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This chapter describes how to use the command-line interface (CLI) to configure EtherChannel on the Catalyst 6000 family switch Layer 2 or Layer 3 interfaces.
This chapter consists of these sections:
EtherChannel bundles individual Ethernet links into a single logical link that provides bandwidth up to 1600 Mbps (Fast EtherChannel full duplex) or 16 Gbps (Gigabit EtherChannel) between a Catalyst 6000 family switch and another switch or host.
A Catalyst 6000 family switch supports a maximum of 256 EtherChannels. You can form an EtherChannel with up to eight compatibly configured Ethernet interfaces on any module in a Catalyst 6000 family switch. All interfaces in each EtherChannel must be the same speed and must all be configured as either Layer 2 or Layer 3 interfaces.
If a segment within an EtherChannel fails, traffic previously carried over the failed link switches to the remaining segments within the EtherChannel. A trap is sent upon a failure identifying the switch, the EtherChannel, and the failed link. Inbound broadcast and multicast packets on one segment in an EtherChannel are blocked from returning on any other segment of the EtherChannel.
Each EtherChannel has a port-channel interface, numbered from 1 to 256. Configuration applied to the port-channel interface applies to all physical interfaces assigned to the port-channel interface.
After you configure an EtherChannel, configuration applied to the port-channel interface affects the EtherChannel and configuration applied to the physical interfaces affects only the interface where you apply the configuration. To change the parameters of all ports in an EtherChannel, apply configuration commands to the port-channel interface; for example, Spanning Tree Protocol commands or commands to configure a Layer 2 EtherChannel as a trunk.
The Port Aggregation Protocol (PAgP) facilitates the automatic creation of EtherChannels by exchanging packets between Ethernet interfaces. PAgP packets are exchanged only between interfaces in auto and desirable modes. Interfaces configured in the on mode do not exchange PAgP packets.
The protocol learns the capabilities of interface groups dynamically and informs the other interfaces. Once PAgP identifies correctly matched Ethernet links, it facilitates grouping the links into an EtherChannel. The EtherChannel is then added to the spanning tree as a single bridge port.
EtherChannel includes three user-configurable modes: on, auto, and desirable (see Table 9-1). Only auto and desirable are PAgP modes.
| Mode | Description |
|---|---|
on | Forces the interface to channel without PAgP. With the on mode, a usable EtherChannel exists only when an interface group in on mode is connected to another interface group in on mode. |
auto | PAgP mode that places an interface into a passive negotiating state, in which the interface responds to PAgP packets it receives but does not initiate PAgP packet negotiation. (Default) |
desirable | PAgP mode that places an interface into an active negotiating state, in which the interface initiates negotiations with other interfaces by sending PAgP packets. |
Both the auto and desirable modes allow interfaces to negotiate with partner interfaces to determine if they can form an EtherChannel, based on criteria such as interface speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.
Interfaces can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible. For example:
EtherChannel balances traffic load across the links in a channel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel.
EtherChannel load balancing can use either MAC addresses or IP addresses and either source or destination or both source and destination addresses. The selected mode applies to all EtherChannels configured on the switch.
Use the option that provides the greatest variety in your configuration. For example, if the traffic on a channel is going only to a single MAC address, using the destination MAC address always chooses the same link in the channel; using source addresses or IP addresses may result in better load balancing.
If improperly configured, some EtherChannel interfaces are disabled automatically to avoid network loops and other problems. Follow these guidelines to avoid configuration problems:
These sections describe how to configure EtherChannel:
To configure Layer 3 EtherChannels, create the port-channel logical interface and then put the Ethernet interfaces into the port-channel.
These sections describe Layer 3 EtherChannel configuration:
To create a port-channel interface for a Layer 3 EtherChannel, perform this task:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# interface port-channel port_channel_number | Create the port-channel interface. The group number can be from 1 to 256. | ||
| Router(config-if)# ip address ip_address mask | Assign an IP address and subnet mask to the EtherChannel. | ||
| Router(config-if)# exit | Exit the interface configuration mode. | ||
| Router(config)# exit | Exit the configuration mode. | ||
| Router# show running-config interface port-channel port_channel_number | Verify the configuration. |
This example shows how to create port-channel interface 1:
Router# configure terminal Router(config)# interface port-channel 1 Router(config-if)# ip address 172.32.52.10 255.255.255.0 Router(config-if)# exit Router(config)# exit
This example shows how to verify the configuration of port-channel interface 1:
Router# show running-config interface port-channel 1 Building configuration... Current configuration: ! interface Port-channel1 ip address 172.32.52.10 255.255.255.0 no ip directed-broadcast end Router#
To put Ethernet interfaces into a Layer 3 EtherChannel, perform this task for each interface:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# interface {ethernet | fastethernet | gigabitethernet} slot/port
| Select a physical interface to configure. | ||
| Router(config-if)# no ip address | Ensure that there is no IP address assigned to the physical interface. | ||
| Router(config-if)# channel-group group port_channel_number mode {auto | desirable | on} | Configure the interface in a port-channel and specify the PAgP mode. | ||
| Router(config-if)# exit | Exit the interface configuration mode. | ||
| Router(config)# exit | Exit the configuration mode. | ||
| Router# show running-config interface port-channel port_channel_number
Router# show running-config interface {ethernet | fastethernet | gigabitethernet} slot/port
Router# show interfaces {ethernet | fastethernet | gigabitethernet} slot/port etherchannel
Router# show etherchnl 1 port-channel
| Verify the configuration. |
This example shows how to put Fast Ethernet interfaces 5/4 and 5/5 into port-channel 1 with PAgP mode desirable:
Router# configure terminal Router(config)# interface range fastethernet 5/4 -5 Router(config-if)# no ip address Router(config-if)# channel-group group 1 mode desirable Router(config-if)# exit
This example shows how to verify the configuration of Fast Ethernet interface 5/4:
Router# show running-config interface fastethernet 5/4
Building configuration...
Current configuration:
!
interface FastEthernet5/4
no ip address
no ip directed-broadcast
channel-group group 1 mode auto
end
Router# show interfaces fastethernet 5/4 etherchannel
Port state = EC-Enbld Up In-Bndl Usr-Config
Channel group = 1 Mode = Desirable Gcchange = 0
Port-channel = Po1 GC = 0x00010001 Psudo-agport = Po1
Port indx = 0 Load = 0x55
Flags: S - Device is sending Slow hello. C - Device is in Consistent state.
A - Device is in Auto mode. P - Device learns on physical port.
Timers: H - Hello timer is running. Q - Quit timer is running.
S - Switching timer is running. I - Interface timer is running.
Local information:
Hello Partner PAgP Learning Group
Port Flags State Timers Interval Count Priority Method Ifindex
Fa5/4 SC U6/S7 30s 1 128 Any 55
Partner's information:
Partner Partner Partner Partner Group
Port Name Device ID Port Age Flags Cap.
Fa5/4 JAB031301 0050.0f10.230c 2/45 1s SAC 2D
Age of the port in the current state: 00h:54m:52s
Router#
This example shows how to verify the configuration of port-channel interface 1 after the interfaces have been configured:
Router# show etherchnl 1 port-channel
Port-channels in the group:
----------------------
Port-channel: Po1
------------
Age of the Port-channel = 01h:56m:20s
Logical slot/port = 10/1 Number of ports in agport = 2
GC = 0x00010001 HotStandBy port = null
Passive port list = Fa5/4 Fa5/5
Port state = Port-channel L3-Ag Ag-Inuse
Ports in the Port-channel:
Index Load Port
-------------------
0 55 Fa5/4
1 AA Fa5/5
Time since last port bundled: 01h:55m:44s Fa5/5
Router#
To configure Layer 2 EtherChannels, configure the Ethernet interfaces with the channel-group command, which creates the port-channel logical interface.
To configure Layer 2 Ethernet interfaces as a Layer 2 EtherChannel, perform this task for each interface:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# interface {ethernet | fastethernet | gigabitethernet} slot/port
| Select a physical interface to configure. | ||
| Router(config-if)# channel-group group port_channel_number mode {auto | desirable | on} | Configure the interface in a port-channel and specify the PAgP mode. | ||
| Router(config-if)# exit | Exit the interface configuration mode. | ||
| Router(config)# exit | Exit the configuration mode. | ||
| Router# show running-config interface {ethernet | fastethernet | gigabitethernet} slot/port
Router# show interface {ethernet | fastethernet | gigabitethernet} slot/port etherchannel
| Verify the configuration. |
This example shows how to put Fast Ethernet interfaces 5/6 and 5/7 into port-channel 2 with PAgP mode desirable:
Router# configure terminal Router(config)# interface range fastethernet 5/6 -7 Router(config-if)# channel-group group 2 mode desirable Router(config-if)# exit
This example shows how to verify the configuration of port-channel interface 2:
Router# show running-config interface port-channel 2 Building configuration... Current configuration: ! interface Port-channel2 no ip address switchport switchport access vlan 10 switchport mode access end Router#
This example shows how to verify the configuration of Fast Ethernet interface 5/6:
Router# show running-config interface fastethernet 5/6
Building configuration...
Current configuration:
!
interface FastEthernet5/6
no ip address
switchport
switchport access vlan 10
switchport mode access
channel-group group 2 mode desirable
end
Router# show interfaces fastethernet 5/6 etherchannel
Port state = EC-Enbld Up In-Bndl Usr-Config
Channel group = 2 Mode = Desirable Gcchange = 0
Port-channel = Po2 GC = 0x00020001
Port indx = 1 Load = 0x55
Flags: S - Device is sending Slow hello. C - Device is in Consistent state.
A - Device is in Auto mode. P - Device learns on physical port.
Timers: H - Hello timer is running. Q - Quit timer is running.
S - Switching timer is running. I - Interface timer is running.
Local information:
Hello Partner PAgP Learning Group
Port Flags State Timers Interval Count Priority Method Ifindex
Fa5/6 SC U6/S7 30s 1 128 Any 56
Partner's information:
Partner Partner Partner Partner Group
Port Name Device ID Port Age Flags Cap.
Fa5/6 JAB031301 0050.0f10.230c 2/47 18s SAC 2F
Age of the port in the current state: 00h:10m:57s
This example shows how to verify the configuration of port-channel interface 2 after the interfaces have been configured:
Router# show etherchnl 2 port-channel
Port-channels in the group:
----------------------
Port-channel: Po2
------------
Age of the Port-channel = 00h:23m:33s
Logical slot/port = 10/2 Number of ports in agport = 2
GC = 0x00020001 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Ports in the Port-channel:
Index Load Port
-------------------
1 55 Fa5/6
0 AA Fa5/7
Time since last port bundled: 00h:23m:33s Fa5/6
Router#
To configure EtherChannel load balancing, perform this task:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# [no] port-channel load-balance {dip | dmac | sdip | sdmac | sip | smac} | Configure EtherChannel load balancing. Use the no port-channel load-balance command to return EtherChannel load balancing to the default configuration. | ||
| Router# show etherchannel load-balance | Verify the configuration. |
The load-balancing keywords are:
This example shows how to configure EtherChannel to use source and destination IP addresses:
Router# configure terminal Router(config)# port-channel load-balance sdip Router(config)# exit Router(config)#
This example shows how to verify the configuration:
Router# show etherchannel load-balance Source XOR Destination IP address Router#
To remove an Ethernet interface from an EtherChannel, perform this task:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# interface {ethernet | fastethernet | gigabitethernet} slot/port
| Select a physical interface to configure. | ||
| Router(config-if)# no channel-group | Remove the interface from the port-channel interface. | ||
| Router(config-if)# exit | Exit the interface configuration mode. | ||
| Router(config)# exit | Exit the configuration mode. | ||
| Router# show running-config interface {ethernet | fastethernet | gigabitethernet} slot/port
Router# show interface {ethernet | fastethernet | gigabitethernet} slot/port etherchannel
| Verify the configuration. |
This example shows how to remove Fast Ethernet interface 5/4 from port-channel 1:
Router# configure terminal Router(config)# interface range fastethernet 5/4 -5 Router(config-if)# no channel-group group 1 Router(config-if)# exit
To remove an EtherChannel, perform this task:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)# no interface port-channel port_channel_number | Remove the port-channel interface. | ||
| Router(config)# exit | Exit the configuration mode. | ||
| Router# show etherchnl summary | Verify the configuration. |
This example shows how to remove port channel 1:
Router# configure terminal Router(config)# no interface port-channel 1 Router(config)# exit
Posted: Mon Jan 3 14:06:00 PST 2000
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