Adding Static Arp Entries With Multicast Mac Addresses - Allied Telesis AT-8600 Release Note

Software Version 2.8.1
Adding Static ARP
Entries
Accepting Packets
with Conflicting
Addresses
Software Version 2.8.1
C613-10477-00 REV B
Command Changes
The following table summarises the new and modified commands:
Command
set ip arpwaittimeout
show ip
Adding Static ARP Entries with Multicast MAC
Addresses
This Software Version allows you to add ARP entries with multicast MAC
addresses and allows the router or switch to accept packets with unicast IP
addresses and multicast MAC addresses. It introduces the enable ip
macdisparity and disable ip macdisparity commands to support this.
Valid ARP entries are normally restricted to unicast IP with unicast MAC
addresses. However, ARP entries can be configured with multicast MAC
addresses when macdisparity is enabled. Static ARP entries with multicast
MAC addresses are necessary for some third party networking solutions, such
as server clustering.
Before you can add an ARP entry with a multicast MAC address, you must
enable macdisparity using the command:
enable ip macdisparity
Once this feature is enabled, you can add an ARP entry with a multicast MAC
address using the add ip arp command.
Enabling macdisparity also allows the router or switch to accept packets with
conflicting IP and MAC addresses. Normally the router or switch discards
these packets as being invalid.
Conflicting IP and MAC addresses include:
■
A multicast IP address with a unicast MAC address
■
A unicast IP address with a multicast MAC address
macdisparity is disabled by default. When disabled, only ARP entries with
unicast IP and MAC addresses can be added, and packets with conflicting
addresses are discarded. Other routers or switches in the network may not
accept packets with conflicting addresses unless configured to. To disable this
functionality, use the command:
disable ip macdisparity
ARP entries with multicast MAC addresses must be removed before the
disable ip macdisparity command will work. To see details on the current ARP
entries, use the command:
show ip arp
To see whether macdisparity is enabled or disabled, use the command:
show ip
Change
New command
New Arp wait timeout field
69