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The Fast EtherChannel feature allows multiple Fast Ethernet point-to-point links to be bundled into one logical link to provide bidirectional bandwidth of up to 800 Mbps. Fast EtherChannel builds on standards based on 802.3 full-duplex Fast Ethernet to provide fault-tolerant, high-speed links between devices and servers.
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
The Fast EtherChannel feature can be configured between:
Fast EtherChannel provides higher bidirectional bandwidth, redundancy, and load sharing. Up to four Fast Ethernet interfaces can be bundled in a port-channel, and the device can support up to four port channels. The Fast EtherChannel feature is capable of load balancing traffic across Fast Ethernet links. Unicast, broadcast, and multicast traffic are distributed across the links providing higher performance and redundant parallel paths. In the event of a link failure, traffic is automatically redirected to other functional links within the Fast EtherChannel.
In the Fast EtherChannel feature, IP traffic is distributed over the port-channel interface, while traffic from other routing protocols is sent over a single link. Bridged traffic is distributed on the basis of the Layer 3 information in the packet. If the Layer 3 information does not exist in the packet, the traffic is sent over the first link.
Fast EtherChannel supports all features currently supported on the Fast Ethernet interface. You must configure these features on the port-channel interface rather than on the individual Fast Ethernet interfaces. Fast EtherChannel connections are fully compatible with Cisco VLAN and routing technologies. The Inter-Switch Link (ISL) VLAN trunking protocol can carry multiple VLANs across a Fast EtherChannel. Devices attached to Fast EtherChannel links can provide full multiprotocol routing with support for host standby using the Hot Standby Router Protocol (HSRP).
The port-channel (consisting of up to four Fast Ethernet interfaces) is treated as a single interface. A port-channel is used in Cisco software to maintain compatibility with existing commands on the Catalyst 5000 switch. You can create the Fast EtherChannel by using the interface port-channel interface configuration command. You can assign up to four Fast Ethernet interfaces to a port-channel by using the channel-group interface configuration command.
Additional Fast EtherChannel features include:
For more information about configuring HSRP, see the "Configuring IP Services" chapter in the IP Application Services Configuration Guide.
For more information about configuring Cisco Express Forwarding, see the "Configuring Cisco Express Forwarding" module of the IP Switching Configuration Guide.
For information about how to configure Ethernet or Fast Ethernet, see the "Configuring Fast Ethernet Interfaces" section and the "Configuring Gigabit Ethernet Interfaces" section.
Note |
If you want to use the Cisco Discovery Protocol (formerly known as CDP), you must configure it on the physical Ethernet, Fast Ethernet, or Gigabit Ethernet interface and not on the port-channel interface. |
Caution |
Fast EtherChannel supports Cisco Express Forwarding and distributed Cisco Express Forwarding, depending on your release. We recommend that you clear all explicit ip route-cache distributed commands from Fast Ethernet interfaces before enabling distributed Cisco Express Forwarding on the port-channel interface to give the port-channel interface proper control of its physical Fast Ethernet links. When you enable Cisco Express Forwarding or distributed Cisco Express Forwarding globally, all interfaces that support Cisco Express Forwarding or distributed Cisco Express Forwarding are enabled. When Cisco Express Forwarding or distributed Cisco Express Forwarding is enabled on the port-channel interface, it is automatically enabled on each of the Fast Ethernet interfaces in the channel group. However, if you have previously disabled Cisco Express Forwarding or distributed Cisco Express Forwarding on the Fast Ethernet interface, Cisco Express Forwarding or distributed Cisco Express Forwarding is not automatically enabled. In this case, you must enable Cisco Express Forwarding or distributed Cisco Express Forwarding on the Fast Ethernet interface. |
Caution |
The port-channel interface is a routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on physical Fast Ethernet interfaces because bridges may create loops. Also, you must disable the spanning tree protocol. |
The Cisco software automatically removes a Fast Ethernet interface from the Fast EtherChannel if the interface goes down, and the software automatically adds the Fast Ethernet interface to the Fast EtherChannel when the interface comes up.
Fast EtherChannel relies on keepalives to detect whether the line protocol is up or down. Keepalives are enabled by default on Fast Ethernet interfaces. If the line protocol on the interface goes down because of not receiving a keepalive signal, the Fast EtherChannel detects that the line protocol is down and removes the interface from the Fast EtherChannel. However, if the line protocol remains up because keepalives are disabled on the Fast Ethernet interface, the Fast EtherChannel cannot detect this link failure and does not remove the interface from the Fast EtherChannel even if the line protocol goes down. This behavior can cause unpredictable results. The implementation of the Port Aggregation Protocol in a subsequent release of this feature will remove the dependency on keepalives.
See the Configuration Examples for Fast EtherChannel section for configuration examples.
Device> enable Device# configure terminal Device(config)# interface port-channel 3 Device(config-if)# ip address 10.108.1.27 255.0.0.0 Device(config-if)# mac-address 1111.2222.3333 Device(config-if)# end Device# show interface port-channel
Device> enable Device# configure terminal Device(config)# interface fastethernet 0 Device(config-if)# no ip address Device(config-if)# channel-group 3 Device(config)# end Device# show interfaces port-channel
Device> enable Device# configure terminal Device(config)# interface fastethernet 0 Device(config-if)# no channel-group Device(config-if)# end
Device> enable Device# configure terminal Device(config)# interface gigabitethernet 0 Device(config-if)# no ip address Device(config-if)# channel-group 3 Device(config-if)# end Device(config)# show interfaces port-channel
Device> enable Device# configure terminal Device(config)# interface gigabitethernet 0 Device(config-if)# no channel-group Device(config-if)# end
Related Topic | Document Title |
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Cisco IOS commands |
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Interface and Hardware Component commands |
Cisco IOS Interface and Hardware Component Command Reference |
Description | Link |
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The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1 | Feature Information for Fast EtherChannel |
Feature Name | Releases | Feature Information |
---|---|---|
Fast EtherChannel |
12.1(4)E 12.2(52)SG |
The Fast EtherChannel feature allows multiple Fast Ethernet point-to-point links to be bundled into one logical link to provide bidirectional bandwidth of up to 800 Mbps. Fast EtherChannel builds on standards based on 802.3 full-duplex Fast Ethernet to provide fault-tolerant, high-speed links between devices and servers. |
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