LACP (Link Aggregation Control Protocol) is an open standards protocol (IEEE802.3ad) that allows multiple physical interfaces to be aggregated into one logical link.
Each logical link can contain up-to 8 physical members. All member ports within the bundle must have the same physical settings such as port type, speed and duplex.
Within LACP there are 2 modes available, Active and Passive.
- Active – Within Active mode the switch tries to negotiate and form LACP with its neighbor.
- Passive – Within Passive mode LACP is enabled but the switch waits for the neighbor to initiate the negotiation LACP.
Create LACP Bundle
Creating an LACP bundle is simple, you define the port-channel number onto each of the interfaces.
Switch(config-if)#interface range gi0/1-3 Switch(config-if-range)#channel-group 33 mode active Creating a port-channel interface Port-channel 33
Below is an example of some of the common show commands.
Switch#sh lacp 33 neighbor Flags: S - Device is requesting Slow LACPDUs F - Device is requesting Fast LACPDUs A - Device is in Active mode P - Device is in Passive mode Channel group 33 neighbors Partner's information: LACP port Admin Oper Port Port Port Flags Priority Dev ID Age key Key Number State Gi0/1 SA 32768 fa16.3efa.dce3 24s 0x0 0x18 0x2 0x3D Gi0/2 SA 32768 fa16.3efa.dce3 6s 0x0 0x18 0x3 0x3D Gi0/3 SA 32768 fa16.3efa.dce3 16s 0x0 0x18 0x4 0x3D
Switch#sh lacp 33 counters LACPDUs Marker Marker Response LACPDUs Port Sent Recv Sent Recv Sent Recv Pkts Err --------------------------------------------------------------------- Channel group: 33 Gi0/1 62 56 0 0 0 0 0 Gi0/2 64 56 0 0 0 0 0 Gi0/3 64 55 0 0 0 0 0
LACP provides the ability to define the number of active members within the bundle, in essence allowing you to have create hot-standby bundle members.
Switch(config)#int po33 Switch(config-if)#lacp max-bundle ? <1-8> Max number of ports to bundle in this Port Channel
Once you have configured the maximum ports allowed within a bundle the port priority can be configured. Setting priority’s on each of the ports provides you with greater control and allows you to determine what ports are first added to the bundle and what ports are added into the bundle in the event of interface failure.
Switch(config)#int gi0/3 Switch(config-if)#lacp port-priority 300
Switch#sh lacp internal Flags: S - Device is requesting Slow LACPDUs F - Device is requesting Fast LACPDUs A - Device is in Active mode P - Device is in Passive mode Channel group 33 LACP port Admin Oper Port Port Port Flags State Priority Key Key Number State Gi0/1 SA bndl 32768 0x18 0x18 0x2 0x3D Gi0/2 SA bndl 32768 0x18 0x18 0x3 0x3D Gi0/3 SA bndl 300 0x18 0x18 0x4 0x3D
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