Nortel 6220 User Manual page 141

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Permit Multicast Button-- Select this checkbox if you wish to permit
multicast.
Prune Multicast Button-- Select this checkbox if you wish to prune
multicast.
Enable Learned Table Lockdown--A standard Bridge/Router watches the
source addresses of each packet it receives on any of its interfaces.
As new addresses are seen, entries are added in the "learned table" that
contain the particular source address and the interface number that
address was received on. If that source address is later seen on a
different interface, the Bridge will immediately change the interface
number in the learned entry table. This condition could happen in a
correctly functioning network if someone moved the computer to a
different part of the network.
This could also happen if someone was trying to capture network packets
by spoofing the Bridge. Enabling learned table lockdown will prevent
the interface number from being changed once the source address has
been seen.
A standard Bridge will also time-out the learned table records every ten
(10) minutes. If learned table lockdown is enabled, these records will not
be timed-out. Once a record is learned, it will not be changed or deleted
until either the Secure Data Mode station reboots or the learned table
becomes completely filled and needs to be reset.
Note: A typical Secure Data Mode learned table can contain over
12,000 records.
Enable Expanded IP/ARP Support
Enabling this feature will cause the Secure Data Mode station to watch
the IP/ARP packets that occur on the network. Normally, no action is
taken in response to an IP/ARP packet that is not destined for a host that
is being Proxy ARPed by the Secure Data Mode station. When this
function is selected, the Secure Data Mode station will add the IP address
to its IP/ARP table when it sees an ARP packet from another source.
This feature is helpful on an ARP network because it will build a
database of MAC layer address to IP address pairs.
Note: The IP/ARP table is never timed out in this mode.
WLAN Cable Access Point 6220 CSU NTPM99CA Rel 2.0 Issue 5 Dec 2005