Backoff Timer

Backoff time indicates the time during which the MME or S4-SGSN refrains from sending the subsequent PDN connection establishment requests to the PGW for the congested APN, for services other than service users or emergency services.

The backoff timer feature enables rejecting new attaches for the failure condition when IP addresses are exhausted.

When IP addresses are exhausted, the PGW-C/SMF detects the status as failure and adds backoff timer in Create Session Response. SGW forwards the backoff timer value to the MME in the Create Session Response.