IP Options

• An IP packet header may end with a list of one or more options

• • This list will always be padded to a 32-bit boundary

• A number of IP options have been defined

• • Security level
  • Record route
  • Timestamp
  • Loose source routing
  • Strict source routing
  • Router alert

• Most options are unsupported, ignored or discarded

• • Their functionality has been assigned to other mechanisms
  • Some options can be generated with the “ping” program
  • Router alert is commonly used for multicast (IGMP) packets