QoS on logical interface (vlan, dialer, ...)

[blau grana]

Hi all

I have question regarding implementation of QoS on logical interface. I tried to search for the answer if it is even possible, but all I could find was that it is not because logical interface handles queuing and shaping differently than typical L3 port.

Lets say that I have router with 1 wan port DSL used as backup and four L2 switchports, where 3 of them are LAN ports (vlan10) and last is used as primary WAN uplink (vlan20).

I would like to set QoS on interface vlan 20 to prioritize voice, is ti possible and if not why?

Can somebody explain or suggest some documents to study.

Thanks

[markvaneck]

For QOS on DSL, apply the QOS in the ATM virtual circuit

Check the upstream sync speed ( show dsl int atm [number] ) and create a parent policy map to shape to an average of that speed and nest the actual policy inside

example :

policy-map CHILD

class VOIP-MATCH

    priority 128

policy-map PARENT

class class-default

    shape average 512000

  service-policy CHILD

interface ATM0.1 point-to-point

pvc 8/35

  vbr-rt 512 512

  tx-ring-limit 3

  service-policy output PARENT

  pppoe-client dial-pool-number 1

tx-ring-limit 3 shortens the hardware queue to allow the layer-3 queue to kick in sooner. Service policies only apply to packets in the layer-3 queues. The default vaule is 16, I find 3 works perfectly in my environment, but you can test with different vaules.

I use this method on 877s and 1841s with ADSL WICs and it works well. Use qos pre-classify if you're tunneling over it.

What type of WAN link are you using on vlan 20 ?

[blau grana]

Hi, thanks for answer

primary link is Ethernet connection to some ISP.

vlan 20

name WAN_UPLINK

Fa0/0

switchport mode access

switchport access vlan 20

int vlan 20

ip add 192.168.0.2 255.255.255.252

ip route 0.0.0.0 0.0.0.0 vlan 20 192.168.0.1

[markvaneck · Accepted solution]

What router and IOS version are you using ?

Can you turn Fa0/0 into a layer 3 port by issuing the no switchport command ?

If you can, then you can assign the IP to Fa0/0 and have better QOS options availble.

You need to apply a service policy that assigns the DSCP markings in the inbound direction on VLAN 10. You will run into a problem when applying a policy in the outbound direction on vlan 20 that queues and prioritizes traffic and will give you a configuration failed error as SVIs do not usually support CBWFQ and LLQ

Lets first see if Fa0/0 can be a routed port and take it from there

Are you familar with creating class-maps and policy-maps or would you like some examples ?

[blau grana]

Let's say that I have cisco 866, it has 4 fastethernet ports (Fa0-3) and 1 gigabitethernet port Gi0, which can not become routed ports and have own IP address. And port Gi1 which is WAN port operating ether in dsl or ethernet mode.

I used Gi1 for DSL link -> it is supposed to be backup link.

Port Gi0 is used as primary WAN port:

Gi0

switchport mode access

switchport access vlan 20

int vlan 20

ip add 192.168.0.2 255.255.255.252

And now I would like to implement QoS for voice traffic on Vlan20 port.

I am familiar with QoS configuration and alghorithm how it works but I do not know how it really physically work, what is supported and what is not.

I am very thankful for information which you provided so far, I do not expect you to teach me or explain everything from basics. But maybe advise some site/book/document to read. Everything what I found so far was configuration of class/policy maps, there is plenty of this. For example, I did not find any information that SVI do not support policy in outbound....

[davy.timmermans]

I think you can create a QoS policy as you already know and apply the service policy to the gig0 port in the out direction.

A QoS policy doesn't need to be applied to a L3 port