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

1. Static rout

Static routes are manually configured by the network administrator and need to be manually configured when the network topology changes.

1.1 static rout

Static routes are divided into static routes, default routes and static routes pointing to null0.

1.1.1 what is a static route?

In the existing network, static routing is often used only when it is simple, or only for small networks, because static routing is simple and does not have too complex routing principles.

In fact, static routing is also widely used in some complex networks, and static routing is often used to control the connection between internal and external networks.

How do I configure static routes?

The first step is to write the network segment = network address + mask composition.

Then follow the interface or IP address of the next hop.

Example:

Ip route 192.168.1.0 255.255.255.0 F0/0

Network segment: network address 192.168.1.0, mask 255.255.255.0

Next Hop: F0Comp0

1.1.2 default rout

A default route is a special static route.

In the real network, the default route is mostly used for the exit of a network (connecting to the operator network equipment), which throws all the unknown traffic of the intranet to the operator.

1. Customer terminals (computers, mobile phones) need to access unknown traffic or public network, and send the traffic to the layer 3 gateway through the default gateway.

two。 The layer 3 gateway is directed to the next-hop device egress router via a default route.

3. The egress route is directed to the next-hop device operator through the default route.

According to the longest mask matching principle, it is easy to understand how the default route works. If there is a route match with any other mask, you will certainly not be able to match a route with a mask of 0. Matches the default route when no routes match to this point.

1.1.3 static route null0

What is null0?

Null0 is actually an empty interface, and as long as the data is thrown into this interface, the data is discarded.

Routes to null0 are often designed to prevent loops.

For example, null0 is used in BGP route summarization, because there must be routes for BGP summarization, and for the loop problems caused by summarizing redundant network segments, while other correct network segments, because there are fine routes (longer than summary routes) will not match to the summary null0.

For example, in some scenarios, when the network segment of nat may not exist, null0 will be used to generate routes and no loops will be generated.

In the dynamic routing protocols learned later, a summary route is automatically generated when route summarization is performed, and this summary route points to null0.

The seemingly simple static reason is actually not that simple.

For example, static routes can be combined with various uses such as SLA, such as priority routing, such as import in various protocols, it is necessary to use static routes flexibly in complex networks, which will be added later.

to be continued

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