交换机双工速率匹配

交换机若是双工出现问题，可能会出现很严重的丢包现象；若是速率不同，就直接无法正常通信。那么出现这种情况该怎么配置？

---

实验拓扑

使用两台交换机直连，每台下面再连接一台VPC。地址规划如下：

名称	IP地址
PC1	192.168.10.10/24
PC2	192.168.10.20/24

---

配置方法

接口模式下配置speed以及duplex。

SW1#configure terminal
SW1(config)#interface fastEthernet 1/0
SW1(config-if)#speed ?
  10    Force 10 Mbps operation
  100   Force 100 Mbps operation
  auto  Enable AUTO speed configuration
SW1(config-if)#duplex ?
  auto  Enable AUTO duplex configuration
  full  Force full duplex operation
  half  Force half-duplex operation

---

配置过程

SW1

• SW1关闭路由功能

SW1#configure terminal
SW1(config)#no ip routing

• 配置全双工，接口速率为100。

SW1(config)#interface fastEthernet 1/0
SW1(config-if)#speed 100
SW1(config-if)#duplex full

• 查询配置，show interfaces fastEthernet 1/0，第七行。

SW1(config-if)#end
SW1#show interfaces fastEthernet 1/0
FastEthernet1/0 is up, line protocol is up
  Hardware is Fast Ethernet, address is c201.2c14.f100 (bia c201.2c14.f100)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:04, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

SW2

• SW2配置与SW1相同，以下为简写配置过程。

SW2#conf t
SW2(config)#no ip routing
SW2(config)#int f1/0
SW2(config-if)#spe 100
SW2(config-if)#du f
SW2(config-if)#do show int f1/0
FastEthernet1/0 is up, line protocol is up
  Hardware is Fast Ethernet, address is c202.5d60.f100 (bia c202.5d60.f100)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:01, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

---

PING 测试

配置 IP 地址

PC1> ip 192.168.10.10 255.255.255.0
Checking for duplicate address...
PC1 : 192.168.10.10 255.255.255.0

PC2> ip 192.168.10.20
Checking for duplicate address...
PC1 : 192.168.10.20 255.255.255.0

PING

PC1> ping 192.168.10.20
84 bytes from 192.168.10.20 icmp_seq=1 ttl=64 time=1.884 ms
84 bytes from 192.168.10.20 icmp_seq=2 ttl=64 time=1.838 ms
84 bytes from 192.168.10.20 icmp_seq=3 ttl=64 time=0.947 ms
84 bytes from 192.168.10.20 icmp_seq=4 ttl=64 time=1.835 ms
84 bytes from 192.168.10.20 icmp_seq=5 ttl=64 time=0.846 ms

PC2> ping 192.168.10.10
84 bytes from 192.168.10.10 icmp_seq=1 ttl=64 time=0.922 ms
84 bytes from 192.168.10.10 icmp_seq=2 ttl=64 time=0.954 ms
84 bytes from 192.168.10.10 icmp_seq=3 ttl=64 time=1.846 ms
84 bytes from 192.168.10.10 icmp_seq=4 ttl=64 time=1.846 ms
84 bytes from 192.168.10.10 icmp_seq=5 ttl=64 time=0.995 ms

---

最后

交换机之间双工速率匹配如上，下一篇关于静态路由实验。