Oracle Video server, Manual

Page: 69 / 78

Networking in the OVS System
System Architecture 2-33
Ethernet
This section discusses these Ethernet terms:
■
Packets
■
Bus/Broadcast Topology
■
Best-Effort Delivery
Packets A packet is the basic unit of information that travels between computers
on a LAN. All data transmitted over a LAN, whether a small message or a large
video file, is divided into packets. Each packet contains a header and data. The
header contains:
■
information about data in the packet
■
sequencing information
■
the address of the receiving computer
■
a checksum of the packet data
For Oracle Media Net packets, the receiving computer gathers the packets it
receives and reassembles them based on the packet sequence in the header. The
receiver can identify missing packets based on information in the headers of the
received packets and corrupted packets based on the checksum information in their
headers. If a packet is missing or has been corrupted, the receiver requests that the
sending computer resend the packet and waits for its return before reassembling
the data for the user.
Bus/Broadcast Topology
The most common type of Ethernet topology is a bus
topology , in which all computers on the network are connected to the same
communication channel. When one computer wants to send data over the network
to another, it checks the data channel for data packet traffic and broadcasts the first
packet when the channel is clear. If the data takes up multiple packets, the sender
waits again until the channel is clear to transmit the next packet. This continues
until all the packets have been sent. As a packet is broadcast on the channel, it is
seen by all computers on the network. The packet is only useful to the computer to
which it is addressed, denoted by the address in the packet header. This type of
network is called shared Ethernet because all computers on the network share the
same data channel.