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Figure 6.1 The Protocol Stack
The MPEG-2/DVB layer is specified in ISO/IEC IS 13818 – Generic Coding of
Moving Pictures and Associated Audio. The UDP layer is compliant with RFC768 –
User Datagram Protocol. A configurable number of 188 Byte MPEG-2 TS packets
are mapped straight into an UDP frame with no additional overhead. The MTU for
Ethernet is usually 1500 bytes. This limits the number of MPEG-2 TS packets per
UDP frame to lie within one to seven.
The IP layer is according to RFC791 – Internet Protocol Specification.
Figure 6.2 show
s a more detailed picture of the MPEG-2 data transfer. TS-packets
Figure 6.2 Building the Ethernet Frame
are mapped in a datagram, using User Data Protocol (UDP), Internet Protocol (IP)
and Ethernet.
Link layer – 10/100BaseT Ethernet
Transport layer - IP
TCP/UDP UDP – User Datagram Protocol
MPEG-2/DVB layer
MPEG-2 Transport Stream
(Multi-Program Transport
Stream or Single-Program
Transport Stream)
Control traffic for in-band
management
(telnet, http, snmp)
…
Information 14H
Information
Information
20H
8H
188
188 TS
p
ackets
(
1
UDP data
g
ram
IP data
g
ram
Ethernet frame
EN/LZT 790 0003/2 R1A
6-6