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]