Section: 11.2.2 Features supported by direct peer GTP-C entities
Content: A node shall signal to a direct peer node the list of features it supports by sending the Sending Node Features IE in every Echo Request and Echo Response messages to that node. An exception to this is where the sending node does not support or use any features towards the peer node and is not prepared to accept a message which is constructed by making use of any features. The peer receiving the Sending Node Features IE shall store the list of features supported by the sending node per IP address and only update this list based on the Sending Node Features IE in the Echo Request and Echo Response messages, and it shall only use common supported features to initiate subsequent GTPv2 messages towards this IP address. Receipt of an Echo Request or an Echo Response message without the Sending Node Features IE shall indicate that the sending node does not support any feature specified in Table 8.83-1 on the corresponding interface.