Routing is at the core of every data network, moving information across an internetwork from source to destination. Routers are the devices responsible for the transfer of packets from one network to the next.
Routers learn about remote networks either dynamically, using routing protocols, or manually, using static routes. In many cases, routers use a combination of both dynamic routing protocols and static routes. This chapter focuses on static routing.
Static routes are very common and do not require the same amount of processing and overhead as dynamic routing protocols.
In this chapter, sample topologies will be used to configure IPv4 and IPv6 static routes and to present troubleshooting techniques. In the process, several important IOS commands and the resulting output will be examined. An introduction to the routing table using both directly connected networks and static routes will be included.
This chapter will also contrast classful routing and the widely implemented classless routing methods. It will cover Classless Inter-Domain Routing (CIDR) and the variable-length subnet mask (VLSM) methods. CIDR and VLSM have helped conserve the IPv4 address space using subnetting and summarization techniques.