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Tx Discards

Level 1
Level 1

Hey guys I am looking at one of the switches my team supports and my coworker says these discards are normal but wanted to bring it up here to see what you guys thought.  Never hurts to have a second set of eyes.


Ethernet1/7 is up
Dedicated Interface
Hardware: 100/1000/10000 Ethernet, address: 005d.73bb.032e (bia 005d.73bb.032e)
Description: (removed)
MTU 1500 bytes, BW 10000000 Kbit, DLY 10 usec
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA
Port mode is trunk
full-duplex, 10 Gb/s, media type is 10G
Beacon is turned off
Input flow-control is off, output flow-control is off
Rate mode is dedicated
Switchport monitor is off
EtherType is 0x8100
Last link flapped 16week(s) 3day(s)
Last clearing of "show interface" counters never
49 interface resets
Load-Interval #1: 30 seconds
30 seconds input rate 29566440 bits/sec, 4498 packets/sec
30 seconds output rate 6799352 bits/sec, 6533 packets/sec
Load-Interval #2: 5 minute (300 seconds)
input rate 35.85 Mbps, 5.25 Kpps; output rate 26.64 Mbps, 7.67 Kpps
555451266221 unicast packets 27763003 multicast packets 10723948 broadcast packets
555489745529 input packets 674583438787620 bytes
413999684193 jumbo packets 0 storm suppression bytes
0 runts 0 giants 2 CRC 0 no buffer
2 input error 0 short frame 0 overrun 0 underrun 0 ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
121432 Rx pause
301558823413 unicast packets 88885049 multicast packets 220875983 broadcast packets
301868584477 output packets 263323627212334 bytes
0 jumbo packets
32 output errors 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble 3937101 output discard
0 Tx pause


Kernel uptime is 1482 day(s), 21 hour(s), 11 minute(s), 36 second(s)

5 Replies 5

Hall of Fame
Hall of Fame

is this nexus switch, what model and what nexus code running on it.

clear the counter and check how quick they increasing ?

clear counter Ethernet1/7 (this clears all counter to Zero)

check some troubleshooting tips : (since we don't have nexus model i was just referring in general).



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Yes this is a 3500

BIOS: version 4.2.0
loader: version N/A
kickstart: version 6.0(2)A7(2)
system: version 6.0(2)A7(2)
Power Sequencer Firmware:
Module 1: version v2.1
BIOS compile time: 09/23/2017
kickstart image file is: bootflash:///n3500-uk9-kickstart.6.0.2.A7.2.bin
kickstart compile time: 2/18/2016 8:00:00 [02/18/2016 17:46:27]
system image file is: bootflash:///n3500-uk9.6.0.2.A7.2.bin
system compile time: 2/18/2016 8:00:00 [02/18/2016 18:10:06]


cisco Nexus 3548 Chassis ("48x10GE Supervisor")
Intel(R) Pentium(R) CPU @ 2.00GHz
with 3794056 kB of memory.
Processor Board ID FOC220314NA


Device name: DAL-10G-Core1
bootflash: 3915776 kB


Kernel uptime is 1484 day(s), 8 hour(s), 49 minute(s), 9 second(s)


Last reset
Reason: Unknown
System version: 6.0(2)A7(2)

Joseph W. Doherty
Hall of Fame
Hall of Fame

Can TX drops be normal?  Yes they can.  However, possibly they can be more than necessary.  Also, depending on needs of the application, an excessive drop rate might not be an issue or any drops could be problematic.

Insufficient information to say whether your drops are problematic.

Will add, just looking at the overall drop ratio tells little beyond drops are happening.

Level 1
Level 1

show queuing interface ethernet 1/7
Ethernet1/7 queuing information:
qos-group sched-type oper-bandwidth
0 WRR 100
Multicast statistics:
Mcast pkts dropped : 0
Unicast statistics:
qos-group 0
HW MTU: 1500 (1500 configured)
drop-type: drop, xon: 0, xoff: 0
Ucast pkts dropped : 3937101

The NSK is type of SW check the frame with it outbound it not inbound' 

So this type of SW will drop frame if it 

1- frame is not correct if crs is not correct this due to cable issue 

2- the frame mtu is mismatch 

Check this two points


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