What is the purpose of the LLID in EPON?
If the OLT (the central node of the EPON) were to be implemented as a PHY with a single MAC attached to it, this would cause serious trouble for any bridge (=switch) to which the MAC were connected. Consider a MAC frame coming into the bridge from an ONU (a subscriber node) via an EPON port. The bridge associates the source address of the frame with the port on which it came in, i.e. the EPON port. When at a later time another MAC frame comes in from an ONU, this time destined for the MAC address previously learned, it will not be transmitted back to the EPON port, because the bridge assumes that the frame was already received by all the stations on the attached “broadcast” LAN. However, this is not the case; upstream transmissions are not received by other ONUs. Standard bridging has no way of accomodating an attached LAN that behaves as a broadcast LAN in downstream and as a point-to-point LAN in upstream.
The solution to this problem was designed in close cooperation with Working Group 802.1. Instead of one single MAC, the OLT would have a different dedicated MAC for every ONU attached to the EPON. As a result, higher layers can consider the EPON as a collection of logical point-to-point links. From the individual MACs down to the OLT PHY, the logical point-to-point links share a common GMII; hence, a way to identify data frames for/from the different ONUs is required. The Logical Link identifier (LLID) was created for this purpose. The LLID is carried along by the frame in the bytes of its preamble.
How the data transfer in an EPON system?
An EPON system uses the single-fiber wavelength division multiplexing (WDM) technology (with downlink central wavelength of 1490 nm and uplink central wavelength of 1310 nm) to implement single-fiber bidirectional transmission, supporting a transmission distance of up to 20 km (12.43 miles).
What’s the ONU optical TX power and RX sensitivity?
Wavelength: Tx 1310nm, Rx1490nm
Tx Optical Power: 0~5dBm
Rx Sensitivity: -27dBm
Saturation Optical Power: -8dBm
What is your ONT Tx power level and RX sensitivity?
The OLT support Class B+.
Transmission Distance:20KM
PON port speed: symmetrical 1.25Gbps
Waves: 1310nm TX,1490nm RX
TX Optical power : 0~5dBm
RX Sensitivity: -27dBm
How many ONU can your OLT connect?
The ONU quantity connected to the OLT depend on the OLT PON ports quantity and optical splitter ratio.
For example, 2PON port OLT can connect 64pcs EPON ONU in 1:32 splitter ratio; If in 1:64 ratio, it can manage 128pcs ONU.
What is epon ?
Ethernet Passive Optical Network (EPON), defined by IEEE 802.3ah, is a point to multipoint (Pt-MPt) network topology implemented with passive optical splitters, along with optical fiber PMDs that support this topology. EPON is based upon a mechanism named MPCP (Multi-Point Control Protocol), which uses messages, state machines, and timers, to control access to a P2MP topology. Each ONU in the P2MP topology contains an instance of the MPCP protocol, which communicates with an instance of MPCP in the OLT. On the basis of the EPON/MPCP protocol lies the P2P Emulation Sublayer, which makes an underlying P2MP network appear as a collection of point-to-point links to the higher protocol layers (at and above the MAC Client). It achieves this by prepending a Logical Link Identification (LLID) to the beginning of each packet, replacing two octets of the preamble. In addition, a mechanism for network Operations, Administration and Maintenance (OAM) is included to facilitate network operation and troubleshooting.
Is the wireless AP meet 802.11ac?
Yes, C-Data Wireless Ap Ceiling type CW8837AP and outdoor type CW9833AP both meet 802.11ac standard.
What is EOC?
Ethernet Over Coax also called EOC for short. It is an equipment which used for triple play service in a new generation broadcasting network. Widely used by consumers and telecommunications operators in existing 75 ohm coaxial cable installations (from cable television or CATV), to carry broadband data into and through the home, and into multiple dwelling unit (MDU) installations.
C-Data EOC network is built with EOC Master and EOC Slave.
What is HFC?
Hybrid fiber-coaxial (HFC) is a telecommunications industry term for a broadband network that combines optical fiber and coaxial cable.
In a hybrid fiber-coaxial cable system, the television channels are sent from the cable system’s distribution facility, the headend, to local communities through optical fiber trunk lines. At the local community, a box called an optical node translates the signal from a light beam to electrical signal, and sends it over coaxial cable lines for distribution to subscriber residences. The fiberoptic trunk lines provide adequate bandwidth to allow future expansion and new bandwidth-intensive services.
What is MC?
A fiber media converter ( MC for short) is a simple networking device that makes it possible to connect two dissimilar media types such as twisted pair with fiber optic cabling. They were introduced to the industry in the 1990s, and are important in interconnecting fiber optic cabling-based systems with existing copper-based, structured cabling systems. They are also used in metropolitan area network (MAN) access and data transport services to enterprise customers.
什么是GPON?
GPON(Gigabit-Capable PON) 技术是基于ITU-TG.984.x标准的最新一代宽带无源光综合接入标准,具有高带宽,高效率,大覆盖范围,用户接口丰富等众多优点,被大多数运营商视为实现接入网业务宽带化,综合化改造的理想技术。GPON最早由FSAN组织于2002年9月提出,ITU-T在此基础上于2003年3月完成了ITU-T G.984.1 和G.984.2的制定,2004年2月和6月完成了G.984.3的标准化。从而最终形成了GPON的标准族。
什么是10G PON?
宽带进入千兆接入时代,10G PON 逐渐成为PON的主流技术,传统PON正在向10G PON 升级,宽带将提升10倍。10G PON 规模商用落地开展,将直接助力FTTH向千兆接入速率演进。
10G PON有诸多方面的优势,可在现有硬件架构的基础上升级网络,极大降低成本,并且缩短改造周期,更关键的是,PON向10G PON的升级,可使带宽提升10倍。即仅通过关键部件的升级,就可以从“百兆时代”跨入“千兆时代”。
千兆带宽并不是极限,随着8K超高清视频及物联网技术的高速发展,尤其是5G时代的到来,将给网络带来更大的带宽增长需求,在此背景下,10G PON也将不断发展,将向100G PON演进。
从标准进展来看,100G PON已在IEEE/FSAN/ITU-T等标准化组织中立项。IEEE成立了NG EPON研究组,标准命名为P802.3ca,主要针对25G PON、50G PON、100G PON进行标准化制定,计划在2019年5月正式发布标准;ITU-T也成立了25G PON研究组,对单波长速率提升进行研究。
什么是PON?
PON(Passive Optical Network:无源光纤网络)。 PON(无源光网络)是指(光配线网中)不含有任何电子器件及电子电源,ODN全部由光分路器(Splitter)等无源器件组成,不需要贵重的有源电子设备。一个无源光网络包括一个安装于中心控制站的光线路终端(OLT),以及一批配套的安装于用户场所的光网络单元(ONUs)。在OLT与ONU之间的光配线网(ODN)包含了光纤以及无源分光器或者耦合器。
什么是FTTH?
自2003年宣传推广以来,FTTH已走过了14年,自2013年《宽带中国》战略发布也又经历了4年,FTTH从光通信人的梦想演变成现实,并成为人们工作、学习、生活不可或缺的基础设施。
FTTH是光纤直接到家庭的外语缩写,中文缩写为光纤到户。具体说,FTTH是指将光网络单元(ONU)安装在住家用户或企业用户处,是光接入系列中除FTTD(光纤到桌面)外最靠近用户的光接入网应用类型。FTTH的显著技术特点是不但提供更大的带宽,而且增强了网络对数据格式、速率、波长和协议的透明性,放宽了对环境条件和供电等要求,简化了维护和安装。说到FTTH,首先就必须谈到光纤接入。光纤接入是指局端与用户之间完全以光纤作为传输媒体。光纤接入可以分为有源光接入和无源光接入。光纤用户网的主要技术是光波传输技术。目前光纤传输的复用技术发展相当快,多数已处于实用化。根据光纤深入用户的程度,可分为FTTC、FTTZ、FTTO、FTTF、FTTH等。
FTTH的优势主要是有5点:第一,它是无源网络,从局端到用户,中间基本上可以做到无源;第二,它的带宽是比较宽的,长距离正好符合运营商的大规模运用方式;第三,因为它是在光纤上承载的业务,所以并没有什么问题;第四,由于它的带宽比较宽,支持的协议比较灵活;第五,随着技术的发展,包括点对点、1.25G和FTTH的方式都制定了比较完善的功能。
什么是FTTB?
FTTB(Fiber To The Building):是FTTX+LAN的一种网络连接模式,主要是将光信号接入办公大楼或者公寓大厦的总配线箱内部,实现光纤信号的接入,而在办公室大楼或公寓大厦的内部,则仍然是利用同轴电缆、双绞线或光纤实现信号的分拨输入,以实现高速数据的应用。我们称为FTTX+LAN的宽带接入网(简称FTTB),这是一种最合理、最实用、最经济有效的宽带接入方法。
优点
速度快 :光纤到楼,网线到户,用户上下行速率一般可达10Mbps-50Mbps,最高可达到100Mbps。
容量大 :每户可独享双向均衡10M-50Mbps带宽。
投资省:FTTB主要用于老小区改造,在已经网线、电话线、同轴电缆入户的小区不用在部署光纤,省去一大笔布线费用。
价格低:单位带宽比FTTH和CMTS都便宜
应用广:包括高速上网、VOD视频点播、家庭办公(SOHO)、远程教育、视频会议、远程办公(ROBO)、远程医疗和网间互联等。
什么是无线AP?
无线AP(AP,Access Point,无线访问节点、会话点或存取桥接器)是一个包含很广的名称,它不仅包含单纯性无线接入点(无线AP),也同样是无线路由器(含无线网关、无线网桥)等类设备的统称。它主要是提供无线工作站对有线局域网和从有线局域网对无线工作站的访问,在访问接入点覆盖范围内的无线工作站可以通过它进行相互通信。
单纯性无线AP就是一个无线的交换机,提供无线信号发射接收的功能。单纯性无线AP的工作原理是将网络信号通过双绞线传送过来,经过AP产品的编译,将电信号转换成为无线电讯号发送出来,形成无线网的覆盖。根据不同的功率,其可以实现不同程度、不同范围的网络覆盖,一般无线AP的最大覆盖距离可达500米。 多数单纯性无线AP本身不具备路由功能,包括DNS、DHCP、Firewall在内的服务器功能都必须有独立的路由或是计算机来完成。
HGU、SFU、MDU、MTU和SBU有什么区别?
SFU(Single Family Unit) 单住户单元型ONU
主要用于FTTH场景下的单独家庭用户,仅支持宽带接入的普通终端,一般具有1~4个以太网接口,提供以太网/IP业务,通过内置光机或IAD设备可以支持CATV业务或VoIP业务。如今经常同家用路由器配合使用,以提供更强的业务能力。
HGU(Home Gateway Unit)家庭网关单元型ONU
主要用于FTTH场合下的单独家庭用户,相比SFU具有家庭网关功能,相当于带PON上联接口的家庭网关,一般具有2~4个以太网接口、1个WLAN接口和1个USB接口,提供以太网/IP业务,通过内置光机或IAD设备可以支持CATV业务或VoIP业务,支持TR-069远程管理。
MDU(Multi.Dwelling Unit)多住户单元型ONU
主要应用于FTTB/FTTC/FTTCab模式下的多个住宅用户场合,具有宽带接入终端功能,一般具有至少4个用户侧接口,在电信运营商的设备选型中,往往包括以太网接口、ADSL2+接口或VDSL2接口等,提供以太网/IP业务。在广电运营商的网络应用中,由于业务内容差异,一般仅包含以太网接口,进行PON+LAN方式的接入。
MTU(Multi-Tenant Unit)多租户单元型ONU
主要用于FTTB场景下的多个企业用户或同一个企业内的多个个人用户,具有宽带接入终端功能,具有多个以太网接口(一般至少8个)、E1接口和POTS接口,提供以太网/IP业务、TDM业务和VoIP业务(内置IAD)。
SBU(Single Business Unit)单商户单元型ONU
主要用于在FTTO的场合下,单独企业用户和企业里的单个办公室接入。支持宽带接入终端功能,在电信运营网络中,一般具有以太网接口、E1接口、VOIP接口等,提供以太网/IP业务和TDM业务。