Arp suppression on unnumbered interfaces, Enabling and disabling arp suppression – Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) User Manual
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Multi-Service IronWare Switching Configuration Guide
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Configuring IP parameters
19
port enabled
port state: UP
ip address: 1.1.1.1/24
Unnumbered interface, Using IP address of ve 9
unnumbered arp-suppression is enabled
Port belongs to VRF: default-vrf
(output truncated)
The second highlighted line indicates whether ARP suppression is enabled or disabled. Refer to
“ARP suppression on unnumbered interfaces”
for information about ARP suppression.
ARP suppression on unnumbered interfaces
When you configure unnumbered interfaces, those interfaces are configured with ARP suppression
by default. This means that ARP requests are not sent out on unnumbered interfaces. If many
VLANs belong to the same subnet, this avoids an ARP storm.
Donor interfaces continue to send out ARP requests because, by default, ARP suppression is
disabled on donor interfaces.
ARP suppression is achieved by enabling ARP suppression and performing one of the following:
•
Configure DHCP option 82 (recommended).
This configuration must be enabled on each VLAN belonging to the donor or unnumbered
interface. When DHCP option 82 is enabled, the ARP request is sent only to the corresponding
VLAN (identified in the Dynamic ARP Inspection (DAI) table) instead of all the unnumbered
VLANs. For details of DHCP option 82 and the DAI table, refer to
•
Configure static DAI entries.
You must configure static DAI entries for scenarios where the host is not discovered through
DHCP, such as when a host is provided with a static IP address. Refer to
page 755 for instructions.
NOTE
If you enable ARP suppression on a donor interface, you must configure static Dynamic ARP
Inspection (DAI) entries for protocol neighbor IP addresses to ensure that protocol operations on the
donor interface succeed.
on page 749 for information about ARP requests.
Enabling and disabling ARP suppression
To enable or disable ARP suppression on an unnumbered or donor interface, enter commands
such as the following:
Brocade (config)# interface ve 9
Brocade (config-vif-9)# ip unnumbered-arp-suppression
Brocade (config)# interface ve 10
Brocade (config-vif-10)# no ip unnumbered-arp-suppression
The commands enable ARP suppression on ve 9 and disable ARP suppression on ve 10. To fully
achieve ARP suppression, configure one of the following: