Configuring Redundant Flex Links - Cisco WS-C6506 Software Manual

Chapter 4 Configuring Ethernet, Fast Ethernet, Gigabit Ethernet, and 10-Gigabit Ethernet Switching
This example shows how to enable RXCRC port error detection on port 3/1:
Console> (enable) set port errordetection 3/1 rxcrc enable
Port(s)
Console> (enable) show port errordetection 3/1
Port
-----
3/1
Console> (enable)

Configuring Redundant Flex Links

The redundant flex links provide an alternative solution to the Spanning Tree Protocol (STP) by allowing
users to disable STP and still provide link-level redundancy. The redundant flex links provide a link backup
capability with rapid switchover redundancy. Flex link redundancy allows you to specify two ports to form
the redundant link capability. You configure one port as the active port and the other port as the backup or
peer port. The active port is in the forwarding state while the backup port is in the blocking state and does not
allow traffic to pass through.
When the active port of the flex links experiences a failure, the MAC addresses are flushed and flooded. The
backup port of the flex links learns the MAC addresses and restores connectivity. The failover convergence
time depends on the number of VLANs and the number of MAC addresses. You cannot enable STP on the
flex-link ports but you can run STP on other ports in the switch.
We recommend that you use redundant flex links for configurations that have multiple Layer 2 access
Tip
switches with common VLANs that are connected to a Layer 2 concentrator switch through two uplink
ports.
These sections describe how to configure redundant flex links on the Catalyst 6500 series switches:
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Redundant Flex Link Configuration Guidelines and Restrictions
This section describes the guidelines and restrictions for configuring redundant flex links:
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OL-8978-04
3/1 set to errordetection rxcrc enable.
Rxcrc Txcrc
-------- --------
enabled disabled
Redundant Flex Link Configuration Guidelines and Restrictions, page 4-17
Specifying the Active and Backup Ports for the Flex Links, page 4-18
Displaying the Port Configuration of the Flex Links, page 4-18
Clearing the Port Configuration of the Flex Links, page 4-18
The maximum number of flex-link pairs (one active port and one backup port) is 16 per switch.
Flex-link ports cannot be part of an EtherChannel.
STP—Flex-link ports do not join STP operations. Flex-link ports do not generate STP bridge
protocol data units (BPDUs) and they drop all received BPDUs.
Switched Port Analyzer (SPAN)—SPAN works with flex-link ports.
VLAN Trunk Protocol (VTP)—As VTP pruning requires working with STP, it does not work on
flex-link ports.
Internet Group Management Protocol (IGMP)—IGMP works with flex-link ports.
Dynamic Trunking Protocol (DTP)—DTP can run on a flex-link port.
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
Setting the Port Configuration
4-17