History

• Routing in some form or another is as old as the Internet

• • ARPANET IMP’s were gateways to local networks
  • • Supported a variety of protocol stacks, not much TCP/IP until 80’s

• IP routing as we know it dates to about 1985

• • Cisco popularized IP routers as an efficient way of connecting LANs on a campus

• Four basic generations of IP routers

• • Circa 1985-1990: PC/workstation based, simple, slow
  • Circa 1990-1995: Some CPU offload onto interfaces
  • Circa 1995-2000: CPU and bus out of forwarding path
  • Circa 2000-??: Network and general-purpose processors allow semi-off-the-shelf design instead of using custom ASICs