285 lines
8.4 KiB
Markdown
285 lines
8.4 KiB
Markdown
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# 路由
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### 一、路由概述
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1. **什么是路由**
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> 数据包从一个网络到另外一个网络转发数据包的过程
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2. **支持路由功能的设备**
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> 路由器、三层交换机、防火墙
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3. **路由器转发数据包的依据**
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- 每一台路由器都维护着一张路由表
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- 路由器是依靠这张路由表来转发数据的
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- 这张路由表就类似于我们生活中的地图
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4. **查看路由表**
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```
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<Huawei>display ip routing-table //查看路由表
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目的地址 /掩码 协议 优先级 开销值 下一跳 出接口
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Destination/Mask Proto Pre Cost NextHop Interface
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```
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5. **路由分类**
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- 直连路由：路由器接口所直连的网段形成的路由信息 ,配置路由器接口IP并为UP状态自动生成
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- 非直连路由：
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静态路由：由管理员手动为路由器指定的路由信息
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动态路由：路由器通过路由协议学习到的路由信息
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- 静态路由配置格式：
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```
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ip route-static 目标网络号 子网掩码 下一跳
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```
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### 二、静态路由实验
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1. **拓扑**
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2. **需求**
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> 实现PC1可以和PC2 互联互通
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3. **分析**
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> PC1在192.168.1.0/24网段
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> PC2在192.168.4.0/24网段
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> 因为是跨网段通信，也叫非直连网段通信，所以我们使用静态路由
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> PC把目的地和自己不再同一网段的数据包，统统的交给网关，让网关帮忙转发数据
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4. **配置步骤**
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- 给PC配置IP地址
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- 给路由器R1和R2配置接口IP地址
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- 在路由器R1中配置去往192.168.4.0/24网段的路由
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- 在路由器R2中配置回程路由，去往192.168.1.0/24网段的路由
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5. **配置命令**
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- PC1的IP地址配置：192.168.1.1，网关地址192.168.1.254
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PC2的IP地址配置：192.168.2.1，网关地址192.168.2.254
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- 第一步：配置R1路由器（接口IP地址和静态路由 ）
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- R1的配置：
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```
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<R1>u t m
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<R1>sys
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[R1]int g0/0/0 //进入接口g0/0/0
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[R1-GigabitEthernet0/0/0]ip address 192.168.2.1 24 //配置接口IP地址
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[R1-GigabitEthernet0/0/0]int g0/0/1 //进入接口g0/0/1
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[R1-GigabitEthernet0/0/1]ip address 192.168.1.254 24 //配置接口IP地址
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[R1-GigabitEthernet0/0/1]quit //退回到系统视图
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[R1]ip route-static 192.168.4.0 24 192.168.2.2 //配置静态路由，目的地：192.168.4.0/24 网段，下一跳地址：192.168.2.2
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```
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- 第二步：配置R2路由器（接口IP地址和静态路由）
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- R2的配置：
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```
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<R2>un t m
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<R2>sys
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[R2]int g0/0/0
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[R2-GigabitEthernet0/0/0]ip address 192.168.4.254 24
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[R2-GigabitEthernet0/0/0]int g0/0/1
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[R2-GigabitEthernet0/0/1]ip address 192.168.2.2 24
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[R2-GigabitEthernet0/0/1]quit
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[R2]ip route-static 192.168.1.0 24 192.168.2.1
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```
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- 第三步：验证测试
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```
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<R1>display ip routing-table 192.168.4.1 //验证R1有没有去往4.1的路由
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Destination/Mask Proto Pre Cost NextHop Interface
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192.168.4.0/24 Static 60 0 192.168.2.2 GigabitEthernet0/0/0
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<R2>display ip routing-table 192.168.1.1 //验证R2有没有去往1.1的回程路由
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Destination/Mask Proto Pre Cost NextHop Interface
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192.168.1.0/24 Static 60 0 192.168.2.1 GigabitEthernet0/0/1
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```
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- 重要字段解析
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- Destination：表示这条路由的目的地址
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- Mask：表示目的地址的子网掩码长度
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- Proto：表示这条路由的路由协议
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- Pre：表示这条路由的路由协议优先级，优先级数值越小越优先
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- NextHop：表示这条路由的下一跳地址， 下一跳地址就是指数据转发的下一个设备
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- Interface：表示这条路由的出接口，指明数据将从本地路由器哪个接口转发出去
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> 备注： 不同的路由协议优先级不一致，比如：
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> Direct：直连路由优先级为 0
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> Static：静态路由优先级默认为 60
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> OSPF： OSPF优先级默认为 10
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### 三、路由的配置
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1. **路由器转发数据包IP地址与MAC地址的封装变化**
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> 不同网络的主机通信，IP地址始终保持不变，MAC地址一直在变。
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> 数据包在网络中传输时，源IP地址和目的IP地址一直不变，但是源MAC地址和目的MAC地址每经过一个网段，就会发生一次变化
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2. **多路由器-配置静态路由实现全网互通**
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1. 拓扑
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2. 需求
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> 全网互通
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3. 配置
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> 配置路由器的接口IP地址，掩码
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>
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> 配置PC的IP地址，掩码、网关
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>
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> 配置静态路由(非直连网段通信)
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- 步骤1：配置R1和R2和R3的接口IP地址
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```
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[R1]interface GigabitEthernet 0/0/0
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[R1-GigabitEthernet0/0/0]IP address 192.168.1.254 24
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[R1-GigabitEthernet0/0/0]QUIT
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[R1]interface GigabitEthernet 0/0/1
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[R1-GigabitEthernet0/0/1]IP address 192.168.2.1 24
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```
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```
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[R2]interface GigabitEthernet 0/0/1
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[R2-GigabitEthernet0/0/1]IP address 192.168.2.2 24
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[R2-GigabitEthernet0/0/1]QUIT
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[R2]interface GigabitEthernet 0/0/0
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[R2-GigabitEthernet0/0/0]ip address 192.168.3.1 24
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```
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```
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[R3]interface GigabitEthernet 0/0/1
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[R3-GigabitEthernet0/0/1]ip address 192.168.3.2 24
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[R3-GigabitEthernet0/0/1]quit
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[R3]interface GigabitEthernet 0/0/0
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[R3-GigabitEthernet0/0/0]ip address 192.168.4.254 24
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```
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- 步骤2：配置PC1和PC2的IP地址及网关
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- 步骤3：配置静态路由
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```
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[R1]ip route-static 192.168.3.0 24 192.168.2.2
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[R1]ip route-static 192.168.4.0 24 192.168.2.2
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```
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```
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[R3]ip route-static 192.168.2.0 24 192.168.3.1
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[R3]ip route-static 192.168.1.0 24 192.168.3.1
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```
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```
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[R2]ip route-static 192.168.4.0 24 192.168.3.2
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[R2]ip route-static 192.168.1.0 24 192.168.2.1
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```
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- 验证与测试
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```
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PC1 ping 192.168.4.1
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192.168.3.2
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192.168.2.2
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```
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3. **默认路由实验**
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- 默认路由配置格式：
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> ip route-static 0.0.0.0 0 下一跳
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> 0.0.0.0表示任意网络ID
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> 0表示任意子网掩码
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- 拓扑
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> 接前一个实验环境
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- 删除R1与R3的明细静态路由
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```
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[R1]undo ip route-static 192.168.3.0 24 192.168.2.2
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[R1]undo ip route-static 192.168.4.0 24 192.168.2.2
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```
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```
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[R3]undo ip route-static 192.168.2.0 24 192.168.3.1
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[R3]undo ip route-static 192.168.1.0 24 192.168.3.1
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```
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- R1与R3配置置认路由
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```
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[R1]ip route-static 0.0.0.0 0 192.168.2.2
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[R3]ip route-static 0.0.0.0 0 192.168.3.1
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```
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- 验证与测试
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```
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PC1 ping 192.168.4.1
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192.168.3.2
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```
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4. **默认路由的隐患**
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- 拓扑
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- 需求
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> 全网互联互通
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- 配置命令
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- R4的配置
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```
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[R4]int g0/0/0
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[R4-GigabitEthernet0/0/0]ip address 192.168.1.254 24
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[R4-GigabitEthernet0/0/0]int g0/0/1
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[R4-GigabitEthernet0/0/1]ip address 192.168.2.1 24
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[R4]ip route-static 0.0.0.0 0 192.168.2.2 //配置默认路由
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```
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- R5的配置
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```
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[R5]int g0/0/1
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[R5-GigabitEthernet0/0/1]ip address 192.168.2.2 24
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[R5-GigabitEthernet0/0/1]int g0/0/0
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[R5-GigabitEthernet0/0/0]ip address 192.168.3.254 24
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[R5]ip route-static 0.0.0.0 0 192.168.2.1 //配置默认路由
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```
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- 验证测试
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```
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PC1 ping PC2 发现可以互联互通
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在做别的验证：PC1 ping 192.168.5.1（这个网段在网络中不存在）
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这个时候就会出现三层路由环路
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所以，两台直连的设备不能相对的配置默认路由，一边是默认路由，那么另外一边要配置明细路由
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```
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