1) Assume that susbcriber is having lower specifications handset which can support of 300kbps in 2G radio, when susbcriber creates a session/starts browsing then GGSN will send QOS in CCR-I as 300kbps & PCRF will reply CCA-I as 400kbps (Assume that at PCRF end 400kbps plan is configured), subscriber can browse successfully & no extra messages in network
2) Assume that susbcriber is having lower specifications handset which can support of 300kbps in 2G radio, when susbcriber creates a session/starts browsing then GGSN will send QOS in CCR-I as 300kbps, PCRF will reply CCA-I as 400kbps (Assume that at PCRF end 400kbps plan is configured), subscriber can browse successfully, after sometime GGSN send CCR-U1 messages with event trigger revalidation timer expired & qos as 300kbps, PCRF will again execute policy function & allocate 400kbps in CCA-U1. Now GGSN again sends an CCR-U2 with 300kbps QOS-CHANGE as event trigger & again PCRF send 400kbps in CCA-U2, like this it go on loop.
/IPCANTYPE=3GPP-EPS mode/
Concern is why same qos send in case-1 is no loop messages, where as loop in case-2