Ernie's Ethernet Switch Port Rules for 10/100MB Interface Links

1. End user ports for PCs and Laptops should always be set to auto-negotiate on both sides of the link
   - Cisco Switch:
      speed auto
      duplex auto
   - PC or Laptop also in auto
    
   - Never set one side of any link to a forced mode and leave the other side in "auto" (This will definitely result in a duplex mismatch!)
   - Do not set end user switch ports to forced 100MB Full-Duplex. (Many users are not "Admins" on their PC and will not be able to set their device!)
   - Do not get cute and set the laptop to 100MB Full-Duplex. (When the user goes home, their low end switch only knows how to do "Auto" most likely!)
    
2. Switch to Switch and / or Switch to Server ports should always be locked to 100MB Full-Duplex on both sides of the link
   - Cisco Switch (both switches / both sides of the physical link):
      speed 100
      duplex full
      * Requires a "Cross Over" cable since forcing a link shuts off "Auto-MDIX" as well on switch to switch connections (not needed for switch to server)
   - Server set for 100MB Full-Duplex also
    
   - Always set both sides of a link (switch and server) to 100MB Full-Duplex

Myth: "Setting one side of a link to 100MB Full-Duplex is good enough, auto-negotiate will figure out the other side and make a match"
           False! If one side of a link is forced to 100MB Full-Duplex and the other side is in "auto" will result in duplex mismatch.

Golden Rule: If  you set one side of a link to 100MB Full-Duplex, always set the other side to 100MB Full-Duplex as well.
                    * Requires a "Cross Over" cable on switch to switch connections.