通过arp命令得到IP地址与MAC地址的对应关系,通过MAC地址找到交换机上对应的端口
如何根据IP地址查交换机端口呢
在一个Cisco 交换网络中间，已知某台机器的IP地址，怎样找出它相连到了哪台交换机的哪个端口上呢?
最方便快捷的方式使使用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式来找出答案: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:议决检查系统的ARP缓存表可以找出某IP所对应的MAC地址。因为ARP不能跨VLAN进行，所以相连各个VLAN的路由模块MSFC就是最佳的选择--通常它在每一个VLAN都有一个端口(interface vlan n)，能正确地进行ARP解释。6509MSFC#ping 10.10.1.65Type 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 ms6509MSFC#show arp in 10.10.1.65Internet 10.10.1.65 2 0006.2973.121d ARPA Vlan2议决以上命令，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 EntryVLAN 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运动的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 EntryVLAN 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运动的MAC地址，那么这个端口应该相连到别的交换机或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 10.10.1.250Type 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 ms6509MSFC#show arp in 10.10.1.250Internet 10.10.1.250 4 0009.6b8c.64ec ARPA Vlan2 下载地址 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 EntryVLAN 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 =16509SE> (enable) show cam dy 3/11* = Static Entry. + = Permanent Entry. # = System Entry. R = Router Entry.X = Port Security Entry $ = Dot1x Security EntryVLAN 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
因为该端口相连到另一台交换机或HUB,必须继续追查，方式如下:6509SE> (enable) show cdp nei 3/11* - indicates vlan mismatch.[ 不重启98更改IP地址 ]# - indicates duplex mismatch.Port Device-ID Port-ID Platform3/11 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，那么说明相连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IP地址,交换机。本例子中是Cisco 设备，全部我们可以继续:6509SE> (enable) show cdp nei 3/11 dePort (Our Port): 3/11Device-ID: Cisco2924Device Addresses:IP Address: 10.10.0.60Holdtime: 153 secCapabilities: TRANSPARENT_BRIDGE SWITCHVersion:Cisco Internetwork Operating System SoftwareIOS (tm) C2900XL Software (C2900XL-C3H2S-M), Version 12.0(5.2)XU,MAINTENANCE INTERIM SOFTWARECopyright (c) 1986-2000 by cisco Systems, Inc.Compiled Mon 17-Jul-00 17:35 by ayounesPlatform: cisco WS-C2924M-XLPort-ID (Port on Neighbors's Device): GigabitEthernet1/1VTP Management Domain: lanNative VLAN: 1Duplex: fullSystem Name: unknownSystem Object ID: unknownManagement Addresses: unknownPhysical Location: unknownCisco2924#show mac-address-table dynamic address 0009.6b8c.64ecNon-static Address Table:Destination Address Address Type VLAN Destination Port------------------- ------------ ---- --------------------0009.6b8c.64ec Dynamic 2 FastEthernet0/2Cisco2924#show mac-address-table dynamic interface f0/2Non-static Address Table:Destination Address Address Type VLAN Destination Port------------------- ------------ ---- --------------------0009.6b8c.64ec Dynamic 2 FastEthernet0/2议决以上命令可知，MAC地址0009.6b8c.64ec 与Cisco 2924交换机相连，且是该端口上唯一运动的MAC地址，所以IP为10.10.1.250的机器应该就相连在这个端口上。