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Web Configuration
QoS-DSCP Setting
In order to understand what is differentiated services code point (DSCP), you should be familiar with the differen-
tiated services model (Diffserv).
Diffserv is a class of service (CoS) model that enhances best-effort Internet services via differentiating traffic by
users, service requirements and other criteria. Packets are specifically marked, allowing network nodes to provide
different levels of service via priority queuing or bandwidth allocation, or by choosing dedicated routes for specific
traffic flows.
As displayed in following diagram, the IPV4 packet has a TOS filed. Diffserv defines TOS field in IP packet headers
referred to as DSCP. Hosts or routes that pass traffic to a Diffserv-enabled network typically mark each trans-
mitted packet with an appropriate DSCP. The DSCP markings are used by Diffserv network routers to appropriately
classify packets and to apply particular queue handing or scheduling behavior.
Layer 3 IPV4 Packet
Version/
TOS
Length
ID
Offset/
TTL
Protocol
Checksum
IP-SA
IP-DA
Data
Length
(1 Word)
Mark
TOS Filed-IP priority (TOS front 3 bit) or DSCP (front 6 bit)
7
6
5
4
3
2
1
0
IP Priority
Undefined
DSCP
Flow Control
D-Link DSL-500B User Manual
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