GE SymDec 4, Руководство пользователя, Страница: 28 / 90

SymDec 4
User Manual
22
Note: Configured incorrectly IP multicast can become a serious drain on your networks resources! If you are at all uncertain
on how to setup IP multicast, please contact your network administrator or IS professional.
The Internet Assigned Numbers Authority (IANA) controls the assignment of IP multicast addresses. It has
assigned the Class D address space to be used for IP multicast. This means that all IP multicast group addresses
will fall in the range of 224.0.0.0 to 239.255.255.255. This address range is only used for the group address or
destination address of IP multicast traffic. The source address for multicast video is always the source or
senders IP address.
UDP Sender and UDP Receiver Overview
UDP (User Datagram Protocol), is a connectionless protocol that, like TCP, runs on top of IP networks. Unlike
TCP/IP, UDP/IP provides very few error recovery services, offering instead a direct way to send and receive
datagrams over an IP network. It's used primarily for broadcasting messages over a network. A UDP sender
sends out digital video over an IP network. A UDP sender can be the SymDec-1, SymDec 4, Symveo IP
Camera, or SymNet (Encoder). A UDP receiver is typically a SymDec-1, SymNav software, or a SymDec 4,
which can display and record the streamed video. The SymNet (Decoder) can also be setup as a receiver, but it
can only display the streamed video since it does not have recording capability.
To prevent a waste of network resources, the UDP sender does not send out streaming video until a receiver
informs the sender that it is interested in receiving the stream. The UDP receiver sends out a
START message
every 30 seconds to the IP address in its streaming settings menu. The streaming settings page is located on the
receiving device's web page.
When a sender receives a START message, it will start streaming out to the receiver's that are requesting it.
When the sender does not receive any START message for one minute, it will stop sending to that device.
To speed up the initialization process after bootup and configuration changes, The UDP sender sends out a
READY_TO_SEND message to the multicast IP address. When the receiver gets this message, it will send out
the START message immediately if it is configured to receive from that sender (It does not wait for 30 seconds).
Note: The above information also applies if your Sender and Receiver are configured to use TCP instead of UDP.
SymNav software
SymNav software is the next generation of software that supports MPEG4 based video compression. The
Symdec-1, SymDec 4, SymNet, and SymVeo IP Camera all use MPEG4 compression.
SymNav software also connects to these products using UDP/TCP protocols depending on what is configured.
The default setting is UDP. Changing from UDP to TCP or TCP to UDP is accomplished through the SymNav
software application.
SymNav software can connect to a maximum of 4 video streams. This can be 4 separate SymDec units with 1
stream each or 2 SymDecs with 2 streams each.
Sample Network Setup
We recommend that video streaming is setup on a private network. The following configuration setup is based
on the following network diagram. These settings are implemented through the individual unit's web page. To
access the unit's web page simply launch your Internet browser and input the unit's IP address in the address