cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2311
Views
5
Helpful
2
Replies

3850 QoS Design?

Toivo
Beginner
Beginner

I'm trying to muddle my way through the Cisco 3850 (WS-C3850-48P) MQC configuration (wired only, nothing wireless-related) and I ran into some questions.

Some technical documentation says that the switch has 8 queues on wired interfaces. However, I've had little luck finding out the exact configuration of these queues, or whether they are configured according to policies. (1P7Q?T?) Is that entire nomenclature and design obsoleted by hierarchical QoS?

Also,

show interfaces gigabitEthernet 1/0/48 capabilities

says:

tx-(4q3t) (3t: Two configurable values and one fixed.)

which directly contradicts the claim of 8 queues? Is this a display bug, or have I fundamentally misunderstood the queue architecture?

When I define 8 class-maps, as inspired by the QoS SRNDs (both 2005 and 4.0), and use a policy-map to assign these classes to queues (1 priority, 7 others) I get:

Jun 18 10:46:25.276:  Policy <policy-name> rejected:Has more than 7 user defined classes

Any quidance what non-user defined classes there are, and what the queueing settings for these are? Alternatively, is there an SRND suggestion what to do with a switch that has 7 queues (1P6Q?), or how to configure the 3850 in general to conform to the SRN design?

Finally, are there useful troubleshooting commands aside from "show policy-map interface <interface>" to help in understanding what DSCP/CoS values the switch is seeing and queueing, and how a given interface is configured?

2 Replies 2

Ton V Engelen
Participant
Participant

Hi

i ve been working on qos, 3850 and got a little further

1. tx-(4q3t) (3t: Two configurable values and one fixed.)

This is a cosmetic bug according to cisco

2. are there useful troubleshooting commands?

I found this to be usefull to check the output policy on for instance the uplinks:

# sh platform qos queue stats gIgabitEthernet 2/1/1

DATA Port:0 Enqueue Counters            
-------------------------------            
Queue Buffers Enqueue-TH0 Enqueue-TH1 Enqueue-TH2            
----- ------- ----------- ----------- -----------
    0       0           0           0 13313578536
    1       0           0           0   315401264

    2       0           0           0           0
    3       0           0           0  9881427430
    4       0           0           0           0
    5       0           0           0           0
    6       0           0           0           0
    7       0           0           0           0

DATA Port:0 Drop Counters             
-------------------------------             
Queue Drop-TH0    Drop-TH1    Drop-TH2    SBufDrop    QebDrop             
----- ----------- ----------- ----------- ----------- -----------
    0           0           0           0           0           0
    1           0           0           0           0           0
    2           0           0           0           0           0
    3           0           0      485411           0           0
    4           0           0           0           0           0
    5           0           0           0           0           0
    6           0           0           0           0           0
    7           0           0           0           0           0
AQM Broadcast Early WTD COUNTERS(In terms of Bytes)
--------------------------------------------------
  PORT TYPE          ENQUEUE             DROP
--------------------------------------------------
UPLINK PORT-0        N/A               0
UPLINK PORT-1        N/A               0
UPLINK PORT-2        N/A               0
UPLINK PORT-3        N/A               0
NETWORK PORTS           0                  0
RCP PORTS               0                  0
CPU PORT                0                  0
Note: Queuing stats are in bytes

Also check out the other subcommands

sh platform qos

Are you guys able to tell me what drop-th2 is?  I have a person complaining about choppy phone calls, and I'm seeing a massive increase in that drop-th2 counter?  

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: