Shulou(Shulou.com)06/01 Report--

1. Real-life routing tables

In real life, the routing table is a road sign that allows you to reach your destination. And the data of computer equipment to reach the target also needs to have a "road sign", which is called routing in the network.

two。 Routin

Routing is the key to the operation of the network, learning the network is often studying how to use routing, how to plan.

In real life, we have road signs to show the way, and we can also use mobile phone maps to navigate the way. Similarly, you may not know the route at all, but the taxi driver will send you to the target. There is also an one-to-one correspondence in the network world, the network world is the reflection of the real world, and the network is created by people.

2.1. What is routing?

Send data from the source device to the next device. Just like road signs in real life, go to the crossroads and use the road signs to guide you to your goal.

2.2. Functions of the router

The router is a routing service and is used for three-layer routing.

The main job of the router is to find the best path through each host packet of the router, and effectively transmit the data to the destination site.

2.3. Three principles of routing:

1. Longest mask routing principle: when multiple routes can match the destination address, select the route with the longest mask

Example: when the masks of / 24 and / 25 bits can be matched, the longest mask is matched and the routing interface E0 of / 25 is selected.

two。 Administrative distance (AD) routing principle: when multiple routes can match the destination address, and the mask is the same (skip the longest mask matching principle), administrative distance is used for routing, the smaller the administrative distance, the better.

3. Metric (metric value): when multiple routes can match the destination address, and the mask is the same (skip the longest mask matching principle), and the administrative distance is the same (the same protocol, the administrative distance (AD) routing principle is skipped). Judge the measurement value within the same agreement

2.3. Route classification

Routing is divided into: directly connected routes, static routes, dynamic routes

1. Directly connected routing: a route connected between devices and device interfaces

two。 Static routes: manually configured rout

3. Dynamic routing: routes learned through dynamic routing protocols

2.3.1 directly connected rout

The route between the device and the device interface:

View the directly connected routes in the routing table: the directly connected routes in the routing table above are composed as follows:

To be continued.

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