I. Introduction
II. What are Routers, Anyway?
III. Populating the Routing Table (RIB)
A. The RIB installation task
Evolution of Cisco Platforms (Sidebar)
1. Previously Unknown Route
2. More Specific Route
3. Lower Administrative Distance
4. Interior Routing Metric
B. Default Whatevers
1. Default Route
2. Default gateway
3. Default network
4. Gateway of Last Resort
IV. Packet Forwarding
A. Processing at the Input Interface
1. Physical Layer Processing
2. Framing and Error Control
B. Basic Forwarding
1. The FIB
How many Internet Routes? (Sidebar)
2. Lookup and Forwarding
C. Filtering and Special Cases in Forwarding
1. Load Sharing
Tag and Label Switching (Sidebar)
Where to Place Filters? (Sidebar)
2. Destination Unreachable and Destination Administratively Prohibited
3. Time to Live Exceeded
4. In and Out the Same Interface
Ping and Traceroute: Complementary Mechanisms (Sidebar)
D. Output Processing
1. IP Fragmentation
2. Replication for Multicasting and Broadcasting
3. Medium Issues
4. Output Prioritization