Ether-channel or (link aggregation)

Ether-channel or (link aggregation). Ether-channel is a technology that allows us to bundle multiple physical links into a single logical link. Ether-channel is used to aggregate bandwidth between multiple layer 2 / layer 3 interfaces

In other words, Ether channel is a link aggregation technology on Cisco devices (primarily switches) that allows us to combine multiple physical links and make them into a single logical link. Multiple physical links into a single logical link. The advantage of Ether channels is that it provides high bandwidth.

Ether-channel increases bandwidth and provides redundancy by aggregating individual links between switches. Ether-channel load balances traffic over all the links in the bundle.

We can use a maximum 8 physical interfaces to configure the bundle into a single logical link

let's see the configuration of the Ether-channel with the port-channel trunk.

Topology:

• configure the bundle of four links. make it one logical link.
• configure pagp
• configure the portchannel interface as a Trunk link.

SW-1(config)#interface range fastEthernet 0/1–4

SW-1(config-if-range)#channel-protocol pagp

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

SW-1(config-if-range)#exit

Creating a port-channel interface Port-channel 1

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up

SW-1(config-if-range)# interface range fastEthernet 0/5–8

SW-1(config-if-range)#channel-protocol pagp

SW-1(config-if-range)#channel-group 2 mode desirable

SW-1(config-if-range)#exit

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to up

SW-2(config)#interface range fastEthernet 0/1–4

SW-2(config-if-range)#channel-protocol pagp

SW-2(config-if-range)#channel-group 1 mode desirable

SW-2(config-if-range)#exit

%LINK-3-UPDOWN: Interface Port-channel1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to down

%LINK-5-CHANGED: Interface Port-channel1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up

SW-2(config)#interface range fastEthernet 0/5–8

SW-2(config-if-range)#channel-protocol pagp

SW-2(config-if-range)#channel-group 3 mode auto

SW-2(config-if-range)#exit

Creating a port-channel interface Port-channel 3

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to up

SW-3(config)#interface range fastEthernet 0/1–4

SW-3(config-if-range)#channel-protocol pagp

SW-3(config-if-range)#channel-group 4 mode auto

SW-3(config-if-range)#exit

Creating a port-channel interface Port-channel 4

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up

SW-3(config)#interface range fastEthernet 0/5–8

SW-3(config-if-range)#channel-protocol pagp

SW-3(config-if-range)#channel-group 3 mode desirable

SW-3(config-if-range)#exit

Creating a port-channel interface Port-channel 3

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to up

%LINK-5-CHANGED: Interface Port-channel3, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel3, changed state to up

SW-4(config)#interface range fastEthernet 0/1–4

SW-4(config-if-range)#channel-protocol pagp

SW-4(config-if-range)#channel-group 4 mode desirable

SW-4(config-if-range)#exit

Creating a port-channel interface Port-channel 4

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up

%LINK-5-CHANGED: Interface Port-channel4, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel4, changed state to up

SW-4(config)#interface range fastEthernet 0/5–8

SW-4(config-if-range)#channel-protocol pagp

SW-4(config-if-range)#channel-group 2 mode auto

SW-4(config-if-range)#exit

Creating a port-channel interface Port-channel 2

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/5, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/6, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to up

%LINK-5-CHANGED: Interface Port-channel2, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel2, changed state to up

SW-1#show etherchannel summary

Flags: D — down P — in port-channel

I — stand-alone s — suspended

H — Hot-standby (LACP only)

R — Layer3 S — Layer2

U — in use f — failed to allocate aggregator

u — unsuitable for bundling

w — waiting to be aggregated

d — default port

Number of channel-groups in use: 2

Number of aggregators: 2

Group Port-channel Protocol Ports

— — — + — — — — — — -+ — — — — — -+ — — — — — — — — — — — — — — — — — — — — — — —

1 Po1(SU) PAgP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)

2 Po2(SU) PAgP Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(P)

SW-1#show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 0001.9704.C446

Cost 7

Port 28(Port-channel2)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 00E0.F7BB.EAB0

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Po1 Desg FWD 7 128.27 Shr

Po2 Root FWD 7 128.28 Shr

SW-2# show etherchannel summary

Flags: D — down P — in port-channel

I — stand-alone s — suspended

H — Hot-standby (LACP only)

R — Layer3 S — Layer2

U — in use f — failed to allocate aggregator

u — unsuitable for bundling

w — waiting to be aggregated

d — default port

Number of channel-groups in use: 2

Number of aggregators: 2

Group Port-channel Protocol Ports

— — — + — — — — — — -+ — — — — — -+ — — — — — — — — — — — — — — — — — — — — — — —

1 Po1(SU) PAgP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)

3 Po3(SU) PAgP Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(P)

SW-2# show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 0001.9704.C446

Cost 14

Port 28(Port-channel3)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 00D0.BC66.E3E5

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Po3 Root FWD 7 128.28 Shr

Po1 Altn BLK 7 128.27 Shr

SW-2# show ip interface brief

Interface IP-Address OK? Method Status Protocol

Port-channel1 unassigned YES manual up up

Port-channel3 unassigned YES manual up up

FastEthernet0/1 unassigned YES manual up up

FastEthernet0/2 unassigned YES manual up up

FastEthernet0/3 unassigned YES manual up up

FastEthernet0/4 unassigned YES manual up up

FastEthernet0/5 unassigned YES manual up up

FastEthernet0/6 unassigned YES manual up up

FastEthernet0/7 unassigned YES manual up up

FastEthernet0/8 unassigned YES manual up up

SW-3# show etherchannel summary

Flags: D — down P — in port-channel

I — stand-alone s — suspended

H — Hot-standby (LACP only)

R — Layer3 S — Layer2

U — in use f — failed to allocate aggregator

u — unsuitable for bundling

w — waiting to be aggregated

d — default port

Number of channel-groups in use: 2

Number of aggregators: 2

Group Port-channel Protocol Ports

— — — + — — — — — — -+ — — — — — -+ — — — — — — — — — — — — — — — — — — — — — — —

3 Po3(SU) PAgP Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(P)

4 Po4(SU) PAgP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)

SW-3# show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 0001.9704.C446

Cost 7

Port 27(Port-channel4)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 0003.E4B3.E4ED

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Po3 Desg FWD 7 128.28 Shr

Po4 Root FWD 7 128.27 Shr

SW-3# show ip interface brief

Interface IP-Address OK? Method Status Protocol

Port-channel3 unassigned YES manual up up

Port-channel4 unassigned YES manual up up

FastEthernet0/1 unassigned YES manual up up

FastEthernet0/2 unassigned YES manual up up

FastEthernet0/3 unassigned YES manual up up

FastEthernet0/4 unassigned YES manual up up

FastEthernet0/5 unassigned YES manual up up

FastEthernet0/6 unassigned YES manual up up

FastEthernet0/7 unassigned YES manual up up

FastEthernet0/8 unassigned YES manual up up

SW-4# show etherchannel summary

Flags: D — down P — in port-channel

I — stand-alone s — suspended

H — Hot-standby (LACP only)

R — Layer3 S — Layer2

U — in use f — failed to allocate aggregator

u — unsuitable for bundling

w — waiting to be aggregated

d — default port

Number of channel-groups in use: 2

Number of aggregators: 2

Group Port-channel Protocol Ports

— — — + — — — — — — -+ — — — — — -+ — — — — — — — — — — — — — — — — — — — — — — —

2 Po2(SU) PAgP Fa0/5(P) Fa0/6(P) Fa0/7(P) Fa0/8(P)

4 Po4(SU) PAgP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)

SW-4# show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 0001.9704.C446

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 0001.9704.C446

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Po4 Desg FWD 7 128.27 Shr

Po2 Desg FWD 7 128.28 Shr

SW-4# show ip interface brief

Interface IP-Address OK? Method Status Protocol

Port-channel2 unassigned YES manual up up

Port-channel4 unassigned YES manual up up

FastEthernet0/1 unassigned YES manual up up

FastEthernet0/2 unassigned YES manual up up

FastEthernet0/3 unassigned YES manual up up

FastEthernet0/4 unassigned YES manual up up

FastEthernet0/5 unassigned YES manual up up

FastEthernet0/6 unassigned YES manual up up

FastEthernet0/7 unassigned YES manual up up

FastEthernet0/8 unassigned YES manual up up

SW-1(config)#interface port-channel 1

SW-1(config-if)#switchport mode trunk

SW-1(config-if)#exit

SW-1(config)#interface port-channel 2

SW-1(config-if)#switchport mode trunk

SW-1(config-if)#exit

SW-2(config)#interface port-channel 1

SW-2(config-if)#switchport mode trunk

SW-2(config-if)#exit

%SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel1 on VLAN0001. Port consistency restored.

%SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel1 on VLAN0001. Port consistency restored.

SW-2(config)#interface port-channel 3

SW-2(config-if)#switchport mode trunk

SW-2(config-if)#exit

SW-3(config)#interface port-channel 3

SW-3(config-if)#switchport mode trunk

SW-3(config-if)#exit

SW-3(config)#interface port-channel 4

SW-3(config-if)#switchport mode trunk

SW-3(config-if)#exit

SW-4(config)#interface port-channel 2

SW-4(config-if)#switchport mode trunk

SW-4(config-if)#exit

SW-4(config)#interface port-channel 4

SW-4(config-if)#switchport mode trunk

SW-4(config-if)#exit

SW-1#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Po1 on 802.1q trunking 1

Po2 on 802.1q trunking 1

Port Vlans allowed on trunk

Po1 1–1005

Po2 1–1005

Port Vlans allowed and active in management domain

Po1 1

Po2 1

Port Vlans in spanning tree forwarding state and not pruned

Po1 1

Po2 1

SW-2#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Po1 on 802.1q trunking 1

Po3 on 802.1q trunking 1

Port Vlans allowed on trunk

Po1 1–1005

Po3 1–1005

Port Vlans allowed and active in management domain

Po1 1

Po3 1

Port Vlans in spanning tree forwarding state and not pruned

Po1 none

Po3 1

SW-4#show interfaces trunk

Port Mode Encapsulation Status Native vlan

Po2 on 802.1q trunking 1

Po4 on 802.1q trunking 1

Port Vlans allowed on trunk

Po2 1–1005

Po4 1–1005

Port Vlans allowed and active in management domain

Po2 1

Po4 1

Port Vlans in spanning tree forwarding state and not pruned

Po2 1

Po4 1

SW-2#show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 0001.9704.C446

Cost 14

Port 28(Port-channel3)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 00D0.BC66.E3E5

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 20

Interface Role Sts Cost Prio.Nbr Type

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Po3 Root FWD 7 128.28 Shr

Po1 Altn BLK 7 128.27 Shr