Avaya Configuring Line Services Bedienungsanleitung Seite 41

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About Line Protocols
115391-A Rev. A 2-3
Ethernet Frame Formats
There are two MAC-layer frame format specifications used in Ethernet LANs.
The first specification is called Ethernet. The second, standardized by the IEEE, is
called 802.3. One way that they differ is in message format (F
igure 2-1). Instead
of a Length field in the MAC-layer header, Ethernet messages include a Type
field, indicating which higher-layer protocol is used in the Data field.
Figure 2-1. Ethernet and 802.3 Message Formats
The Bay Networks Ethernet/802.3 interface supports IEEE 802.3 and Version
1.0/2.0 Ethernet frame formats.
Ethernet Media
A bisynchronous10-Mb/s Ethernet LAN (10Base-T) uses thick or thin Ethernet
(coaxial cable) or Category 3 twisted-pair cable.
The bisynchronous100-Mb/s Ethernet LAN (100Base-T, sometimes called fast
Ethernet) uses three different media interfaces:
100Base-TX uses two pairs of unshielded twisted-pair wires and allows both
full-duplex and half-duplex operation.
100Base-FX uses fiber cabling that supports half- and full-duplex operation.
100Base-T4 uses new physical layer signals to run over four pairs of
Category 3 unshielded twisted-pair wires. The signals use all four wire pairs,
so only half-duplex operation is supported.
802.3 message format
Ethernet message format
Destination
address
Source
address
Destination
address
Source
address
Type Data
CRC
Data
CRC
Length
LS0002A
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