根據IP地址查交換機端口號

1. 找出該IP 所對應的MAC 地址

知道了IP地址，就知道了它所在VLAN的網關，通過查看網關的ARP 緩存表可以找出該IP 所對應的MAC 地址。比如我們要查找10.3.6.106這個IP，我們找到它所在的VLAN網關10.0.3.254，登陸網關後：

R04_Soft>ping 10.3.6.106

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.3.6.106, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
R04_Soft>show arp | in 10.3.6.106
Internet 10.3.6.106              1   000f.fee6.2012 ARPA   Vlan202

這樣我們就得到了它的MAC地址：00-0f-fe-e6-20-12

2. 在交換機上找出MAC 地址所對應的端口

R04_Soft>show mac-address-table dynamic address 00-0f-fe-e6-20-12
Unicast Entries
vlan   mac address     type        protocols               port
-------+---------------+--------+---------------------+--------------------
202    000f.fee6.2012   dynamic ip,ipx,other          GigabitEthernet3/3

這樣我們就得到了它的目標端口GigabitEthernet3/3。我們可以看看這個端口所連設備的詳細信息。
R04_Soft>show cdp nei Gi3/3 de
-------------------------
Device ID: B03S55
Entry address(es):
IP address: 10.0.3.55
Platform: cisco WS-C2960G-24TC-L, Capabilities: Switch IGMP
Interface: GigabitEthernet3/3, Port ID (outgoing port): GigabitEthernet0/21
Holdtime : 125 sec

Version :
Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version 12.2(25)FX, RELEAS
E SOFTWARE (fc1)
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Wed 12-Oct-05 22:05 by yenanh

advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=0000000
0FFFFFFFF010221FF000000000000001873A56C80FF0000
VTP Management Domain: 'cs'
Native VLAN: 1
Duplex: full
Management address(es):
IP address: 10.0.3.55
Unidirectional Mode: off

顯然這是一個交換機，那麼我們進入這臺下層交換機10.0.3.55繼續追查

B03S55>show mac-address-table dynamic address 00-0f-fe-e6-20-12
Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
202    000f.fee6.2012    DYNAMIC     Gi0/23
Total Mac Addresses for this criterion: 1

B03S55>show cdp nei Gi0/23 de
-------------------------
Device ID: B03S57
Entry address(es):
IP address: 10.0.3.57
Platform: cisco WS-C2960-24TT-L, Capabilities: Switch IGMP
Interface: GigabitEthernet0/23, Port ID (outgoing port): GigabitEthernet0/1
Holdtime : 148 sec

Version :
Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version 12.2(25)FX, RELEAS
E SOFTWARE (fc1)
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Wed 12-Oct-05 22:05 by yenanh

advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=0000000
0FFFFFFFF010221FF0000000000000018194DCB80FF0000
VTP Management Domain: 'cs'
Native VLAN: 1
Duplex: full
Management address(es):
IP address: 10.0.3.57

顯然這又是一臺下層交換機 = -|||，我們繼續往下。
要說明的是我們還可以通過確認該mac是否是這個端口唯一活動mac地址來明確是否是該MAC地址所在端口，比如：

B03S55>show mac-address-table dynamic interface gi0/23
Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
1    0018.194d.cb81    DYNAMIC     Gi0/23
1    0018.194d.cbc0    DYNAMIC     Gi0/23
202    0001.6c96.21a5    DYNAMIC     Gi0/23
202    000f.fee6.2012    DYNAMIC     Gi0/23
202    0012.3fcd.2121    DYNAMIC     Gi0/23
202    0012.3fcd.24c7    DYNAMIC     Gi0/23
202    0012.3fcd.2508    DYNAMIC     Gi0/23
202    0015.58e5.3898    DYNAMIC     Gi0/23
202    0015.58e5.3933    DYNAMIC     Gi0/23
202    0015.58e9.efb0    DYNAMIC     Gi0/23
202    0019.d14f.e0fd    DYNAMIC     Gi0/23
202    0019.d14f.e34e    DYNAMIC     Gi0/23
202    001a.6b65.ef77    DYNAMIC     Gi0/23
202    001b.b981.6c84    DYNAMIC     Gi0/23
202    001b.b984.6afd    DYNAMIC     Gi0/23
202    0021.85ce.b813    DYNAMIC     Gi0/23
202    0021.9719.dc12    DYNAMIC     Gi0/23
202    0024.811f.abbf    DYNAMIC     Gi0/23
202    005b.484f.0d53    DYNAMIC     Gi0/23
--More--

顯然不是 = =。我們繼續往下查下層交換機10.0.3.57

B03S57>show mac-address-table dynamic address 00-0f-fe-e6-20-12
Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
202    000f.fee6.2012    DYNAMIC     Fa0/22
Total Mac Addresses for this criterion: 1
B03S57>show mac-address-table dynamic interface Fa0/22
Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
202    000f.fee6.2012    DYNAMIC     Fa0/22
Total Mac Addresses for this criterion: 1

這個IP地址在這個交換機的22口上，接下來你可以幹你想幹的事了......