Orion A10E - Figure 4-2 Structure of IP Packet Head; Figure 4-3 Structure of IP Priority and DSCP Priority; Figure 4-4 Structure of VLAN Packets; Figure 4-1 Traffic Classification

Orion Networks
A10E/A28E/A28F Configuration Guide
4 QoS
Orion Networks
98
Figure 4-1 Traffic classification
IP priority and DSCP priority
Structure of IP packet head shows as below, the head contains 8bit ToS field. According to
RFC1122 definition, IP priority (IP Precedence) uses the highest 3 bits (0–3) with value range
of 0–7; RFC2474 defines ToS field again, and applies the first 6 bits (0–5) to DSCP priority
with value range 0–63, the last 2 bits (bit-6 and bit-7) are reserved. The structure of two
priority types is shown in Figure 4-3:
Figure 4-2 Structure of IP packet head
Figure 4-3 Structure of IP priority and DSCP priority
CoS priority
VLAN packet over IEEE 802.1Q standard makes modification on Ethernet packet, increase 4
bytes 802.1Q tag between source address field and protocol type field, as shown below. The
tag includes field of 2 bytes TPID (Tag Protocol Identifier, value at 0x8100) and field of 2
bytes Tag Control Information (TCI).
Figure 4-4 Structure of VLAN packets