Specifications

Chapter 1 Introduction IPmux-11 Installation and Operation Manual
1-8 Functional Description
Frame Format
The Ethernet frame sent by IPmux-11 is a UDP datagram that transfers E1/T1
payload bytes over IP over Ethernet (UDP payload + UDP header + IP header +
Ethernet header). The UDP payload is equal to TDM bytes per frame
(TDM bytes/frame configuration).
Table 1-2 specifies the structure of the different headers, special fields, and the
payload in the Ethernet packet.
MAC IP UDP
Payload
Figure 1-6. TDMoIP Frame Structure
Table 1-2. Ethernet Frame Structure
Field length (bytes) Field
7 Preamble
1 SFD
6 Destination MAC Address
6 Source MAC Address
2 Type
1 Vers/HLEN
1 Service Type
2 Total Length
2 Identification
1 Flags/Fragment Offset (most)
1 Fragment Offset (least)
1 Time to Live
1 Protocol
2 Header Checksum
4 Source IP Address
4 Destination IP Address
2 UDP Source Port
2 UDP Destination Port
2 UDP Message Length
2 UDP Checksum
... Payload
4 CRC
MAC
Layer
IP Layer
MAC
Layer
UDP
Layer
Data
Layer
LLC
Layer
N
ote: IEEE 802.1p&Q VLAN
Tagging (additional 4 bytes if
enabled)
Note: The UDP source port
field is used to transfer the
destination bundle number in
s
tatic and dynamic CAS
modes.