SNR S2989G-48TX-RPS — настройка маршрутизации и черной дыры в IPv4 [238/553]

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S2989G-24TX Operation Manual

Chapter 4 Routing Protocol Related Configuration

4-13

192.168.0.1/21

SWITCH1

SWITCH2

192.168.0.2/21

192.168.1.0/24

………

192.168.7.0/24

4.3.2

IPv4 Black Hole Routing Configuration Task

1. Configure IPv4 Black Hole Routing

Command

Explaination

Global Configuration Mode

ip route {<ip-prefix>

<mask>|<ip-prefix>/<prefix-length>}

null0 [<distance>]

no ip route {<ip-prefix>

<mask>|<ip-prefix>/<prefix-length>}

null0

To configure the static Black Hole Routing. The

no form of this command will remove the

specified Black Hole Routing configuration.

4.3.3

Black Hole Routing Configuration Exmaples

Example 1: IPv4 Black Hole Routing function.

Figure 4-3 IPv4 Black Hole Routing Configuration Example

As it is shown in the figure, in Switch 2, eight in all interfaces are configured as Layer

3 VLAN interfaces for access interfaces. The network addresses are 192.168.1.0/24 ~

192.268.7.0/24. A default routing is configured on Switch 2 to connect to Switch 1. And a

backward default routing is configured on Switch 1 to Switch 2, whose network address is

192.168.0.0/21. Commonly, this configuration will work well. However, if one of the Layer

3 interfaces in Switch 2 goes down, for example, the interface belonged to 192.168.1.0/24.

When datagrams arrives at VLAN1 in Switch 2, there will be no routing rules for these

datagrams. The switch then will forward these datagrams according to the default routing,