7.1 Path Management Messages

29.2743GPP3GPP Evolved Packet System (EPS)Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)Release 18Stage 3TS

7.1.0 General

Three path management messages are specified for GTP-C: Echo Request, Echo Response and Version Not Supported Indication.

The usage of Echo Request / Response procedure is specified in 3GPP TS 23.007 [17].

7.1.1 Echo Request

Table 7.1.1-1 specifies the information elements included in the Echo Request message.

The Recovery information element contains the local Restart Counter, which is specified in 3GPP TS 23.007 [17])

The optional Private Extension contains vendor or operator specific information.

Table 7.1.1-1: Information Elements in Echo Request

Information elements	P	Condition / Comment	IE Type	Ins.
Recovery	M		Recovery	0
Sending Node Features	CO	This IE shall be sent towards a peer node on any GTPv2 interface if the sending node supports at least one feature on this interface or if the sending node supports at least one feature and does not know the interface type towards the peer node. This IE may be present otherwise.	Node Features	0
Private Extension	O		Private Extension	VS

7.1.2 Echo Response

Table 7.1.2-1 specifies the information elements included in the Echo Response message.

The Recovery information element contains the local Restart Counter, which is specified in 3GPP TS 23.007 [17])

The optional Private Extension contains vendor or operator specific information.

Table 7.1.2-1: Information Elements in Echo Response

Information elements	P	Condition / Comment	IE Type	Ins.
Recovery	M		Recovery	0
Sending Node Features	CO	This IE shall be sent towards a peer node on any GTPv2 interface if the sending node supports at least one feature on this interface or if the sending node supports at least one feature and does not know the interface type towards the peer node. This IE may be present otherwise.	Node Features	0
Private Extension	O		Private Extension	VS

NOTE: Having no Cause IE in the Echo Response message is an exceptional case for a triggered message. Hence, a GTP entity that detects a GTP protocol error, e.g Mandatory IE missing, in the Echo Request message, ignores the IE(s) that are in error and sends Echo Response. In addition it can log the error.

7.1.3 Version Not Supported Indication

This message contains only the GTPv2 header and indicates the latest GTP version that the sending entity supports.