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How to Prioritize traffic based on DSCP marking, on SecureStacks


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Article ID: 7589

Products
SecureStack C3
SecureStack C2
SecureStack B3
SecureStack B2

Protocols/Features
Policy
VoIP
DSCP
CoS

Goals
Prioritize incoming traffic based on DSCP marking
Sample configuration

Cause
This SecureStack policy configuration will, for all ports, prioritize incoming frames - VLAN-tagged or not - which have DSCP value 46 or 48 (5811).
Note1: In the applied network, those values are used by the routers to identify Voice over IP traffic. This will not be true of all networks.
Note2: SecureStack B3 and B2 units will require a Policy License (5781) before this configuration may be applied to them.

Solutionset policy profile 1 name VoIP
set policy port *.*.* 1
set policy rule 1 iptos 176 mask 6 cos 5
set policy rule 1 iptos 184 mask 6 cos 5[/code]
By default the outgoing prioritized (priority 5) frames will hit transmit queue#4, while non-prioritized (priority 0) traffic will hit transmit queue#1.
Queue#1 by default receives no service if anything is waiting in queue#4 ('show port txq').
If outgoing frames are VLAN-tagged, the tag of affected frames will carry a Priority of 5.

The specific rules you use will depend upon which bits of the TOS byte you wish to examine:
    If you want DSCP values 44 and 46 and don't care about the remaining two TOS bits: set policy rule 1 iptos 176 mask 6 cos 5 [= TOS bits 101100xx] set policy rule 1 iptos 184 mask 6 cos 5 [= TOS bits 101110xx][/code]
    If you want DSCP values 44 and 46 and want to ensure that the remaining two TOS bits are zero: set policy rule 1 iptos 176 mask 8 cos 5 [= TOS bits 10110000] set policy rule 1 iptos 184 mask 8 cos 5 [= TOS bits 10111000][/code]
    If you want TOS values 44 and 46: set policy rule 1 iptos 46 mask 8 cos 5 [= TOS bits 00101100] set policy rule 1 iptos 48 mask 8 cos 5 [= TOS bits 00101110][/code]
Please contact Enterasys Networks Technical Services for further assistance, as necessary.

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