Forwarding Database (Fdb); Overview Of The Fdb; Fdb Contents; Fdb Entry Types - Extreme Networks BlackDiamond 6800 User Manual

5

Forwarding Database (FDB)

This chapter describes the contents of the forwarding database (FDB), how the FDB
works, and how to configure the FDB.
O
VERVIEW OF THE
The BlackDiamond maintains a database of all media access control (MAC) addresses
received on all of its ports. It uses the information in this database to decide whether a
frame should be forwarded or filtered.
FDB C
The database holds up to a maximum of 128K entries. Each entry consists of the MAC
address of the device, an identifier for the port on which it was received, and an
identifier for the VLAN to which the device belongs. Frames destined for devices that
are not in the FDB are flooded to all members of the VLAN.
FDB E
The following are three types of entries in the FDB:
• Dynamic entries — Initially, all entries in the database are dynamic. Entries in the
database are removed (aged-out) if, after a period of time (aging time), the device
has not transmitted. This prevents the database from becoming full with obsolete
entries by ensuring that when a device is removed from the network, its entry is
deleted from the database. Dynamic entries are deleted from the database if the
B D U G
LACK IAMOND SER UIDE
FDB
ONTENTS
T
NTRY YPES
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