Chapter 7: Static Routing Quiz

Chapter 7: Static Routing

• Static routing involves manually adding routes to a router's routing table.
• Routers can learn about remote networks manually (static routes) or automatically (dynamic routing protocols).
• Static routes provide better security than dynamic routing because the routes aren't advertised on the network.
• Static routes also use fewer CPU cycles and bandwidth than dynamic routing protocols.
• Static routing is not suitable for large networks or networks that frequently change, as the administrator must manually update the routes.
• Static routes are suitable for smaller networks or when the network topology is constant.

Objectives

• Explain the advantages and disadvantages of static routing.
• Explain the purpose of different types of static routes.
• Configure IPv4 static routes by specifying a next-hop address.
• Configure IPv4 default routes.
• Configure an IPv4 summary network address to reduce the number of routing table updates.
• Configure a floating static route to provide a backup connection.
• Explain how a router processes packets when a static route is configured.
• Troubleshoot common static and default route configuration issues.

Static Route Applications

• Connect to a specific network.
• Provide a Gateway of Last Resort for a stub network (a network that only has one connection to another network).
• Reduce the number of routes advertised by summarizing several contiguous networks as one static route.
• Create a backup route in case a primary route link fails.

Standard Static Route

• Static routes are used to reach a stub network.
• In the example diagram (page 10), a static route is utilized to enable direct communication to a stub network.
• No dynamic routing protocol needs to be utilized to reach the stub network.

Default Static Route

• A default static route matches all packets that do not match a more specific route.
• The default route identifies the gateway IP address to which the router sends all IP packets without a specific route.
• It uses 0.0.0.0/0 as the destination IP address.

Summary Static Route

• A summary static route can be used to represent multiple networks using a single route.
• The example on page 12 shows how four separate networks (172.21.0.0/16, 172.20.0.0/16, 172.23.0.0/16, and 172.22.0.0/16), can be represented by the single summary route 172.20.0.0/14.
• This reduces the number of routes in the routing table.
• Using a summary route significantly reduces the size of the routing table.

Floating Static Route

• Used as a backup route for other static or dynamically learned routes.
• A floating static route is only used when the primary route is unavailable.
• In cases of a failure of a primary route. a floating route will be used instead.
• To accomplish this, the floating static route is configured with a higher administrative distance than the primary route.

Configure IPv4 Static Routes

• The ip route command is used to configure static routes.
• The command syntax is ip route network-address subnet-mask {ip-address | exit-intf}, where:
  • network-address is the destination network address.
  • subnet-mask is the subnet mask of the destination network.
  • {ip-address | exit-intf} specifies either the next-hop IP address or the output interface.

Configure IPv4 Static Routes: Next-Hop Options

• Next-hop route (recursive): Only the next-hop IP address is specified.
• Directly attached (connected) static route: Only the router exit interface is specified.
• Fully specified static route: The next-hop IP address and exit interface are both specified.

Verify Static Routes

• Commands such as show ip route, show ip route static, and show ip route network can be used to verify static routes.
• ping and traceroute are useful for verifying connectivity.

Configure IPv4 Default Routes

• A default static route matches any network, using the command ip route 0.0.0.0 0.0.0.0 {ip-address | exit-intf}.

Configure IPv4 Summary Routes

• Route summarization, also known as aggregation, combines multiple network addresses into a single address with a less-specific subnet mask, reducing route table entries.

Troubleshoot Static Routes

• Common IOS troubleshooting commands like ping, traceroute, show ip route, show ip interface brief, and show cdp neighbors detail help diagnose problems with missing routes.

Chapter 7 Summary

• Static routes are manually configured using an IP address as the next-hop router.
• Resolving next-hop IP to an interface is done by the routing table process.
• Point-to-point serial links benefit from using the exit interface to configure static routes.
• Multi-access networks like Ethernet can configure a static route using an exit interface and a next-hop IP address.
• Static routes default administrative distance is 1.