Routing and Switching Essentials ch 6
Next-Hop Options
The next hop can be identified by an IP address, exit interface, or both: Next-hop route - Only the next-hop IP address is specified. Directly connected static route - Only the router exit interface is specified. Fully specified static route - The next-hop IP address and exit interface are specified.
Default Static Route
A default route identifies the gateway IP address to which the router sends all IP packets in the case where it does have an entry in its routing table. A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address
Reach Remote Networks
A router can learn about remote networks in one of three ways: 1) Manually - Remote networks are manually entered into the route table using static routes. "S" 2) Dynamically - Remote routes are automatically learned using a dynamic routing protocol. "R"
Floating Static Route
Floating static routes are static routes that are used to provide a backup path to a primary static or dynamic route, in the event of a link failure. The floating static route is only used when the primary route is not available. To accomplish this, the floating static route is configured with a higher administrative distance than the primary route.
Floating Static Routes
Floating static routes are static routes that have an administrative distance greater than the administrative distance of another static route or dynamic routes: The administrative distance of a static route can be increased to make the route less desirable than that of another static route or a route learned through a dynamic routing protocol. In this way, the static route "floats" and is not used when the route with the better administrative distance is active. However, if the preferred route is lost, the floating static route can take over, and traffic can be sent through this alternate route.
Fully Specified Static Route
In a fully specified static route: Both the output interface and the next-hop IP address are specified. This is another type of static route that is used in older IOSs This form of static route is used when the output interface is a multi-access interface and it is necessary to explicitly identify the next hop. The next hop must be directly connected to the specified exit interface.
When to Use Static Routes
Providing ease of routing table maintenance in smaller networks Routing to and from stub networks. A stub network is a network accessed by a single route, and the router has no other neighbors. (i.e. a dead end street that has only one entrance.) There is not a more specific match with another route in the routing table For Default, Summary and Floating (Backup) routes
Static Route Applications
Static Routes are often used to: Connect to a specific network. Provide a Gateway of Last Resort for a stub 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.
Why Use Static Routing?
Static routing has the following disadvantages: Initial configuration and maintenance is time-consuming. Configuration is error-prone, especially in large networks. Administrator intervention is required to maintain changing route information. Does not scale well with growing networks; maintenance becomes cumbersome. Requires complete knowledge of the whole network for proper implementation.
Why Use Static Routing?
Static routing provides some advantages over dynamic routing, including: Static routes are not advertised over the network, resulting in better security. Static routes use less bandwidth than dynamic routing protocols, no CPU cycles are used to calculate and communicate routes. The path a static route uses to send data is known.
