3. Static Routing

Static Routing

A routing method where routes to remote networks are manually entered into the router's routing table.

Router Learning Remote Networks

A router can learn remote networks manually using static routes or dynamically using a routing protocol.

Static Route Topology Behavior

Static routes are not automatically updated when the topology changes and must be manually reconfigured.

Common Static Route Uses

Smaller networks that are not expected to grow, stub networks, and a single default route to represent a path to other networks.

Stub Network

A network that is accessed by a single route and has one neighbor.

Static Route Applications

Connect to a specific network, connect a stub router, summarize routing table entries, and create a backup route.

Standard Static Route

A static route configured to reach a specific remote network.

Default Static Route

A route that matches packets when no more specific route exists in the routing table.

IPv4 Default Route

0.0.0.0/0

Gateway of Last Resort

A default route used when no more specific route exists in the routing table.

Default Static Route Usage

Connecting an edge router to an ISP or connecting a stub router to its single upstream neighbor.

Summary Static Route

A single static route that represents multiple routes using one summarized network address.

Static Route Summarization Requirement

Destination networks must be contiguous.

Static Route Summarization Path Requirement

Multiple routes must use the same exit interface or next hop.

Floating Static Route

A static route configured as a backup path with a higher administrative distance than the preferred route.

Floating Static Route Purpose

Provides a backup route when the primary route becomes unavailable.

Default Administrative Distance of Static Route

1

Administrative Distance of EIGRP

90

Administrative Distance of OSPF

110

Administrative Distance of RIP

120

Higher Administrative Distance

The route becomes less preferred and is used only when the preferred route is unavailable.

IPv4 Static Route Command

ip route network-address subnet-mask ip-address | exit-int

network-address

The destination network address of the remote network.

subnet-mask

The subnet mask of the remote network being added to the routing table.

ip-address

The next-hop router's IP address.

exit-int

The outgoing interface used to forward packets toward the destination network.

IPv4 Static Route Next-Hop Options

Next-hop IP address, exit interface, or both the next-hop IP address and exit interface.

Next-Hop Static Route

A static route that specifies only the next-hop IP address.

Route Resolvability

The router's process of determining the exit interface needed to reach the specified next-hop address.

Recursive Lookup

A process where the router performs another routing-table lookup to determine how to reach the next-hop address.

Down Exit Interface Effect

The static route is not installed in the routing table.

Directly Connected Static Route

A static route that specifies the router's exit interface instead of a next-hop IP address.

Fully Specified Static Route

A static route that specifies both the next-hop IP address and the exit interface.

IPv6 Fully Specified Static Route Requirement

Required when an IPv6 link-local address is used as the next-hop.

Static Route Verification

show ip route static

Static Route Routing Table Code

S

Candidate Default Route Symbol

*

/0 Meaning

None of the bits are required to match.

IPv4 Default Static Route Command

ip route 0.0.0.0 0.0.0.0 next-hop-ip | exit-interface

IPv6 Routing Command

ipv6 unicast-routing

IPv6 Static Route Command

ipv6 route ipv6-prefix prefix-length ipv6-address | exit-intf

IPv6 Static Route Types

Next-hop static IPv6 route, directly connected static IPv6 route, and fully specified static IPv6 route.

IPv6 Default Static Route

A route that matches all IPv6 packets not specified by another route.

IPv6 Default Route Prefix

::/0

IPv6 /0 Meaning

None of the bits are required to match.

Static Route Troubleshooting Commands

ping, traceroute, show ip route, show ip interface brief, and show cdp neighbors detail.