IP城域网业务控制层BRAS可靠性设计方案探讨

BRAS作为IP城域网业务控制层管理用户及流量的核心设备,其可靠性设计是实现城域网高QoS的重要保证。在目前BRAS热备技术尚不完善的情况下,本文提出了端口聚合、分场景冷备等多种可靠性设计方案,并对各种方案的优劣势及适用场景进行了分析和探讨。     

临沂广电IP核心网络规划与设备选型

临沂广电分步建设IP网络,认为前期在没有用户的情况下建设IP城域网络及其BRAS等投资浪费严重,所以尝试分期建设网络,一期集中部署两台BRAS,所有市区及县区分前端OLT直接上联至中心BRAS设备。充分利用BRAS设备的二层隔离及其PON设备的隔离特性,减少接入层的二层网络覆盖,以减少VLAN的数量降低维护成本。考虑到大客户发展的不明确性,一期不建设SR路由器,其功能暂时由BRAS来代替,同时探讨了基于上述思路的设备选型问题。     

IPTV transport architecture alternatives and economic considerations

Telecommunications companies are under increased pressure due to competition from multiple system operators, and the changing communications and entertainment needs of residential consumers. These pressures are driving the telecommunications companies to design and deploy metro networks capable of delivering broadcast video and VOD services through IP-based broadband connectivity (known as IPTV). One important architectural consideration for these IPTV networks is the core layer 1 transport infrastructure that supports economical delivery of these high-bandwidth services. This article surveys some of the major layer 1 optical transport network alternatives including DWDM, SONET, and Ethernet-on-fiber as well as its passive WDM/DWDM (PWDM) variation. The article analyzes the architectural and cost performance metrics for these transport options, and explores the economic crossover points with regard to the key network and service parameters such as bandwidth demand, number of subscribers, network topology, and operational constraints. DWDM technology, when coupled with native Ethernet aggregation, is found to have significant applicability for IPTV transport networks. DWDM offers value in capital cost and operations, while delivering the required bandwidth and performance. Ethernet aggregation capability within the transport infrastructure adds scalability, flexibility, and cost advantage for the multiservice network applications of the future.     

Ethernet passive optical network (EPON): building a next-generationoptical access network

This article describes Ethernet passive optical networks, an emerging local subscriber access architecture that combines low-cost point-to-multipoint fiber infrastructure with Ethernet. EPONs are designed to carry Ethernet frames at standard Ethernet rates. An EPON uses a single trunk fiber that extends from a central office to a passive optical splitter, which then fans out to multiple optical drop fibers connected to subscriber nodes. Other than the end terminating equipment, no component in the network requires electrical power, hence the term passive. Local carriers have long been interested in passive optical networks for the benefits they offer: minimal fiber infrastructure and no powering requirement in the outside plant. With Ethernet now emerging as the protocol of choice for carrying IP traffic in metro and access networks, EPON has emerged as a potential optimized architecture for fiber to the building and fiber to the home     

城域网组播复制点位置设定分析

随着ITV业务的快速发展,城域网上单台BRAS设备承载的ITV用户数量将越来越多,BRAS下行的单播流量将极大地占用接入网带宽。组播复制点是否需要从现有的BRAS上下移到接入网设备,下移的效果如何,何时下移合适,本文针对这些问题对两种组播复制点位置设定方案进行了分析,预测和检验了下移后的效果,提出了下移的业务场景。     

EPON技术原理

EPON(以太网无源光网络)是面向下一代网络的接入技术,它是一个多业务平台,可以同时提供具有QoS(服务质量)保证的IP(互联网协议)业务和传统TDM(时分多路复用)业务.因此,采用EPON技术,运营商不仅可以在同一传输平台上根据用户的需要随时开通多种业务,而且易于向全IP业务网络过渡,为此介绍了EPON的体系结构,分析了EPON的上行链路和下行链路的传输原理.     

Operation, administration, and maintenance of Ethernet services in wide area networks

Recent developments in Ethernet technology, such as 10G Ethernet interfaces, Ethernet passive optical networks, and resilient packet rings are pushing Ethernet from the local area network environment to metropolitan and wide area network environments. For Ethernet service providers, managing Ethernet services efficiently is key to a sustainable business model. This article discusses issues in providing OAM features and capabilities to Ethernet services over metro and wide area networks. We analyze current Ethernet features that can be leveraged in an Ethernet OAM framework, and introduce requirements and new functionalities to support Ethernet services in wide area networks.     

EPON系统中VLAN的设计与实现

EPON(以太无源光网)作为一种新的接入技术,利用VLAN(虚拟局域网)可以满足用户对多种业务的需求,同时也可优化网络性能和满足同一EPON系统多运营商接入的需求。本文首先介绍了EPON中交换芯片对VLAN的支持,接着从用户空间、内核空间和芯片驱动三个层面描述了VLAN的设计,从而实现VLAN的配置与动态管理。     

A Simple One-System Solution COF-PON for Metro/Access Networks

In this paper, next-generation ultralong reach code division multiplexing (CDM) on fiber (COF) passive optical network (COF-PON) based on CDM (multiplexing carried out in electrical domain) presented here. We describe the system configuration, COF transceiver, key merits such as bidirectional transmission (on the same wavelength with single fiber), extending the reach by coding gain, and offering huge bandwidth to large number of subscribers by overlaying on coarse wavelength division multiplexing (CWDM)/wavelength division multiplexing (WDM). We believe our newly proposed ultralong reach COF-PON will help to drastically reduce the Capex and Opex costs by consolidating metro and access networks into one simple network. We demonstrated initial experimental results over 100-km bidirectional COF-PON overlay on 4lambda-CWDM channels' transmission without the use of an optical amplifier     

Packet-aware transport for metro networks

Today's metro networks have evolved from the need to support traditional voice and private line services. However, the tremendous growth in access to frame relay, ATM, IP, and Ethernet services, coupled with the desire of enterprise customers to interconnect via Ethernet interfaces, suggests the need for a new approach. This article proposes a new architecture for packet-aware transport networks (PATN) that supports both packet and traditional TDM services and leverages an assemblage of emerging technologies to provide efficient aggregation and switching of packet traffic in metro networks. The PATN has the potential to provide significant cost savings to carriers by reducing the number of network elements, reducing transport costs through statistical multiplexing, and eliminating the need for redundant multiplexing operations.     

城域以太网体系标准、业务模型和新技术剖析

本文从市场和用户需求出发,剖析了传统以大网作为城域网建网模式的优点及不足.通过对城域以大网体系架构和标准草案进展的阐述,重点介绍了城域以太网业务模型、基于VPLS/VPWS的城域以大网技术以及相应的解决方案.     

深圳网通小区GEPON解决方案

随着互联网用户数量的快速增加,对接入网带宽的需求也不断增长.千兆以太网无源光网络(GEPON)技术已成为网络接入技术的新贵,它是集高速数据、视频及语音业务于一体的综合接入解决方案.利用光纤到户/光纤到大楼/光纤到路边(FTTH/FTTB/FTTC),可为家庭用户、企业用户等提供高达1 Gbit/s的最大带宽.GEPON以其经济的造价、方便的接入、易维护和简单的网络结构,正得到越来越多的通信运营商及厂商的支持和认可.文章介绍了深圳网通小区GEPON解决方案.     

A reconfigurable ethernet/SONET circuit-based metro network architecture

We propose a service concept in which high-speed Ethernet interfaces from end hosts are dynamically cross-connected to equivalent-rate Ethernet-over-SONET (EoS) optical circuits for transport across metro-area networks and/or wide-area networks. We call our service concept reconfigurable Ethernet/SONET circuits to end users (RESCUE). We describe how RESCUE can be used for two applications: dial-up service to Internet service provider routers and file transfers. We propose to deploy RESCUE service as an "add-on" to current Internet access for many reasons. Primary among these is that it allows a metro optical circuit-switched network to be operated at a high utilization, which is important to achieve a cost-effective bandwidth-efficient network. Given that end hosts with access to RESCUE service will have a choice of two paths, the primary Internet path and a secondary RESCUE option, end-host applications will need to make a routing decision. We carry out a quantitative analysis to provide a basis for this routing decision for both dial-up service and file transfers. For example, with the file-transfer application, if call-blocking probability on the optical circuit-switched network is 30% and the packet-loss rate on the transmission control protocol/Internet protocol path is 1%, a circuit setup should be attempted for files 180 KB or larger in low-propagation delay environments.     

Genetic expression programming: a new approach for QoS traffic prediction in EPONs

The Ethernet passive optical network is being regarded as the most promising for next-generation optical access solutions in the access networks. In time division multiplexing, passive optical network technology (TDM-PON) and the dynamic bandwidth allocation (DBA) play a crucial key role to achieve efficient bandwidth allocation and fairness among subscribers. Therefore, the traffic prediction in DBA during the waiting time must be put into the account. In this paper, we propose a new prediction approach with an evolutionary algorithm genetic expression programming (GEP) prediction incorporated with Limited IPACT referred as GLI-DBA to tackle the queue variation during waiting times as well as to reduce the high-priority packet delay. Simulation results show that the GEP prediction in DBA can reduce the expedited forwarding (EF) packet delay, shorten the EF queue length, enhance the quality of services and maintain the fairness among the optical network units (ONUs). We conducted and evaluated the detail simulation in two different scenarios with distinctive traffic proportion. Simulation results show that the GLI-DBA has EF packet delay improvement up to 30 % over dynamic bandwidth allocation for multiple of services (DBAM). It also shows that our proposed prediction scheme performs better than the DBAM when the number of ONUs increases.     

Physical Topology Discovery for Metro Ethernet Networks

Automatic discovery of physical topology plays a crucial role in enhancing the manageability of modern metro Ethernet networks. Despite the importance of the problem, earlier research and commercial network management tools have typically concentrated on either discovering logical topology, or proprietary solutions targeting specific product families. Recent works have demonstrated that network topology can be determined using the standard simple network management protocol (SNMP) management information base (MIB), but these algorithms depend on address forwarding table (AFT) entries and can find only spanning tree paths in an Ethernet mesh network. A previous work by Breibart et al. requires that AFT entries be complete; however, that can be a risky assumption in a realistic Ethernet mesh network. In this paper, we have proposed a new physical topology discovery algorithm which works without complete knowledge of AFT entries. Our algorithm can discover a complete physical topology including inactive interfaces eliminated by the spanning tree protocol in metro Ethernet networks. The effectiveness of the algorithm is demonstrated by implementation.     

Phone number portability for PCS systems with ATM backbones usingdistributed dynamic hashing

Current cellular subscribers have a geographic phone number (e.g., in AMPS and US digital cellular systems) or a number which contains the network provider's identity (e.g., in GSM), and whenever subscribers register or receive (and possibly, originate) a call, a home location register (HLR) database has to be queried. The wired infrastructure supports a function called global title translation (GTT) that converts the subscriber's number to an HLR database address. A special feature of next generation wireless access service will be to support personal communication services (PCS) and wireless subscribers with portable personal numbers, or nongeographic phone numbers (NGPNs), that do not indicate the service provider or HLR database serving the user. In addition, the GTT function may not be available when the wired backbone is an ATM network. Thus a key function required in future wireless access systems with wired ATM backbones will be the ability to translate an NGPN to the identity of the HLR which serves the subscriber, a process we call NGPN translation. We discuss the requirements of NGPN translation and some alternative schemes. We propose two schemes for fast, efficient, scalable and flexible NGPN translation which use ideas of dynamic hashing, caching, and indirection. The schemes use a hash function in the visiting location registers (VLRs) (or serving SCP) and a set of distributed translation servers which store the NGPN-to-HLR mapping. We discuss how the operations required to maintain the translation information can be performed. Finally, we perform a simplified analysis of the scalability of the alternative schemes as well as the hash-based schemes we propose     

有线无线一体化的扁平校园网设计

分析了高校校园网拓扑结构现存的问题,依据扁平化的大二层网络设计思路,提出了一种以BARS设备为网络核心的有线无线一体化网络拓扑结构。该拓扑结构能够最大限度地保护现有投资,只需在核心层增加BRAS设备,将原有交换机全部作为二层设备上联至BRAS即可。利用BRAS设备的性能和特性完成了内外网用户的隧道建立、隔离、流控、故障定位等精细化管理;利用大二层结构特性实现网内IPv4/IPv6双栈及多播业务,各种品牌有线无线设备的统一管理。该拓扑结构应用在实际网络环境中时BRAS设备必须进行热备,无线AC需要支持本地转发。     

RADIUS代理在宽带接入认证中的应用

RADIUS代理是设置在BRAS和RADIUS服务器之间的代理设备,完成RADIUS消息转发。RADIUS代理通过"不转发,自己应答"和"修改RADIUS会话的报文属性"等方面来实现对用户及业务的灵活控制,从而避免对RADIUS服务器的大规模改造。     

A broadband utopia [fast broadband connectivity]

The Utah Telecommunication Open Infrastructure Agency (Utopia) promises to deliver to each of its 3,000 subscribers high-speed Internet access, telephony and television programming through a fiber-optic cable at data rates that reach 30 megabits per second. Encompassing 14 cities in the northeastern Utah, the optical-fiber broadband network is expected to soon reach speeds of 50 and even 100 Mb/s. Because Utopia sends TV programming as Internet packets, it puts a huge reservoir of bandwidth at the disposal of its providers. In addition to its dedicated bandwidth connections, Utopia relies on the Ethernet standard to carry Internet protocol data packets all the way from the central office to the individual subscriber without changing the format, greatly simplifying the network.     

An adaptive Paris Metro Pricing scheme for mobile data networks

Because static pricing models (such as flat‐rate or tiered‐rate models) cannot improve user utility for subscribers and ease network congestion for operators during peak time, Smart Data Pricing has become an important incentive for mobile data markets. Paris Metro Pricing (PMP), which is a static pricing mode inspired by the pricing model for the Paris metro system, uses differentiated prices to motivate users to choose different train classes. Before choosing a class, people will consider their expected quality of service versus the prices that they are willing to pay. Even though PMP cannot guarantee the actual quality of service during service time, a balance between users' utilities and operators' revenue is achieved. In this paper, we propose an adaptive PMP scheme, so‐called APMP, which determines the dynamic access prices of different classes for the next 24 h. The accessible prices should try to increase the revenue while operators can serve more subscribers. Our simulation results show that APMP can significantly improve total revenue and average revenue per user for the operator. Copyright © 2016 John Wiley & Sons, Ltd.