SECE_1.3.6.1.4.1.2011.5.25.165.2.2.2.10 hwARPMissVlanSpeedLimitALarm

Description

SECE/4/ARPMISS_VLAN_SPEEDLIMIT_ALARM: OID [oid] The vlan arp-miss packet speed exceed the speed-limit value configured [INTEGER], Vlan [INTEGER].

The rate of ARP Miss messages in a VLAN exceeds the upper limit, and the number of discarded ARP Miss messages exceeds the configured alarm threshold.

Attribute

Alarm ID	Alarm Severity	Alarm Type
1.3.6.1.4.1.2011.5.25.165.2.2.2.10	Warning	equipmentAlarm(5)

Parameters

Name	Meaning
oid	Indicates the MIB object ID of the alarm.
INTEGER	Indicates the alarm threshold.
Vlan	Indicates the outer VLAN ID of packets.

Impact on the System

If the alarm is generated, the rate of ARP Miss messages triggered by user traffic exceeds the upper limit. The device discards excess traffic. As a result, user traffic may be interrupted intermittently.

Possible Causes

If a host sends a large number of IP packets with unresolvable destination IP addresses to attack a device (the device has a route to the destination IP address of a packet but has no ARP entry matching the next hop of the route), the device generates a large number of ARP Miss messages. When the rate of ARP Miss messages in the VLAN exceeds the upper limit and the number of discarded ARP Miss messages exceeds the alarm threshold, the device generates the alarm.

Procedure

Run the reset cpu-defend statistics command to clear statistics on the ARP Miss messages sent to the CPU.
Wait for 1 minute, and run the display cpu-defend statistics all command to check the number of ARP Miss messages sent to the CPU within 1 minute. Check whether a large number of packets are discarded:
- If so, go to step 3.
- If not, verify that the network is secure and use either of the following methods to prevent generation of this alarm:
  - Run the undo arp-miss anti-attack rate-limit alarm enable command to disable the alarm function in the VLAN for the ARP Miss messages discarded when the rate of ARP Miss messages exceeds the upper limit.
    
    After the alarm function is disabled, the device will not report an alarm when the number of discarded ARP Miss messages exceeds the alarm threshold.
  - Run the info-center source SECE channel 4 log state off command to disable the device from sending SECE alarm information.
Run the display arp all command to check ARP entries.
If the MAC address field in an ARP entry displays Incomplete, the device fails to learn this ARP entry.
Obtain packet headers on the interface connecting the device to the user, and locate the attack source according to the source addresses of ARP Request packets.
Check whether the attacker is infected with viruses.
- If so, you are advised to remove viruses from the user host. You can also add the address of the user to the blacklist or configure a blackhole MAC address entry to discard ARP request packets sent by the attacker.
- If not, go to step 5.
Run the display arp-miss speed-limit source-ip command to check the configuration of ARP Miss rate limiting based on source IP address.
Run the arp-miss speed-limit source-ip ip-address [ mask mask ] maximum maximum block timer timer command to set the rate limit for ARP Miss messages based on source IP address and set the handling method for ARP Miss messages to block.
If the alarm is frequently generated, collect alarm information and contact technical support personnel.

Related Information

None