Address Management

With the Address Management page, you can:

Changing the Aging Time and Removing Dynamic Addresses

The switch dynamically learns the source address of packets it receives and adds the MAC address of the source, the VLAN to which it belongs, and the associated port number to the dynamic address table.

Each switch maintains an address table of ports that belong to the VLAN and their associated addresses. An address can be learned in more than one VLAN, and a dynamic address learned in one VLAN can be entered as a secure address in another VLAN. An address that is learned in one VLAN is unknown in another VLAN until it is entered or learned.

The switch updates the Dynamic Address Table as stations are added or removed from the network, adding new entries and aging those not in use. The switch also updates the address table by deleting all dynamic addresses associated with a port on which a VLAN membership change occurred.

Using the Dynamic Address Table, you can:

Changing the Aging Time

The switch learns the MAC address of attached devices by reading the source address of arriving packets. The switch adds these addresses to the address table and keeps them for the time specified in the Aging Time field. The aging time defines how long dynamic addresses not read by the switch stay in the table.

To change the aging time for addresses in the Dynamic Address Table:

  1. In the Aging Time field, highlight the value and enter a number from 10 to 1000000 (seconds; about 11.5 days).
    The aging interval applies to all switch VLANs. The default is 300 seconds.
    Note: Setting too short an aging time can cause addresses to be prematurely removed from the table. Then when the switch receives a packet for an unknown destination, it floods the packet to all ports in the same VLAN as the receiving port. This unnecessary flooding can impact performance. Setting too long an aging time can cause the address table to be filled with unused addresses; it can cause delays when a workstation is moved to a new port.
  2. Click Apply.

Removing All Dynamic Addresses

To remove all address, click Remove All.

After all entries are removed, the switch relearns them. However, when the switch encounters a packet for an unknown destination, it floods the packet to all ports. Flooding continues until the switch relearns all the addresses.

Adding and Removing Secure MAC Addresses

A secure address is a manually entered unicast address that is forwarded to only one port per VLAN. Secure addresses do not age, are retained when the switch reboots, and can be manually entered or learned.

Note: When a VLAN membership change occurs, the switch keeps the secure address but stops forwarding to this address in the old VLAN. If the port is moved back to the old VLAN, the port is a destination port for the secure address again.

You can enter a secure port address even when the port does not yet belong to the VLAN. When the port is later assigned to the VLAN, the switch forwards packets destined for that address to the port.

By setting up secure ports and secure addresses, you can prevent the switch from forwarding packets with source addresses outside the group. If a secure port receives a packet with a MAC address that you manually added and associated with another secure port, you can configure the switch to generate an alert and disable the port. If you define only a single secure address, you can guarantee the full bandwidth of the port to the attached workstation or server. To set up secure addresses and secure ports, use the Secure Address Table on this page and the Port Security page.

Using the Secure Address Table, you can:

Adding a Secure Unicast Address

You add a secure unicast address one port at a time. If you enter an address that is already assigned to another port, the switch reassigns the secure address to the new port.

The number of secure addresses associated with a port is limited by the size of the Maximum Addresses field on the Port Security page. You can reconfigure this field if necessary.

To add a secure unicast address:

  1. In the MAC Address field, enter the destination (secure) MAC address in the format .huh..
    Use hexadecimal numbers.
  2. From the Interface drop-down list, select the interface and port number that forwards the packet to the secure address.
  3. In the VLAN ID field, enter the ID that is configured for the port.
  4. Click <<Add<<.
    The MAC address, the VLAN ID, and the interface appear in the Secure Address list.
  5. After you have entered the secure address, select Security > Port Security from the menu bar.

Removing a Secure Unicast Address

Because secure addresses do not age, you must manually remove them.

To remove a secure unicast address:

  1. From the Secure Address list, select the secure address to be deleted.
  2. Click Remove.

Note: You can remove all secure addresses from the Secure Address list by clicking Remove All.

Adding and Removing Static Addresses

You can manually add unicast or multicast static addresses to the Static Address Table. After you add a static address, the Static Address Forwarding Map appears. Use this forwarding map to select the ports to which the switch forwards packets with this static address. Port selection is limited to ports that belong to the same VLAN.

In VLANs with a static address, the switch forwards packets destined to the configured address. If the switch receives this address as a destination address in other VLANs where no static address is configured, the switch floods the packet within the received VLAN. If this address is received as a source address in other VLANs where no static address is configured, the switch does not learn the address.

The switch does not age static addresses from the table when they are not in use and does not lose them when reset. When a VLAN membership change occurs, the switch keeps the static address but the port undergoing change is eliminated from the destination maps in the old VLAN.

Note: In Enterprise Edition Software, you cannot configure a dynamic-access port as the source or destination port in a static address entry.

With the Static Address Table, you can:

Adding a Static Address

You can add static addresses and define port forwarding.

To add a static address:

  1. In the MAC Address field, enter the MAC address in the format hhuh.hhhh.hhhh.
    Use hexadecimal numbers.
  2. In the VLAN ID field, enter an ID that is assigned to more than one port.
  3. Click <<Add<<.
    The Static Address Forwarding Map appears.
  4. For each Rx On (source) port that receives a packet with this static address as the destination address, select the Forward To (destination) port checkboxes so that the switch forwards the packet through these ports to the destination.
    Note: Port selection on the forwarding map is limited to ports that belong to the same VLAN. Ports displayed without checkboxes belong to a different VLAN. If you want to forward to a port for which there is no checkbox, add that port to a VLAN to which the receiving port belongs.
    Note: By default, an EtherChannel (EC) port group forwards a packet based on its source address. For the default source-based port groups, configure the static address to forward to all ports in the port group to avoid losing packets. For destination-based port groups, configure the address to forward to only one port in the group to avoid transmitting duplicate packets.
  5. Click Apply.
    The MAC address, the VLAN ID, and the interface appear in the Static Address list.

To display the forwarding characteristics of a static address, select it from the Static Address list and click Forwarding.

Removing a Static Address

Because static addresses do not age, you must manually remove them.

To remove a static address:

  1. From the Static Address list, select the static address to be deleted.
  2. Click Remove.

Note: You can remove all static addresses from the Static Address list by clicking Remove All.