Cisco Nexus 1000V - Troubleshooting Asymmetric Port Channels

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Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
OL-31593-01
Chapter 11 Port Channels and Trunking
Troubleshooting Asymmetric Port Channels
• show port-channel internal event-history interface ethernet slot-number
• show system internal ethpm event-history interface port-channel channel-number
• show system internal ethpm event-history interface ethernet slot-number
• show vlan internal trunk interface ethernet slot-number
• show vlan internal trunk interface port-channel channel-number
• debug port-channel error
• module vem module-number execute vemcmd show port
• module vem module-number execute vemcmd show pc
• module vem module-number execute vemcmd show trunk
Example 11-1 shows output of the show port-channel summary command.
Example 11-1 show port-channel summary Command
switch# show port-channel summary
Flags: D - Down P - Up in port-channel (members)
I - Individual H - Hot-standby (LACP only)
s - Suspended r - Module-removed
S - Switched R - Routed
U - Up (port-channel)
--------------------------------------------------------------------------------
Group Port- Type Protocol Member Ports
Channel
--------------------------------------------------------------------------------
1 Po1(SU) Eth NONE Eth3/4(P)
2 Po2(SU) Eth NONE Eth3/2(P) Eth3/6(P)
Troubleshooting Asymmetric Port Channels
When you are troubleshooting asymmetric port channels, follow these guidelines:
• Use APC when you want to configure a port channel whose members are connected to two different
upstream switches.
• APC depends on Cisco Discovery Protocol (CDP). Make sure CDP is enabled on the VSM and
upstream switches.
• Physical ports within an APC get assigned subgroup IDs based on the CDP information received
from upstream switches.
• A user can manually configure subgroup IDs in interface configuration submode.
• Make sure that you configured subgroup CDP either with a port profile or on the port channel
interface.
• Ports in APC come up only when they are assigned subgroup IDs manually or through CDP.
• Enter the show cdp neighbors command on the VSM and check the output.
• Once the ports came up, check that ports are put in the correct subgroups by entering the module
vem module-number execute vemcmd show pc command on the VEM.
• Use the debug port-channel trace command to collect information.