Network technologies and trends

Jan 6 2009   6:11AM GMT

Cisco Etherchannel Overview and how it can be configured in Cisco Catalyst Switches – Series 6

Yasir Irfan Yasir Irfan Profile: Yasir Irfan

In the previous five posts I was talking about the Etherchannel  , types of protocols used , rules and restrictions applied to an Etherchannel  . Now it’s the time to see how an Etherchannel   can be configured in a Cisco Catalyst Switch.

An Etherchannel in a Cisco IOS can be defined as Layer 2 Etherchannel or a Layer 3 Etherchannel.

For a Layer 2 Etherchannel, physical ports are placed into an Etherchannel group.

For a Layer 3 Etherchannel, layer 3 SVI (Switch Virtual Interface) is created, and then the physical ports are placed into an Etherchannel group which is bound to the L3 SVI.

 

Now let’s see how to configure a Configure a Layer 2 Etherchannel in a Cisco Catalyst Switch using a PAGP (port aggregation protocol) Protocol. In my previous posts I did discussed about the PAGP protocol, it’s a Cisco proprietary protocol, can be applied only in Cisco Catalyst Switches.

Here is the scenario which we will follow

From the above diagram we have two Cisco 3560 Catalyst Switches named ITKESW01 and ITKESW02.

We will configure a Layer 2 Etherchannel between the Cisco 3560 Catalyst Switches  ITKESW01 and ITKESW02. The  Giga Ethernet ports 0/45, 0/46/,0/47 & 0/48 on a Cisco 3560 Catalyst Switches  ITKESW01 are trunk ports  and they are connected to Giga Ethernet ports 0/1,0/2,0/3 and 0/4 (also trunk ports) in Cisco 3560 Catalyst Switch  ITKESW02.

 

The configuration is as follows

 

Configuration in the Cisco 3560 Catalyst Switch  ITKESW01

 

First run the command “Show interfaces trunk

 

ITKESW01#sho interfaces trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Gi0/45      on                        802.1q         trunking            1

Gi0/46      on                        802.1q         trunking            1

Gi0/47      on                        802.1q         trunking            1

Gi0/48      on                        802.1q         trunking            1

 

Port        Vlans allowed on trunk

Gi0/45        1-4094

Gi0/46        1-4094

Gi0/47        1-4094

Gi0/48        1-4094

 

Port        Vlans allowed and active in management domain

Gi0/45        1

Gi0/46        1

Gi0/47        1

Gi0/48        1

 

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/45       1

Gi0/46       1

Gi0/47       1

Gi0/48       1

 

ITKESW01#

 

Second Step configure the Giga Ethernet ports 0/45 to 0/48 in the Etherchannel

 

ITKESW01#config t

ITKESW01(config)# interface range gigabitEthernet 0/45 – 48

ITKESW01(config-if-range)#channel-protocol pagp

 

Note: PAgP protocol is configured to be used in this channel

 

ITKESW01 (config-if-range)# channel-group 1 mode desirable

Note: A logical port-channel interface is automatically created when ports are grouped into a channel group.

Configure the mode desirable to be used in PAgP 

 

Configuration in the Cisco 3560 Catalyst Switch  ITKESW02

 

 

ITKESW02#sho interfaces trunk

 

Port        Mode             Encapsulation  Status        Native vlan

Gi0/1      on                        802.1q         trunking            1

Gi0/2      on                        802.1q         trunking            1

Gi0/3      on                        802.1q         trunking            1

Gi0/4      on                        802.1q         trunking            1

 

 

Port        Vlans allowed on trunk

Gi0/1        1-4094

Gi0/2        1-4094

Gi0/3        1-4094

Gi0/4        1-4094

 

 

Port        Vlans allowed and active in management domain

Gi0/1        1

Gi0/2        1

Gi0/3        1

Gi0/4        1

 

 

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/1       1

Gi0/2       1

Gi0/3       1

Gi0/4       1

 

ITKESW02#

 

Second Step configure the Giga Ethernet ports 0/1 to 0/4 in the Etherchannel

 

ITKESW02#config t

ITKESW02(config)# interface range gigabitEthernet 0/1 – 4

ITKESW02(config-if-range)#channel-protocol pagp

 

Note: PAgP protocol is configured to be used in this channel

 

ITKESW02 (config-if-range)# channel-group 1 mode auto

Note: A logical port-channel interface is automatically created when ports are grouped into a channel group.

Configure the mode auto to be used in PAgP 

Now run show command to display the Etherchannel configurations on the Cisco 3560 Catalyst Switches  ITKESW01 and ITKESW02

ITKESW01#sho etherchannel 1 summary

Flags:  D – down        P – in port-channel

        I – stand-alone s – suspended

        H – Hot-standby (LACP only)

        R – Layer3      S – Layer2

        u – unsuitable for bundling

        U – in use      f – failed to allocate aggregator

        d – default port

 

Number of channel-groups in use: 1

Number of aggregators:           1

 

Group  Port-channel  Protocol    Ports

——+————-+———–+———————————————–

1      Po1(SD)          PAgP      Gi0/45 (P)   Gi0/46 (P)  Gi0/47 (P)  Gi0/48 (P)  

ITKESW01#

 

ITKESW02#sho etherchannel 1 summary

Flags:  D – down        P – in port-channel

        I – stand-alone s – suspended

        H – Hot-standby (LACP only)

        R – Layer3      S – Layer2

        u – unsuitable for bundling

        U – in use      f – failed to allocate aggregator

        d – default port

 

Number of channel-groups in use: 1

Number of aggregators:           1

 

Group  Port-channel  Protocol    Ports

——+————-+———–+———————————————–

1      Po1(SD)          PAgP      Gi0/1 (P)   Gi0/2 (P)  Gi0/3 (P)  Gi0/4 (P)  

ITKESW02#

 

In upcoming posts I will show how to configure a Layer 2 Etherchannel  using LACP protocol

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