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This chapter is from the book

This chapter is from the book

Summary (2.6)

In this chapter, you learned how IPv4 and IPv6 static routes can be used to reach remote networks. Remote networks are networks that can only be reached by forwarding the packet to another router. Static routes are easily configured. However, in large networks, this manual operation can become quite cumbersome. Static routes are still used, even when a dynamic routing protocol is implemented.

Static routes can be configured with a next-hop IP address, which is commonly the IP address of the next-hop router. When a next-hop IP address is used, the routing table process must resolve this address to an exit interface. On point-to-point serial links, it is usually more efficient to configure the static route with an exit interface. On multi-access networks, such as Ethernet, both a next-hop IP address and an exit interface can be configured on the static route.

Static routes have a default administrative distance of 1. This administrative distance also applies to static routes configured with a next-hop address, as well as an exit interface.

A static route is only entered in the routing table if the next-hop IP address can be resolved through an exit interface. Whether the static route is configured with a next-hop IP address or exit interface, if the exit interface that is used to forward that packet is not in the routing table, the static route is not included in the routing table.

Using CIDR, several static routes can be configured as a single summary route. This means fewer entries in the routing table and results in a faster routing table lookup process. CIDR also manages the IPv4 address space more efficiently.

VLSM subnetting is similar to traditional subnetting in that bits are borrowed to create subnets. With VLSM, the network is first subnetted, and then the subnets are subnetted again. This process can be repeated multiple times to create subnets of various sizes.

The ultimate summary route is a default route, configured with a 0.0.0.0 network address and a 0.0.0.0 subnet mask for IPv4, and the prefix/prefix-length ::/0 for IPv6. If there is not a more specific match in the routing table, the routing table uses the default route to forward the packet to another router.

A floating static route can be configured to back up a main link by manipulating its administrative value.

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