Hello,
We have a system in VLAN 1, it has IP 146.103.0.113. The catalysts have interface VLAN1 disabled and no ip address assigned. Sometimes, we cannot SSH or telnet from itnetadm towards the catalysts. We can do so from another system called Monalisa (, 146.103.0.112, you can ssh from itnetadm towards monalisa). When this condition exists, and I do a show ARP on the catalyst, I can see the MAC address of itnetadm directly in the ARP cash of the switch on its VLAN 1 interface. That is the reason why the ssh does not work: the switch answers the ssh tcp setup directly, because it has a direct ARP entry, but I don't know why. Bug? There is no reason why the switch has an ARP entry of a node on another subnet.
Itnetadm is also syslog server and tftp server. We can induce this situation by doing a copy run tftp://146.103.0.113/test.cfg on the cli. After doing that, the arp entry of itnetadm apprears again (for no reason in my opinion) in the ARP cahce, but this time, on vlan 142, with the MAC address of the router instead of the MAC address of Itnetadm.
See the result in the arp table:
cat5131#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.14.2.1 44 0000.0c07.ac8e ARPA Vlan142
Internet 10.14.2.118 - 7cad.7431.2941 ARPA Vlan142
Internet 146.103.0.113 7 0017.a4a7.effc ARPA Vlan1
cat5131#
cat5131#clear arp
cat5131#
cat5131#
cat5131#
cat5131#copy run tftp://146.103.0.113/test.cfg
Address or name of remote host [146.103.0.113]?
Destination filename [test.cfg]?
!!
43581 bytes copied in 3.129 secs (13928 bytes/sec)
cat5131#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.14.2.1 0 0000.0c07.ac8e ARPA Vlan142
Internet 10.14.2.118 - 7cad.7431.2941 ARPA Vlan142
Internet 146.103.0.113 0 547f.eeb0.c9c1 ARPA Vlan142
cat5131#
If I do a debug arp , i see some messages arp gleaning ....
What is the explanation of the arp gleaning because this message appear after the command " copy running-config to tftp "
Thanks for your help,
kind regards,
