Three test cases covering the MME pool selection logic in OsmoS1GW:
* TC_mme_pool_reject_fallback: S1GW falls back to the next pool entry when the first MME rejects S1SetupReq with S1SetupFailure. * TC_mme_pool_timeout_fallback: S1GW falls back when the first MME does not respond to S1SetupReq within the timeout. * TC_mme_pool_all_reject: all pool entries reject S1SetupReq; S1GW must send S1SetupFailure to the eNB and tear down the connection.
Infrastructure added to support these tests:
* S1AP_Server.ttcn: S1AP_ServerList type; directed register/unregister helpers (f_ConnHdlr_s1ap_register_to / _unregister_from) for use when multiple S1AP_Server_CT instances are active simultaneously. * S1GW_ConnHdlr.ttcn: f_ConnHdlr_s1ap_setup_pool() drives the pool setup sequence: pre-registers with all servers, sends S1SetupReq once (S1GW re-transmits it per-MME), then iterates through the expected behaviors (ACCEPT / REJECT / TIMEOUT) waiting for each server in turn. * S1GW_Tests.ttcn: f_init_s1ap_srv(N) starts N MME emulators on consecutive IP addresses; f_TC_exec_pool() orchestrates pool tests. * osmo-s1gw.config: a 'mme_pool' section with three entries is added alongside the existing sctp_client section. Older OsmoS1GW (without pooling support) will use sctp_client to connect to a single MME and the pool test cases will simply fail, as expected. Newer OsmoS1GW will use mme_pool and all three test cases will pass.
