On the command prompt run the below steps in order
1. net stop winmgmt then go to the C:\Windows\system32\wbem directory and delete the Repository directory
2. net start winmgmt
3. cd /d %windir%\system32\wbem 4. for %i in (*.dll) do RegSvr32 -s %i 5. for %i in (*.exe) do %i /RegServer
and
6. cd /d %windir%\sysWOW64\wbem 7. for %i in (*.dll) do RegSvr32 -s %i 8. for %i in (*.exe) do %i /RegServer
reboot and let me know ...
NOTE: A word of advice... Rebuilding the WMI repository will most probably result in some 3rd party products not working until their setup is re-run & their MOF re-added back to the repository.
ODL's Third Release – “Lithium” - Introduces New SDN Features & Capabilities
● Increased scalability and performance ● Network services for cloud data center platforms ● New features for security and automation ● New and enhanced APIs for interoperability ● Six new protocols to support an ever-widening set of use cases ( OpFlex is one of the six protocols)
Abstract
The OpFlex architecture provides a distributed control system based
on a declarative policy information model. The policies are defined
at a logically centralized policy repository (PR) and enforced within
a set of distributed policy elements (PE). The PR communicates with
the subordinate PEs using the OpFlex Control protocol. This protocol
allows for bidirectional communication of policy, events, statistics,
and faults. This document defines the OpFlex Control Protocol.
OpFlex is a policy driven system used to control a large set of
physical and virtual devices. The OpFlex system architecture
consists of a number of logical components. These are the
OpFlex protocol uses JSON,
XML, or OpFlex-Binary-RPC as the wire encoding. Policy
Repository (PR) It handles policy
resolution requests from the Policy Elements within the same
administrative domain. These policies are configured directly
by the user via a policy administration interface (API/UI/CLI/etc.)
PR - MIM (Management Information Model)
The hierarchical structure starts at a root
node and all policies within the system can be reached via parent and
child containment relationships. Each node has a unique Uniform
Resource Identifier (URI) [RFC3986] that indicates its place in the
tree.
PR -Managed Objects
MOs that contain statistic, fault, or health MOs are said to be
observable
Properties, Child Relation, Parent Relation, MO Relations, Statistics, Faults, Health Endpoint Registry (EPR) The Endpoint Registry (EPR) is the component that stores the current
operational state of the endpoints (EP) within the system
The EP registration information contains the scope of
the EP such as the Tenant or logical network as well as location information such as the hypervisor where the EP resides. The EPR can
be used by PEs to query the current EPR registrations as well as
receive updates when the information changes.
Observer
The Observer serves as the monitoring subsystem that provides a
detailed view of the system operational state and performance. It
serves as a data repository for information related to trending,
forensics, and long-term visibility data such as statistics, events,
and faults. Policy
Elements (PE). Policy elements reside on
physical or virtual devices that are subjected to policy control
under a given administrative domain. Two types of the PE triggers
(a) Local
triggers involve local MO state transitions such as new control node
additions, removals, or other operational events.
(b) Policy triggers
invoked by other PEs are transmitted using the OpFlex Control
Protocol
Security
OpFlex
Control Protocol SHOULD be secured using Transport Layer Security
(TLS) [RFC5246].
A TCP port will be requested from IANA for the OpFlex Control
Protocol.
Terminology:
AD: Administrative Domain. A logical instantiation of
the OpFlex system components controlled by a single
administrative policy.
EP: Endpoint. A device connected to the system.
EPR: Endpoint Registry. A logically centralized entity
containing the endpoint registrations within
associated administrative domain.
OB: Observer. A logically centralized entity that serves
as a repository for statistics, faults, and events.
PE: Policy Element. A function associated with entities
comprising the policy administrative domain that is
responsible for local rendering of policy.
PR: Policy Repository. A logically centralized entity
containing the definition of all policies governing
the behavior of the associated administrative domain.
OpFlex Device: Entity under the management of a Policy Element.
Predictable and deterministic routing decisions in the case of failover
Optimal routing decisions based on bandwidth and load
The way this is done will depend on where in the network the NFV functionality is hosted. There are three basic methods:
Standard servers running NFV functionality in the same topological network location as the appliance. This saves on hardware costs but does not reduce network complexity.
Much of the network functionality, including switches and appliances, can be virtualized in a hypervisor. This is the approach taken by Nicira and others. This may be appropriate in data center environments.
OpenFlow-capable switches can selectively shunt traffic to standard servers running NFV functionality off the main data path.
Virtual eXtensible Local Area Network (VXLAN) [3],
Network Virtualization using Generic Routing Encapsulation (NVGRE) [4]
Stateless Transport Tunneling (STT)
Virtual eXtensible Local Area Network (VXLAN)
The VXLAN technology was developed primarily by VMware and Cisco as a means to mitigate the
inflexibility and limitations of networking technologySome of the main characteristics of VXLAN are:
VXLAN utilizes MAC-in-IP tunneling
Each virtual network or overlay is called a VXLAN segment.
VXLAN segments are identified by a 24-bit segment ID, allowing for up to 224 (approximately
16 million) segments.
VXLAN tunnels are stateless.
VXLAN segment endpoints are the switches that perform the encapsulation and are called virtual tunnel endpoints (VTEPs).
VXLAN packets are unicast between the two VTEPs and use UDP-over-IP packet formats.
It is UDP based. The UDP port number for VXLAN is 4789
Network Virtualization using Generic Routing Encapsulation (NVGRE)
The NVGRE technology was developed primarily by Microsoft, with other contributors including Intel,
Dell, and Hewlett-Packard. Some of the main characteristics of NVGRE are:
NVGRE utilizes MAC-in-IP tunneling.
Each virtual network or overlay is called a virtual layer two network.
NVGRE virtual networks are identified by a 24-bit virtual subnet identifier, allowing for up to 22 (16 million) networks.
NVGRE tunnels, like GRE tunnels, are stateless.
NVGRE packets are unicast between the twoNVGRE end points, each running on a switch.NVGR utilizes the header format specified by the GRE standard [11,12].
Stateless Transport Tunneling (STT)
Stateless Transport Tunneling (STT) is a recent entry into the field of tunneling technologies used for network virtualization. Its major sponsor was originally Nicira. Some of the main characteristics of STT are:
STT utilizes MAC-in-IP tunneling.
The general idea of a virtual network exists in STT but is enclosed in a more general identifier called a context ID.
STT context IDs are 64 bits, allowing for a much larger number of virtual networks and a broader range of service models.
STT attempts to achieve performance gains over NVGRE and VXLAN by leveraging the TCP Segmentation Offload (TSO) found in the network interface cards (NICs) of many servers. TSO is a mechanism implemented on server NICs that allows large packets of data to be sent from the server to the NIC in a single send request, thus reducing the overhead associated with multiple smaller requests.
STT, as the name implies, is stateless.
STT packets are unicast between tunnel end points, utilizing TCP in the stateless manner associated with TSO. This means that it does not use the typical TCP windowing scheme, which requires state for TCP synchronization and flow control.
Open flow is to define both the communications protocol between the SDN data plane and SDN control plan and part of the behavior of the data plan.
The Open Network Foundation (ONF) was created for the express purpose of accelerating the delivery and commercialization of SDN.
Three fundamental packet paths are (1) A. Forward the packet out a local port, possibly modifying certain header fields first (2) B. Drop the packet (3) C. Pass the packet to the controller.
Openflow switch implementation is either OpenFlow only or OpenFlow-hybrid. OpenFlow only switch is one that forwards packets only according to the OpenFlow logic. An OpenFlow hybrid is a switch that can also switch packets its legacy mode as an Ethernet switch or IP router, it requires a preprocessing classification mechanism that directs packets to either OpenFlow processing or the traditional packet processing.
The OpenFlow control plane differs from the legacy control plan in three key ways.
(a) It supports to program different data plan elements with a common, standard language.
(b) it exists on a separate hardware device than the forwarding plan. Administrator can program data plan elements remotely over the Internet.
(c) controller can program multiple data plan elements from a single control plan instance.
OpenFlow controller is responsible for programming all the packet-matching and forwarding rules in the switch.
The following data are copied by weightless official website.
Key characteristics
Excellent capacity and scalability for IoT deployment
FDMA+TDMA in 12.5kHz narrow band channels offer optimal capacity for uplink-dominated traffic from a very large number of devices with moderate payload sizes
Operates over the whole range of license-exempt sub-GHz ISM/SRD bands for global deployment: 169/433/470/780/868/915/923MHz
Flexible channel assignment for frequency re-use in large-scale deployments
Adaptive data rate from 200bps to 100kbps to optimise radio resource usage depending on device link quality
Transmit power control for both downlink and uplink to reduce interference and maximize network capacity
Time-synchronised base stations for efficient radio resource scheduling and utilisation
Bidirectional
Supports both network-originated and device-originated traffic
Paging capability
Low latency in both uplink and downlink
Fast network acquisition
Forward Error Correction (FEC)
Automatic Retransmission Request (ARQ)
Adaptive Channel Coding (ACC)
Handover
Roaming
Cell re-selection
Long range
Lower data rates with channel coding provide similar link budget to other LPWAN technologies
2km in urban environment
Industrial-grade reliability
Fully acknowledged communications
Auto-retransmission upon failure
Frequency and time synchronisation
Supports narrowband channels (12.5KHz) with frequency hopping for robustness to multi-path and narrowband interference
Channel coding
Supports licensed spectrum operation
Ultra-low energy consumption
GMSK and offset-QPSK modulation for optimal power amplifier efficiency
Interference-immune offset-QPSK modulation using Spread Spectrum for improved link quality in busy radio environments
Transmit power up to 17dBm to allow operation from coin cell batteries
Adaptive transmit power and data rate to maximise battery-life
Power consumption in idle state when stationary below 100uW
Secure and efficient networking
Authentication to the network
AES-128/256 encryption
Radio resource management and scheduling across the overall network to ensure quality-of-service to all devices
Support for over-the-air firmware upgrade and security key negotiation or replacement
Fast network acquisition and frequency/time synchronisation
Low cost and complexity
Using standard GMSK and offset-QPSK modulation channels ensures broad availability of hardware and no dependency on a single vendor
Compared to UNB, narrowband operation is less sensitive to frequency offset and drift, allowing the use of lower cost, lower power XOs or DCXOs instead of TCXOs
Maximal transmit power of 17dBm allows for integrated power amplifier
Open standard
Brings the reliability and performance of cellular technologies at a fraction of the cost by avoiding any legacy or backward-compatibility concerns
Ensures interoperability between the manufacturers
Provides for multivendor support to stimulate ongoing innovation and minimise end user costs
Royalty free IP minimises production costs
The Weightless-P Specification and demonstration hardware will be available later this year. Base stations, endpoints and development kits will be commercially available in Q1 2016.
4、將協議自身的開銷控制到最小。見下： 1）用於發現和維護鄰居關係的是定期發送的是不含路由信息的hello報文，非常短小。包含路由信息的報文時是觸發更新的機制。（有路由變化時才會發送）。但為了增強協議的健壯性，每1800秒全部重發一次。 2）在廣播網絡中，使用組播地址（而非廣播）發送報文，減少對其它不運行ospf 的網絡設備的干擾。 3）在各類可以多址訪問的網絡中（廣播，NBMA），通過選舉DR，使同網段的路由器之間的路由交換（同步）次數由 O（N*N）次減少為 O （N）次。 4）提出STUB區域的概念，使得STUB區域內不再傳播引入的ASE路由。 5）在ABR（區域邊界路由器）上支持路由聚合，進一步減少區域間的路由信息傳遞。 6）在點到點接口類型中，通過配置按需播號屬性（OSPF over On Demand Circuits），使得ospf不再定時發送hello報文及定期更新路由信息。只在網絡拓撲真正變化時才發送更新信息。
3. EIGRP的無環路計算和收斂速度是基於分佈式的DUAL算法的，這種算法實際上是將不確定的路由信息（active route）散播（向鄰居發query報文），得到所有鄰居的確認後（reply報文）再收斂的過程，鄰居在不確定該路由信息可靠性的情況下又會重複這種散播，因此某些情況下可能會出現該路由信息一直處於active狀態（這種路由被稱為stuck in active route），並且，如果在active route的這次DUAL計算過程中，出現到該路由的後繼（successor）的metric發生變化的情況，就會進入多重計算，這些都會影響DUAL算法的收斂速度。而OSPF算法則沒有這種問題，所以從收斂速度上看，雖然整體相近，但在某種特殊情況下，EIGRP還有不理想的情況。
<<Internet of Things - Thread Group>> Thread產品認證計畫將於今年九月上路，目前遵循Thread的晶片和軟體堆疊已可自安謀國際(ARM)、飛思卡爾(Freescale)、芯科實驗室(Silicon Labs)等業者取得，可用以開發終端產品；預計2015年底首批通過認證的產品即可問世 <<無線充電>>
MHL(行動高畫質鏈結)聯盟近期也發布支援8K、120Hz畫面更新率(FPS)的superMHL規範，同樣也將Type-C Alt Mode納入規格清單。 MHL標準是從HDMI衍伸而來，但superMHL在解析度、六傳輸管線(Lane)架構、聲效、多資料流程和Type-C Alt Mode支援上皆超前HDMI 2.0標準布局； USB Type C 規格一出，除了可能掀起消費性電子產品的連結埠革命，也帶動了傳輸介面的革新，視訊電子標準協會（Video Electronics Standards Association， VESA）與 USB3.0 推廣小組推動 DisplayPort Alternate Mode USB Type C ，准許 DisplayPort 信號透過 USB Type C 傳輸，未來支援此規範的裝置，用一條傳輸線（雙 Type C 接頭）就能啟動 DisplayPort、HDMI、DVI 或 VGA 等不同規格螢幕，或許未來一條傳輸線就可走天下。
（Source：VESA）
USB Type C 的靈活性可讓 DisplayPort Alt Mode 在四個可用的通道中選用一個或兩個通道傳輸資料，其他兩個通道則可同時用以傳輸 SuperSpeed USB 資料，透過這四個通道的運用可驅動 4K 和甚至 5K 高畫質影像，並能提供 100 瓦的功率。這項替代方案預計今年下半年進行安規測試、預計 2016 年將有商品問世。
