20-4
Cisco Nexus 1000V Troubleshooting Guide, Release 5.2(1)SV3(1.1)
OL-31593-01
Chapter 20 DHCP, DAI, and IPSG
Troubleshooting Dropped ARP Responses
Troubleshooting Dropped ARP Responses
The following are possible causes, and solutions for dropped ARP responses.
Possible Causes
Solution
ARP inspection is not configured on the VSM
On the VSM, verify that ARP inspection is configured as expected.
show ip arp inspection
For detailed information about configuring DAI, see the
Cisco Nexus 1000V
Security Configuration Guide
.
DHCP snooping is not enabled globally on the
VSM or is not enabled on the VLAN.
On the VSM, verify the DHCP snooping configuration.
show ip dhcp snooping
For detailed information about enabling DHCP and configuring DAI, see
the
Cisco Nexus 1000V Security Configuration Guide
.
DHCP snooping is not enabled on the VEM or
is not enabled on the VLAN.
1.
From the VSM, verify the VEM DHCP snooping configuration.
module vem
mod#
execute vemcmd show dhcps vlan
2.
Do one of the following:
–
Correct any errors in the VSM DHCP configuration. For detailed
information, see the
Cisco Nexus 1000V Security Configuration
Guide
.
–
If the configuration appears correct on the VSM but fails on the
VEM, capture and analyze the error logs from both the VSM and
the VEM to identify the reason for the failure.
If snooping is disabled, the binding entry is not
statically configured in the binding table.
1.
On the VSM, display the binding table.
show ip dhcp snooping binding
2.
Correct any errors in the static binding table.
For detailed information about clearing entries from the table, enabling
DHCP, and configuring DAI, see the
Cisco Nexus 1000V Security
Configuration Guide
.
The binding that corresponds to the VM
sending the ARP response is not present in the
binding table.
1.
On the VSM, display the binding table.
show ip dhcp snooping binding
2.
Correct any errors in the static binding table.
For detailed information about clearing entries from the table, enabling
DHCP, and configuring DAI, see the
Cisco Nexus 1000V Security
Configuration Guide
.
3.
If all configurations are correct, make sure to turn on DHCP snooping
before DAI or IPSG to make sure the Cisco Nexus 1000V has enough
time to add the binding in the snooping database.
For more information, see the
Cisco Nexus 1000V Security
Configuration Guide
.