Configuring Arp Defense Against Ip Packet Attacks; Configuring Arp Source Suppression; Enabling Arp Black Hole Routing - HP 6125G Configuration Manual

Task

Configuring ARP defense against IP packet attacks

If the device receives a large number of IP packets from a host addressed to unreachable destinations:
• The device sends a large number of ARP requests to the destination subnets, and thus the load of the
destination subnets increases.
The device keeps trying to resolve destination IP addresses, which increases the load on the CPU.
•
To protect the device from IP packet attacks, you can enable the ARP source suppression function or ARP
black hole routing function.
If the packets have the same source address, you can enable the ARP source suppression function. With
the function enabled, you can set a threshold for the number of ARP requests that a sending host can
trigger in five seconds with packets with unresolvable destination IP addresses. When the number of ARP
requests exceeds that threshold, the device suppresses the host from triggering any ARP requests in the
following five seconds.
If the packets have various source addresses, you can enable the ARP black hole routing function. After
receiving an IP packet whose destination IP address cannot be resolved by ARP, the device with this
function enabled immediately creates a black hole route and simply drops all packets matching the route
during the aging time of the black hole route.

Configuring ARP source suppression

Step
1. Enter system view.
2. Enable ARP source suppression.
3. Set the maximum number of packets with the
same source IP address but unresolvable
destination IP addresses that the device can
receive in five consecutive seconds.

Enabling ARP black hole routing

Configuring ARP automatic scanning and fixed
ARP
Configuring ARP gateway protection
Configuring ARP filtering
235
Command
system-view
arp source-suppression enable
arp source-suppression limit
limit-value
Remarks
Optional.
Configure this function on
gateways (recommended).
Optional.
Configure this function on access
devices (recommended).
Optional.
Configure this function on access
devices (recommended).
Remarks
N/A
Disabled by default.
Optional.
10 by default.