Enabling dynamic arp entry check, Enabling natural mask support for arp requests – H3C Technologies H3C S12500 Series Switches User Manual
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used before their age timers expire are deleted from the ARP table. You can adjust the age timers for
dynamic ARP entries according to the actual network condition.
To set the age timer for dynamic ARP entries:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Set the age timer for dynamic
ARP entries.
arp timer aging aging-time
Optional.
20 minutes by default.
Enabling dynamic ARP entry check
The dynamic ARP entry check function controls whether the switch supports dynamic ARP entries with
multicast MAC addresses.
When dynamic ARP entry check is enabled, the switch cannot learn dynamic ARP entries containing
multicast MAC addresses.
When dynamic ARP entry check is disabled, the switch can learn dynamic ARP entries containing
multicast MAC addresses.
To enable dynamic ARP entry check:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable dynamic ARP entry
check.
arp check enable
Optional.
Enabled by default. A switch does not
learn any ARP entry with a multicast
MAC address.
Enabling natural mask support for ARP requests
This feature enables the switch to learn the sender IP and MAC address in a received ARP request whose
sender IP address is on the same classful network as but a different subnet from the IP address of the
receiving interface. A classful network refers to a class A, B, or C network.
For example, VLAN-interface 10 with IP address 10.10.10.5/24 receives an ARP request from
10.11.11.1/8. Because the subnet address calculated by the AND operation of 10.11.11.1 and the receiving
interface's 24-bit subnet mask is not on the subnet 10.10.10.5/24, VLAN-interface 10 cannot process the
ARP packet.
With this feature enabled, the switch calculates the subnet address by using the default mask of the class
A network where 10.10.10.5/24 resides. Because 10.10.10.5/24 is on the same class A network as
10.11.11.1/8, VLAN-interface 10 can learn the sender IP and MAC addresses in the request.
To enable natural mask support for ARP requests: