recently, i have deployed some new 2960 stackable switch to replace 3750 switches(will be used in other location),
I enabled IP dhcp snooping, DAI and IPSG feature, some as previous configuration in 3750 switches.
I found some strange behavior.
I turned on IP dhcp snooping first, and run for a few days to make sure the switch has the binding entry for every clients/ip phone, (i manually reset the phone), then i enable DAI for data vlan and voice vlan, everything works fine.
finally, i enable IPSG, the ip phone with PC attached behind works fine, but some ip phones without pc attached lost connection and screen shows registering. i check the switch IPSG info, it shows
2960PT_21FLR_ES01#show ip verify source
Interface Filter-type Filter-mode IP-address Mac-address Vlan
--------- ----------- ----------- --------------- ----------------- ----
Gi1/0/21 ip active 10.167.153.112 53
Gi1/0/21 ip active deny-all 34
Gi1/0/40 ip active 10.167.153.116 53
Gi1/0/40 ip active deny-all 34
Gi1/0/41 ip active 10.167.153.166 53
Gi1/0/41 ip active 10.167.134.103 34
Gi2/0/7 ip active 10.167.153.160 53
Gi2/0/7 ip active 10.167.134.164 34
[voice vlan 34, data vlan 53]
Gi1/0/21 is connecting to a phone without PC attached, and the phone works fine.
Gi1/0/40 is also connecting to a phone without PC attached, and lost connection immediately.
once i disable the IPSG at the respective port (gi1/0/40), the phone returns to normal.
ip dhcp snooping vlan 34,53
no ip dhcp snooping information option
ip dhcp snooping database flash:dhcpsnooping.dat
ip dhcp snooping database write-delay 15
ip dhcp snooping
ip arp inspection vlan 34,53
switchport access vlan 34
switchport mode access
switchport voice vlan 53
srr-queue bandwidth share 10 10 60 20
mls qos trust device cisco-phone
mls qos trust cos
auto qos voip cisco-phone
service-policy input AutoQoS-Police-CiscoPhone
ip dhcp snooping limit rate 10
any one encountered the some problem before? any suggestion?
thanks a lot