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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 can be configured between Cisco 7500 series routers and Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) or between a Cisco 7500 series router or a Cisco 7000 series router with the RSP7000 and RSP700CI and a Catalyst 5000 switch.
The Fast EtherChannel provides higher bidirectional bandwidth, redundancy, and load sharing. Up to four Fast Ethernet interfaces can be bundled in a Fast EtherChannel, and the router or switch can support up to four Fast EtherChannels. The Fast EtherChannel feature is capable of load balancing traffic across the Fast Ethernet links. Unicast, broadcast, and multicast traffic is distributed across the links providing higher performance and redundant parallel paths. In the event of a link failure, traffic is redirected to remaining links within the Fast EtherChannel without user intervention.
In the first release of this feature, IP traffic is distributed over the Fast EtherChannel interface while traffic from other routing protocols is sent over a single link. Bridged traffic is distributed based on 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.
The Fast EtherChannel interface supports all features currently supported on the Fast Ethernet interface. You must configure these features on the Fast EtherChannel interface rather than on the individual Fast Ethernet interfaces. Fast EtherChannel connections are fully compatible with Cisco IOS virtual LAN (VLAN) and routing technologies. The Inter-Switch Link (ISL) VLAN trunking protocol can carry multiple VLANs across a Fast EtherChannel, and routers attached to Fast EtherChannel links can provide full multiprotocol routing with support for host standby using Host Standby Router Protocol (HSRP).
The Fast EtherChannel interface (consisting of up to four Fast Ethernet interfaces) is treated as a single interface. The Fast EtherChannel interface is created by using the interface port-channel interface configuration command. The term port channel is used in the Cisco IOS software to maintain compatibility with existing commands on the Catalyst 5000 switch. Up to four Fast Ethernet interfaces can be assigned to a Fast EtherChannel interface by using the channel-group interface configuration command.
This feature is supported on these platforms:
Configuring a Fast EtherChannel consists of the following required steps:
To configure the Fast EtherChannel interface, perform the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
| Step 1 Create the Fast EtherChannel interface and enter interface configuration mode. The channel-number can be 1 to 4. | interface port-channel channel-number |
| Step 2 Assign an IP address and subnet mask to the Fast EtherChannel interface. | ip address ip-address mask |
| Step 3 Optionally, enable other supported interface commands to meet your needs and exit when done. | exit |
For information on other configuration tasks for the Fast EtherChannel, refer to the "Configure an Ethernet or Fast Ethernet Interface" section in the "Configuring Interfaces" chapter of the Configuration Fundamentals Configuration Guide.
For information on other commands that can be used by the Fast EtherChannel, refer to the Cisco IOS Release 11.1 configuration guides.
To assign the Fast Ethernet interfaces to the Fast EtherChannel, perform the following tasks beginning in global configuration mode:
| Task | Command |
|---|---|
| Step 1 Create or modify an existing Fast Ethernet interface and enter interface configuration mode. | interface fastethernet slot/port-adapter/port |
| Step 2 If the Fast Ethernet interface already exists and has an IP address assigned, disable the IP address before performing the next step.
The Fast Ethernet uses the IP address assigned to the Fast EtherChannel interface. | no ip address |
| Step 3 Assign the Fast Ethernet interfaces to the Fast EtherChannel. The channel number is the same as the channel number you specified when you created the Fast EtherChannel. | channel-group channel-number |
| Step 4 Exit interface configuration mode and repeat Step 1 through Step 4 to add up to four Fast Ethernet interfaces to the Fast EtherChannel. | exit |
 | Caution The Fast EtherChannel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet interfaces because it creates loops. Also, spanning tree must be disabled in the first release of this feature. |
To remove a Fast Ethernet interface from a Fast EtherChannel, perform the following tasks beginning in global configuration mode:
The Cisco IOS 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 is back up.
Currently, Fast EtherChannel relies on keepalives to detect whether the line protocol is up or down. Keepalives are enabled by default on the Fast Ethernet interfaces. If the line protocol on the interface goes down because it did not receive 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 (other than a cable disconnect) and does not remove the interface from the Fast EtherChannel even if the line protocol goes down. This can result in unpredictable behavior. The implementation of the Port Aggregation Protocol (PAgP) in a subsequent release of this feature will remove the dependency on keepalives.
See the "Configuration Example" section later in this document for configuration examples.
You can monitor the status of the Fast EtherChannel interface by using the show interfaces port-channel EXEC command.
Figure 1 shows four point-to-point Fast Ethernet interfaces that are aggregated into a single Fast EtherChannel interface.
Following is an example of creating a Fast EtherChannel with four Fast Ethernet interfaces. In this example, ISL is enabled on the Fast EtherChannel and an IP address is assigned to the subinterface.
router#configure terminalrouter(config)#interface port-channel 1router(config-if)#no shutdownrouter(config-if)#exitrouter(config)#interface port-channel 1.1router(config-if)#ip address 1.1.1.10 255.255.255.0router(config-if)#encapsulation isl 100router(config-if)#exitrouter(config)#interface fastethernet 0/0router(config-if)#no ip addressrouter(config-if)#channel-group 1Fast Ethernet 0/0 added as member-1 to port-channel1. router(config-if)#exitrouter(config)#interface fastethernet 0/1router(config-if)#no ip addressrouter(config-if)#channel-group 1Fast Ethernet 0/1 added as member-2 to port-channel1. router(config-if)#exitrouter(config)#interface fastethernet 1/0router(config-if)#no ip addressrouter(config-if)#channel-group 1Fast Ethernet 1/0 added as member-3 to port-channel1. router(config-if)#exitrouter(config)#interface fastethernet 1/1router(config-if)#no ip addressrouter(config-if)#channel-group 1Fast Ethernet 1/1 added as member-4 to port-channel1. router(config-if)#exitrouter(config)#exitrouter#
The following is a partial example of a configuration file. The MAC address is automatically added to the Fast Ethernet interface when the interfaces are added to the Fast EtherChannel.
interface Port-channel1 ip address 1.1.1.10 255.255.255.0 ! interface Port-channel1.1 encapsulation isl 100 ! interface FastEthernet0/0 mac-address 00e0.1476.7600 no ip address channel-group 1 ! interface FastEthernet0/1 mac-address 00e0.1476.7600 no ip address channel-group 1 ! interface FastEthernet1/0 mac-address 00e0.1476.7600 no ip address channel-group 1 ! interface FastEthernet1/1 mac-address 00e0.1476.7600 no ip address channel-group 1
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 11.2 command references.
To assign a Fast Ethernet interface to a Fast EtherChannel group, use the channel-group interface command. To remove a Fast Ethernet interface from a Fast EtherChannel group, use the no form of the command.
channel-group number| number | Fast EtherChannel number; 1 to 4. This is the number assigned to the Fast Etherchannel interface when using the interface port-channel global configuration command. |
No channel group is assigned.
Interface configuration
This command first appeared in Cisco IOS Release 11.1 CA.
Before you assign a Fast Ethernet interface to a Fast EtherChannel, you must first create the Fast EtherChannel. To create a Fast EtherChannel, use the interfaces port-channel global configuration command.
If the Fast Ethernet has an IP address assigned, you must disable it before adding the Fast Ethernet interface to the Fast EtherChannel. To disable an existing IP address on the Fast Ethernet interface, use the no ip address interface configuration command.
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 can be configured between Cisco 7500 series routers and Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) or between a Cisco 7500 series router or a Cisco 7000 series router with the RSP7000 and RSP700CI and a Catalyst 5000 switch.
Up to four Fast Ethernet interfaces can be added to a Fast EtherChannel.
| Caution The Fast EtherChannel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet interfaces because it creates loops. Also, spanning tree must be disabled in the first release of this feature. |
To display information about the Fast EtherChannel, use the show interfaces port-channel EXEC command.
The following example adds Fast Ethernet 1/0 to an existing Fast EtherChannel (port-channel) 1:
interface fastethernet 1/0 channel-group 1
interface port-channel
show interfaces port-channel
To clear the interface counters, use the clear counters EXEC command.
clear counters [type number]| type | (Optional) Interface type; one of the keywords listed in Usage Guidelines. |
| number | (Optional) Port number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
This command was modified in Cisco IOS Release 11.1 CA to include the port-channel interface type keyword.
This command clears all the current interface counters from the interface unless the optional arguments type and number are specified to clear only a specific interface type (serial, Ethernet, Token Ring, and so on).
| Keyword | Interface Type |
|---|---|
| async | Asynchronous interface |
| bri | Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) |
| dialer | Dialer interface |
| ethernet | Ethernet interface |
| fast-ethernet | Fast Ethernet interface |
| fddi | Fiber Distributed Data Interface (FDDI) |
| hssi | High-Speed Serial Interface (HSSI) |
| lex | LAN Extender interface |
| loopback | Loopback interface |
| null | Null interface |
| port-channel | Fast EtherChannel interface |
| pos | Packet OC-3 interface |
| serial | Synchronous serial interface |
| tokenring | Token Ring interface |
| tunnel | Tunnel interface |
| vg-anylan | 100VG-AnyLAN port adapter |
The following example clears all interface counters:
clear counters
The following example clears the interface counters on a Fast Etherchannel interface:
clear counters port-channel 1
To reset the hardware logic on an interface, use the clear interface EXEC command.
clear interface type number| type | Interface type; one of the keywords listed in Usage Guidelines. |
| number | Port number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
This command was modified in Cisco IOS Release 11.1 CA to include the port-channel interface type keyword.
Under normal circumstances, you do not need to clear the hardware logic on interfaces.
| Keyword | Interface Type |
|---|---|
| async | Async interface |
| atm | Asynchronous Transfer Mode (ATM) interface |
| bri | Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) |
| ethernet | Ethernet interface |
| fddi | Fiber Distributed Data Interface (FDDI) |
| hssi | High-Speed Serial Interface (HSSI) |
| loopback | Loopback interface |
| null | Null interface |
| port-channel | Fast EtherChannel interface |
| pos | Packet OC-3 Interface Processor |
| serial | Synchronous serial interface |
| tokenring | Token Ring interface |
| tunnel | Tunnel interface |
| vg-anylan | 100VG-AnyLAN port adapter |
The following example resets the interface logic on Fast Etherchannel interface 1:
clear interface port-channel 1
To specify a Fast Etherchannel and enter interface configuration mode, use the interface port-channel global configuration command.
interface port-channel number| number | Port channel number; 1 to 4. |
None
Global configuration
This command first appeared in Cisco IOS Release 11.1 CA.
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 can be configured between Cisco 7500 series routers and Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) or between a Cisco 7500 series router or a Cisco 7000 series router with the RSP7000 and RSP700CI and a Catalyst 5000 switch.
You can configure the Fast EtherChannel as you would do to any Fast Ethernet interface.
After you create a Fast EtherChannel, you assign Fast Ethernet interfaces (up to four) to the Fast EtherChannel interface.
| Caution The Fast EtherChannel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet interfaces because it creates loops. Also, spanning tree must be disabled in the first release of this feature. |
The following example specifies a Fast EtherChannel for channel group 1:
interface port-channel 1
channel-group
show interfaces port-channel
To display the information about the Fast EtherChannel on Cisco 7500 series routers and Cisco 7000 series routers with the RSP7000 and RSP7000CI, use the show interfaces port-channel EXEC command.
show interfaces port-channel [number]| number | (Optional) Port channel number; 1 to 4. |
EXEC
This command first appeared in Cisco IOS Release 11.1 CA.
The following is sample output from the show interfaces port-channel command:
Router# show interfaces port-channel 1
Port-channel1 is up, line protocol is up
Hardware is FEChannel, address is 0000.0ca8.6220 (bia 0000.0000.0000)
MTU 1500 bytes, BW 400000 Kbit, DLY 100 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive not set, fdx
ARP type: ARPA, ARP Timeout 04:00:00
No. of active members in this channel: 4
Member 0 : FastEthernet1/0/0
Member 1 : FastEthernet1/1/0
Member 2 : FastEthernet4/0/0
Member 3 : FastEthernet4/1/0
Last input 01:22:13, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
223 packets input, 11462 bytes, 0 no buffer
Received 1 broadcasts, 0 runts, 0 giants
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 watchdog, 0 multicast
0 input packets with dribble condition detected
192 packets output, 13232 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Table 3 describes significant fields in this output.
| Field | Description |
|---|---|
| Port-channel1 is up, line protocol is up | Indicates if the interface hardware is currently active and can transmit and receive or if it has been taken down by an administrator. |
| Hardware is | Hardware type (Fast EtherChannel). |
| address is | Address being used by the interface. |
| MTU | Maximum transmission unit of the interface. |
| BW | Bandwidth of the interface in kilobits per second. |
| DLY | Delay of the interface in microseconds. |
| rely | Reliability of the interface as a fraction of 255 (255/255 is 100% reliability), calculated as an exponential average over 5 minutes. |
| load | Load on the interface as a fraction of 255 (255/255 is completely saturated), calculated as an exponential average over 5 minutes. The calculation uses the value from the bandwidth interface configuration command. |
| Encapsulation | Encapsulation method assigned to the interface. |
| loopback | Indicates if loopbacks are set. |
| keepalive | Indicates if keepalives are set. |
| fdx | Indicates the interface is operating in full-duplex mode. |
| ARA type | ARP type on the interface. |
| ARP timeout | Number of hours, minutes, and seconds an ARP cache entry will stay in the cache. |
| No. of active members in this channel: 4 | Number of Fast Ethernet interfaces that are currently active (not down) and part of the Fast EtherChannel group. |
| Member 0: FastEthernet1/0/0 | Specific Fast Ethernet interface that is part of the Fast EtherChannel group. |
| Last input | Number of hours, minutes, and seconds since the last packet was successfully received by an interface. Useful for knowing when a dead interface failed. |
| output | Number of hours, minutes, and seconds since the last packet was successfully transmitted by an interface. |
| output hang | Number of hours, minutes, and seconds (or never) since the interface was last reset because of a transmission that took too long. When the number of hours in any of the "last" fields exceeds 24 hours, the number of days and hours is printed. If that field overflows, asterisks are printed. |
| last clearing | Time at which the counters that measure cumulative statistics (such as number of bytes transmitted and received) shown in this report were last reset to zero. Variables that might affect routing (for example, load and reliability) are not cleared when the counters are cleared.
*** indicates the elapsed time is too large to be displayed. 0:00:00 indicates the counters were cleared more than 231ms (and less then 232ms) ago. |
| Queueing strategy | First-in, first-out queuing strategy (other queueing strategies you might see are priority-list, custom-list, and weighted fair). |
| Output queue, drops input queue, drops | Number of packets in output and input queues. Each number is followed by a slash, the maximum size of the queue, and the number of packets dropped because a queue was full. |
| 5 minute input rate 5 minute output rate | Average number of bits and packets received or transmitted per second in the last 5 minutes. |
| packets input | Total number of error-free packets received by the system. |
| bytes (input) | Total number of bytes, including data and MAC encapsulation, in the error-free packets received by the system. |
| no buffer | Number of received packets discarded because there was no buffer space in the main system. Compare with ignored count. Broadcast storms on Ethernets and bursts of noise on serial lines are often responsible for no input buffer events. |
| broadcasts | Total number of broadcast or multicast packets received by the interface. |
| runts | Number of packets that are discarded because they are smaller than the medium's minimum packet size. |
| giants | Number of packets that are discarded because they exceed the medium's maximum packet size. |
| input errors | Total number of no buffer, runts, giants, CRCs, frame, overrun, ignored, and abort counts. Other input-related errors can also increment the count, so that this sum might not balance with the other counts. |
| CRC | Cyclic redundancy checksum generated by the originating LAN station or far-end device does not match the checksum calculated from the data received. On a LAN, this usually indicates noise or transmission problems on the LAN interface or the LAN bus itself. A high number of CRCs is usually the result of collisions or a station transmitting bad data. On a serial link, CRCs usually indicate noise, gain hits or other transmission problems on the data link. |
| frame | Number of packets received incorrectly having a CRC error and a noninteger number of octets. On a serial line, this is usually the result of noise or other transmission problems. |
| overrun | Number of times the serial receiver hardware was unable to hand received data to a hardware buffer because the input rate exceeded the receiver's ability to handle the data. |
| ignored | Number of received packets ignored by the interface because the interface hardware ran low on internal buffers. These buffers are different than the system buffers mentioned previously in the buffer description. Broadcast storms and bursts of noise can cause the ignored count to be incremented. |
| abort | Illegal sequence of ones bit on the interface. |
| watchdog | Number of times watchdog receive timer expired. It happens when receiving a packet with length greater than 2048. |
| multicast | Number of multicast packets received. |
| input packets with dribble condition detected | Dribble bit error indicates that a frame is slightly too long. This frame error counter is incremented just for informational purposes; the router accepts the frame. |
| packets output | Total number of messages transmitted by the system. |
| bytes (output) | Total number of bytes, including data and MAC encapsulation, transmitted by the system. |
| underruns | Number of times that the far-end transmitter has been running faster than the near-end router's receiver can handle. |
| output errors | Sum of all errors that prevented the final transmission of datagrams out of the interface being examined. Note that this might not balance with the sum of the enumerated output errors, as some datagrams can have more than one error, and others can have errors that do not fall into any of the specifically tabulated categories. |
| collisions | Number of messages retransmitted due to an Ethernet collision. This is usually the result of an overextended LAN (Ethernet or transceiver cable too long, more than two repeaters between stations, or too many cascaded multiport transceivers). A packet that collides is counted only once in output packets. |
| interface resets | Number of times an interface has been completely reset. This can happen if packets queued for transmission were not sent within a certain interval. If the system notices that the carrier detect line of an interface is up, but the line protocol is down, it periodically resets the interface in an effort to restart it. Interface resets can also occur when an unrecoverable interface processor error occurred, or when an interface is looped back or shut down. |
| babbles | The transmit jabber timer expired. |
| late collision | Number of late collisions. Late collision happens when a collision occurs after transmitting the preamble. |
| deferred | Deferred indicates that the chip had to defer while ready to transmit a frame because the carrier was asserted. |
| lost carrier | Number of times the carrier was lost during transmission. |
| no carrier | Number of times the carrier was not present during the transmission. |
| output buffer failures | Number of times that a packet was not output from the output hold queue because of a shortage of MEMD shared memory. |
| output buffers swapped out | Number of packets stored in main memory when the output queue is full; swapping buffers to main memory prevents packets from being dropped when output is congested. The number is high when traffic is bursty. |
For information on other commands that can be used by the Fast EtherChannel, refer to the Cisco IOS Release 11.1 configuration guides and command references.
For information on Fast Ethernet interfaces, refer to the specific hardware documentation that shipped with your product.
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