Hello.
SYMPTOM: Remote-end application latency and disconnects.
ENVIRONMENT: On a primary of two Nexus9K's set up in HSRP, there exists a port channel built from 2 ports. One of the ports shows zero output discards, while the other shows constantly increasing (333 shortly after counter reset. See below data).
Port channel load balancing config is also below.
RELEVANT: The server team insists on implementing load balancing inside the server VSphere config. So there exists load-balancing configs on both the VSphere and also the adjacent Nexus'.
After research I discovered that turning off Nexus load-balancing can only occur globally, not per interface, so turning off Nexus load-balancing is not feasible.
QUESTIONS:
1. Do you agree that a conflict between these two load balancing technologies is probably causing this latency or output discard issue?
2. May you please exactly explain technically what is causing these output discards?
3. If this is the cause, how is this fixed (how are output discards eliminated)?
Thank you!
...
9K1# show port-channel load-balance
System config:
Non-IP: src-dst mac
IP: src-dst ip-l4port rotate 0
Port Channel Load-Balancing Configuration for all modules:
Module 1:
Non-IP: src-dst mac
IP: src-dst ip-l4port rotate 0
9K1# show int ethernet 1/9
Ethernet1/9 is up
admin state is up, Dedicated Interface
Belongs to Po27
Hardware: 1000/10000 Ethernet, address: abcd.efgh.8742
MTU 1500 bytes, BW 10000000 Kbit , DLY 10 usec
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, medium is broadcast
Port mode is trunk
full-duplex, 10 Gb/s, media type is 10G
Beacon is turned off
Auto-Negotiation is turned on FEC mode is Auto
Input flow-control is off, output flow-control is off
Auto-mdix is turned off
Rate mode is dedicated
Switchport monitor is off
EtherType is 0x8100
EEE (efficient-ethernet) : n/a
admin fec state is auto, oper fec state is off
Last link flapped 8week(s) 4day(s)
Last clearing of "show interface" counters 00:10:56
0 interface resets
Load-Interval #1: 30 seconds
30 seconds input rate 24477680 bits/sec, 2529 packets/sec
30 seconds output rate 51013232 bits/sec, 9918 packets/sec
input rate 24.48 Mbps, 2.53 Kpps; output rate 51.01 Mbps, 9.92 Kpps
Load-Interval #2: 5 minute (300 seconds)
300 seconds input rate 28148112 bits/sec, 2717 packets/sec
300 seconds output rate 46218384 bits/sec, 9874 packets/sec
input rate 28.15 Mbps, 2.72 Kpps; output rate 46.22 Mbps, 9.87 Kpps
RX
1763021 unicast packets 79 multicast packets 40 broadcast packets
1763140 input packets 2197441205 bytes
1206549 jumbo packets 0 storm suppression packets
0 runts 0 giants 0 CRC 0 no buffer
0 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
0 Rx pause
TX
7184689 unicast packets 756 multicast packets 262 broadcast packets
7185707 output packets 4811609926 bytes
2693144 jumbo packets
0 output error 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble 333 output discard
0 Tx pause
