QOS giving outbound priority to a port, is it possible with C850/IOS 12.3?

[bbiales00]

I've got a realtime application that uses a particular port, say, 9000 for inbound and outbound UDP traffic. Since I have off-site users that can use up all my outbound bandwidth at times, when they do this, the realtime app suffers. I would love to give this port priority, so these packets go out first no matter what else is going on (I know I cannot control the order the packets arrive...). Unfortunately, I have little IOS experience. I can tweak Access lists and NAT settings, but I don't see how to do this QOS feature with my router. Is it even possible? I've been told it will support QOS, but I'm not so sure... If my current config would help, let me know and I will post it.

Thanks for any insights/direction you can provide.

[bbiales00]

Well, to make this easier, I've attached a scrubbed version of my config. This is, in fact, also my ADSL router, the interface is called Dialer1. There is also a site-to-site VPN in the config, but I think we can ignore that for now. I've removed all the NAT's from the config (which are required to go through the site-to-site VPN...).

I believe our service is 6Mbs in to the router, and 768Kbs out to the internet.

Let me know what's next. Thanks.

[andrew.prince]

OK - I would try something like:-

!

class-map match-all pri-app

match access-group 101

!

!

policy-map mark-app

class pri-app

set precedence 5

class class-default

set precedence 0

!

policy-map App-QoS

class pri-app

priority xx - the number in kilo bits per second you want to assign the app in LLQ

class class-default

fair-queue

random-detect dscp-based

!

interface Dialer1

service-policy output App-QoS

There is an addition to the marking policy - to mark all other traffic = class default.

[bbiales00]

Ok, I'm almost there...

I now have:

class-map match-all pri-app

match access-group 101

!

!

policy-map App-QoS

class pri-app

priority 200

class class-default

fair-queue

policy-map mark-app

class pri-app

set precedence 5

class class-default

set precedence 0

I had to leave off the "random-detect dscp-based" because these are not available on my 877:

Here are the available commands:

r12(config)#policy-map App-QoS

r12(config-pmap)#class class-default

r12(config-pmap-c)#?

QoS policy-map class configuration commands:

bandwidth Bandwidth

compression Activate Compression

drop Drop all packets

exit Exit from QoS class action configuration mode

fair-queue Enable Flow-based Fair Queuing in this Class

netflow-sampler NetFlow action

no Negate or set default values of a command

police Police

priority Strict Scheduling Priority for this Class

queue-limit Queue Max Threshold for Tail Drop

service-policy Configure Flow Next

set Set QoS values

shape Traffic Shaping

And finally, I got an error setting this policy for the Dialer1 interface:

r12(config)#interface dialer1

r12(config-if)#service-policy output App-QoS

Must remove fair-queue configuration first.

Class Based Weighted Fair Queueing will be applied only to the Virtual-Access interfaces associated with an MLP bundle.

r12(config-if)#

I don't fully comprehend the error message. Should I just remove the fair-queue line? So default class packets will simply be FIFO?

Thanks again!

[andrew.prince]

OK - this is an interesting error, so in the dialer interface configure no fair-queue

Then apply the service policy again - is there is another error, I am thinking that the QoS policy could only be applied to a ATM PVC/DSL interface - not 100% sure....will reearch this.

[bbiales00]

Well, I configured no fair-queue and then applied the QoS policy, but not all at once, and here is what it said at that time:

r12(config)#int dialer1

r12(config-if)#service-policy output App-QoS

I/f Virtual-Access1 class pri-app requested bandwidth 200 (kbps), available only 42 (kbps)

r12(config-if)#

I did a DSL Reports bandwidth test and it reported 4000+ receive speed and 600+ upload speed, so I don't understand why it thinks there is only 42kbs to reserve...

This QoS stuff is anything but simple, that is for sure!

So now, I see things are not setup properly, I don't think I ever "saved" that config. So I went back to config mode, entered the following, and my router dropped all its connections, and my telnet session was cancelled...

Here is what I tried:

r12(config)#interface dialer1

r12(config-if)#no fair-queue

r12(config-if)#service-policy output App-QoS

Anyway, when I reconnect, and look at the config, the dialer1 interface has no fair-queue but no policy-map either. So I typed "write mem" and looked again, and the fair-queue is back, here is what Dialer1 looks like...

Still no service policy defined :-(

interface Dialer1

ip address negotiated

ip nat outside

ip virtual-reassembly

encapsulation ppp

dialer pool 1

fair-queue 64 16 256

no cdp enable

ppp authentication pap callin

ppp pap sent-username MyUserName password 0 MyPW

crypto map r12vpn

[andrew.prince]

Apply the service policy map to the "interface ATM0.1 point-to-point"

[andrew.prince]

Also found this link for QoS on DSL 8xx routers:-

http://www.cisco.com/en/US/prod/collateral/routers/ps5855/prod_white_paper0900aecd80645923_ps381_Products_White_Paper.html

HTH.

[bbiales00]

Odd. I could not add to interface atm0.1 I did not write down the error, but it said it could not be put on a subinterface. So I put it on the ATM interface, but while it is there, some counts at the bottom of this report make me think nothing is matching...

Well, here are a couple reports, maybe it is working... What do you think?

r12#sh policy-map int atm0

ATM0

Service-policy output: App-QoS

Class-map: pri-app (match-all)

22365 packets, 6707964 bytes

5 minute offered rate 22000 bps, drop rate 0 bps

Match: access-group 101

Queueing

Strict Priority

Output Queue: Conversation 264

Bandwidth 200 (kbps) Burst 5000 (Bytes)

(pkts matched/bytes matched) 0/0

(total drops/bytes drops) 0/0

Class-map: class-default (match-any)

251771 packets, 62042165 bytes

5 minute offered rate 170000 bps, drop rate 0 bps

Match: any

Queueing

Flow Based Fair Queueing

Maximum Number of Hashed Queues 256

(total queued/total drops/no-buffer drops) 3/0/0

r12#sh policy-map int atm0

ATM0

Service-policy output: App-QoS

Class-map: pri-app (match-all)

22712 packets, 6840907 bytes

5 minute offered rate 26000 bps, drop rate 0 bps

Match: access-group 101

Queueing

Strict Priority

Output Queue: Conversation 264

Bandwidth 200 (kbps) Burst 5000 (Bytes)

(pkts matched/bytes matched) 0/0

(total drops/bytes drops) 0/0

Class-map: class-default (match-any)

251873 packets, 62084585 bytes

5 minute offered rate 162000 bps, drop rate 0 bps

Match: any

Queueing

Flow Based Fair Queueing

Maximum Number of Hashed Queues 256

(total queued/total drops/no-buffer drops) 3/0/0

r12#