Ice based NAT traversal

摘要

An originating P-CSCF node receives a SIP INVITE request from first user equipment (UE) that originates a call to a second UE. If a relay candidate address for the first UE is not present in the SIP INVITE request, the SIP INVITE request is modified to include a first address provided by an originating IMS-AGW node as a relay candidate for the first UE and forwarded to the second UE. The originating P-CSDF node receives a SIP INVITE response message from the second UE in response to the SIP INVITE request. If a relay candidate address for the second UE is not present in the SIP INVITE response, the SIP invite response is modified to include a second address provided by an originating IMS-AGW node as a relay candidate for the second UE and forwarded t the first UE. The address information is used by both UEs in ICE operations.

主权项

1. A method for operating a call originating P-CSCF node for an Interactive Connectivity Establishment (ICE) based network address translation (NAT) traversal in a communications network including an IP Multimedia Subsystem (IMS), a first user equipment (UE), and a second UE, the method comprising:
receiving a SIP Invite message originating from the first UE, the SIP Invite message comprising candidate address information for the first UE; and performing operations as follows when a server reflexive candidate address for the first UE is present in the candidate address information for the first UE and a relay candidate address for the first UE is not present in the candidate address information for the first UE:
modifying the SIP Invite message candidate address information for the first UE to include a first address provided by an originating IMS Access Gateway (AGW) node as the relay candidate address for the first UE; andforwarding the modified SIP Invite message to a further IMS node for routing the SIP Invite message to the second UE; forwarding the received SIP Invite message to the further IMS node for routing the SIP Invite message to the second UE when the server reflexive candidate address for the first UE is not present in the candidate address information for the first UE or the relay candidate address for the first UE is present in the candidate address information for the first UE; and wherein the candidate address information for the first UE is for use by the second UE when performing ICE operations; receiving a SIP Invite response message originating from the second UE, the second UE is behind a terminating IMS AGW node, the SIP Invite response message including candidate address information for the second UE; and performing operations as follows when a server reflexive candidate address for the second UE is present in the candidate address information for the second UE and a relay candidate address is not present in the candidate address information for the second UE:
modifying the SIP Invite response message candidate address information for the second UE to include a second address provided by the originating IMS AGW node as the relay candidate address for the second UE; andforwarding the modified SIP Invite response message to the first UE; wherein the first UE is behind a first NAT device, the first NAT device being connected between the originating IMS AGW node and the first UE, the method further comprising instructing the originating IMS AGW node to perform address latching towards the first UE for discovering the transport address the first NAT device uses for the first UE; and wherein the second UE is behind a second NAT device, the second NAT device being connected between the terminating IMS AGW node and the second UE, the method further comprising instructing the originating IMS AGW node to perform address latching towards the second UE for discovering the transport address the second NAT device uses for the second UE.