Can MME use entire range of TEID?

Question

Do carriers limit the size of the TEID pools?

Answer 1

Four octets have been used for TEID in GTP-C packet header. TEID value ranges from 2^32 - 1. It's my personal thoughts Ideally no operator would like to use a subset of TEID value space since there are a number of interfaces MME has toward other nodes.
For Example: During attach procedure, when MME sends create session request to SGW then It sends "0" as TEID value. MME doesn't know what value SGW will assign in create session response. SGW can TEID value as 2^32 -1 . In such scenario, MME and all the other nodes which have direct interfaces with MME should apply same configuration in respective application like each application will use value ranges from 2^24-1. But still GTP-C packet format will not be altered.

Please correct me if I am wrong.

Answer 2

Yes not just MME but all node can practically use whole TEID. In practice upper bits are used to identify the card/rack/thread etc and lower bit are used to identify the tunnel within the module, though there is no standard to handle TEID in a particular way.