- Preface
- Product Overview
- Configuring the Router for the First Time
- Configuring a Route Switch Processor 720
- Configuring a Supervisor Engine 720
- Configuring a Supervisor Engine 32
- Configuring NSF with SSO Supervisor Engine Redundancy
- Configuring RPR and RPR+ Supervisor Engine Redundancy
- ISSU and eFSU on Cisco 7600 Series Routers
- Configuring Interfaces
- Configuring LAN Ports for Layer 2 Switching
- Configuring Flex Links
- Configuring EtherChannels
- Configuring VTP
- Configuring VLANs
- Configuring Private VLANs
- Configuring Cisco IP Phone Support
- Configuring IEEE 802.1Q Tunneling
- Configuring Layer 2 Protocol Tunneling
- Configuring STP and MST
- Configuring Optional STP Features
- Configuring Layer 3 Interfaces
- IP Subscriber Awareness over Ethernet
- Configuring UDE and UDLR
- Configuring Multiprotocol Label Switching on the PFC
- Configuring IPv4 Multicast VPN Support
- Configuring IP Unicast Layer 3 Switching
- Configuring IPv6 Multicast PFC3 and DFC3 Layer 3 Switching
- Configuring IPv4 Multicast Layer 3 Switching
- Configuring MLDv2 Snooping for IPv6 Multicast Traffic
- Configuring IGMP Snooping for IPv4 Multicast Traffic
- Configuring PIM Snooping
- Configuring Network Security
- Understanding Cisco IOS ACL Support
- Configuring VLAN ACLs
- Private Hosts (Using PACLs)
- Configuring Denial of Service Protection
- Configuring DHCP Snooping
- Configuring Dynamic ARP Inspection
- Configuring Traffic Storm Control
- Unknown Unicast Flood Blocking
- Configuring PFC QoS
- Configuring MPLS QoS on the PFC
- Configuring PFC QoS Statistics Data Export
- Configuring IEEE 802.1X Port-Based Authentication
- Configuring Port Security
- Configuring UDLD
- Configuring NetFlow and NDE
- Configuring Local SPAN, RSPAN, and ERSPAN
- Configuring SNMP IfIndex Persistence
- Power Management and Environmental Monitoring
- Configuring Online Diagnostics
- Configuring Web Cache Services Using WCCP
- Using the Top N Utility
- Using the Layer 2 Traceroute Utility
- Using the Mini Protocol Analyzer
- Online Diagnostic Tests
- Configuring Call Home
- Acronyms
- Cisco IOS Release 12.2SRB Software Images
Cisco 7600 Series Cisco IOS Software Configuration Guide, 12.2SR
Chapter: Unknown Unicast Flood Blocking
Unknown Unicast Flood Blocking
This chapter describes how to configure the unknown unicast flood blocking (UUFB) feature on the Cisco 7600 series routers.
Note 
For complete syntax and usage information for the commands used in this chapter, refer to the Cisco 7600 Series Routers Command References at this URL:
http://www.cisco.com/en/US/products/hw/routers/ps368/prod_command_reference_list.html
Understanding UUFB
Unknown unicast traffic is flooded to all Layer 2 ports in a VLAN. You can prevent this behavior by using the UUFB feature. The UUFB feature blocks unknown unicast traffic flooding and only permits egress traffic with MAC addresses that are known to exit on the port. The UUFB feature is supported on all ports that are configured with the switchport command, including private VLAN (PVLAN) ports.
Configuring UUFB
To configure UUFB, perform this task:
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Step 1 |
Router# configure terminal |
Enters global configuration mode. |
Step 2 |
Router(config)# interface {{type1 slot/port} | {port-channel number}} |
Selects the interface to configure. |
Step 3 |
Router(config-if)# switchport block unicast |
Enables UUFB on the port. |
Step 4 |
Router(config-if)# do show interfaces [type1 slot/port] switchport | include unicast |
Verifies the configuration. |
1 type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet |
This example shows how to configure UUFB on Fast Ethernet port 5/12 and how to verify the configuration:
Router# configure terminal
Router(config)# interface fastethernet 5/12
Router(config-if)# switchport block unicast
Router(config-if)# do show interface fastethernet 5/12 switchport | include unicast
Unknown unicast blocked: enabled
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