12-5
Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
OL-31593-01
Chapter 12 Layer 2 Switching
Layer 2 Switching Problems
• Make sure that the state of the port is up. If not, verify the configuration of the port on the VSM.
Step 4 View the VLANs and port lists on a particular VEM.
switch# module vem module-number execute vemcmd show bd
If you are trying to verify that a port belongs to a particular VLAN, make sure that you see the port name
or LTL in the port list of that VLAN.
Verifying a Connection Between VEMs
You can verify a connection between vEth ports on two separate VEMs.
Step 1 Check if the VLAN associated with the port is created on the VSM.
switch# show vlan
Step 2 Check if the ports are up in the VSM.
switch# show interface brief
Step 3 On the VEM, check if the CBL state of the two ports is set to the value of 1 for forwarding (active).
switch# module vem 3 execute vemcmd show port
Step 4 On the VEM, check if the two vEth ports are listed in the flood list of the VLAN with which they are
trying to communicate.
switch# module vem 3 execute vemcmd show bd
Step 5 Verify that the uplink switch to which the VEMs are connected is carrying the VLAN to which the ports
belong.
Step 6 Find out the port on the upstream switch to which the PNIC (that is supposed to be carrying the VLAN)
on the VEM is connected to.
switch# show cdp neighbors
Example:
switch# show cdp neighbors
Capability Codes: R - Router, T - Trans-Bridge, B - Source-Route-Bridge
S - Switch, H - Host, I - IGMP, r - Repeater,
V - VoIP-Phone, D - Remotely-Managed-Device,
s - Supports-STP-Dispute
Device ID Local Intrfce Hldtme Capability Platform Port ID
swordfish-6k-2 Eth5/2 168 R S I WS-C6506-E Gig1/38
The PNIC (Eth 5/2) is connected to swordfish-6k-2 on port Gig1/38.
Step 7 Log in to the upstream switch and make sure that the port is configured to allow the VLAN that you are
looking for.
switch# show running-config interface gigabitEthernet 1/38
Building configuration...
Current configuration : 161 bytes
!
interface GigabitEthernet1/38
description Srvr-100:vmnic1
switchport
switchport trunk allowed vlan 1,60-69,231-233
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