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EXFO ETS-1000 User Manual

Page 148

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Ethernet Frame Structure

140

ETS-1000

Frame Check Sequence: 4-bytes field contains the checksum.

Ethernet Frame with VLAN tag structure

Tag Protocol Identifier: 16 bits field defines that the frame belongs to
the 802.1Q

[1]

standard.

Tag Control Information: TCI field contains three following fields.

Priority: User (VLAN) Priority. Three bits that contain information
about the frame priority (eight possible priority values are available
(

[1]

)).

CFI: Canonical Format Indicator is an one-byte flag which must be
equal to 0 (null) for Ethernet frames.

VLAN ID: VLAN Identifier (VID) is a 12-bit identifier which is
defined in the 802.1Q standard

[1]

. VID uniquely defines VLAN to

which the current frame belongs to.