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New Member

Setting DSCP to EF on 3750 Switch

I need to set the DSCP value of packets arriving at a switch port to EF. This is for a 3750 running IOS version 12.2(25)SEB4.

I have the following configuration..

access-list 105 permit udp host 10.16.3.5 any

class-map match-all voip

match access-group 105

!

!

policy-map setdscp

class voip

set dscp ef

interface FastEthernet1/0/22

description VOIP GW 10.6.1.35

switchport access vlan 250

switchport mode access

switchport voice vlan 250

ip access-group 105 in

service-policy input setdscp

spanning-tree portfast

UDP packets are not being marked with DSCP = EF

Any suggestions / corrections would be very helpful.

Thanks

3 REPLIES

Re: Setting DSCP to EF on 3750 Switch

If I am reading your configuration right, then it looks like your VOIP network is hanging off Fastethernet1/0/22.

This would mean that the host 10.16.3.5 hangs on a different interface?.

If this is the case, then you should really move the service-policy inbound to the interface/SVI that the host hangs off.

If you just want to get this working (and I have read your config right), then change the service policy and access-group command to output on interface FastEthernet1/0/22, ie

interface FastEthernet1/0/22

description VOIP GW 10.6.1.35

switchport access vlan 250

switchport mode access

switchport voice vlan 250

ip access-group 105 out

service-policy output setdscp

spanning-tree portfast

Add a log statement to the end of your ACL to see if you are getting any hits also but take this off once you have finished as if forces a CEF punt.

As a side note, it is always better to mark inbound and shape/police/queue outbound.

New Member

Re: Setting DSCP to EF on 3750 Switch

The VOIP gateway 10.6.1.35 is on port Fa1/0/22.

The gateway has a PRI circuit on it - so when a call arrives on thet PRI line it goes through the gateway and arrives on the 3750 port. I'm trying to mark the packets that entering the 3750 with dscp = ef so that as those packets traverse our intersite MPLS network they ride over the high priority queue.

Hall of Fame Super Blue

Re: Setting DSCP to EF on 3750 Switch

Is this a typo , you have a description under the interface -

description VOIP GW 10.6.1.35

and yet your acl references 10.16.1.35 ie.

10.6.1.35 does not equal 10.16.1.35

are you seeing any hits on acl 105 ?

Jon

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