[c-nsp] 2960s output drops

[Vinny_Abello at Dell.com]

I don't know about this specifically, but if it's true I know I had to manually tune the buffers on some 3560's just to make them bearable. I'm in the process of migrating away from them onto a 6500 with WS-X6748-GE-TX's instead. For what it's worth, this was how I tuned the 3560's to drastically reduce (but nowhere near eliminate) the output drops due to the tiny buffers:

mls qos srr-queue output cos-map queue 2 threshold 3 0 1 2 3 4 5 6 7
mls qos srr-queue output dscp-map queue 2 threshold 3 0 1 2 3 4 5 6 7
mls qos srr-queue output dscp-map queue 2 threshold 3 8 9 10 11 12 13 14 15
mls qos srr-queue output dscp-map queue 2 threshold 3 16 17 18 19 20 21 22 23
mls qos srr-queue output dscp-map queue 2 threshold 3 24 25 26 27 28 29 30 31
mls qos srr-queue output dscp-map queue 2 threshold 3 32 33 34 35 36 37 38 39
mls qos srr-queue output dscp-map queue 2 threshold 3 40 41 42 43 44 45 46 47
mls qos srr-queue output dscp-map queue 2 threshold 3 48 49 50 51 52 53 54 55
mls qos srr-queue output dscp-map queue 2 threshold 3 56 57 58 59 60 61 62 63
mls qos queue-set output 1 threshold 2 400 400 100 400
mls qos queue-set output 1 buffers 0 100 0 0
mls qos

Props go to some blog I found this on. Hope it helps someone who might be struggling with output drops on this type of platform.

-Vinny

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Nikolay Shopik
Sent: Thursday, April 05, 2012 3:48 AM
To: Tom Sands
Cc: Piotr Wojciechowski; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] 2960s output drops

I hear that 2960S and 3560X have almost similar buffers, do you know
something about this?

On 04/04/12 23:11, Tom Sands wrote:
> Beware that the 2960S incurred a drastic reduction in packet buffers compared to prior the initial 2960 product line (cut the port buffers in half).
> 
> ________________________________________
> From: cisco-nsp-bounces at puck.nether.net [cisco-nsp-bounces at puck.nether.net] on behalf of Nikolay Shopik [shopik at inblock.ru]
> Sent: Wednesday, April 04, 2012 1:54 PM
> To: Piotr Wojciechowski
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] 2960s output drops
> 
> Hardware is Gigabit Ethernet, address is 2c3f.386c.850c (bia 2c3f.386c.850c)
>   Description: trestcom
>   MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
>      reliability 255/255, txload 1/255, rxload 1/255
>   Encapsulation ARPA, loopback not set
>   Keepalive set (10 sec)
>   Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
>   input flow-control is off, output flow-control is unsupported
>   ARP type: ARPA, ARP Timeout 04:00:00
>   Last input 00:00:01, output never, output hang never
>   Last clearing of "show interface" counters 02:41:55
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 2197
>   Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   5 minute input rate 222000 bits/sec, 139 packets/sec
>   5 minute output rate 779000 bits/sec, 159 packets/sec
>      1001165 packets input, 123531512 bytes, 0 no buffer
>      Received 30810 broadcasts (16248 multicasts)
>      0 runts, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      0 watchdog, 16248 multicast, 0 pause input
>      0 input packets with dribble condition detected
>      1428427 packets output, 830613125 bytes, 0 underruns
>      0 output errors, 0 collisions, 0 interface resets
>      0 unknown protocol drops
>      0 babbles, 0 late collision, 0 deferred
>      0 lost carrier, 0 no carrier, 0 pause output
>      0 output buffer failures, 0 output buffers swapped out
> 
> 
> On 04.04.2012 21:58, Piotr Wojciechowski wrote:
>> On 4/4/12 18:35 , Nikolay Shopik wrote:
>>> Hi,
>>>
>>> So we just replaced some aging c3524XL with 2960S and suddenly start
>>> seeing output drops on one of port facing client, while 3524 never had
>>> output drops to this client.
>>>
>>> Traffic levels pretty much low like 1-2mbit with 200-300pps levels. I
>>> believe this is because uplink now 1Gbit, but previously it was just
>>> 100mbit and client port also 100mbit.
>>>
>>> But just wanna confirm with you guys should I ignore these drops or do
>>> something about.
>>
>> What kind of drops are those? Can you provide us show interface output?
>>
>> Regards,
>>
>>
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