An Implementation of the Broadband Home Gateway supporting Multi-Channel IPTV Service

Transcription

1 An Implementation of the Broadband Home Gateway supporting Multi-Channel IPTV Service Wan-Ki Park, Chang-Sic Choi, Youn-Kwae Jeong, Intark Han, Member, IEEE Abstract Home Gateway(HG), called residential gateway(rg) in other words, is a device that interconnects various home electronic devices to one another as well as connects these private home network devices to exterior public network. There are various types of digital home services in IP(Internet Protocol)-based home network system; data service, entertainment service, security service, home automation service and so on. Multimedia related service, especially IPTV(Internet Protocol Television) service, is the attractive one to customer in these home network services. In this paper, we show the implementation of the broadband home gateway supporting multi-channel IPTV service. The proposed and implemented home gateway has an architecture that can provide multi-channel, more than three channels, HD(High Definition) class IPTV service with 20Mbps(megabits per second) bandwidth for each channel. For the improved IPTV service using IP multicast, the proposed HG uses Internet Group Multicast Protocol(IGMP) proxy and IGMP snooping protocol. The proposed HG consists of two main components, system processor for NAT(Network Address Translation) processing and system software functions and an L2(Layer 2) Ethernet switch to interface access network and network distribution in intra-home network. The multicast packets for the multi channel IPTV service go from ingress port for access network interface to egress ports for home network directly based on L2 multicast MAC(Medium Access Control) table in L2 Ethernet switch without via the system processor of the HG. This paper specifies in detail the system structure and implementation of hardware, firmware and software for the proposed HG. 1 Index Terms Home Gateway, IGMP, IGMP Snooping, Digital Home. I. INTRODUCTION In emerging ubiquitous environments, home network including home gateway(hg)[1][2] is one of the most essential things to cope with the consumer s various increasing demands such as broadcasting, security, communication, home automation, etc. In a current home network trend, they try to merge all electronic home devices using IP(Internet Protocol) network connectivity. To merge 1 Wan-Ki Park, Chang-Sic Choi, Youn-Kwae Jeong, and In-Tark are with Electronics and Telecommunications Research Institute(ETRI), Daejeon Korea ( wkpark@etri.re.kr, cschoi@etri.re.kr, ykjeong@etri.re.kr, and ithan@etri.re.kr, respectively). them using the IP network, we have to allot unique IP address to all electronic devices and manage them using the allocated IP address. Applied the public IP system to all these home devices in the worldwide, the number of IP addresses required can not be estimated. So, it is desirable to use private IP addressing mechanism in home network system now because IPv6(Internet Protocol version 6)[3][4] is not universalized yet. HG is a device that connects these private home network devices to exterior public network using the scheme called NAT(Network Address Translation)[3]. Multimedia related service, especially IPTV(Internet Protocol Television)[5] service, is the most attractive one to customer among the home network services. IPTV describes a system where a digital television service is delivered to subscribing consumers using the Internet Protocol over a broadband connection. The playback of IPTV requires either a personal computer or a STB(Set-top Box) connected to a TV(Television). Video content is typically MPEG2-TS(Moving Picture Experts Group2 Transport Stream)[6] delivered with IP multicast, a method in which information can be sent to multiple computers at the same time. In standards-based IPTV systems, the primary underlying protocols used for IPTV are IGMP(Internet Group Multicast Protocol) version 2[7] for channel change, called Zapping, signalling for live TV. In this paper, we show the implementation of the broadband home gateway supporting IPTV service. The proposed and implemented home gateway has an architecture which can provide multi-channel, more than three channel, HD(High Definition) class IPTV service with 20Mbps bandwidth for each channel. The remainder of this paper is organized as follows. We first review related some works to introduce our scheme and the implemented results such as home network including HG, IP multicast[8], IGMP[7] and IGMP snooping[9][10]. Next, we present the proposed HG hardware system architecture and its superiority. Next, we show an implementation scheme in view of driver/firmware and software to process the control packet and data packet in the proposed HG s architecture. We then show a demonstration scenario including other home network services and the results of them to prove the proposed HG s applicability. Finally, we present our conclusions. II. REALTED WORKS Our proposed and implemented HG is based on Fiber to /06/$ IEEE

2 the Home(FTTH) network, specially on Ethernet Passive Optical Network(EPON)[11][12], as an access network interface, which can provide adequate network bandwidth to support various digital home network services including multi-channel IPTV service. MPEG2 TS from the encapsulated with RTP, UDP and IP. A. Network and System for Digital Home Services Fig. 2 Protocol Stack to Transmit the Broadcasting Contents for IPTV Service Fig. 1 An Example of the Network Configuration for Digital Home Network Service In IP based home network described in previous section, all electronic digital home devices are interconnected to one another device as well as connected to exterior public network throughout a home gateway system. Fig. 1 shows an example of the network configuration for various digital home network services. Home gateway has to have powerful processing power and enough network bandwidth to provide above networking service and to cope with various customers requesting services. In considering the costs and system network bandwidth and structure, it is not a trivial problem to provide satisfactory services to them. B. IPTV(Internet Protocol Television) IPTV[5] describes a system where a digital television service is delivered to subscribing consumers using the Internet Protocol over a broadband connection. The playback of IPTV requires either a personal computer or a IP-STB connected to a TV. Video content is typically MPEG2-TS[6] delivered with IP multicast, a method in which information can be sent to multiple computers at the same time. In standards-based IPTV systems, the primary underlying protocols used for IPTV are IGMP version 2[7] for channel change signalling for live TV. Fig. 2 shows the protocol stacks that each entity has to have to provide IPTV service. As shown in Fig. 2, IPTV head-end sends MPEG2-TS[6] type of A/V(Audio/Video) contents to network side after RTP[13], UDP[14], IP and Layer 2 encapsulated, in sequence. Routers including OLT(Optical Line Terminal)[11] in access network do the look-up and forwarding functions using multicast routing protocol based on target address of received packet. HG then forwards the received IP multicast packet based on target address. Finally, IP STB extracts and decodes the C. IGMP and IGMP snooping Fig. 3 shows a protocol stack in each entity to manage the channel registration and release to provide IPTV service. As shown in Fig. 3, the multicast routing protocol, PIM- SM[8] as an example, is used between the routers including LHR(Last Hop Router, OLT) to manage the registration to any multicast group, while IGMP protocol is used between LHR and IP clients(ip STB). As a result of that, HG has to provide IGMP proxy function. IGMP proxy function is a function that HG has a role as IGMP clients in the view of LHR and as a multicast router in the side of IPTV clients(ip STB). Fig. 3 Protocol Stack to Manage the Multicast Group for IPTV Service The IGMP is a protocol of IPv4 systems used to manage IP multicast membership to an intermediate multicast router. According to the IGMP protocol, three kinds of IGMP messages are exchanged between IP multicast router and hosts to manage the group membership: Membership Query(0x11), Membership Report(0x22 and 0x16) and Leave Group(0x17) messages.[7] L2(Layer 2) Ethernet switch has been used widely to implement HG system. Unfortunately, the L2 Ethernet switch cannot supports IP multicast directly because it is not able to investigate the contents of layer 3 information of incoming packet. The L2 Ethernet switch uses IGMP snooping[9][10] and MLD snooping[9][10] for multicast packet instead of the direct IP multicast processing. The processor of HG must manage the L2 multicast MAC(Medium Access Control) table for L2 multicast based on the IGMP snooping. It is the basic function of each host and network devices supporting multicast.

3 III. SYSTEM ARCHITECTURE AND IMPLEMENTATION A. System Architecture We had shown the system and hardware architecture of our proposed HG in [14] and [15]. In [14] and [15], we showed also the mathematical analysis and its evaluation result. Fig. 4 shows the hardware system architecture of the proposed HG. As shown in Fig. 4, the proposed HG has system processor with two MII interfaces. But, both MII interfaces are connected to L2 Ethernet switch unlike conventional HG that one is connected to L2 Ethernet switch and another is connected to access network, directly. And, the access network interface of EPON ONT(Optical Network Termination)[11][12] is connected to L2 Ethernet switch using GMII(Gigabit Medium Independent Interface). B. Data and Control Packet As shown in Fig. 6, IP multicast data packet for IPTV service is forwarded directly to target ports based on L2 multicast MAC forwarding table. The direct forwarding mechanism based on L2 multicast MAC table improves the performance of HG and abbreviates the load of the system processor. The L2 multicast MAC table is controlled by IGMP snooping manager based on IGMP snooping function of the L2 Ethernet switch. Fig. 4 System and Hardware Architecture of the proposed Home Gateway In the proposed FTTH based HG, we use port based VLAN of pseudo hardware based VLAN to separate and isolate the two networks of access network and home network. The two VLANs are VLAN A for access network interface and VLAN B for home network in the same L2 Ethernet switch. Fig. 5 shows the summarized functions and roles which the proposed HG s components and interfaces have. Fig. 5 Functions and Roles of components and Interfaces Fig. 6 IPTV Data and Control Packet Flows in the Proposed Home Gateway C. Driver and Software Implementation To support multi-channel IPTV service, the proposed home gateway is capable of forwarding, more bandwidth than 100Mbps, adequate IP traffic including the IPTV broadcasting stream to home network. In special, it can transfer them into the home network with the minimized forwarding delay. As we described in previous section, we use the IGMP proxy function instead of multicasting protocol to register and release the multicast membership. IGMP proxy is a function to receive and transmit the IGMP messages on behalf of IP STB. And, we use the IGMP snooping function to reduce the processor s work load in proposed home gateway. Fig. 7 shows the proposed home gateway s architecture to support multi-channel HD class IPTV service. In the proposed home gateway, the IP packet stream from access network is forwarded directly to multicast group s clients connected to the L2 Ethernet switch as shown in Fig. 7. In the case of PCI bus interface targeted such as WLAN or IEEE1394, the IP multicast packet is forwarded to multicast group s clients connected to WLAN or IEEE1394

4 via home gateway s processor with multicast forwarding cache(mfc) of operating system. To transmit the IP multicast packet stream to the related multicast membership ports only connected to L2 Ethernet switch, IGMP snooping manager is required. the forwarding based on L2 multicast MAC being managed by the IGMP Snooping Manager and the managed multicast MAC table has a precedence in processing in the L2 Ethernet switch of the proposed home gateway. The IGMP Snooping Manager does the functions to manage L2 multicast MAC table for the L2 switch and to manage the timers for the multicast membership. Fig. 8 Block Diagram for IGMP Snooping Manager Fig. 7 Proposed HG s Architecture for Multi-Channel HD Class IPTV Service In general, a multicast routing protocol is required to support the IPTV broadcasting service based on IP multicast mechanism. The multicast routing protocol is used to transfer the request information, from IP STB to upper multicast router, to register and release the membership channel and to manage the multicast forwarding of a specific IP multicast stream to the home gateway s membership ports. But, it is not desirable to apply the multicast routing software to home gateway because the multicasting protocol is burden to process the multicast related mechanism in the home gateway. So, we implement the IGMP proxy function in the proposed home gateway. IGMP proxy functions as follows. IGMP router function IGMP host function The management function for multicast membership database Timer function to manage the multicast hosts membership IGMP Snooping Manager in Fig. 7 and Fig. 8 is required to forward the multicast packet to the multicast members ports only in home network. With this function, we can prevent the multicast packet to forward to undesirable ports. At the same time, we can reduce the CPU s work load with forwarding directly to the specific hosts without forwarding to the processor. It is a result from D. Implemented System Fig. 9 shows the implemented home gateway hardware board. The implemented system has three types of access network interfaces, an EPON network interface, 10/100/1000base-T and 1000base-X interface, one of which is activated due to system configuration. The EPON network interface 1000base-T interface are connected to L2 Ethernet switch with GMII and 10/100base-T uses MII interface. In case of 1000base-X, 1Gbps(gigabit per second) serdes(serial-deserial) interface is used. Seven ports of 10/100base-T Fast Ethernet interface and single 1000base-T interface for home network interface. Fig. 9 Implemented System Hardware Board IV. TEST SCENARIO AND RESULTS We verified the proposed and implemented system hardware and software through a real system demonstration. Fig. 10 shows a test scenario and an example multi-channel

5 HD class IPTV demonstration to verify our proposed system. (a) Optical Networking, Vol. 1, Nos. 8 & 9, pp , Aug & Sep [12] Kye-Hyun Ahn, Kyeong-Eun Han, and Young-Chon Kim, Hierarchical Dynamic Bandwidth Allocation Algorithm for Multimedia Services over Ethernet PONs, ETRI Journal, Vol. 26, No. 4, pp , Aug [13] RFC1889 : RTP: A Transport Protocol for Real-Time Applications, Jan [14] RFC1240 : OSI connectionless transport services on top of UDP: Version 1., Jun [15] Wan-Ki Park, Dae-Young Kim, Chang-Sic Choi, Youn-Kwae Jeong, Kwang-Roh Park, IPTV-aware Multi-Service Home Gateway based on FTTH Access Network, Proceedings of International Symposium on Consumer Electronics, 2005.(ISCE 2005), pp , Jun [16] Wan-Ki Park, Sung-Il Nam, Chang-Sic Choi, Youn-Kwae Jeong, Kwang-roh Park, An implementation of FTTH based Home Gateway Supporting Various Services, IEEE Transactions on Consumer Electronics, vol 52. no1. 1, pp , Feb (b) Fig. 10 Test Scenario and Example Demonstration (a) A Service Scenario (b) An Example Demonstration V. CONCLUSION The HG system is an interface device that connects an access network, a WAN, to a home network. In this paper, we proposed and showed an implementation results for home gateway supporting multi-channel, more that three channel, HD class IPTV service. Our proposed HG system can provide various digital home service with surplus processing power come from architectural characteristics as well as multi-channel IPTV service. REFERENCES [1] Satish Satish Gupta, Home Gateway, White Paper of Wipro Technologies, Aug [2] M. Greeson, Residential gateways: testing the waters of market viability, Proceedings of The Residential Gateway European Forum 2001 Pre-Forum Workshop, IIR, London, February [3] Greg Goth, Close to the edge: NAT vs. IPv6 just the tip of a larger problem, IEEE Internet Computing, vol. 9, Issue 2, pp. 6-9, March- April [4] RFC1883 : Internet Protocol, Version 6(IPv6) Specification, Dec [5] Walko, J, I Love My IPTV, IEE Communications Engineer, pp , Dec [6] Jerry C., Whitaker, Interactive TV Demystified, Mc-Graw Hill, [7] Internet Engineering Task Force, Internet Group Management Protocol, Version 2, RFC 2236, Nov [8] Internet Engineering Task Force, Protocol Independent Multicast- Sparse Mode (PIM-SM), RFC 2117, June, [9] Internet Engineering Task Force, Considerations for IGMP and MLD snooping Switches, Internet Draft, May [10] Jun Wang, Limin Sun, Xiu Jiang, Zhimei Wu, IGMP snooping: a VLAN-based multicast protocol, Proc. Of Hih Speed Networks and Multimedia Communications 5th IEEE International Conference, pp , July [11] Glen Kramer and Biswanath Mukherjee, Supporting differentiated classes of service in Ethernet passive optical networks, Journal of Wan-Ki Park received the B.E. and M.E. degrees in electronics engineering from Chungnam National University, Korea, in 1991 and 1993 respectively and Ph. D. degree in information and communications engineering from the same university in He joined Agency for Defence Development, in 1993 and had been engaged in the research and development of communication related to military till He joined Electronics and Telecommunications Research Institute, in July 2000 and has been engaged in the research and development of ATM based MPLS system, high speed routing system and home network system, etc. Now, he is senior research engineering staff of home network group. His research interests are home network technologies and home digital multimedia services. Chang-Sic Choi received the B.E. and M.E. degrees in computer engineering from Pusan National University, Korea, in 1997 and 1999 respectively. He joined Electronics and Telecommunication Research Institute in His research interests are home network, home gateway and home server, multimedia QoS, MPLS based IP switch and ATM. Youn-Kwae Jeong received the B.E. and M.E. degrees in electronics engineering from Kyungpook National University, Korea, in 1982 and 1984 respectively and Ph. D. degrees in computer engineering from the same University. He joined Electronics and Telecommunication Research Institute in His research interests are home network, home gateway and home server, multimedia QoS, MPLS based IP switch and CDMA. Intark Han received BE and ME degrees in electronic engineering from Yonsei University, Seoul, Korea, in 1985 and 1991, respectively. He is a PhD candidate at ICU (Information and Communications University), Daejeon Korea. Since 1987 he has been in ETRI (Electronics and Telecommunications Research Institute) as a member of technical staff. In ETRI he was involved in the development of various switching systems from voice, narrow-band ISDN to ATM. Now he works as a team header of home network technologies division. His current research interests include home network especially system design and development of home gateway and home server, switching and QoS in the network.