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QoS for LAN


Sorry to make it long.

We are in a progress setting up QoS on our branch LANs.

In general we have a routing switch (3750 ip services) and access switches (3750 stack with ip base) connected to the routing  swich using etherchannel.

Routing switch is connected to the WAN CE using an access port.

Routing switch does all routing and access switches are just carrying the vlans.

End users (through IP phone or straigth) are connected to access switches and servers, WLC etc. are connected to routing switch.

We want to do all coloring on the routing switch.

WAN provider offers 4+1 clasess: real time, data1, data2, data3, BE

I was trying to figure out how best the classification and marking can be done on the LAN in order to be able to pass marked all traffic to the WAN.

I need some clarification on how the classification can be done best.

My understanding:

1. On access switches access ports connected to IP phones:

trust DSCP

trust device ip phone

I guess traffic sent by the PC will not be trusted or rewritten (unless I set the rewrite option).

2. On trunk ports between access and routing switch

trust DSCP

3. Marking the data from all vlans

Here the voice traffic (signalling and RTP) comes already marked due to trust.

But what about data?

Shall I set up hierarchical policy map on the SVIs? If so how to do that. I found the config guide a bit confusing with the vlan based qos.

Do I need to struggle with that or is there an easier way to achieve the same?

4. WAN uplink port is an L2 port and IP address for p2p connectivity with WAN CE is on SVI.

Here I need to configure the egress queuing to put the marked traffic into the correct queue.

Please correct me if I'm wrong.

Thanks in advance


Reza Sharifi
Hall of Fame Expert

Hi Krisztian,

Have a look at this document.  It explains the marking for voice and data in details in the campus.