LTE: Indirect data forwarding tunnel ?

Question

While handover procedure is being executed, target MME triggers created indirect data forwarding tunnel request to target SGW what does it means and what is the use of it ?

Answer 1

Indirect data forwarding is used when there is a no direct link between source eNodeb to target eNodeB. I means x2 interface. In that situation downlink data which is coming from source SGW to source eNodeB, is forward back to source SGW and then target SGW (using indirect data forwarding tunnel) will send data to target eNodeB.

Comments

I see there is no interface between 2 SGW, how can data is forwarded from source SGW to target SGW? Thanks.