Mental wanderings of a lost mind
Some of the older UC520 systems were shipped with other firmware versions for the 521 and 524 phones. It seems there are a number of feature upgrades with the newer firmwares. One of which is the ability to enable the switch port on a 524SG model phone.
You should load at least 8.1.13 or higher firmware on the system.
Don’t forget to setup the tftp-server and load commands so that your phone updates.
I had the opportunity recently to troubleshoot some erratic and intermittent UC500 problems. The issues were everything from dropped calls to echo on some calls.
It seemed that two phones were actually bad and had to be replaced. But the real fun came when I checked out the log:
 070782: Apr 9 xx:xx:xx.xxx: %IP-3-LOOPPAK: Looping packet detected and dropped -
src=192.168.1.101, dst=192.168.1.1, hl=20, tl=229, prot=17, sport=138, dport=138
in=Vlan1, nexthop=192.168.1.1, out=Vlan1
options=none -Process= “IP Input”, ipl= 0, pid= 75, -Traceback= 0×80E38860 0×8131DCDC 0×8131F3C4 0×81560EC4 0×815611E8 0×81562A64 0×81306F24 0×8130ADD0 0×8130BC04 0×8130BCF4 0×8130BEB8 0×801778EC 0×8017A1EC
These entries were filling up the log fairly quickly. The first thing I noticed was that all the packets had the same port numbers: netbios. At this point I checked the interface configurations and found a configuration like this:
interface Vlan 1
ip address 192.168.1.1
ip helper-address 192.168.1.1
I can’t think of any good reason the helper-address would be pointed to itself, so I removed it. This resolved all the issues the customer was having outside of broken phones.Â
Simple fix, but very interesting impact on system functionality.