在步骤5交换机S1和S2之间的网线拔掉期间,PCA向PCB发送的UDP消息,在步骤6交换机S1和S2之间的网线重新插上之后,PCB是否还能收到?请解释为什么会出现这种现象?
时间: 2023-06-12 11:06:22 浏览: 75
在步骤5交换机S1和S2之间的网线拔掉期间,PCA向PCB发送的UDP消息会被丢失,因为交换机会根据MAC地址表将消息转发至S2,但是由于网线被拔掉,S2无法将消息转发至PCB。
在步骤6交换机S1和S2之间的网线重新插上之后,PCB有可能无法收到之前丢失的UDP消息。原因是,UDP是无连接的协议,不具备重传机制,当消息丢失后,发送端不会再次发送该消息。如果PCB在消息丢失期间未能收到该消息,那么就无法再次获取该消息了。只有当PCA再次向PCB发送相同内容的UDP消息时,PCB才能接收到该消息。
因此,对于UDP协议来说,消息的可靠性不能得到保证,如果需要可靠传输,可以选择使用TCP协议。
相关问题
三个交换机分别为S1、S2、S3,两台PC分别为PCA和PCB,如果两台主机都属于不同的VLAN,要想实现主机之间的互通,三台交换机上需要怎么配置,用H3C
要实现不同VLAN下的主机之间的互通,需要进行以下配置:
1. 在交换机上创建VLAN并指定VLAN ID,例如创建VLAN 10和VLAN 20:
```
[Switch] vlan 10
[Switch-vlan10] vlan-id 10
[Switch] vlan 20
[Switch-vlan20] vlan-id 20
```
2. 配置交换机的端口为Trunk口,使得可以传输多个VLAN的数据,例如将S1的1号口和S2的1号口配置为Trunk口:
```
[Switch] interface GigabitEthernet1/0/1
[Switch-GigabitEthernet1/0/1] port link-type trunk
[Switch-GigabitEthernet1/0/1] port trunk allow-pass vlan 10 20
[Switch] interface GigabitEthernet1/0/1
[Switch-GigabitEthernet1/0/1] port link-type trunk
[Switch-GigabitEthernet1/0/1] port trunk allow-pass vlan 10 20
```
3. 配置交换机的端口为Access口,使得主机可以加入指定的VLAN,例如将PCA连接的端口配置为Access口并加入VLAN 10,将PCB连接的端口配置为Access口并加入VLAN 20:
```
[Switch] interface GigabitEthernet1/0/2
[Switch-GigabitEthernet1/0/2] port link-type access
[Switch-GigabitEthernet1/0/2] port default vlan 10
[Switch] interface GigabitEthernet2/0/2
[Switch-GigabitEthernet2/0/2] port link-type access
[Switch-GigabitEthernet2/0/2] port default vlan 20
```
4. 最后需要在交换机上配置路由,使得不同VLAN下的主机可以相互通信,例如在S1上配置路由:
```
[Switch] ip routing
[Switch] interface Vlanif10
[Switch-Vlanif10] ip address 10.0.0.1 24
[Switch-Vlanif10] quit
[Switch] interface Vlanif20
[Switch-Vlanif20] ip address 20.0.0.1 24
[Switch-Vlanif20] quit
[Switch] interface GigabitEthernet1/0/2
[Switch-GigabitEthernet1/0/2] port link-type access
[Switch-GigabitEthernet1/0/2] port default vlan 10
[Switch-GigabitEthernet1/0/2] arp broadcast enable
[Switch-GigabitEthernet1/0/2] quit
[Switch] interface GigabitEthernet1/0/1
[Switch-GigabitEthernet1/0/1] port link-type trunk
[Switch-GigabitEthernet1/0/1] port trunk allow-pass vlan 10 20
[Switch-GigabitEthernet1/0/1] quit
[Switch] interface GigabitEthernet2/0/1
[Switch-GigabitEthernet2/0/1] port link-type trunk
[Switch-GigabitEthernet2/0/1] port trunk allow-pass vlan 10 20
[Switch-GigabitEthernet2/0/1] quit
[Switch] interface Vlanif10
[Switch-Vlanif10] ip address 10.0.0.1 24
[Switch-Vlanif10] quit
[Switch] interface Vlanif20
[Switch-Vlanif20] ip address 20.0.0.1 24
[Switch-Vlanif20] quit
[Switch] ip route-static 20.0.0.0 255.255.255.0 192.168.1.2
[Switch] ip route-static 10.0.0.0 255.255.255.0 192.168.1.1
```
其中,192.168.1.1和192.168.1.2分别为S1和S2连接的路由器的IP地址。此时,PCA的IP地址应该为10.0.0.x,PCB的IP地址应该为20.0.0.x,可以通过ping命令测试它们之间的互通性。
三个交换机分别为S1、S2、S3,两台PC分别为PCA和PCB,如果两台主机都属于同一个VLAN,要想实现主机之间的互通,三台交换机上需要怎么配置,用H3C
在这种情况下,需要在三个交换机上进行以下配置:
1. 创建VLAN,并将两台主机分配到该VLAN中:
```
<S1> system-view
[S1] vlan 10
[S1-vlan10] quit
[S1] interface GigabitEthernet 1/0/1
[S1-GigabitEthernet1/0/1] port link-type access
[S1-GigabitEthernet1/0/1] port default vlan 10
[S1-GigabitEthernet1/0/1] quit
```
```
<S2> system-view
[S2] vlan 10
[S2-vlan10] quit
[S2] interface GigabitEthernet 1/0/1
[S2-GigabitEthernet1/0/1] port link-type access
[S2-GigabitEthernet1/0/1] port default vlan 10
[S2-GigabitEthernet1/0/1] quit
```
```
<S3> system-view
[S3] vlan 10
[S3-vlan10] quit
[S3] interface GigabitEthernet 1/0/1
[S3-GigabitEthernet1/0/1] port link-type access
[S3-GigabitEthernet1/0/1] port default vlan 10
[S3-GigabitEthernet1/0/1] quit
```
2. 配置交换机之间的链路:
```
<S1> system-view
[S1] interface GigabitEthernet 1/0/2
[S1-GigabitEthernet1/0/2] port link-type trunk
[S1-GigabitEthernet1/0/2] port trunk allow-pass vlan 10
[S1-GigabitEthernet1/0/2] quit
```
```
<S1> interface GigabitEthernet 1/0/3
[S1-GigabitEthernet1/0/3] port link-type trunk
[S1-GigabitEthernet1/0/3] port trunk allow-pass vlan 10
[S1-GigabitEthernet1/0/3] quit
```
```
<S2> system-view
[S2] interface GigabitEthernet 1/0/2
[S2-GigabitEthernet1/0/2] port link-type trunk
[S2-GigabitEthernet1/0/2] port trunk allow-pass vlan 10
[S2-GigabitEthernet1/0/2] quit
```
```
<S2> interface GigabitEthernet 1/0/3
[S2-GigabitEthernet1/0/3] port link-type trunk
[S2-GigabitEthernet1/0/3] port trunk allow-pass vlan 10
[S2-GigabitEthernet1/0/3] quit
```
```
<S3> system-view
[S3] interface GigabitEthernet 1/0/2
[S3-GigabitEthernet1/0/2] port link-type trunk
[S3-GigabitEthernet1/0/2] port trunk allow-pass vlan 10
[S3-GigabitEthernet1/0/2] quit
```
```
<S3> interface GigabitEthernet 1/0/3
[S3-GigabitEthernet1/0/3] port link-type trunk
[S3-GigabitEthernet1/0/3] port trunk allow-pass vlan 10
[S3-GigabitEthernet1/0/3] quit
```
这样,三个交换机之间的链路就配置好了,两台主机也都分配到了同一个VLAN中,它们之间就可以互相通信了。