Wired Intelligent Edge (Campus Switching and Routing)

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Occasional Contributor II

QoS settings

I have been having some issues with one of my AT&T circuits, and after some troubleshooting with them, They sent me the below email. 

 

It has been identified that you are dropping a lot of packets due to their being marked as COS1 (Real Time) and COS2v (Interactive) while your PPCOS (Per Packet Class of Service) profile does not allow for either. Your PPCOS profile allows for 50% of your port speed (CIR) to be allocated to COS3 (p-bit marked as: 2) and 50%-100% as COS4 (p-bit marked as: 0). 

 

If you are marking your 802.1p fields of your packets with either a 5 (Real Time) or a 4 (Interactive), this is likely causing the problem. If you can change those designations to 2’s and 0’s that should care for the performance issue. Note: 802.1p bit fields that contain no COS designation marking are treated as COS4 in our network.

 

I am fairly new to Aruba switching, and I have never configured these types of settings, so I am not sure where to start with this. The switch is a 3810M with the latest code on it. I hope someone can help me out with this. 

 

Thanks in advance guys. You are always awesome. 

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Super Contributor II

Re: QoS settings

Sadly AT&T is using 802.1p instead of DSCP marking. 802.1p marking is carried in the ethernet frame (VLAN tag) and in the IP header. This means that the switch has to set the 802.1p priority correctly.

 

The 802.1p priorities are 0-7. Aruba switches are have 8 queues by default. The default Aruba switch 802.1p to queue is.

 

802.1p Queue Priorities
----- ----------
1 1
2 2
3 0
4 3
5 4
6 5
7 6
8 7

At the switches you can configure the amount of bandwidth per queue using the following command

 

interface x bandwidth-min output <q1> <q2> etc

The values are in percentage.

 

However, there is still one question. How are you classifing and marking the traffic so it's having the correct DSCP and/or 802.1p value? You can write some qos policies for this if that is needed.

 

Simple example

 

class ipv4 "example"
     10 match ip 1.1.1.1 0.0.0.0 2.2.2.2 0.0.0.0
   exit

policy qos "example"
     10 class ipv4 "example" action rate-limit kbps 4000 action ip-precedence 4 action priority 3
   exit

interface 1
   service-policy "example" in
   exit

Note that remarking only is possible inbound and not outbound.


But maybe it's not needed to classify the traffic because marking is already done


Willem Bargeman ACMX#935 | ACCX #822

Please give me kudos if my post was useful!
If your issue is solved mark the post as solution!
Occasional Contributor II

Re: QoS settings

This is the best reply I have gotten from any platfrom so far, so let me start off by saying thank you, this is awesome. What exactly are you doing in the below example. It looks like you are making a "class" of IPV4 traffic that matches

1.1.1.1 0.0.0.0 2.2.2.2 0.0.0.0

that is then used to rate limit and apply precedence and priority. Then it is applied to an interface. What is the IP range you specified above exactly, and how would I apply this policy to ALL IP traffic? also, what does 

action ip-precedence 4 action priority 3

 mean exactly? is that the actualy priority for regurlar and priority traffic? or is that  a queue specification? 

 

Thanks.

Super Contributor II

Re: QoS settings

Sure no problem!

dfishtorn@spartanburgwater.org wrote:

This is the best reply I have gotten from any platfrom so far, so let me start off by saying thank you, this is awesome. What exactly are you doing in the below example. It looks like you are making a "class" of IPV4 traffic that matches

1.1.1.1 0.0.0.0 2.2.2.2 0.0.0.0

that is then used to rate limit and apply precedence and priority. Then it is applied to an interface. What is the IP range you specified above exactly, and how would I apply this policy to ALL IP traffic? also, what does 

action ip-precedence 4 action priority 3

 mean exactly? is that the actualy priority for regurlar and priority traffic? or is that  a queue specification? 


The class in this example will match traffic from 1.1.1.1/32 to 2.2.2.2/32. 

 

The QoS policy will set the 802.1p to 4 and set the QoS priority to 3. This means that the traffic is marked with 802.1p value 4 and the traffic is place in queue 3.


Willem Bargeman ACMX#935 | ACCX #822

Please give me kudos if my post was useful!
If your issue is solved mark the post as solution!
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