Troubleshooting Dropped Arp Responses - Cisco Nexus 1000V Troubleshooting Manual

Troubleshooting Dropped ARP Responses

S e n d d o c u m e n t c o m m e n t s t o n e x u s 1 k - d o c f e e d b a c k @ c i s c o . c o m .
Troubleshooting Dropped ARP Responses
The following are possible causes, and solutions for dropped ARP responses.
Possible Causes
ARP inspection is not configured on the VSM
DHCP snooping is not enabled globally on the
VSM, or is not enabled on the VLAN.
DHCP snooping is not enabled on the VEM, or
is not enabled on the VLAN.
If snooping is disabled, the binding entry is not
statically configured in the binding table.
The binding corresponding to the VM sending
the ARP response is not present in the binding
table.
Cisco Nexus 1000V Troubleshooting Guide, Release 4.2(1)SV2(2.1)
19-4
Solution
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, Release 4.2(1)SV2(1.1))
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, Release
4.2(1)SV2(1.1)).
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, Release 4.2(1)SV2(1.1)).
– If the configuration appears correct on the VSM but fails on the
VEM, capture and analyze the error logs from both VSM and the
VEM to identify the reason for the failure.
On the VSM, display the binding table.
1.
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, Release 4.2(1)SV2(1.1)).
On the VSM, display the binding table.
1.
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, Release 4.2(1)SV2(1.1)).
If all configurations are correct, make sure to turn on DHCP snooping
3.
before DAI or IPSG. This is 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, Release 4.2(1)SV2(1.1)).
Chapter 19 DHCP, DAI, and IPSG
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