QoS - 400Mbps limit how to handle

[simoesmarco8626982]

Hi all,

Hope to find everyone well in these troublesome times.

It's the following, I have a situation at work where I have a link limited to 400Mbps (two switches end to end using policing and with the action to drop) and I have my 1Gbps uplink connected to this link. 

Unfortunately, I can't change the configuration on those two switches but I know they are dropping packets since it's giving exceed when doing the show policy-map command in the interface.

The only thing I can do is try to mitigate this by changing the way my Cisco 3650 operate the port. 

I created a policy-map where I stated using shaper command to average at a max of 350Mbps in order to prevent the packets from hitting the max of the switches doing policing, but unfortunately it didn't worked.

Can anyone help me please in a way where I can put my QoS to limit and take the blunt of the traffic before it reaches the 400Mbps link where it's being dropped? 

[simoesmarco8626982]

Thank you very much Joseph

I grabbed your post and presented it to my managers, they were having a hard time understanding what I was saying and your post explained everything in detail.

Thank you for that. I think finally my costumer is going to get more bandwidth... let's see how it goes

[simoesmarco8626982]

Hi all,

I need to reopen this topic once again due to having some doubts in one of the priority queues.

I configured another site with a similar config but this time my pipe is 500Mbps instead of 400, my config is more precisely this one:

policy-map VIDEO_IN_REMOTE
class VIDEO_IN
set dscp cs4
policy-map system-cpp-policy
policy-map VIDEO_IN_SERVER_COMS
class VIDEO_IN
set dscp cs4
class SERVER_COMS
set dscp ef
policy-map VIDEO_OUT
class VIDEO_OUT
priority level 2 420000
class SERVER_COMS_OUT
priority level 1 10000
queue-buffers ratio 10
class class-default
policy-map ALL_TRAFFIC
class class-default
shape average 470000000
service-policy VIDEO_OUT

but I'm constantly having drops on the Priority level 1 queue as per below... (this queue is only serving one machine and setting a DSCP value of EF)

Service-policy output: ALL_TRAFFIC

Class-map: class-default (match-any)
0 packets
Match: any
Queueing

(total drops) 4906252
(bytes output) 86872034088
shape (average) cir 470000000, bc 1880000, be 1880000
target shape rate 470000000

Service-policy : VIDEO_OUT

queue stats for all priority classes:
Queueing
priority level 2

(total drops) 0
(bytes output) 84047645870

queue stats for all priority classes:
Queueing
priority level 1

(total drops) 4455948
(bytes output) 165268500

Class-map: VIDEO_OUT (match-any)
0 packets
Match: dscp cs4 (32)
Priority: 420000 kbps, burst bytes 10500000,

Priority Level: 2

Class-map: SERVER_COMS_OUT (match-any)
0 packets
Match: dscp ef (46)
Priority: 10000 kbps, burst bytes 250000,

Priority Level: 1
queue-buffers ratio 10

Class-map: class-default (match-any)
0 packets
Match: any

(total drops) 450304
(bytes output) 2659119718

I don't care if the data is lost on the default queue but where I didn't want it to be dropped is on the priority queues.

Is my config for the priority 1 queue not good? Is there something else that I can do to improve this? 

Thank you for your help

[Joseph W. Doherty]

priority level 1 10000

Have you tried increasing the burst parameter?

[simoesmarco8626982]

Hi Joseph,

unfortunately is not possible I get this output:

priority burst cannot be configured for this interface
Configuration failed on GigabitEthernet1/0/20

Right now I have the interface configured like this:

policy-map VIDEO_IN_REMOTE
class VIDEO_IN
set dscp cs4
policy-map system-cpp-policy
policy-map VIDEO_IN_SERVER_COMS
class VIDEO_IN
set dscp cs4
class SERVER_COMS
set dscp ef
policy-map VIDEO_OUT
class VIDEO_OUT
priority level 2 420000
queue-buffers ratio 30
queue-limit dscp cs4 percent 100
class SERVER_COMS_OUT
priority level 1 10000
queue-buffers ratio 60
queue-limit 2000 packets
class class-default
policy-map ALL_TRAFFIC
class class-default
shape average 470000000
service-policy VIDEO_OUT