Output drops on 3850x

[aabdulr2]

Hello experts! This is my first post, so go easy on me 😁!

I have a 3850x switch with 10gb connection for all my outbound traffic and 1 gb connections going to all my sites. My 3850x is doing all the routing to the outside though the 10gb connection. I am seeing a lot of output drops on my 1 gb connection going to my 3 sites. I have confirmed that it's not layer 1 issue and I simply overflowing the 1gb links buffer with traffic. I was reading this article

 https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/200594-Catalyst-3850-Troubleshooting-Output-dr.html#anc2

And it was suggested I use this "qos queue-softmax-multiplier 1200" global config command to increase my soft buffer for interfaces. Also in the article it talked about setting policy maps, I am vaguely aware what policy maps are. My question to you all is, why do I need to set up a policy map (or do I?) if I can run that command in global config mode, will that command work on it's one ? And how effective is it from your experience? Thanks all advance! 

[balaji.bandi]

So you have 10GB connection from provider ? or you connected link to 10GB port.

show us the information about the ports statistics of the port.

show inter te1/1/1  - replace with your port

show interface te 1/1/1 capabilities

show run interface te 1/1/1

[aabdulr2]

These are the output you requested. This interface is facing outside my network going to ISP, all my drops are happening on the inside of the network on the gig interfaces. In my case, I have traffic processed at 10gb and going out at 1gb. The network is set up where I have 1Gb connection to my sites going through my provider. My 3850x handles all the traffic and routes between the sites and the internet, and the connection to all my sites are 1gb and my connection to the internet is 10gb. I hope that clears on where each connection is going.

3850X#show inter te1/1/4

TenGigabitEthernet1/1/4 is up, line protocol is up (connected)
Hardware is Ten Gigabit Ethernet, address is 
Description: 
Internet address is 192.168.18.29/30
MTU 1500 bytes, BW 10000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 10Gb/s, link type is auto, media type is SFP-10GBase-LR
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, output hang never
Last clearing of "show interface" counters 2w3d
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 33602000 bits/sec, 4203 packets/sec
5 minute output rate 13036000 bits/sec, 2931 packets/sec
11733483759 packets input, 13766168472354 bytes, 0 no buffer
Received 188554 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles

512 input errors, 331 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 188554 multicast, 0 pause input
0 input packets with dribble condition detected
6141708184 packets output, 1389614209304 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

3850X#show inter te1/1/4 capabilities
TenGigabitEthernet1/1/4
Model: WS-C3850-12S
Type: SFP-10GBase-LR
Speed: 10000
Duplex: full
Trunk encap. type: 802.1Q
Trunk mode: on,off,desirable,nonegotiate
Channel: yes
Broadcast suppression: percentage(0-100)
Flowcontrol: rx-(off,on,desired),tx-(none)
Fast Start: yes
QoS scheduling: rx-(not configurable on per port basis),
tx-(2p6q3t)
CoS rewrite: yes
ToS rewrite: yes
UDLD: yes
Inline power: no
SPAN: source/destination
PortSecure: yes
Dot1x: yes

interface TenGigabitEthernet1/1/4
description
no switchport
ip address 192.168.18.29 255.255.255.252
end

------------------------------------------------------------------------------------------

Here is an example of one of my 1gb interface that's facing a lot of drops to the other sites

3850X#show int Gi1/0/8
GigabitEthernet1/0/8 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is
Description:
Internet address is 192.168.26.105/30
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is force-up, media type is 1000BaseLX SFP
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:04, output hang never
Last clearing of "show interface" counters 2w3d
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 242002583
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 359000 bits/sec, 415 packets/sec
30 second output rate 5522000 bits/sec, 638 packets/sec
1317430977 packets input, 272572943305 bytes, 0 no buffer
Received 298058 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 298058 multicast, 0 pause input
0 input packets with dribble condition detected
2223781305 packets output, 2553933400511 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

3850X#show int Gi1/0/8 capabilities
GigabitEthernet1/0/8
Model: WS-C3850-12S
Type: 1000BaseLX SFP
Speed: 1000
Duplex: full
Trunk encap. type: 802.1Q
Trunk mode: on,off,desirable,nonegotiate
Channel: yes
Broadcast suppression: percentage(0-100)
Flowcontrol: rx-(off,on,desired),tx-(none)
Fast Start: yes
QoS scheduling: rx-(not configurable on per port basis),
tx-(2p6q3t)
CoS rewrite: yes
ToS rewrite: yes
UDLD: yes
Inline power: no
SPAN: source/destination
PortSecure: yes
Dot1x: yes

3850X#show run int Gi1/0/8
Building configuration...

Current configuration : 188 bytes
!
interface GigabitEthernet1/0/8
description
no switchport
ip address 192.168.26.105 255.255.255.252
load-interval 30
speed nonegotiate
end

I understand that the best approach is to increase my connection to the sites from 1 gig to 10gb but at this time we can't do it due to cost so I thought if implementing QoS can sort this out a bit. I'm not very familiar with QoS and how to configure it but i am trying! 

[Alex Pfeil]

This command may improve the performance. I do not believe you will stop dropping packets. Dropping packets is ok with TCP. You only have a problem if you are not doing QOS properly because you could drop voice and video traffic when you do not want to. It would also be a problem if you were dropping more than 2 percent.

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[aabdulr2]

my drops range from 4% to 8%, in one instance where we were pushing major updates we saw drops up to 50%

[Alex Pfeil]

Have you seen this? I think you should read this whole document. It explains the buffers and the command you are asking about.

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

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[aabdulr2]

Thanks Alex, that's the same document I mentioned in my post. didn't quite understand the policy map part of the article