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QoS Marking Packets


I need to mark the packets than are transmitted by the Streaming Server, inserting the IPP value 3.

I will realize the following configuration:

access-list 99 permit

class-map match-all Traffic
match access-group 99

policy-map Mark
class Traffic
set ip precedence 3

interface fastethernet 0/0

service-policy output Mark



Is this configuration correct?


looks good, that will mark the packets leaving the Core switch. Packets will lose the markings when they cross the Router, so you have to configure the router in the same way if you want the packets that are leaving the router to be marked also.


Thanks for you answer SiddHartham.

I have some question.

1.- To keep the marks of IPP3 of leaving packets of Core Switch, I have to configure "mls wos trus  ip-precedence" in  the FE 0/1 of the Router A ?

2.- How I can check the labeling of the packets? (Wireshark, show commands).



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Routers tend to leave ToS alone, unless you configure them to do otherwise.

For most Catalyst switches, they too leave ToS alone until you enable QoS where they will often reset to IPP 0, unless you configure otherwise.  You also might need an input policy to mark.  Many Catalyst switches don't offer all router QoS egress features.

Wireshark could confirm ToS contents.  Depending on where you want to check, next downstream device might be configured to match on IPP 3 and not do anything - i.e. compare counts to non-IPP 3.


If your Core is router or L3 switch that supports router-style QoS, your configuration is correct. If it is a simple L3 switch (3560, 3750, etc.) than you have no possibility to do classification and marking on outbound direction. Then you need to do it inbound and you may apply it in port-based or VLAN-based fashion. In this case you also need to enable QoS (mls qos command) which automatically means setting CoS and DSCPs on all packets to zero unless it explicitly defined.

It is true concerning routers - they are transparent to IPP/DSCP unless explicitly configured to do something. And also you can not use mls qos trust command on a router - it is a switch-style command and is used on switchports only.

If you need to check labeling of a given packet - use Wireshark or debug ip packet detailed command with logging to buffer, then - show log to view packets.

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