switch老化时间过长导致主机不通解决一例

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一台switch上能ping通，另一台不能ping通，得到的mac address也和另外一台不同。

Core-3750-1#ping 172.16.86.47

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.86.47, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms

Core-3750-1#sh ip arp | in 172.16.86.47

Internet  172.16.86.47            0   984b.e16b.5315  ARPA   Vlan86

Core-3750-1#sh mac address-table | in 984b.e16b.5315

  86    984b.e16b.5315    DYNAMIC     Gi1/0/4

 

Core-3750-2#ping 172.16.86.47

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.86.47, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

Core-3750-2#sh ip arp | in 172.16.86.47

Internet  172.16.86.47           44   3c4a.92fa.93a4  ARPA   Vlan86

Core-3750-2#sh mac address-table | in 3c4a.92fa.93a4

  86    3c4a.92fa.93a4    DYNAMIC     Po1

Core-3750-2#

Core-3750-2#clear arp-cache //在switch2上先清除mac address-tables以解决暂时不能访问的问题。

Core-3750-2#sh ip arp | in 172.16.86.47

Internet  172.16.86.47           16   984b.e16b.5315  ARPA   Vlan86  //已更新回来

//查看及更新switch上的mac address-tables的老化时间

Core-3750-1#sh interfaces po1

Port-channel1 is up, line protocol is up (connected)

  Hardware is EtherChannel, address is 30e4.dba3.fb17 (bia 30e4.dba3.fb17)

  MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, link type is auto, media type is unknown

  input flow-control is off, output flow-control is unsupported

  Members in this channel: Gi1/0/23 Gi1/0/24

  ARP type: ARPA, ARP Timeout 04:00:00  //默认机器老化时间为4小时

  Last input 00:00:00, output 00:00:00, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1700

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 11447000 bits/sec, 2752 packets/sec

  5 minute output rate 13052000 bits/sec, 2762 packets/sec

     63149721869 packets input, 44232956472023 bytes, 0 no buffer

     Received 1581074482 broadcasts (520448140 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 520448140 multicast, 0 pause input

     0 input packets with dribble condition detected

     74776492349 packets output, 62375481517592 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

Core-3750-1#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

Core-3750-1(config)#int po1

Core-3750-1(config-if)#arp timeout 3600

Core-3750-1(config-if)#end

Core-3750-1#wr

Building configuration...

[OK]

Core-3750-1#sh interfaces po1

Port-channel1 is up, line protocol is up (connected)

  Hardware is EtherChannel, address is 30e4.dba3.fb17 (bia 30e4.dba3.fb17)

  MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, link type is auto, media type is unknown

  input flow-control is off, output flow-control is unsupported

  Members in this channel: Gi1/0/23 Gi1/0/24

  ARP type: ARPA, ARP Timeout 01:00:00 //更改老化时间为1小时

  Last input 00:00:00, output 00:00:00, output hang never

  Last clearing of "show interface" counters never

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1700

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 13595000 bits/sec, 2969 packets/sec

  5 minute output rate 13102000 bits/sec, 2891 packets/sec

     63149839463 packets input, 44233057907548 bytes, 0 no buffer

     Received 1581074997 broadcasts (520448426 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 520448426 multicast, 0 pause input

     0 input packets with dribble condition detected

     74776581352 packets output, 62375504932495 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     0 babbles, 0 late collision, 0 deferred

     0 lost carrier, 0 no carrier, 0 PAUSE output

     0 output buffer failures, 0 output buffers swapped out

Core-3750-1#