Tunnels

=GRE Tunnels=


 * Point to Point IP tunnel
 * IP proto 47
 * Can have multiple transport protocols within the payload
 * Steps to establish a tunnel
 * Create tunnel interface
 * Define source and destination
 * Apply payload protocols via addressing
 * Optional keepalives
 * Similar configuration to IP in IP tunnel
 * Different protocol number
 * Not a multi protocol encapsulation
 * Changed with **tunnel mode ipip** on the interface config
 * GRE packet contains multiple v4 headers