Prerequisites
Sections:
Overview:
- There are certain restrictions and prerequisites when it comes to identifying the eligible physical ports that can become aggregated together to form an EtherChannel bundle whether using PAgP, LACP, or static standards
- Failure to follow these guidelines will not allow the EtherChannel to form properly:
Matching Physical Port Parameters
- Speed/Duplex
- Line Protocol/Status state
- Administrative/Operational mode
- Matching EtherChannel protocol
- If ports are defined as Trunks:
- Matching defined VLANs
- Matching trunking mode
- Matching range of Allowed VLANs
Lab Topology
Unmatching Parameter Scenario
Scenario 1: Unmatching parameters preventing the formation of an EtherChannel
- Ports Gi1/0/21 and Gi1/0/23 from the HQ-CoreSW1 switch to be defined in a LACP EtherChannel bundle
Reasons why channel will not form
- Speed and duplex
- Gi1/0/21: Full duplex & 100Mbps speed
- Gi1/0/23: Half duplex & 10Mbps speed
- Administrative mode
- Gi1/0/21: Trunk mode
- Gi1/0/23: Access mode
- Operational mode
- Gi1/0/21: Trunk mode
- Gi1/0/23: Down
- Line Protocol/Status state
- Gi1/0/21: Up/Up
- Gi1/0/23: Down/Down
Matching Parameter Scenario
Scenario 2: Matching Parameters for the formation of an EtherChannel.
- Ports Gi1/0/21 and Gi1/0/23 from HQ-CoreSW1 to be defined in a LACP EtherChannel
Reasons why channel will form
- Speed and duplex
- Gi1/0/21: Full duplex & 100Mbps speed
- Gi1/0/23: Full duplex & 100Mbps speed
- Administrative mode
- Gi1/0/21: Trunk mode
- Gi1/0/23: Trunk mode
- Operational mode
- Gi1/0/21: Trunk mode
- Gi1/0/23: Trunk mode
- Line protocol/status state
- Gi1/0/21: Up/Up
- Gi1/0/23: Up/Up
- Matching VLANs & VLANs allowed List
- Additional check if ports are trunks
- Gi1/0/21
- Allowed VLANs in Trunk: 1-4094
- Active Defined VLANs: 1,20,30,40,80
- Gi1/0/23
- Allowed VLANs in Trunk: 1-4094
- Active Defined VLANs: 1,20,30,40,80
