Cisco Switch IOS Command To Show MAC-to-IP Address Table

On a Cisco 3750 Catalyst switch what would be the command (or commands) to display the MAC Address to IP Address table mappings ?  At a site it needs to be determined, based on a particular IP address, what the associated MAC address is.  Also, is there some way from that command or another command to determine what interface that traffic is originating from ?  TIA ...
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JonathanSpitfireSenior Solutions EngineerCommented:
These commands are fairly universal on just about any Cisco IOS device made within the last 15 years:

show arp (or "sh arp") will give you the ARP table:

Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet             27   b6b4.767f.c4d7  ARPA   Vlan311
Internet              4   80b4.0b69.9f31  ARPA   Vlan311
Internet             22   a044.1cdb.5cdb  ARPA   Vlan310
Internet            178   2010.7a05.951e  ARPA   Vlan311
Internet              1   b63a.4b14.8a46  ARPA   Vlan311

"sh mac address-table" will give you the MAC address of all active devices and what port that MAC address is connected to:

          Mac Address Table

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
 300    0002.b7c9.5355    DYNAMIC     Fa1/0/33
 300    000c.bb39.53cb    DYNAMIC     Gi1/0/2
 300    0019.b79c.3d98    DYNAMIC     Fa1/0/14
 300    00c0.e348.9cb8    DYNAMIC     Fa1/0/19
 310    0003.f2e1.dfe6    DYNAMIC     Gi2/0/4
 310    0004.f2e8.73f5    DYNAMIC     Gi3/0/5
 310    a044.1cdb.5cdb    DYNAMIC     Gi3/0/15

In the example above, you can see that IP address corresponds to MAC address a044.1cdb.5cdb, which is on vlan 310 and connected to physical port Gigabit Ethernet 15 on switch stack 3 (3/0/15 - the first digit is 3 and that tells me that there are at least 3 switches in the stack).

To get information about the stack, just type, "show switch"

Hope this helps!


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LGroup1Author Commented:
Perfect, thanks !
LGroup1Author Commented:
This is perfect, thanks !
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