LTE : How does an MME select SGW for a new user and what things/terms are considered while selecting SGW ?

Question

I know SGW sends "DDN" to MME when it receives down link data for an IDLE UE. MME already knows ARP and other information of a bearer then why SGW includes ARP in DDN for a bearer.

Answer 1

Primarily TAI of UE (serving area) is used to select SGW. Further DNS resolves FQDN to an address. Topology is another controlling parameter for selecting SGW. It all depends on how network is deployed and accordingly selection parameters are triggered. For basic, TAI is used for selecting SGW