UE Access Information Relay for IMS Policy Control
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Solution Overview
Problem
In IMS networks, user equipment (UE) faces challenges in accessing external servers when policy control is applied, as it cannot use STUN Relays/Servers external to the visited network, even if the UE knows their addresses, and the policy and/or charging enforcement function (PCEF) may not differentiate between filters for encapsulation protocols and media streams.
Innovation Solution
A method where the UE sends access information, including network addresses and protocols, to the P-CSCF during the IMS registration phase, allowing the P-CSCF to relay this information to the PCRF, which establishes policy and charging control rules to enable communication with external servers, including STUN Relays, by opening necessary gates for network traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If policy control is applied in the IMS network, then network security and control are improved, but the UE cannot contact external servers (such as STUN Relays) that are not advertised by the visited network
Solution Approach 1:
The UE performs preliminary action by sending access information (including external server addresses) to the P-CSCF during the IMS registration phase, before actually needing to contact external servers. This allows the network to pre-configure policy rules in the PCRF, so that when the UE needs to contact external servers like STUN Relays, the policy gates are already in place, resolving the contradiction between security control and external server accessibility
Solution Approach 2:
The P-CSCF acts as an intermediary between the UE and the PCRF. It receives access information from the UE, relays it to the PCRF, and receives back policy rules. This intermediary mechanism allows the policy control system to manage external server access without blocking legitimate communications, balancing security control with adaptability
2Adaptability or versatility
If the PCEF opens gates for all network traffic, then external server access is improved, but the PCEF cannot differentiate between filters for encapsulation protocols and media streams
Solution Approach 1:
The access information sent by the UE includes segmentation of different protocol types (encapsulation protocols like UDP/IP for STUN, and media streams). The PCRF receives this segmented information and creates differentiated policy rules for each protocol type, allowing the PCEF to apply appropriate filters without opening all gates indiscriminately, thus reducing complexity while maintaining access capability
Solution Approach 2:
Different policy rules with different quality characteristics are applied to different protocol types locally. Encapsulation protocol traffic receives one type of policy treatment, while media stream traffic receives another type of policy treatment. This local quality differentiation allows the PCEF to handle each protocol appropriately without needing complex global filter management
3Reliability
If the UE sends media packets first to allocate NAT addresses, then NAT traversal is enabled, but the UE cannot receive media packets until it sends them first
Solution Approach 1:
The UE performs preliminary action by sending access information including its address information to the P-CSCF during registration, which allows the network to pre-configure policy rules. This preliminary addressing information enables the UE to receive media packets without having to send media packets first, as the address allocation is handled through the policy control mechanism rather than requiring proactive media packet transmission
Data Source
AI summary
It is disclosed a method comprising holding access information relating to a terminal and a first network entity external to a currently visited network of the terminal, the access information being associated with a first network plane below a second network plane relating to network session initiation, and signaling, based on the second network plane, the held access information to a controlling entity; a method comprising receiving the signaled access information, the receiving being performed based on the second network plane, and relaying, based on the second network plane, the received access information to a second network entity; and a method comprising receiving the relayed access information, the receiving being performed based on the second network plane, and configuring the first network plane based on the access information.