CM-IMS video conference system networking requirements
December 14, 2020
1. Cr interface open video conference The interface between AS and MRS is called Cr interface. China Mobile's CM-IMS video conference system improves the Cr interface on the basis of the framework and basic interface primitives provided by the 3GPP protocol and expands to support high-definition video Functions such as conference, scheduled conference, data conference and auxiliary video.
2. The video conference MRS entry mode requires SBC Full Proxy function: NAT traversal between different networks is realized through the proxy of signaling and media. The signaling agent completes the conversion of IP address ports in the SIP header fields such as Contact and Via, and the conversion of RTP / RTCP address ports carried in the media agent SDP.
The networking requirements of A-SBC and I-SBC: In the enterprise LAN, terminals and AS / MRS are divided into different VLANs. If the upstream firewall is connected to a Layer 2 device, VLAN TRUNK should be enabled to map different VLANs inside the firewall to different VLANs; if it is a Layer 3 device, sub-interfaces should be enabled to map different VLANs inside the firewall to different sub-interfaces.
Media sinking requirements: If A-SBC and I-SBC are co-located, SBC will associate the dialogue on both sides of the video conference AS according to the SDP address and port information carried in the SDP offer message of the northbound interface caller, and judge based on the firewall uplink address The terminal and MRS are located on the same corporate network, so that the media address and port in the SDP are set to the address and port in the corporate LAN. If A-SBC and I-SBC are separated, the calling SBC needs to extend the SIP header in the message carrying the SDP offer to carry the firewall uplink address information. The called SBC parses the extended SIP header. If it finds that the called party and the calling party are in the same firewall address or address segment, the media address and port in the SDP are set to the address and port in the corporate LAN.
3. Network interworking Interworking with China Mobile's TD network: setting up VIG equipment at the CM-IMS and TD network interworking point, co-located with the MGCF, and co-located with the MGCF. When the CM-IMS video conference platform calls TD users, the CSCF analyzes the media information to route the call to the VIG, completes SIP and ISUP / BICC signaling conversion at the VIG, and routes the call to the GMSC; the TD user video calls the CM-IMS video In the conference platform, GMSC selects the route to VIG according to the USI and TMR information of ISUP, and VIG completes the signaling conversion between ISUP / BICC and SIP.
Self-built H.323 network interworking with group customers: Build IBCF, IBGP and IWF network elements in the CM-IMS network to achieve H.323 network interworking with group customers. Among them, IBCF and IBGP are the boundary function entities of the control plane and user plane between the operator's CM-IMS network and other SIP and H.323 networks. IWF completes the interworking between different SIPs or between SIP and H.323 protocols.
