LTE: What is IP spoofing and which of the network node prevent to happen it ?

Question

When the IP packet has minimum size (20bytes), what happens to option field. Is it not present or present with all bits set to 0 (all 40bytes of 0's)?

Answer 1

IP spoofing is a mechanism by which an IP packet is generated with invalid source IP address. Network Gateways cross verify the source IP address of an IP packet going outside.
In case of LTE network, PGW assigns IP addresses to UEs. PGW is aware about the IP addresses which have been assigned to UEs. When an uplink packet reaches at PGW from UE, PGW first verify whether source IP address is valid or not. If source IP address is valid than only PGW forwards IP packet towards external network. This way, PGW prevents IP spoofing in LTE network.
Hope, I answered your query.

Answer 2

IP Spoofing is simply put IP source violations by UE by sending out packets with src address which was not assigned by P-GW/PDSN/GGSN. In such a case, NAS device (PGW/PDSN/GGSN) can be configured to implement a certain policy if IP Source Violations exceed a certain limit. The idea is to block such traffic before entering IP Core and avoid any possible sec threats or resource exploitation. In case of PDSN (CDMA NAS), AT device terminal can be enforced for PPP renegotiation. In LTE this could mean PDP context deactivation.