A Novel QoS Guaranteed Mechanism for Multicast Traffic Controls in the Home Network Min Ho Park, Yeonjoon Chung, Wan Ki Park and Eui Hyun Paik Abstract — The home network has been revitalized due to the emergence of the broadband convergence network and the inter-networked home devices. The home gateway, which can be identified as a major component of the home network, enables to interconnect various home devices to one another as well as the Internet. Also, as the number of multimedia services, which requires high bandwidth and real-time support, increase users demand on the guaranteed quality for the services in the home network. In order to satisfy the user requirements, the Internet Service Providers (ISPs) have been providing a QoS mechanism for the home network services. However, the ISPs can not guarantee the end-to-end QoS from source to destination due to the misleading fact that the home gateway is recognized as an end terminal in terms of the ISP's viewpoint. Thus the QoS guaranteed mechanism for the remaining path, from the home gateway to the home devices, should be considered within the home network domain. In this paper, we propose a novel mechanism to guarantee the home network QoS for the services based on multicast traffics such as the IPTV or multilateral video conferencing. In order to meet the user requirements on the home network QoS, the proposed mechanism manages resources, classifies the traffic and also executes call admission controls for the service requested in the home network by utilizing the IGMP snooping scheme. Through the experiments of implementing the multicast based IPTV services, we will verify the proposed mechanism.
to realize the home network environment, home gateway (HG) is needed for interconnecting multiple home devices to one another as well as to the Internet as shown in the fig. 1 [1]. Various home network services are emerging as the number of the home devices increases. Especially, the multicast based services which consumes high bandwidth and requires the real-time supports are introduced. The Internet Television (IPTV) and multilateral video conferencing are good examples. For those services, the home users require differential levels of the service quality compare with less bandwidth consuming and non real-time services such as e-mail or file transfer protocol (FTP). In order to satisfy the requirements of the home users, the Internet Service Provider (ISP) provides a QoS mechanism for their subscribers. However the ISP can not guarantee the end-to-end QoS from the source located outside of home to the destination located in inside of home. Because the HG is recognized as an end terminal in terms of ISP’s view point, the ISP can not see the home devices which are real end terminal. This problem is caused by network address translation (NAT) function due to the lack of IPv4 address [2]. It also breaks the end-to-end philosophy of the Internet [2]. Thus QoS guaranteed mechanism for the remaining path, from the HG to the home devices, should be considered within the home network domain.
Index Terms —home network, QoS, multicast and home gateway.
I. INTORODUCTION Recently, the home network has been revitalized due to the emergence of the broadband convergence network (BcN) and the inter-networked home devices. The home network is considered as an infrastructure for the ubiquitous computing environments that provide computing and communication services all the time, everywhere. In order Min Ho Park is with the Electronics and Telecommunications Research Institute, Yuseong, Daejeon 305-350, Korea (e-mail:
[email protected]). Yeonjoon Chung is with the Electronics and Telecommunications Research Institute, Yuseong, Daejeon 305-350, Korea (e-mail:
[email protected]). Wan Ki Park is with the Electronics and Telecommunications Research Institute, Yuseong, Daejeon 305-350, Korea (e-mail:
[email protected]) Eui Hyun Paik is with the Electronics and Telecommunications Research Institute, Yuseong, Daejeon 305-350, Korea (e-mail:
[email protected]).
1-4244-0216-6/06/$20.00 ©2006 IEEE
Ethernet
AV Network
IEEE1394
Public Network
Home Gateway
Data Network Wireless PLC
Control Network
Fig. 1. Home Network Environment
In the conventional HG, all ingress packets from the access network are always delivered to the destined target clients through the main processor (MP). The packet flow in the HG degrades the performance of the MP as the traffic loads increases. Especially, the multicast traffic causes serious system overloads and reduces the efficiency of bandwidth utilization because all ingress multicast packets are replicated and flooded into the all output ports of the HG. In order to solve the problem, we developed a scheme which manages the layer 2 forwarding table (L2FT) of an
Ethernet switch in the HG based on the fact that multicast MAC addresses can not changed while transferring between the networks[3]. When the multicast packets are coming from an access network interface of the HG, the Ethernet switch firstly checks destination MAC addresses fields of the multicast frames. If the destination MAC address is registered in the L2FT, the switch directly forwards the multicast packet to the designated output ports without processing overheads of the MP. We have verified this scheme alleviated the workload of the MP, enhanced the performance of HG and efficiently utilized HN bandwidth in [4][5][6]. Although we proposed an efficient solution for the control of multicast traffics in [4], congestions can be occurred in some ports of the HG. It is mainly due to the fact that each service requires high bandwidth and real time supports as the number of HN services increases. When congestions are occurred, packets will be dropped and therefore the HN QoS can not be guaranteed. In this paper, we propose and develop the novel QoS mechanism for the control of multicast traffics in the HG. The proposed mechanism manages the HN resources, executes call admission controls (CACs), classifies packets by destination MAC address, and utilizes the forwarding mechanism for multicast packets in [4]. When HN hosts invoke multicast services, hosts firstly send IGMP join message to an IGMP proxy block of the HG with information of required bandwidth for the service. The IGMP proxy searches the resource table managed by the HN resource manager. If resources are available, the IGMP proxy requests to the IGMP snooping block that multicast MAC address of the host and a output port of the switch should be registered in the L2FT with a QoS guaranteed priority value, and then the resource table is updated. Otherwise, these values should be registered with the besteffort priority value. After L2FT is updated, the IGMP proxy joins a particular multicast group to the next hop multicast router and then multicast traffic is delivered to the switch port of the HG. As packets are delivered to the switch, it compares destination MAC address of the packets with entries in the L2FT. If entry is matched and priority is determined, those packets are scheduled with priority value and directly forwarded to the destination host. Otherwise, those packets are classified as unicast traffics and delivered to the MP of the HG. Through the experiments of implementing the multicast based IPTV services, we will verify the proposed mechanism can guarantee the QoS for multicast traffic in HN. The rest of the paper is organized as follows. In Section 2, we briefly describe the hardware specification, available services and packet forwarding scheme of our developed HG [4][5][6]. In Section 3, we present proposed home network QoS mechanism for multicast traffic control over HG. The experimental results are given in section 4. In Section 5, we conclude the paper and indicate directions for the future work.
II.
FTTH-HOME GATEWAY
In this section, we briefly describe hardware specification, available services and packet forwarding scheme of our developed home gateway namely FTTH (fiber to the home)HG in [4][5][6]. The FTTH-HG is the communications and broadcasts convergence gateway over the FTTH access network. It has a network processor as a main processor. For the access network interfaces, it has a 1Gbps EPON (Ethernet Passive Optical Network), 1000base-T and 1000base-X gigabit interfaces, a Fast Ethernet interface and VDSL (Very high speed Digital Subscriber Line) interface. For the home network interfaces, it has a various interfaces such as 6 fast Ethernets, IEEE 1394, wireless LAN, telephone and so on. Table 1 summarizes the hardware specification and available protocol/services of the FTTHHG. TABLE 1 SPECIFICATION OF THE FTTH-HOMEGATEWAY Processor & Memory Operating System Access Network Interface
Home Network Interface
Protocols
Application Services
Management
- Network processor @533MHz - 32MB Flash Memory/256MB SDRAM - Embedded Linux - Kernel 2.4.20 -1Gbps EPON Interface (IEEE802.3ah) -Gigabit Ethernet(1000base-T / 1000base-X) - Fast Ethernet - VDSL - 6 Ports Fast Ethernet & 1 Port Gigabit Ethernet - IEEE1394b(UTP Interface) - WLAN (802.11a/b/g) - Internet Telephone Interface (G.711/G.723.1 Codec, SLIC, PSTN Switching) - Video Door Phone (Voice & MPEG-4 Video encoding) - IPv4/IPv6 Dual Stack - IEEE 1394 / IPover1394 - RIP, RIPng - IGMP/IGMP Proxy/IGMP Snooping - NAT, DHCP Server/Client - RTP/RTCP, RTSP, SIP, SOAP, HTTP, DNS, SNMP - Hardwared accelerated IPSec in [9] - IP Broadcasting Service - SIP-based Internet Telephone Service - Visitor Confirmation Service - Net-filtering Firewall - SNMP-based Management - Web-based Management - Remote Software Upgrade
By using the IGMP proxy, FTTH-HG does not need to run multicast routing protocol to receive multicast packets [7]. The IGMP snooping enables layer 2 forwarding of multicast data includes the IPTV contents. Through the IGMP snooping, we can offload the huge amount of packet processing from the main processor when we receive the multicast based service like IP TV [8]. Fig. 2 shows the packet forwarding scheme of the FTTHHG. As shown in the fig. 2, all ingress traffic received through EPON (Ethernet Passive Optical Network) [10] interface from access network to Ethernet switch. The Ethernet switch is separated two VLANs (Virtual Local Area Networks), VLAN ‘A’ and ‘B’. The VLAN ‘A’ is domain for access network and VLAN ‘B’ is for home network. All ingress traffic from access network is
classified into unicast and multicast traffic. The unicast traffic is delivered to the main processor for the further processing, but multicast traffic is delivered to target output port based on L2 multicast MAC table across the VLANs. The IGMP proxy and IGMP snooping functions are make it possible. This mechanism makes alleviating the load of the main processor because the traffic aim to the main processor is decreased.
PCI Bus
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WLANs IEEE 802.11 a/b/g
L2 Switch EPON Interface
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........
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Fig. 2. Packet forwarding scheme of FTTH-HG
III. PROPOSED HOME NETWORK QOS MECHANISM FOR MULTICAST TRAFFIC
Software Processing Hardware Processing
In this section, we describe proposed home network QoS mechanism for multicast traffic. Fig. 3 shows the block diagram of proposed mechanism. We simply divided proposed framework into two parts. The upper part in fig. 3 is processed by software and the lower part is processed by hardware. The lower part is consist of access network interface (ANI) block, unicast-multicast classifier (UMC) block, multicast forwarding (MF) block, bandwidth monitor(BM) block, home network interface (HNI) block and priority scheduler (PS) block. The ANI connects the HG and access network through EPON interface. All ingress traffic from access network and all outgoing traffic from home network pass through the interface. The UMC block classifies the traffic into multicast and unicast. If the classified traffic is unicast, it sends the traffic to the unicast control block. Otherwise, it sends the traffic to MF block. The MF block directly forwards the packet to the PS block. The PS block schedules and forwards the packet to the destination host through the HNI. PS differently schedules the every packet with the packet’s priority which is registered in the multicast forwarding table (MFT). The PS has four different priority queues and the each priority queue has different service rates with 8, 4, 2 and 1, respectively. We allocate 8, 4 to the guaranteed priority and 2, 1 to the best effort priority. The software part is consist of IGMP proxy (IGP) block, IGMP snooping(IGS) block, home network QoS Manager (QM) block, resource manager (RM) block and unicast processing (UP) block. By using the IGP, we can reduce not only the cost of the HG but also operational overhead of
multicast routing protocol such as PIM(protocol independent multicast) or DVMRP(distance vector multicast routing protocol) [11][12]. Another advantage is that it makes the HG independent of the multicast routing protocol used by the access and core network multicast routers. The IGS block enables directly forwarding of the multicast packet without processing in the main processor. Without IGS block all ingress multicast packets are processed by main processor and broadcasted to the all outgoing interface of the HG. Thus, by using the IGS, we can alleviate the load of the main processor and encourage providing various services at the same time. The RM block manages the home network bandwidth resources for each port of the HG. Since we assume that home network is star topology, RM only manages the available bandwidth of the every port of the HG. The QM block receives the QoS requests from the multicast clients and manages the home network QoS. When it receives the QoS request, it firstly consults with the RM whether the request could be accepted or not depends on the available bandwidth for every port that packets are traversed from ANI to HNI. The UP block is general unicast packet processing block of TCP/IP protocol suite such as routing, network address translation (NAT), packet filtering and so on.
Unicast Processing Block
IGMP Proxy
Home Network QoS Manager
IGMP Snooping
Resource Manger
Bandwidth Monitor
Access NW Interface
UniCast Multicast Classifier
Multicast Forwarding Table
UU
Priority Scheduler
Home NW Interface
Fig. 3. Block diagram of proposed mechanism
Overall flow of QoS guaranteed multicast service is composed of service negotiation phase, service delivery phase and service release phase. Fig. 4 shows the first two phases. At the service negotiation phase, the multicast client sends the QoS request packet to the QM with required bandwidth, firstly. The QM consults with RM about available bandwidth. If the available bandwidth is enough to accept the required bandwidth, then RM reserves the bandwidth for every port, update resource table for given ports and notifies that given request is accepted with traffic priority value to the multicast client. Otherwise, RM notifies that given QoS guaranteed request is rejected and requested service is treated as best effort service. If the multicast client is received the accept message from the QM with traffic priority, it joins the specific multicast group with the given
priority and multicast MAC address. After then, IGP requests MCF update with given priority and multicast MAC address. The IGS block sets the MFT. Finally, IGP joins the specific multicast group to the multicast router located in the access network.
Home Gateway Multicast Router
Uni/Multi Multi. Fwd IGMP Classifier Table Snooping
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Multicast Client
Group leave message Request Update MCF Request Update MCF
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Resource Release Request Release Resource
Notify result Notify result Group Join
Request MCF update with priority
Request MCF update with priority
MCF update with priority Group Join to upper router
Service multicast traffic Traffic classify Service multicast traffic Determine output port Service multicast traffic
Fig. 4. Flow of service negotiation and service delivery phase
At the service delivery phase, the multicast router forwards the multicast traffic to the HG. When the UMC receives the traffic through the ANI, it classifies the traffic into unicast and multicast. Output port and priority of classified multicast traffic is determined based on comparing the destination multicast MAC address and entries in MFT. Next, the traffic is directly forwarded to the priority scheduler. After then, the delivered traffic is scheduled with determined priority and delivered to the destination host, finally. The fig. 5 shows the resource release phase. As shown in the resource release phase, the multicast client sends the group leave message to the IGP block, firstly. The IGP block requests MFT update message to the MF block. The MF block deletes the given entry in the MFT. After then, IGP requests to the QM for releasing the reserved resources and sends the group leave message to the multicast router located in the access network, sequentially. After receiving request from IGP, QM requests to the RM for releasing resources. Next, RM releases the resources and updates its resource table.
Fig. 5. Flow of resource release phase
IV. EXPERIMENTAL RESULT In this section we evaluate experimental result with real traffic. Fig. 6 shows the experimental test bed. As shown in the fig. 6, we generated 20Mbps IPTV multicast stream and 100 Mbps unicast stream. The Ethernet frame size of each stream is about 1350 and 1500 byte, respectively. The total 120 Mbps traffic is flowed in the HG from the access network router through the gigabit interface. The HG classified traffic into the unicast traffic as best effort traffic and the multicast traffic as guaranteed traffic based on the priority information of L2FT. Since the MP of FTTH-HG can simultaneously process the 100 Mbps and the multicast traffic do not need the further processing of MP, all of the unicast traffic can be processed in the MP. However at the output port, the each HNI is 100 Mbps interface, 20 Mbps multicast traffic is guaranteed but 20 Mbps unicast traffic among 100 Mbps is dropped based on the priority scheduling. Thus, the IPTV client can be receive the 20 Mbps multicast traffic without packet loss but the traffic generator can receive about 80 Mbps traffic with traffic loss. The Fig. 7 shows the snapshot of the QoS guaranteed multicasting IPTV service and physical configuration of our experimental testbed. V. CONCLUSION AND FURTHER WORKS In this paper, we proposed a novel home network QoS mechanism for the multicast services such as IPTV or multilateral video conference. The proposed mechanism manages home network resources, classifies the traffic and also executes call admission controls for the service requested in the home network by utilizing the IGMP snooping scheme. The service which wants to guarantee the QoS should negotiate with QM in HG. The QM consults with RM about available bandwidth for the requested services. After then the service receives the result about whether its service QoS is guaranteed or not. If the service
is allowed that guarantying the QoS, the HG classifies the traffic based on destination multicast MAC address, schedules the multicast packet with high priority and forwards the packet to the home device. Otherwise, those services are classified as best-effort service. We will further verify the performance of proposed mechanism with intensive experiments and combine with unicast QoS mechanism.
[10] G. Kramer and B. Mukherjee, “Supporting differentiated classes of service in Ethernet Passive Optical Networks,” Journal of Optical Networking, vol. 1, pp. 280-298, Aug&Sep. 2002. [11] Internet Engineering Task Force, “Protocol Independent MulticastSparse Mode (PIM-SM): Protocol Specification,” RFC 2362, June, 1998. [12] Internet Engineering Task Force, “Distance Vector Multicast Routing Protocol,” RFC 1075, November, 1988.
Traffic generator
IPTV Stream Generator 20 Mbps Multicast Traffic
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a
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100 Mbps Traffic
Hub 80 Mbps Unicast Best-effort Traffic
20 Mbps Multicast Traffic
Access Router with multicast routing protocol
IPTV Client
Fig. 6. Experimental Testbed
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IPTV Stream Generator
b Fig. 7. QoS guaranteed mulitcast service and physical network configuration; a - Traffic Generator, FTTH-HG, HUB and IPTV Client, b - IPTV Stream Generator and Access network router. Min Ho Park received his B.S. in information and communication engineering from Dongguk University, seoul, Korea in 2002 and M.S. in information and communication engineering from ICU, Daejeon, Korea in 2004. Since then he has been at HomeNetwork Group, Digital Home Research Division in ETRI (Electronics and Telecommunication Research Institute). His areas of interest include network QoS, IPv6 deployment strategies of the ubiquitous computing environment and routing issues of wireless mobile networks.
Yeonjoon Chung received his Ph.D in electrical and computer engineering from university of Minnesota, USA, in 2003. Since then he has been at HomeNetwork group, Digital Home Research Division in ETRI (Electronics and Telecommunication Research Institute). His areas of interest include multimedia networks and network QoS issues in wired/wireless networks. 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 2006. He joined Agency for Defence Development, in 1993 and had been engaged in the research and development of communication related to military till 2000. 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. Eui Hyun Paik received B.E./M.S/Ph.D. degree in Computer Science from SoongSil University, Seoul, Korea. He joined the ETRI(Electronics and Telecommunications Research Institute) in 1987. Since then, he has been engaged in the research and development of TDX switch system, ATM, and E-PON system. He is currently working in fields of Home Network Technology, as a project leader of Ubiquitous Home Service Research Team in ETRI. His current interests include the areas of home network system, next generation home server technology, context-aware computing, and middleware technology for IPTV.
