Etherchannels

Consists of two parts:
 * 1) Port channel interface (Logical)
 * 2) Member interfaces (Physical)

The goal is to hide the member interfaces from the upper layer protocols (Spanning tree). Doing this is a means for cheap, incremental upgrades. This also adds redundancy at the link layer, ensuring a failed link does not drop the communication between switches.


 * Flows over the link cannot exceed the speed of member links.
 * Should only see LAG interfaces rather than member interfaces in CAM tables

For the exam questions, checking out VSS, VPC best practices. Need to know high level information.

Channel modes:
 * On - NO negotation
 * Desirable/Auto - PaGP
 * Active/Passive - LACP

Load balancing over LAG:
 * Source/Dst MAC
 * Source/Dst IP
 * Source/Dst Port
 * Balancing is only locally significant and outbound, can be mismatched on the other end
 * Should be adjusted based on traffic patterns


 * LAG is independent of port mode, can be access, trunk, layer2, layer3, etc...
 * LAG suffers from order of operations issues. Same config can work on one box and not on other based on way it was configured.