A quick recap

• Every router forwards packets by consulting its routing table – destination network, next hop, and outgoing interface
• The router uses longest prefix match to pick the most specific route when several could apply
• This lecture focuses on one way those routes get into the table: an administrator typing them in manually

Route sources

• Connected (C) and Local (L): created automatically from an interface's IP address – Administrative Distance = 0
• Static (S): manually configured by an administrator – Administrative Distance = 1 by default
• Dynamic routing protocols (e.g., O for OSPF, D for EIGRP, R for RIP): learned automatically from neighbouring routers
• A router can hold routes from several sources for the same network at once – administrative distance decides which one is installed