When do IP's show up in the SHOW ARP command?

I do not fully understand when an IP address will show up in the output of the SHOW ARP command.  For example, I have a VLAN on my CISCO 4006 Switch and I know there 4 dell PC's are connected to it.  I thought that the IP's for those PC's would show up in the output of a SHOW ARP command so I could then get the MAC addresses of those PC's, run a SHOW MAC ADDRESS command, and find the port they are connected to.  However, even though these PC's have been connected for quite some time, their IP addresses do not appear when I run a SHOW ARP command.  
frank_nyeAsked:
Who is Participating?
 
RPPreacherConnect With a Mentor Commented:
When something makes an ARP request to them.

Just ping each PC, the switch should populate the ARP table.
0
 
knightfoxCommented:
that correct.. you should be able to do a show arp.  Could you please try and ping one of the IP addresses then run:

Router#sh ip arp
Internet  x.x.x.x             -   000b.fc48.xxx  ARPA   Vlanxxx
Internet  x.x.x.x             -   000b.fc48.xxx  ARPA   Vlanxxx
Internet  x.x.x.x             -   000b.fc48.xxxx  ARPA   Vlanxxx
Internet  x.x.x.x             -   000b.fc48.xxx  ARPA   Vlanxxx

/Fox

0
 
knightfoxCommented:
then to show the port do:

Router#sh mac-address table | i xxxx

xxx is the last four chars of the mac address... and you should see

 xxx    0000.0c07.xxx    DYNAMIC    Gi0/1

/Fox
0
Worried about phishing attacks?

90% of attacks start with a phish. It’s critical that IT admins and MSSPs have the right security in place to protect their end users from these phishing attacks. Check out our latest feature brief for tips and tricks to keep your employees off a hackers line!

 
frank_nyeAuthor Commented:
If I do a PING command while in ENABLE mode on the switch, does it start a ping and continually run it or does it just send out a few pings and then stop?  On some devices (I think some test equipment like a Fluke Etherscope) I have seen a PING request go out and then it just keeps on running and runing.  I want to make sure I don't start something like that on the Switch.  If I just run the command PING 10.0.4.20 on the switch, will it only send out a few pings?
0
 
RPPreacherCommented:
5 pings.
0
 
knightfoxCommented:
you can do it either ping.. and enter the number of pings you want.. or just use ping x.x.x.x and use

CTRL + Shift + 6 to escape the ping

/Fox
0
 
frank_nyeAuthor Commented:
Thanks everyone.  I got it.
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.