Extreme Networks Summit 300-48, Руководство пользователя программного обеспечения

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104 Summit 300-48 Switch Software User Guide
Forwarding Database (FDB)
interface are stored as permanent. The Summit 300-48 switches support a maximum of 128
permanent entries.
Once created, permanent entries stay the same as when they were created. For example, the
permanent entry store is not updated when any of the following take place:
— A VLAN identifier (VLANid) is changed.
—
A port mode is changed (tagged/untagged).
— A port is deleted from a VLAN.
— A port is disabled.
— A port enters blocking state.
— A port QoS setting is changed.
— A port goes down (link down).
• Blackhole entrie s — A blackhole entry configures the switch to discard packets with a specified
MAC destination address. Blackhole entries are useful as a security measure or in special
circumstances where a specific destination address must be discarded. Blackhole entries are treated
like permanent entries in the event of a switch reset or power off/on cycle. Blackhole entries are
never aged-out of the database.
How FDB Entries Get Added
Entries are added into the FDB in the following two ways:
• The switch can learn entries. The system updates its FDB with the source MAC address from a
packet, the VLAN, and the port identifier on which the source packet is received.
• You can enter and update entries using a MIB browser, an SNMP Network Manager, or the
command-line interface (CLI).
Associating a QoS Profile with an FDB Entry
You can associate a QoS profile with a MAC address (and VLAN) of a device that will be dynamically
learned. The FDB treats the entry like a dynamic entry (it is learned, it can be aged out of the database,
and so on). The switch applies the QoS profile as soon as the FDB entry is learned.
NOTE
For more information on QoS, refer to Chapter 11.