Westermo RedFox Series - Manual (Page 696)

Westermo OS Management Guide
Version 4.17.0-0
31.1.3.3.2 Setting DSCP
WeOS can set the 6 DSCP bits in the IP ToS field with a modifier rule. The two last
bits (Enhanced Congestion Notification) are not modified by this operation.
The decimal values 0-63 must be used when setting DSCP.
Several RFCs define standard DSCP values called ”Per-Hop Behaviors” or PHBs.
WeOS does not support the PHB names for configuration, but the table below can
be used to convert PHB names to the corresponding decimal values.
PHB Name DSCP value
DF 0
CS1 8
AF11 10
AF12 12
AF13 14
CS2 16
AF21 18
AF22 20
AF23 22
CS3 24
AF31 26
PHB Name DSCP value
AF32 28
AF33 30
CS4 32
AF41 34
AF42 36
AF43 38
CS5 40
VA 44
EF 46
CS6 48
CS7 56
31.1.3.3.3 DSCP Adjust priority
There is an additional parameter called ”adjust priority” that can be added to a
DSCP modifier rule. This parameter enables adjustment of the router’s internal
packet priority handling inline with the modified DSCP value. Furthermore, if
traffic is routed out on a port that has tagged VLAN, this will affect the IEEE
802.1p priority field in the outbound packets.
This is useful in some scenarios when the DSCP is overridden. The priority ad-
justment function is made to mimic the behaviour of the Layer-2 priority support
when configured in the IP ToS/DiffServ mode, as described in
chapter 8 , sec-
tion 8.1.4 .
Enabling this flag will introduce more work for the CPU inside the WeOS unit for
every packet that is modified. As this decreases the maximum routing perfor-
mance, it should only be enabled when necessary.
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