Configuring QoS DiffServ Configuration
Configuration Guide
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DiffServ Configuration
To complete differentiated services configuration, follow these steps:
1) Configure the priority mode to classify packets with different priorities.
2) Configure the schedule mode to control the forwarding sequence of packets.
Configuration Guidelines
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Deploy the priority mode appropriate to your network requirements.
Three modes are supported on the switch, 802.1P Priority, DSCP Priority and Port
Priority.
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802.1P Priority
802.1P defines the first three bits in 802.1Q Tag as PRI field. The PRI values are from 0
to 7. 802.1P priority determines the priority of packets based on the PRI value.
In this mode, the switch only prioritizes packets with VLAN tag, regardless of the IP
header of the packets.
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DSCP Priority
DSCP priority determines the priority of packets based on the ToS (Type of Service)
field in their IP header. RFC2474 re-defines the ToS field in the IP packet header as DS
field. The first six bits (bit 0-bit 5) of the DS field is used to represent DSCP priority. The
DSCP values are from 0 to 63.
In this mode, the switch only prioritizes IP packets.
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Port Priority
In this mode, the switch prioritizes packets according to their ingress ports, regardless
of the packet field or type.
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The switch implements the priority mode in the following sequence when two or more
modes are enabled.
Implementing sequence: DSCP Priority > 802.1P Priority > Port Priority
If all the three priority modes are enabled, the switch will distinguish the received
packets and map the packets to different priority queues. IP packets are mapped based
on DSCP priority mode, non-IP packets with 802.1Q tag are mapped based on 802.1P
priority mode, and the untagged non-IP packets are mapped based on port priority
mode.
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