QoS Selectors

[John Blakley]

All,

I have a router with a basic policy-map:

policy-map VOIP

class VOIP

priority 768

class class-default

fair-queue

random-detect dscp-based

cs6 71855/4018548 0/0 0/0 32 40 1/10

When I do a "sh policy-map inter s0/0", I get matches on CS6 under the class-default. If I'm not marking the packet, is the device? Is this where remarking comes in if I want to change what it wants to report?

I think this is a video camera that has an embedded web server. I've been fighting with voip phones at this location, and this video system has traffic pegged at 100% when they're connected to it with high resolution. I haven't been able to convince anyone at the location to use low res yet. If I want to control the amount of traffic going from that device, should I shape that traffic or police it? The phones will stay the same at 768k, and this is on a T1 P2P circuit.

Thanks,

John

[Edison Ortiz]

BTW, if policing confuses you there :) You can do the same with the following:

ip access-list extended Video-Camera

permit [video-camera ip and src port]

class-map Video-Camera

match ip access-group name Video-Camera

policy-map Inbound-MQC

class Video-Camera

set dscp AF31

class class-default

random-detect dscp-based

This is a more straightforward approach :)

With the police command, you have the ability to remark traffic that meets the bandwidth requirement and remark traffic with another marking that exceeds the bandwidth. Pretty useful tool.

[John Blakley]

I started thinking about this. Because I'm seeing traffic matching on the VoIP class, is all of my other default traffic that's coming through the switch being marked as CS6?

Serial0/0

Service-policy output: VOIP

Class-map: VOIP (match-any)

21716081 packets, 1988364582 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: access-group 110

21716080 packets, 1988364562 bytes

5 minute rate 0 bps

Queueing

Strict Priority

Output Queue: Conversation 264

Bandwidth 768 (kbps) Burst 19200 (Bytes)

(pkts matched/bytes matched) 1797007/175537353

(total drops/bytes drops) 0/0

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

22479678 packets, 16547729203 bytes

5 minute offered rate 5000 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) 0/78/0

exponential weight: 9

dscp Transmitted Random drop Tail drop Minimum Maximum Mark

pkts/bytes pkts/bytes pkts/bytes thresh thresh prob

af11 0/0 0/0 0/0 32 40 1/10

af12 0/0 0/0 0/0 28 40 1/10

af13 0/0 0/0 0/0 24 40 1/10

af21 0/0 0/0 0/0 32 40 1/10

af22 0/0 0/0 0/0 28 40 1/10

af23 0/0 0/0 0/0 24 40 1/10

af31 0/0 0/0 0/0 32 40 1/10

af32 0/0 0/0 0/0 28 40 1/10

af33 0/0 0/0 0/0 24 40 1/10

af41 0/0 0/0 0/0 32 40 1/10

af42 0/0 0/0 0/0 28 40 1/10

af43 0/0 0/0 0/0 24 40 1/10

cs1 0/0 0/0 0/0 22 40 1/10

cs2 0/0 0/0 0/0 24 40 1/10

cs3 0/0 0/0 0/0 26 40 1/10

cs4 0/0 0/0 0/0 28 40 1/10

cs5 0/0 0/0 0/0 30 40 1/10

cs6 72372/4055890 0/0 0/0 32 40 1/10

cs7 0/0 0/0 0/0 34 40 1/10

ef 0/0 0/0 0/0 36 40 1/10

rsvp 0/0 0/0 0/0 36 40 1/10

default 22407237/16543569726 78/106186 0/0 20 40 1/10

Also, I looked at the QoS mappings on the switch, and if I'm reading them right, it looks like CS6 is the same thing as DSCP 4 (I'm not sure though.)

Thanks!

John

[Joseph W. Doherty]

"it looks like CS6 is the same thing as DSCP 4 (I'm not sure though.) "

No, they're different.

[Edison Ortiz]

No, you have CS6 and other traffic:

cs6 72372/4055890 0/0 0/0 32 40 1/10

default 22407237/16543569726 78/106186 0/0 20 40 1/10

__

CS6 = to DSCP 4? That mapping is bad. CS6 = Binary 110 000 = DSCP 48

[John Blakley]

This is what the switch is showing me:

Dscp-queue map:

d1 : d2 0 1 2 3 4 5 6 7 8 9

-------------------------------------

0 : 01 01 01 01 01 01 01 01 01 01

1 : 01 01 01 01 01 01 02 02 02 02

2 : 02 02 02 02 02 02 02 02 02 02

3 : 02 02 03 03 03 03 03 03 03 03

4 : 03 03 03 03 03 03 03 03 04 04

5 : 04 04 04 04 04 04 04 04 04 04

6 : 04 04 04 04

Now you can see why I'm wondering what it's doing. This is the evil Dell switch :-)

John

[Edison Ortiz]

That's a dscp to queue map and DSCP48 is placed in Queue 4 highlighted below:

Dscp-queue map:

d1 : d2 0 1 2 3 4 5 6 7 8 9

-------------------------------------

0 : 01 01 01 01 01 01 01 01 01 01

1 : 01 01 01 01 01 01 02 02 02 02

2 : 02 02 02 02 02 02 02 02 02 02

3 : 02 02 03 03 03 03 03 03 03 03

4 : 03 03 03 03 03 03 03 03 04 04

5 : 04 04 04 04 04 04 04 04 04 04

6 : 04 04 04 04

Edit: Misread the map, it looks like a dscp-cos map while it was a dscp-queue map.

Do you have any other maps?

[John Blakley]

So, I take it that the switch may not be causing my problem with marking the traffic incorrectly?

Oh, I see how to read this chart:

DSCP 48 is d1(4) -> d2(8)....

I found a dscp-dscp mutation map that looks like this, but the numbers that this chart showed when compared to the dscp mutation map would show that it's going to send a packet received on an ingress port as dscp 04 which doesn't look right. Maybe I'm looking at it in reverse, and it receives dscp48 and sends out as CoS4?

Thanks,

John

[Edison Ortiz]

Maybe I'm looking at it in reverse, and it receives dscp48 and sends out as CoS4?

We would need to see the mapping for that before coming to that conclusion. It's a Dell switch :)

[Joseph W. Doherty]

"Oh, I see how to read this chart:

DSCP 48 is d1(4) -> d2(8).... "

Correct.

"Maybe I'm looking at it in reverse, and it receives dscp48 and sends out as CoS4? "

Well, 1) map is labeled "Dscp-queue map:", 2) IEEE 802.1Q CoS values are 0..7; these are the reasons I believe "4" to be queue 4, not a CoS 4, but if you can find a manual for the device, it would likely indicate which.

[John Blakley]

The only other map that I found was the cos-queue map:

Cos-queue map:

cos-qid

0 - 1

1 - 1

2 - 2

3 - 2

4 - 3

5 - 3

6 - 4

7 - 4

It looks like it *should* be going in queue 3, but I'm not sure how to tell what queue 3 is. All of the ports are to trust the dscp markings.

This is the only other map that I had. There's not much you can do with these switches.

John

[Edison Ortiz]

Ok, fair enough. We are digressing here :)

The router is receiving CS6 and the switch isn't remarking the packet.

If you know the src-ip and src-port, create an ACL at the router - match that ACL on a class-map and remark it to AF31.

If you know how to remark packets in the Dell switch or have the ability to change the QoS config on the appliance itself - then that can be another option.

Right now, I can only help you how to do it at the router :)

__

Edison.

[John Blakley]

I completely agree; I think we're beating a dead horse =)

I'm sure I'll have other questions about something else later, but for now we'll let this thread die. ;-)

Thanks!

John

[Joseph W. Doherty]

It looks like Dell maps DSCP values into one of 4 queues. CS6 is(?) mapping into Q4, and if that's a priority queue (or gets most of the bandwidth), that could explain some of your problem but only if the switch port is congested or Dell is doing some kind of shaping.

[John Blakley]

Oh, and I'm not crazy about these Dell switches just to let you know :)