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New Member

QoS Router on a stick

I'm trying to figure out the QoS for a router on a stick location with multiple vlans using either the 1800 or 2800 series routers. The switching QoS is done and works fine. On the router, should I apply a service policy both inbound and outbound, or just outbound, or something else entirely?

Case 1:

policy-map 1-ARM-LAN-EDGE

class VOICE

priority percent 5

class REAL-TIME-INTERACTIVE

priority percent 30 384000

class NETWORK-CONTROL

bandwidth percent 5

class CALL-SIGNALING

bandwidth percent 5

class MULTIMEDIA-CONFERENCING

bandwidth percent 5

random-detect dscp-based

class SCAVENGER

bandwidth percent 1

class class-default

random-detect

interface FastEthernet0/0

no ip address

speed 100

duplex full

!

interface FastEthernet0/0.100

description VLAN SUBNET

ip address xxxxxxxxxxxxx

service-policy input 1-ARM-LAN-EDGE

service-policy output 1-ARM-LAN-EDGE

Case 2:

policy-map 1-ARM-LAN-EDGE

class VOICE

priority percent 5

class REAL-TIME-INTERACTIVE

priority percent 30 384000

class NETWORK-CONTROL

bandwidth percent 5

class CALL-SIGNALING

bandwidth percent 5

class MULTIMEDIA-CONFERENCING

bandwidth percent 5

random-detect dscp-based

class SCAVENGER

bandwidth percent 1

class class-default

random-detect

interface FastEthernet0/0

no ip address

speed 100

duplex full

!

interface FastEthernet0/0.100

description VLAN SUBNET

ip address xxxxxxxxxxxxx

service-policy output 1-ARM-LAN-EDGE

Thanks!

7 REPLIES
Hall of Fame Super Silver

Re: QoS Router on a stick

Hello Matthew,

a policy-map that implements a scheduler with LLQ (priority) and CBWFQ (bandwidth) can be applied only outbound.

If all your traffic is already marked at the LAN switch level you just need to manage the output queueing.

If you need to mark ingress traffic on a vlan you will need a different service policy where each class-map invoked has some form of DSCP marking that can be used outbound by the scheduler of another interface.

Be aware that when using percentages all these are referred to the interface bandwidth so you may need to tune the bandwidth on each VLAN subif (default value should be inherited by physical interface value 100000 Kbps for a FE)

in order to avoid to oversubscribe in that case you will get an error message when trying to apply the policy-map on the second VLAN subif.

Hope to help

Giuseppe

New Member

Re: QoS Router on a stick

Ok, thank you. All of the traffic is properly marked by the time it gets to the one armed router. So it sounds like I only need the outbound service policy attached to the sub-interfaces, if I understand you correctly.

As far as the percentages go, would specifying the data rate be a better way to go?

Thanks again!

Hall of Fame Super Silver

Re: QoS Router on a stick

Hello Matthew,

you can use the percentages if you like but you need to resize the bandwidth under each subif using bandwidth command.

So for two subifs

bandwith 50000

under each subif

and so on

Otherwise you can use data rates.

I would use policy-maps with different names in order to simplify monitoring.

You can use sh policy-map int fas0/1.x to see what is happening on each subif but using a different name for each service-policy even if their config is the same is better.

Hope to help

Giuseppe

[Please Rate if Helps, thanks]

New Member

Re: QoS Router on a stick

I tried to apply the policy to the 1st sub-interface and received an error message of: CBWFQ : Not supported on subinterfaces

If I apply it to fa0/1, it takes. Anybody know if this will work, otherwise I'll try it in the lab tomorrow.

Thanks!

New Member

Re: QoS Router on a stick

Super Bronze

Re: QoS Router on a stick

fyi: I've had success with the procedures you found in your reference.

Hall of Fame Super Silver

Re: QoS Router on a stick

Hello Matthew,

it should work.

Support on subif is actually platform dependent : high end router allows to do it.

In this case all the questions about bandwidth are not a concern here.

To keep trace of traffic on single subinterfaces you should consider to use an output acl that will count packets on each class

Hope to help

Giuseppe

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