The way EtherChannel load balancing works is that the switch assigns a hash result from 0-7 based on the configured hash method ( load balancing algorithm ) for the type of traffic. This hash result is commonly called as Result Bundle Hash (RBH).
Now we need to convert Load value from Hexadecimal to Binary numbers. Therefore:
+ Gi1/1: 36 (Hex) = 00110110 (Bin) -> Bits 3, 4, 6, 7 are chosen
+ Gi1/2: 84 (Hex) = 10000100 (Bin) -> Bits 1, 6 are chosen
+ Gi1/3: 16 (Hex) = 00010110 (Bin) -> Bits 4, 6, 7 are chosen
Therefore if the RBH is 3, it will choose Gi1/1. If RBH is 4, it will choose Gi1/1 and Gi1/3 interfaces. If RBH is 6 it will choose all three above interfaces. And the bit sharing ratio is 3:3:2 (from “No of bits” column) hence two links has higher probability of getting utilized as compared to the third link.
All interfaces in an EtherChannel must be configured identically to form an EtherChannel. Specific settings that must be identical include:
+ Speed settings
+ Duplex settings
+ STP settings
+ VLAN membership (for access ports)
+ Native VLAN (for trunk ports)
+ Allowed VLANs (for trunk ports)
+ Trunking Encapsulation (ISL or 802.1Q, for trunk ports)
LACP is the IEEE Standard (IEEE 802.3ad) and is the most common dynamic Etherchannel protocol, whereas PAgP is a Cisco proprietary protocol and works only between supported vendors and Cisco devices.