Can someone explain me the concept of an orphan packet?
and why i'm asking this? Because i´m seing in the syslog server the following msg:
*dtlArpTask: May 28 11:48:12.117: %DTL-4-ARP_ORPHANPKT_DETECTED: dtl_net.c:1425 STA(Target MAC Address) [,] ARP (op ARP REQUEST) received with invalid SPA(Source IP Address) 169.254.146.36/TPA(Destination IP Address) 169.254.146.36
Can anyone explain me this?
The message mean that there is a packet that does not belong to any valid registered client on the AP/WLC.
This can happen if a client was able to pass authentication but not able to get an IP address.(which looks like your case above where you have 169.254.x.x IP address).
If client could not get an IP address from DHCP it will automatically fall back to use APIPA Ip address (169.254..etc). Because this IP is not valid on the subnet the client is connected to the traffic will be consindered orphan traffic.
It also sometimes happens when some is connecting to web-auth WLAN and the session timeout expires while the DHCP enabled. in this case the L2 may try to re-connect automatically but the client is not releasing its IP before connectivity so it considered it having an IP address already and prevents him from connectivity. If session-timeout expires the client traffic will be considered orphan until it reconnect at L2 back again. (This is actually a sbuset of what fbarboza expressed above).
In your case your clients have bad ip address. assign them a good ip address and all will be fine.