EtherChannel is a technology that combines multiple physical ports into a single logical link to increase bandwidth and provide fault tolerance. It supports three aggregation methods: LACP, PAgP, and static (manual configuration).
ASW -Access switch
DSW - Distribution switch
Port channel / LAG
#STATIC ETHERCHANNEL- ussually up to 16 (Catalist) / 256 (Nexus) port channel`s groups and up to 8 ports in each group
#PAgP - ussually up to 16 (Catalist) / 256 (Nexus) port channel`s groups and up to 8 ports in each group
#LACP 802.3ad - ussually up to 16 (Catalist) / 256 (Nexus) port channel`s groups and up to 16 ports in each group (8 active + 8 passive)
#Modes
#-Source MAC addresses - all frames with the same source MAC addresses will always use the same interface
#-Destination MAC address - all frames with the same destination address will always use the same interface
#-Source and Destination MAC addresses
#-Source IP
#-Destination IP
#-Source and Destination IP
====================LACP======================
active --> LACP
passive --> LACP
====
passive + passive --> no etherchannel
active + passive --> OK
active + active --> OK
====================PAgP======================
auto --> PAgP
desirable --> PAgP
====
auto + auto --> no etherchannel
desirable + auto --> OK
desirable + desirable --> OK
==============Static Ethercannel==============
on --> Static Ethercannel only
====
on + on --> OK
other combinations --> no etherchannel
#Check all interfaces have same speed and configuration, then do
enable
configure terminal
show etherchannel load-balance #show current mode
port-channel load-balance { src-mac| dst-mac | src-dst-mac | src-ip | dst-ip | src-dst-ip } #to choose mode
interface range GigabitEthernet0/1 - 2
channel-group <group_number> mode <choose a mode>
exit
interface Port-channel <group_number>
switchport mode trunk #access can be set too
switchport trunk allowed vlan 10,20,30 #add allowed VLANs (example)
exit
show etherchannel summary #to show etherchannel status, mode and its ports
show running-config | section Port-channel
show interfaces Port-channel <group_number>
show spanning-tree interface Port-channel <group_number>