端口如何根据IP地址查交换机端口

在一个Cisco交换网络中间， 已知某台机器的IP地址，如何找出它连接到了哪台交换机的哪个端口上呢?最方便快捷的方法使使用CiscoWorks 2000 LMS网管软件的User tracking功能，图形化界面，一目了然。

如果没有这个软件，也可以使用以下手工分析方法来找出答案:

示例网络:核心交换机为6509(交换引擎SE用CatOS, MSFC运行IOS软件)

1. 找出该IP所对应的MAC地址:

通过查看系统的ARP缓存表可以找出某IP所对应的MAC地址。由于ARP不能跨VLAN进行，所以连接各个VLAN的路由模块MSFC就是最佳的选择--一般它在每一个VLAN都有一个端口(interface vlann) ，能正确地进行ARP解释。

6509MSFC#ping 10. 10. 1.65

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10. 10. 1.65, timeout is2 seconds:

! ! ! ! !

Success rate is 100 percent (5/5) , round-trip min/avg/max= 1/1/4 ms

6509MSFC#show arp | in 10. 10. 1.65

Internet 10. 10. 1.65 2 0006.2973. 121d ARPA Vlan2

通过以上命令， 我们知道10. 10. 1.65 的 MAC地址是

0006.2973. 121d,这是IOS设备的MAC地址表达方式，在CatOS中，应写为00-06-29-73-12-1d.

2.在交换机上找出MAC地址所对应的端口

6509SE> (enable) show cam 00-06-29-73-12-1d

* = Static Entry. + = Permanent Entry. # = System Entry.R = Router Entry.

X = Port Security Entry $ = Dot1x Security Entry

VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /[Protocol Type]

2 00-06-29-73-12-1d 9/41 [ALL]

Total Matching CAM Entries Displayed =1

这是不是说IP为10. 10. 1.65的机器就接在端口9/41上呢?

不一定。如果以下命令中显示该端口上只有一个活动的MAC地址，那么答案就是肯定的:

6509SE> (enable) show cam dynamic 9/41

* = Static Entry. + = Permanent Entry. # = System Entry.R = Router Entry.

X = Port Security Entry $ = Dot1x Security Entry

VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /[Protocol Type]

---- ------------------ -----

-------------------------------------------

2 00-06-29-73-12-1d 9/41 [ALL]

Total Matching CAM Entries Displayed =1

如果该命令显示该端口上有多个活动的MAC地址，那么这个端口应该连接到别的交换机或HUB设备上，见下面的例子(查找IP为

10. 10. 1.250所对应的交换机端口) :

6509MSFC#ping 10. 10. 1.250

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10. 10. 1.250, timeout is2 seconds:

! ! ! ! !

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

6509MSFC#show arp | in 10. 10. 1.250

Internet 10. 10. 1.250 4 0009.6b8c.64ec ARPA Vlan2

6509SE> (enable) show cam 00-09-6b-8c-64-ec

* = Static Entry. + = Permanent Entry. # = System Entry.

R = Router Entry.

X = Port Security Entry $ = Dot1x Security Entry

VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /[Protocol Type]

---- ------------------ -----

-------------------------------------------

2 00-09-6b-8c-64-ec 3/11 [ALL]

Total Matching CAM Entries Displayed =1

6509SE> (enable) show cam dy 3/11

* = Static Entry. + = Permanent Entry. # = System Entry.R = Router Entry.

X = Port Security Entry $ = Dot1x Security Entry

VLAN Dest MAC/Route Des [CoS] Destination Ports or VCs /[Protocol Type]

1 00-03-e3-4b-06-80 3/11 [ALL]

1 00-08-02-e6-b0-cd 3/11 [ALL]

1 00-02-a5-ee-f2-4f 3/11 [ALL]

1 00-09-6b-8c-66-d6 3/11 [ALL]

1 00-09-6b-63-17-d9 3/11 [ALL]

1 00-0b-cd-03-ec-f5 3/11 [ALL]

1 00-09-6b-63-17-d8 3/11 [ALL]

1 00-08-02-e6-b0-c1 3/11 [ALL]

1 00-08-02-e6-b0-85 3/11 [ALL]

1 00-08-02-e6-b0-81 3/11 [ALL]

1 00-02-a5-ef-16-af 3/11 [ALL]

1 00-02-a5-ee-f2-93 3/11 [ALL]

1 00-02-55-c6-05-61 3/11 [ALL]

2 00-09-6b-8c-64-ec 3/11 [ALL]

1 00-08-02-e6-b0-ed 3/11 [ALL]

1 00-08-02-e6-b0-a9 3/11 [ALL]

1 00-02-55-54-7a-e0 3/11 [ALL]

1 00-02-a5-ef-15-a6 3/11 [ALL]

1 00-08-02-e6-af-8f 3/11 [ALL]

1 00-08-02-e6-b0-bd 3/11 [ALL]

1 00-0b-cd-03-db-8b 3/11 [ALL]

1 00-09-6b-8c-25-50 3/11 [ALL]

Do you wish to continue y/n [n]? n

由于该端口连接到另一台交换机或HUB,必须继续追查，方法如下:

6509SE> (enable) show cdp nei 3/11

* - indicates vlan mismatch.

# - indicates duplex mismatch.

Port Device-ID Port-ID Platform

------------------------- ------------

3/11 Cisco2924 GigabitEthernet1/1 cisco WS-C2924M-XL

该命令显示对端设备是一台Cisco2924，如果没有显示，那么说明连接的是别的厂家的设备，可能要到该交换机上用类似的办法继续追查。本例子中是Cisco设备，所有我们可以继续:

6509SE> (enable) show cdp nei 3/11 de

Port (Our Port) : 3/11

Device-ID: Cisco2924

Device Addresses:

IP Address: 10. 10.0.60

Holdtime: 153 sec

Capabi l ities: TRANSPARENT_BRIDGE SWITCH

Version:

Cisco Internetwork Operating System Software

IOS (tm) C2900XL Software (C2900XL-C3H2S-M) , Version

12.0(5.2)XU, MAINTENANCE INTERIM SOFTWARE

Copyright (c) 1986-2000 by cisco Systems, Inc.

Compiled Mon 17-Jul-00 17:35 by ayounes

Platform: cisco WS-C2924M-XL

Port-ID (Port on Neighbors' s Device) : GigabitEthernet1/1

VTP Management Domain: lan

Native VLAN: 1

Duplex: full

System Name: unknown

System Object ID: unknown

Management Addresses: unknown

Physical Location: unknown

Cisco2924#show mac-address-table dynamic address

0009.6b8c.64ec

Non-static Address Table:

Destination Address Address Type VLAN Destination Port

--------------------

0009.6b8c.64ec Dynamic 2 FastEthernet0/2

Cisco2924#show mac-address-table dynamic interface f0/2

Non-static Address Table:

Destination Address Address Type VLAN Destination Port

------------------- ------------ ----

--------------------

0009.6b8c.64ec Dynamic 2 FastEthernet0/2

通过以上命令可知， MAC地址0009.6b8c.64ec与Cisco 2924交换机相连，且是该端口上唯一活动的MAC地址，所以I P为10. 10. 1.250的机器应该就连接在这个端口上。