3Com WXR100 3CRWXR10095A manual Forwarding, Database, Port associated with the MAC address

96CHAPTER 5: CONFIGURING AND MANAGING PORTS AND VLANS

Managing the Layer A WX switch uses a Layer 2 forwarding database (FDB) to forward traffic

2 Forwarding	within a VLAN. The entries in the forwarding database map MAC
Database	addresses to the physical or virtual ports connected to those MAC
	addresses within a particular VLAN. To forward a packet to another
	device in a VLAN, the WX switch searches the forwarding database for
	the packet’s destination MAC address, then forwards the packet out the
	port associated with the MAC address.

Types of Forwarding Database Entries

How Entries Enter the Forwarding Database

The forwarding database can contain the following types of entries:

„Dynamic — A dynamic entry is a temporary entry that remains in the database only until the entry is no longer used. By default, a dynamic entry ages out if it remains unused for 300 seconds (5 minutes). All dynamic entries are removed if the WX switch is powered down or rebooted.

„Static — A static entry does not age out, regardless of how often the entry is used. However, like dynamic entries, static entries are removed if the WX switch is powered down or rebooted.

„Permanent — A permanent entry does not age out, regardless of how often the entry is used. In addition, a permanent entry remains in the forwarding database even following a reboot or power cycle.

An entry enters the forwarding database in one of the following ways:

„Learned from traffic received by the WX switch — When the WX switch receives a packet, the switch adds the packet’s source MAC address to the forwarding database if the database does not already contain an entry for that MAC address.

„Added by the system administrator — You can add static and permanent unicast entries to the forwarding database. (You cannot add a multicast or broadcast address as a permanent or static forwarding database entry.)

„Added by the WX switch itself — For example, the authentication protocols can add entries for wired and wireless authentication users. The WX switch also adds any static entries added by the system administrator and saved in the configuration file.