ALM-303046920 ARP Detects an IP Address Conflict

Description

ARP/4/ARP_IPCONFLICT_TRAP:OID [OID] ARP detects IP conflict. (IP address=[IPADDR], Local interface=[OCTET], Local MAC=[OCTET], Local vlan=[INTEGER], Local CE vlan=[INTEGER], Receive interface=[OCTET], Receive MAC=[OCTET], Receive vlan=[INTEGER], Receive CE vlan=[INTEGER], IP conflict type=[OCTET]).

An IP address conflict was detected by ARP.

Attribute

Alarm ID	Alarm Severity	Alarm Type
303046920	Warning	environmentalAlarm

Parameters

Name	Meaning
OID	Indicates the MIB object ID of the alarm.
IP address	Indicates the IP address that conflicts.
Local interface	Indicates the interface recorded in the ARP entry of the IP address.
Local MAC	Indicates the MAC address recorded in the ARP entry of the IP address.
Local vlan	Indicates the VLAN recorded in the ARP entry of the IP address.
Local CE vlan	Indicates the CE VLAN recorded in the ARP entry of the IP address.
Receive interface	Indicates the inbound interface of the second ARP packet with the IP address.
Receive MAC	Indicates the source MAC address of the second ARP packet with the IP address.
Receive vlan	Indicates the VLAN configured on the inbound interface of the second ARP packet with the IP address.
Receive CE vlan	Indicates the CE VLAN configured on the inbound interface of the second ARP packet with the IP address.
IP conflict type	Indicates the IP address conflict type.

Impact on the System

This alarm indicates that an IP address conflict occurred. If the IP address conflict is not eliminated timely, route flapping may occur and services may be interrupted.

Possible Causes

The source IP address in an ARP packet is the same as the IP address of the inbound interface that receives the ARP packet, but the source MAC address in the ARP packet is different from the MAC address of the inbound interface.
The source IP address in an ARP packet is the same as the IP address in an existing ARP entry, but the source MAC address is different from the MAC address in the ARP entry.
The source IP address in an ARP packet is 0.0.0.0 (probe ARP packet), the destination IP address is the same as the IP address of the inbound interface that receives the ARP packet, but the source MAC address in the ARP packet is different from the MAC address of the inbound interface.

Procedure

Identify the devices or users who use the same IP address.
- If the devices or users using the same IP address can be identified, change the IP address of one device or user. Then, go to step 2.
- If the devices or users using the same IP address cannot be identified, collect alarm information and configuration information, and then contact technical support engineers.
Run the display arp ip-conflict track command to check whether there is any IP address conflict information, or check whether there is any alarm generated for IP address conflict.
- If there is any IP address conflict, go to step 1.
- If there is no IP address conflict, no further action is required.