Control On The Mac And Llc Sublayers - Alaxala AX2200S Series Configuration Manual

13.1.3 Control on the MAC and LLC sublayers

The following figure shows frame formats.
Figure 13-2 Frame formats
(1) MAC sublayer frame format
(a) Preamble and SFD field
The Preamble and SFD field contains a 64-bit binary number. The first 62 bits are
repetitions of 10, and the last two bits are 11 (1010...1011). This field is added to the
beginning of the frame when the frame is sent. Frames without this 64-bit pattern cannot be
received.
(b) DA and SA fields
The DA and SA fields support a 48-bit format. They do not support 16-bit or local address
formats.
(c) TYPE/LENGTH field
The following table describes how the TYPE/LENGTH field is handled.
Table 13-1 Handling of the TYPE/LENGTH field
TYPE/LENGTH value
0x0000 to 0x05DC
0x05DD or larger
(d) FCS field
The FCS field uses a 32-bit CRC.
(2) LLC sublayer frame format
The Switch supports IEEE 802.2 LLC type 1 (UI frame only). In Ethernet V2, there is no
LLC sublayer.
How the Switch handles the value
IEEE 802.3 CSMA/CD frame length
Ethernet V2.0 frame type
13 Ethernet
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