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EXFO ETS-1000G User Manual

Page 182

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Ethernet Frame Structure

172

ETS-1000G

Frame Check Sequence — a checksum. A 4-byte field that contains a
checksum.

Tag Protocol Identifier — the “Protocol Identifier tag. 16 bits that
determine whether a frame belongs to 802.1Q standard [9].

Tag Control Information — Information for tag management.

TCI contains three fields.

Priority — User (VLAN) Priority. Three bits which carry information
about a frame's priority (eight frame priority values are supported).

CFI — Canonical Format Indicator. A one-bit flag that is always equal to
zero for Ethernet frames.

VLAN ID — VLAN Identifier (VID). A 12-bit VLAN identifier that is
defined in 802.1Q standard [9]. It uniquely identifies the VLAN a frame
belongs to.