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.
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.
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.
when we configure an EtherChannel there are two
protocols we can choose from:
- PAgP (Cisco proprietary)
- LACP (IEEE standard)
EtherChannel mode
EtherChannel can be
dynamically configured between switches using two protocols
- PAgP (Port Aggregation Protocol)
- LACP (Link Aggregation Control Protocol)
PAgP there are a number of options which we can choose from, the
interface can be configured as:
On (interface becomes a member of the EtherChannel but it will not negotiate).
Desirable (the interface will actively ask the other side
to be an EtherChannel).
Auto (the interface will wait passively for the other side
to ask to be an EtherChannel).
Off (no EtherChannel configured on the interface).
Link Aggregation Control Protocol (LACP) is similar to PAgP. We also have different options
to choose from when we are going to configure the interface:
On (interfaces become a member of the EtherChannel but
it does not negotiate).
Active (the interface will actively ask the other side to
be an EtherChannel).
Passive (the interface will wait passively for the other
side to ask to be an EtherChannel).
Off (no EtherChannel configured on the interface).
Successful combination of EtherChannel: -
On – On
Desirable –Desirable
Desirable – Auto
Active –Active
Active – passive
let's see the configuration: -
Topology: -
 |
| Link Aggregation |
Goal:-
- configure the topology as per the diagram.
- configure the four physical links range fa 0/1-4 from switch 1
- configure the four physical links range fa0/11-14 from switch 2
- configure pagp which is cisco proprietary protocol.
SW-1(config)#interface range fastEthernet 0/1-4
SW-1(config-if-range)#channel-protocol ?
lacp Prepare interface for LACP protocol
pagp Prepare interface for PAgP protocol
SW-1(config-if-range)#channel-protocol pagp
SW-1(config-if-range)#channel-group 11 mode ?
active Enable LACP unconditionally
auto Enable PAgP only if a PAgP device is detected
desirable Enable PAgP unconditionally
on Enable Etherchannel only
passive Enable LACP only if a LACP device is detected
SW-1(config-if-range)#channel-group 11 mode desirable
SW-1(config-if-range)#end
SW-1(config)#interface port-channel 11
SW-1(config-if)#switchport trunk encapsulation dot1q
SW-1(config-if)#switchport mode trunk
SW-1(config-if)#end
SW-2(config)#interface range fastEthernet 0/11-14
SW-2(config-if-range)#channel-protocol pagp
SW-2(config-if-range)#channel-group 11 mode desirable
SW-2(config-if-range)#end
SW-2(config)#interface port-channel 11
SW-2(config-if)#switchport trunk encapsulation dot1q
SW-2(config-if)#switchport mode trunk
SW-2(config-if)#end
SW-1#show etherchannel port-channel
Channel-group listing:
----------------------
Group: 11
----------
Port-channels in the group:
---------------------------
Port-channel: Po11
------------
Age of the Port-channel = 00d:00h:12m:38s
Logical slot/port = 2/11 Number of ports = 4
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel
Protocol = PAGP
Port Security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Fa0/2 Desirable-Sl 0
0 00 Fa0/3 Desirable-Sl 0
0 00 Fa0/1 Desirable-Sl 0
0 00 Fa0/4 Desirable-Sl 0
Time since last port bundled: 00d:00h:09m:48s Fa0/4
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: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+----------------------------------------------
11 Po11(SU) PAgP Fa0/1(P) Fa0/2(P) Fa0/3(P) Fa0/4(P)
SW-1#show etherchannel
Channel-group listing:
----------------------
Group: 11
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Portchannels = 1
Protocol: PAGP
SW-2#show etherchannel port-channel
Channel-group listing:
----------------------
Group: 11
----------
Port-channels in the group:
---------------------------
Port-channel: Po11
------------
Age of the Port-channel = 00d:00h:16m:06s
Logical slot/port = 2/11 Number of ports = 4
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel
Protocol = PAGP
Port Security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Fa0/11 Desirable-Sl 0
0 00 Fa0/12 Desirable-Sl 0
0 00 Fa0/13 Desirable-Sl 0
0 00 Fa0/14 Desirable-Sl 0
Time since last port bundled: 00d:00h:07m:03s Fa0/14
SW-2#show etherchannel
Channel-group listing:
----------------------
Group: 11
----------
Group state = L2
Ports: 4 Maxports = 8
Port-channels: 1 Max Portchannels = 1
Protocol: PAGP
SW-1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Port-channel11 unassigned YES unset up up
FastEthernet0/1 unassigned YES NVRAM up up
FastEthernet0/2 unassigned YES NVRAM up up
FastEthernet0/3 unassigned YES NVRAM up up
FastEthernet0/4 unassigned YES NVRAM up up
FastEthernet0/5 unassigned YES NVRAM up up
SW-1#show spanning-tree
VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 0090.0CA7.0E42
Cost 7
Port 27(Port-channel11)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 00D0.D363.00A3
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 20
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po11 Root FWD 7 128.27 Shr
SW-1#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Po11 on 802.1q trunking 1
Port Vlans allowed on trunk
Po11 1-1005
Port Vlans allowed and active in management domain
Po11 1
Port Vlans in spanning tree forwarding state and not pruned
Po11 1
SW-2#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Po11 on 802.1q trunking 1
Port Vlans allowed on trunk
Po11 1-1005
Port Vlans allowed and active in management domain
Po11 1
Port Vlans in spanning tree forwarding state and not pruned
Po11 1
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