show arp problem

Network Switches

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show arp problem

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Hello,

I have one Dell 3448 now. It have big different between "show arp" and "show bridge address-table".  Please check the below output.  Is it why they have big different?

When I type show arp

# show arp

ARP timeout: 60000 Seconds

   Interface      IP address        HW address          status
--------------- --------------- ------------------- ---------------
vlan 1          192.168.168.200  00:18:51:9d:50:b6   dynamic

but when I type using show bridge address-table

# show bridge address-table
Aging time is 300 sec

  Vlan        Mac Address       Port     Type
-------- --------------------- ------ ----------
   1       00:17:0e:a1:64:09     e1    dynamic
   1       00:18:18:70:b1:18     e1    dynamic
   1       00:18:51:9d:50:b6     e1    dynamic
   1       00:18:51:b1:4a:70     e1    dynamic
   1       00:1c:23:d1:99:00     e1    dynamic
   1       00:24:dc:0b:a1:07     e1    dynamic
   1       00:26:f1:b9:09:80     e1    dynamic
   1       00:26:f1:bb:88:80     e1    dynamic
   1       00:30:18:a9:c9:11     e1    dynamic
   1       00:80:48:ba:d1:30    e25     secure
   1       84:2b:2b:0a:6b:1f    e25     secure
   1       84:2b:2b:0a:6b:21    e25     secure
   1       d4:85:64:6b:38:b0     e1    dynamic
   1       d4:85:64:6b:e0:94     e1    dynamic
   1       d4:85:64:c8:10:4a     e1    dynamic
   1       d8:d3:85:ae:26:0c     e1    dynamic

Thanks!

All Replies
  • The show ARP command displays entries in the ARP table, and the show bridge address-table command displays all entries in the bridge-forwarding database.

    The ARP table allows a device to resolve a Layer 3 address (IP address) into a Layer 2 address (MAC address). The ARP table is populated as devices issue ARP broadcasts looking for a network device’s Layer 2 (MAC address).

    The forwarding database is used at layer 2 to store the MAC addresses that have been learned and which ports that MAC address was learned on.

    I hope this information helps. Are you seeing any specific issue, or just a general question?

    Thanks

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  • Hi,

    Thanks for your description.

    Firstly want to know how ARP learn, my understand is when some traffic go thru that port.  For example e25.  The ARP table will record at least MAC will shown.  However, the above result will not shown it have arp data recorded for e25

    Furthermore, I am looking for some method that mapping each ethernet port + IP + MAC together, and then trying to work some method for doing port security which base on port + IP + MAC address together.  

    Did any idea base on this?  But it have device limitation, because it just is Dell 3448

    Thanks!

  • Unfortunately on the switch there is not a show command that will display the MAC and IP Address for a device plugged into a specific port. There is some third party software out there that can acquire this information from the network.

    If a device is not showing up in the show bridge address-table, what we can do is issue a ping command from the device to another device on the network. That should send out a broadcast, and then be listed.

    Here is another post, where we went through a similar situation.

    en.community.dell.com/.../20219908.aspx

    The end result is that it is quicker and easier to use 3rd party software to help map out network devices and what plugs into them.

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  • Hello,

    I also tried to generate some traffic out to see can switch get the information from there no not.  However, that is no luck for me, so that is some of my queries.

    The another situation you mentioned also very similar but not usable for me.  Also, I just using lower end product, so many command also did not support.

    BTW, any 3rd parties software can suggest?  or PM to me if not allow to post here.  

    Thanks!

  • I do not have any specific mapping software that I would recommend over any other. But doing a quick search I found some that look like they would provide the information you need.

    http://angryip.org/w/Download

    http://nmap.org/

    I am sure there are several more like these out and available.

    If you find something that works for you, let us know what you used and how you liked it.

    Download the Dell Quick Resource Locator app today to access PowerEdge support content on your mobile device! (iOS, Android, Windows)