LTE: What is the maximum no. of PLMNs served by a MME in MME pool ?

Question

I saw S1 SETUP RESPONSE message which has value of "maxnoofPLMNsPerMME" is 32.
But one eNodeB can broadcast up to six PLMNs only. In that case what could be the reason of assigning value 32 to the "maxnoofPLMNsPerMME" parameter ?

Answer 1

You are correct that an MME can be configured with max 32 PLMNs and eNB can be configured with max 6 PLMNs. Both these are operator configurable. Now, before broadcasting the PLMNs, eNB cross-checks if it's configured PLMNs are matching with the PLMNs in the MME's list. It broadcasts only those PLMNs which pass this check.
I believe, an MME can have a very large tracking area and within that different eNBs can be configured with different PLMNs by operator. That may be a reason why 3GPP has made the standardization in this manner and have chosen the numbers.