Section: 7.7.9 Unknown or unexpected Information Element
Content: The receiver of a GTP message including an unexpected information element with known Type value, but with the instance value that is not defined for this message shall discard the IE and log an error. The receiver shall process the message. An information element with a Type value which is defined in clause 8.1 of the present specification but whose Instance Value is not expected in the received GTP signalling message according to the grammar defined in clause 7 of the present specification shall be silently discarded (skipped) and the rest of the message processed as if this information element was not present. NOTE: An Information Element in an encoded GTPv2 message or grouped IE is identified by the pair of IE Type and Instance value.