Netgear XCM8810 - 8800 SERIES 10-SLOT CHASSIS SWITCH ユーザーズマニュアル
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Chapter 10. FDB
NETGEAR 8800 User Manual
Managing MAC Address Learning
By default, MAC address learning is enabled on all ports. MAC addresses are added to the
FDB as described in
FDB as described in
When MAC address learning is disabled on a port, the switch no longer stores the source
address information in the FDB. However, the switch can still examine the source MAC
address for incoming packets and either forward or drop the packets based on this address.
The source address examination serves as a preprocessor for packets. Forwarded packets
are forwarded to other processes, not to other ports. For example, if the switch forwards a
packet based on the source address, the packet can still be dropped based on the
destination address or the egress flooding configuration.
address information in the FDB. However, the switch can still examine the source MAC
address for incoming packets and either forward or drop the packets based on this address.
The source address examination serves as a preprocessor for packets. Forwarded packets
are forwarded to other processes, not to other ports. For example, if the switch forwards a
packet based on the source address, the packet can still be dropped based on the
destination address or the egress flooding configuration.
When MAC address learning is disabled, the two supported behaviors are labeled as follows
in the software:
in the software:
•
forward-packets
•
drop-packets
The forward-packets behavior forwards all received packets for further processing. No action
is taken based on the source address.
is taken based on the source address.
When the drop-packets option is chosen and all unicast, multicast, and broadcast packets
from a source address not in the FDB are dropped. No further processing occurs for dropped
packets.
from a source address not in the FDB are dropped. No further processing occurs for dropped
packets.
The disable learning forward-packets option saves switch resources (FDB space), however, it
can consume network resources when egress flooding is enabled. When egress flooding is
disabled or the drop-packet option is specified, disabling learning adds security by limiting
access to only those devices listed in the FDB.
can consume network resources when egress flooding is enabled. When egress flooding is
disabled or the drop-packet option is specified, disabling learning adds security by limiting
access to only those devices listed in the FDB.
To disable learning on specified ports, use the following command:
disable learning {drop-packets | forward-packets} port [<port_list> | all]
Note:
If neither option is specified, the
drop-packets
behavior is selected.
To enable learning on specified ports, use the following command:
enable learning {drop-packets | forward-packets} ports [all | <port_list>]
MAC address learning is disabled on a service VLAN (SVLAN) or backbone VLAN (BVLAN)
to create a Provider Backbone Bridge (PBB).
to create a Provider Backbone Bridge (PBB).
To enable or disable learning on an entire SVLAN or BVLAN, use the following commands
with the appropriate options:
with the appropriate options:
enable learning vlan <vlan-name>