Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

FG IPTV-C-1120e.doc

174 views

Published on

  • Be the first to comment

  • Be the first to like this

FG IPTV-C-1120e.doc

  1. 1. INTERNATIONAL TELECOMMUNICATION UNION FOCUS GROUP ON IPTV TELECOMMUNICATION FG IPTV-C-1120 STANDARDIZATION SECTOR STUDY PERIOD 2005-2008 English only WG(s): 4 7th FG IPTV meeting: Qawra, St Paul’s Bay, Malta, 11 – 18 December 2007   CONTRIBUTION Source: Huawei Technologies Co., Ltd. Title: Some Editorial Comments to Overlay Multicast Networking 1, Introduction As agreed by WG4 in previous 6th FGIPTV meeting, Section 10 – “Overlay Multicast Networking” in the working document – “IPTV Multicast frameworks” should be separated into two parts. One part keeps most of the general, high level description of overlay multicast functions in Section 10, while another part which addresses some detailed description of overlay multicast is moved to Appendix. This contribution suggests such editorial comments to some sub-clauses of Section 10. 2, Discussion <<The following text is part of high level description of overlay multicast networking and can be kept in Section 10 as main text.>> 10.1.3 IMA Backup Because data stream will break if IMA goes out of work, it is important to deploy backup function for IMA to guarantee service quality. The following IMA backup selection functions are required:  Nodes broadcast their load status to other nodes of multicast overlay.  Nodes responsible for backup selection select backup nodes based on the received load status. 10.1.4 Media Signalling Proxy Media signalling proxy is a function to get media status in overlay multicast network by transfer media connection signalling between end hosts and obtain media session status of end hosts. In order to get media status of overlay multicast network, media signalling proxy is recommeded to be supported by IPTV overlay multicast system. 10.3.4 Network Measurement Function In order to ensure high end-to-end IPTV service quality, overlay multicast measurement system can be deployed to measure the IP network performance between overlay nodes such that the appropriate overlay path is selected. Network measurement includes receiving, measurement and forwarding functions.  Receiving function receives measurement requests and forwards them to measurement function.  Measurement function measures network performance between network node and aggregation node or different aggregation nodes based on above measurement requests and forwards results to forwarding function which feeds back results to overlay. <<The following text is part of detailed description of overlay multicast networking and can be moved to Appendix.>> AXXX IMA Backup In IPTV overlay multicast, IMA is deployed to control the construction of multicast session and deliver data among the overlay. Data stream will break if IMA goes out of work. So it is important to deploy backup function for IMA to guarantee service quality. As shown in figure XX, nodes of overlay multicast will report its status to others. The report path could be different according to different IMA selection mechanism. For a node (IMA or terminal), report will be transferred to the siblings if backup IMA is selected among siblings or transferred only to PIMA if backup IMA is selected by PIMA. In other scenario, reports will be transferred only to IMA if IMA selects its backup itself or IMAs may even exchange data packets among their siblings to backup each other. Contacts: Ning Zong Tel: +86 25 84565469 Huawei Technology Email: zongning@huawei.com Attention: This is a document submitted to the work of ITU-T and is intended for use by the participants to the activities of ITU-T's Focus Group on IPTV, and their respective staff and collaborators in their ITU-related work. It is made publicly available for information purposes but shall not be redistributed without the prior written consent of ITU. Copyright on this document is owned by the author, unless otherwise mentioned. This document is not an ITU-T Recommendation, an ITU publication, or part thereof.
  2. 2. -2- FG IPTV-C-1120 PIMA re port re port CIMA CIMA re port re port re port te rminal te rminal te rminal Figure XX: IMA backup function Whatever the backup selection mechanism is, following IMA backup selection functions are required:  Nodes broadcast their load status to other nodes of multicast overlay.  Nodes responsible for backup selection select backup nodes based on the received load status. AXXX Media Signalling Proxy In IPTV overlay multicast, media is connected between end users. If media signalling is directly transferred between end users, IPTV system could not get the exact media connection status to perform related functions such as accounting for each user. It is proposed that media signalling proxy for overlay multicast is located between each two end users to perform media protocol proxy for each two users, hence could report media connection status. Media signalling proxy is a function to get media status in overlay multicast network by transfer media connection signalling between end hosts and obtain media session status of end hosts. In order to get media status of overlay multicast network, media signalling proxy is recommeded to be supported by IPTV overlay multicast system. Figure X shows how media signaling proxy operates. IMA Media Signaling Proxy (RTSP proxy) Medi signallin prox Media a g (RTSP y Signaling & proxy) Connection RTSP RTSP Status End users End users End users End users Figure XX: Media signalling proxy AXXX Network Measurement Function In IPTV overlay multicast, the multicast path is constructed between overlay nodes in the application layer to perform media deliver functions. In order to ensure high end-to-end service quality of the IPTV services, overlay multicast measurement system needs to be deployed to measure the IP network performance, e.g. bandwidth, packet loss between overlay nodes such that the appropriate overlay path is selected. As shown in Figure XX, as part of resource control, network measurement functions include receiving function, measurement function and forwarding function:  Receiving function receives measurement requests from session manager and forwards them to measurement function.  Measurement function measures the network performance between network node and aggregation node or different aggregation nodes based on the above measurement requests and forwards the results to forwarding function.  Forwarding function sends the results to overlay network or other network measurement to share information.
  3. 3. -3- FG IPTV-C-1120 overlay network overlay network receiving Resource control forwarding function measuring IP network IP network Figure XX: Network Measurement Functions 3. Proposal We propose to make some editorial comments to “Overlay Multicast Networking” according to the above suggestions. ____________

×