静态路由

1. Static Routing Implementation

1.1 Static Routing

A router can learn about remote networks in one of two ways:

• manually - Remote networks are manually entered into the route table using static routes.
• dynamically - Remote routes are automatically learned using a dynamic routing protocol.

Dynamic VS Static Routing

	Dynamic Routing	Static Routing
Configuration complexity	Generally independent of the network size	Increasees with network size
Topology Changes	Automatically adapts to topology changes	Administrator intervention required
Scaling	Suitable for simple and complex topologies	Suitable for simple topologies
Security	Less secure	More secure
Resource Usage	uses CPU, memor, link bandwidth	no extra resources needed
Predicability	route depends on the current topology	route to destiantion is alwasy same

 

Static routing has three primary uses:

•  Providing ease of routing table maintenance in smaller networks that are not expected to grow significantly.
•  Routing to and from stub networks.
•  Using a single default route to represent a path to any network that does not have a more specific match with another route in the routing table.

 

1.2 Types of Static Routes

•  Standard static route
•  Default static route
•  Summary static route
•  Floating static route

Standard static Routes: connect a specific remote network.

 

Default static routes are used:

•  When no other routes in the routing table match the packet destination IP address. In other words, when a more specific match does not exist. A common use is when connecting a company's edge router to the ISP network.
•  When a router has only one other router to which it is connected. This condition is known as a stub router.

 

To reduce the number of routing table entries, multiple static routes can be summarized into a single static route if:

•    The destination networks are contiguous and can be summarized into a single network address.
•    The multiple static routes all use the same exit interface or next-hop IP address.

 

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.

 

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实验：

静态路由&SLA