP addresses. However, if the SME 100 and other
devices are being connected to an existing network, advise the network administrator and
ask them to assign suitable addresses.
On an independent network, nearly any type of address can be used (in theory).
However, it is generally recommended that class C addresses are used
(192.0.0.1 through 223.255.255.253).
There are two rules for choosing IP addresses:
• The network identifier must be the same for each address.
• The host identifier must be unique for each address.
Applying these rules to class C addresses, the first three decimal values of the IP addresses
must all be the same, while the last value is used to uniquely identify each device.
SME 100 • Reference Information 167