Design for Speed

• “Make the common case fast”

• Forwarding engines are designed to operate at line speed on “normal” IP packets

• • Streams of small packets can stress a router to its limits
  • Minimize reading and writing latencies with a wide bus

• “Abnormal” packets are given to main CPU for more complicated processing

• • IP options
  • ICMP
  • Packets destined to this router
  • Requires bus traversal and more computation
  • • Slow!