Configuring Bridging

Unkown Unicast Flood Blocking (UUFB) is a standard feature on switches that allows the administrator to block all unknown unicast from being flooded. This is primarily a security feature and also protects the system from excessive flooding.

In a normal switch when a MAC has not yet been learned in the system, the switch will flood it to all ports except the receiving port much like a broadcast. This is expensive on switching resources and, in addition, allows an attacker to learn a lot about the adjacent ports. Additionally, many MAC spoofing exploits fill the Mac table with bogus macs to force legitimate traffic to flood so that it can be snooped and possibly set up a MiTM attack. Stopping the flooding of unknown unicast addresses these issues.

To set Aging Time and UUFB use the following procedure.

1. Logon to EMS and in the Network common tree, right-click on the target OLT and select Properties from the dropdown list.
   
   
2. Select the Bridging tab, input Aging Time (default 300), and check the Block Unknown Unicast Packets box.
   
   
    
3. Click on Apply to save the changes.