在一個Cisco 交換網絡中間，已知某臺機器的IP地址，如何找出它連接到了哪臺交換機的哪個端口上呢?最方便快捷的方法使使用CiscoWorks 2000 LMS網管軟件的User tracking 功能，圖形化界面，一目了然。
如果沒有這個軟件，也可以使用以下手工分析方法來找出答案:
示例網絡:核心交換機為6509(交換引擎SE用CatOS, MSFC運行IOS軟件)
1. 找出該IP所對應的MAC地址:
通過查看系統(tǒng)的ARP緩存表可以找出某IP所對應的MAC地址。由于ARP不能跨VLAN進行，所以連接各個VLAN的路由模塊MSFC就是最佳的選擇--一般它在每一個VLAN都有一個端口(interface vlan n)，能正確地進行ARP解釋。
6509MSFC#ping 10.10.1.65
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.1.65, timeout is 2 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
通過以上命令，我們知道10.10.1.65的MAC地址是0006.2973.121d, 這是IOS設備的MAC地址表達方式，在CatOS中，應寫為00-06-29-73-12-1d.
2.在交換機上找出MAC地址所對應的端口
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
這是不是說IP為 10.10.1.65的機器就接在端口9/41上呢?
不一定。如果以下命令中顯示該端口上只有一個活動的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
如果該命令顯示該端口上有多個活動的MAC地址，那么這個端口應該連接到別的交換機或HUB設備上，見下面的例子(查找IP為10.10.1.250所對應的交換機端口):
6509MSFC#ping 10.10.1.250
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.1.250, timeout is 2 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
由于該端口連接到另一臺交換機或HUB,必須繼續(xù)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
該命令顯示對端設備是一臺Cisco2924，如果沒有顯示，那么說明連接的是別的廠家的設備，可能要到該交換機上用類似的辦法繼續(xù)追查。本例子中是Cisco 設備，所有我們可以繼續(xù):
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
Capabilities: 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
通過以上命令可知，MAC地址0009.6b8c.64ec 與Cisco 2924交換機相連，且是該端口上唯一活動的MAC地址，所以IP為10.10.1.250的機器應該就連接在這個端口上。
關鍵詞標簽：交換機端口
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