Ericsson SPR1100, Handbook

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RTP Layer
The RTP layer is optional, and will add an 8-byte RTP header to the new packet. This header
contains a sequence number and a time stamp.
UDP Layer
The UDP layer is according to RFC768 “User Datagram Protocol”. The user can control the
target UDP port number for the MPEG-2 stream. A configurable number of 188-byte long
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 1 to 7. The following illustration shows the mapping of MPEG-2
transport streams into UDP packets.
IP Layer
The IP layer is according to RFC791 “Internet Protocol Specification”. The user is allowed
access to the following IP header fields: IP source address, IP destination address, Time-To-
Live field, Type-Of-Service field. Performing static mapping between class-D IP addresses
and the corresponding Ethernet multicast MAC addresses supports limited IP Multicasting
(Type 1).
Ethernet Layer
The data link layer is Ethernet according to IEEE 802.3/802.3u (auto sensing 10/100 Mbps,
Twisted Pair, RJ-45 connector).
IP Overhead
The IP overhead calculation when mapping MPEG-2 TS packets into IP frames is shown in
the following table.
Overhead factor Comments
MPEG-2 TS 1.0