[c-nsp] Cisco 3850-24XS Output Discards, Buffer Sizes of TenGig interfaces

[Giles Coochey]

Hi All,

I am managing a number of 3850-24XS Catalysts, running Denali 16.3.5b.

These have 24 10Gig interfaces and they're seeing a large number of 
output discards on these.

The output of the following command shows the hardmax/softmax queues on 
the interface:

#show platform hardware fed switch active qos queue config interface te1/0/1
DATA Port:7 GPN:873 AFD:Disabled QoSMap:0 HW Queues: 56 - 63
   DrainFast:Disabled PortSoftStart:2 - 1080
----------------------------------------------------------
   DTS Hardmax   Softmax  PortSMin GlblSMin  PortStEnd
   --- --------  -------- -------- --------- ---------
  0   1  5   120  2   480  6   320   0     0   5  1440
  1   1  4     0  6   720  3   480   2   180   5  1440
  2   1  4     0  5     0  5     0   0     0   5  1440
  3   1  4     0  5     0  5     0   0     0   5  1440
  4   1  4     0  5     0  5     0   0     0   5  1440
  5   1  4     0  5     0  5     0   0     0   5  1440
  6   1  4     0  5     0  5     0   0     0   5  1440
  7   1  4     0  5     0  5     0   0     0   5  1440

According to the following link about Troubleshooting Output drops on 
this platform these are the buffer values for a 1Gig interface?

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

Does anyone know whether there is a bug-id for this, and whether it is 
fixed in any Denali 16.3.x ?

In the document it specifies that:

The show command that can be used to see this allocation is ‘show 
platform qos queue config <interface>’.

For a 1Gig interface,

3850#show platform qos queue config gigabitEthernet 1/0/1
DATA Port:20 GPN:66 AFD:Disabled QoSMap:0 HW Queues: 160 - 167
   DrainFast:Disabled PortSoftStart:1 - 1080
----------------------------------------------------------
   DTS Hardmax   Softmax  PortSMin GlblSMin  PortStEnd
   --- --------  -------- -------- --------- ---------
  0   1  5   120  6   480  6   320   0     0   3  1440
  1   1  4     0  7   720  3   480   2   180   3  1440
  2   1  4     0  5     0  5     0   0     0   3  1440
  3   1  4     0  5     0  5     0   0     0   3  1440
  4   1  4     0  5     0  5     0   0     0   3  1440
  5   1  4     0  5     0  5     0   0     0   3  1440
  6   1  4     0  5     0  5     0   0     0   3  1440
  7   1  4     0  5     0  5     0   0     0   3  1440

<<output omitted>>

For a 10Gig interface,

3850#show platform qos queue config tenGigabitEthernet 1/0/37
DATA Port:1 GPN:37 AFD:Disabled QoSMap:0 HW Queues: 8 - 15
   DrainFast:Disabled PortSoftStart:2 - 6480
----------------------------------------------------------
   DTS Hardmax   Softmax  PortSMin GlblSMin  PortStEnd
   --- --------  -------- -------- --------- ---------
  0   1  6   720  8  2880  7  1280   0     0   4  8640
  1   1  4     0  9  4320  8  1920   3  1080   4  8640
  2   1  4     0  5     0  5     0   0     0   4  8640
  3   1  4     0  5     0  5     0   0     0   4  8640
  4   1  4     0  5     0  5     0   0     0   4  8640