cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
1988
Views
0
Helpful
2
Replies

3850 QoS Buffer allocations

finn.poulsen
Level 3
Level 3

Hi,

Anyone discovered what the "show platform qos queue config <interface>" actually reveals - two examples :

Without a service policy :

switch#sh platform qos queue config gigabitEthernet 1/1/1
DATA Port:0 GPN:49 AFD:Disabled QoSMap:0 HW Queues: 0 - 7
  DrainFast:Disabled PortSoftStart:1 - 600
----------------------------------------------------------
  DTS Hardmax   Softmax  PortSMin GlblSMin  PortStEnd
  --- --------  -------- -------- --------- ---------
0   1  5   120  6   480  0     0   0     0   0   800
1   1  4     0  7   720  2   480   2   180   2   800
2   1  4     0  5     0  0     0   0     0   0   800
3   1  4     0  5     0  0     0   0     0   0   800
4   1  4     0  5     0  0     0   0     0   0   800
5   1  4     0  5     0  0     0   0     0   0   800
6   1  4     0  5     0  0     0   0     0   0   800
7   1  4     0  5     0  0     0   0     0   0   800

<snip>

With a 4 class policy-map (1P3Q3T) :

switch#sh platform qos queue config gigabitEthernet 1/0/1
DATA Port:21 GPN:1 AFD:Disabled QoSMap:1 HW Queues: 168 - 175
  DrainFast:Disabled PortSoftStart:1 - 600
----------------------------------------------------------
  DTS Hardmax   Softmax  PortSMin GlblSMin  PortStEnd
  --- --------  -------- -------- --------- ---------
0   1  6    84  8   336  0     0   0     0   0   800
1   1  4     0  2    60  3    40   3    15   3   800
2   1  4     0  9   120  4   320   4   120   4   800
3   1  4     0 10   324  5   216   5    81   5   800
4   1  4     0  5     0  0     0   0     0   0   800
5   1  4     0  5     0  0     0   0     0   0   800
6   1  4     0  5     0  0     0   0     0   0   800
7   1  4     0  5     0  0     0   0     0   0   800

<snip>

Q1 is priority queue (10%)

Q2 has Queue-Buffers ratio 5% (bandwidth remaining 6%)

Q3 has Queue-Buffers ratio 40% (bandwidth remaining 45%)

Q4 is class-default (no bandwidth or buffers configuration)

I realize that "Hardmax" is reserved buffers and "Softmax" can be borrowed from the common pool - but what does the 3 remaining columns reveal?

And why does the total common pool allowance go down from 1200 (480+720) to 840 (336+60+120+324), when attaching the service policy to the interface ?

Unfortunately the output of the "show platform commands" are very poorly documented.

 

And yes, I'm experiencing drops in default class.

Best Regards

Finn

 

 

 

2 Replies 2

cairo ioc
Level 1
Level 1

Hi Finn,

Did you manage to get an answer for your above question ?

I have spent days searching for some answers but did not find any

Regards,

Amr

Hi,

Best description I've found is here :

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/200594-Catalyst-3850-Troubleshooting-Output-dr.html

I've also found out that the allocation changes from release to release (can't remember exact details) - so the total number of buffer changes.

Best regards

Finn

Review Cisco Networking for a $25 gift card