MY WAY

WLAN的工作原理

•    WLAN是共享式网络，AP是共享设备，功能类似于以太网的HUB。

•    数据的传输是通过无线电信号。

•    双向无线通讯（半双工，时分多路复用）

•    同一个无线电频率用于数据的发送和接收（收发器），

•    同一时间只有一个站点可以传输数据，其他所有站点监听。

•    如果一个站点想要传输数据，必须等到无线通道没有被其他站点占用。

•    这种传输方式类似于同轴电缆或半双工以太网和以太网HUB。AP的工作模式类似于HUB。每站点的平均数据传输速率，就是总带宽除以站点数量。

•    相关知识介绍：

•       单工

•       双工（半双工、全双工）

•    LAN：CSMA/CD：载波监听多路访问/冲突检测

•    WLAN：CSMA/CA：载波监听多路访问/冲突避免

不同的WLAN-SSID

•    SSID是用于逻辑上区分WLAN

•    SSID必须在客户端和AP上匹配

•    AP对SSID进行广播

•    Client可以不配置SSID，从AP进行学习

•    SSID广播可以在AP上设置为禁止，但必须在客户端上手动设置SSID。

•    Client连接AP步骤：

•       Client发送探测请求

•       AP发送探测响应

•       Client初始化连接

•       AP接受连接

•       AP添加Client的MAC地址到连接表中

点击下载：ARUBA-NETWORKS.pdf

什么是TAC以及目前TAC提供技术支持的分类

56CTO-TAC（Technical Assistance Center）(技术支持中心)在线的BBS提供技术问题和技术产品的支持服务。

现在，我们只提供一种类型的TAC服务：在线服务请求提交（OLSR）。目前，这种类型的OLSR服务只开了4个分类的服务：

公司网络TOPO设计、CISCO产品技术支持、网络故障技术支持、UC（统一通信）产品技术支持

在线服务请求提交：首先你需要到服务请求中心提交你的问题，然后我们的工程师将会解决你的问题，并将结果通过EMAIL,BBS,QQ,MSN,SKYBE反馈给你。


在线服务请求列表：

★公司网络TOPO设计

为各种企业、公司、个人提供详细的网络设计方案

★CISCO产品技术支持

包括所有类型的CISCO的交换机和路由器产品的技术支持

★网络故障技术支持

包括各种类型方案设计或者使用过程中遇到的技术问题

★UC（统一通信）产品技术支持

现在技术发展的步伐就是统一通信的各种视频和音频设备

我们将在三天内解决您的问题。

在不久的将来，随着我们技术力量的提高，我们工程师团队的成长。我们将提供更多种类的TAC分类服务。

我将TCP/IP卷一的课后习题总结出来了，方便各位查阅。

这里面的题目，也是CCIE常考的知识点，希望各位认真对待。

要将每种题型以及知识点牢记于心，并且要注意英语题目的解答方法。

考试时，不见得你写出了key words就会得分，要注意语法，尽量去模仿这个PDF里面的语句。

点击下载：TCP/IP Volume I--课后习题总结

这个只是简略版，更多的内容还在整理中。

过后会发出完整版，里面将包括各种常考Feature，以及各种Feature的解释和配置方法。

准备CCIE RS的朋友，可以先看看这个。

点击下载：Cisco CCIE R_S Exam Feature Quick Reference Sheets[Feature速查表.测试版](MAY.2009).pdf

Lab Exam

Mobile CCIE Labs provide greater access to take your CCIE Routing & Switching Lab exam

Configuring a Network to Given Specifications

The CCIE lab exam is an eight-hour, hands-on exam which requires you to configure a series of complex networks to given specifications. Knowledge of troubleshooting is an important skill and candidates are expected to diagnose and solve issues as part of the CCIE lab exam. You will not configure end-user systems, but are responsible for all devices residing in the network (hubs, etc.). Point values and testing criteria are provided. More detail is found on the Routing and Switching Lab Exam Blueprint and the list of Lab Equipment and IOS Versions.

Cost

Lab exams cost USD$1,400 per attempt, not including travel and lodging expenses. Costs may vary due to exchange rates and local taxes (VAT, GST). You are responsible for any fees your financial institution charges to complete the payment transaction.

Price not confirmed and is subject to change until full payment is made. Please reference the CCIE Policies for more information.

Lab Environment

The Cisco documentation CD is available in the lab room, but the exam assumes knowledge of the more common protocols and technologies. As of March 2006, the documentation can only be navigated using the index; the search function has been disabled. No outside reference materials are permitted in the lab room. You must report any suspected equipment issues to the proctor during the exam; adjustments cannot be made once the exam is over.

Lab Exam Grading

Each question on the lab has specific criterion. The labs are graded by proctors who ensure all the criterion are met and points are awarded accordingly. The proctors use automatic tools to gather information from the routers to perform some preliminary evaluations, but the final determination of a correct or incorrect configuration is done by a trained proctor.

Results

You can review your lab exam results online (login required), usually within 48 hours. Results are Pass/Fail and failing score reports indicate major topic areas where additional study and preparation may be useful.

Reevaluation of Lab Results

You may request a reevaluation of results for Routing and Switching, Security and Service Provider labs for up to 14 days following your exam date. Use the link next to your lab record called "Request for Reread". Due to the equipment used, rereads are not available for the Voice and Storage Networking exams. Each reread costs US$250 plus any applicable local taxes. Payment is made online via credit card and your card will be charged upon receipt of the request. You may not cancel the reread request once the process has been initiated and refunds are only given when the results change from Fail to Pass.

A reread consists of a second proctor loading your configurations onto a rack to recreate the test and rescore the entire exam. This process may take up to three weeks after receipt of payment. Only one reread per lab attempt is permitted. The result of the reread is an updated score report with success rates for each major section. Be aware that scores may decrease. Exams receive a Pass mark only when the total exam score exceeds 80%. Before requesting a reread, consider that, historically, only 0.3% of exams have been changed from Fail to Pass.

NEW: Troubleshooting

Beginning October 18, 2009, the CCIE R&S lab exam will feature a two-hour troubleshooting section.  Candidates will be presented with a series of trouble tickets for preconfigured networks and need to diagnose and resolve the network fault or faults.  As with the configuration section, the network must be up and running for a candidate to receive credit.  Candidates who finish the troubleshooting section early may proceed on to the configuration section, but they will not be allowed to go back to troubleshooting since their equipment will need to be reinitialized for the configuration portion.

Lab Locations

CCIE R&S lab exams are offered at the Cisco locations noted below. In addition, Cisco has introduced Mobile CCIE Labs to provide access to the lab exam in regions without a Cisco CCIE lab location.

Use the following links to find information on start times, directions and hotel recommendations.

Bangalore, India
Beijing, China
Brussels, Belgium
Dubai, UAE
Hong Kong, PRC
RTP, USA
San Jose, USA
Sao Paulo, Brazil
Sydney, Australia
Tokyo, Japan

 (NEW:Troubleshooting
       从09年10月18号开始，CCIE实验室考试将设置一种长达两个小时的故障排除部分。内容包括：将呈现给应试者一系列配置网络的trouble tickets，应试者则需要诊断和解决相关网络错误或故障。在配置这一环节中，要求该网络必须能够运转，则应试者将获得相应的credit。及早成功完成故障排除环节的应试者，将继续配置环节，然因其设备的配置部分将重新初始化，应试者则不允许返回上一troubleshooting部分。)

                                                感谢Translator Eleanor提供翻译

This is a PDF about Frequently+Asked+Questions,include BGP,EIGRP,OSPF.

Download: Frequently+Asked+Questions

晚上10点，看到这样的结果，我过了吗，我想是过了。
感觉现在非常安静，特别安静。
只记得是07年的夏天学习CCNA的日子，只记得09年这三个月看书做实验的日子。
我想我是精神上赢得了CCIE。
谢谢父母的支持，丫头的理解，朋友的关心。
我真不知道能说什么，CCIE道路上的朋友们，加油。

Broadcast queue is a major feature that is used in medium to large IP or IPX networks where routing and service access point (SAP) broadcasts must flow across the Frame Relay network. The broadcast queue is managed independently of the normal interface queue, has its own buffers, and has a configurable size and service rate. This broadcast queue is not used for bridging spanning-tree updates (BPDUs) because of timing sensitivities. These packets will flow through the normal queues. The interface command to enable broadcast queue follows:

frame-relay broadcast-queue size byte-rate packet-rate

A broadcast queue is given a maximum transmission rate (throughput) limit measured in bytes per second and packets per second. The queue is serviced to ensure that only this maximum is provided. The broadcast queue has priority when transmitting at a rate below the configured maximum, and hence has a guaranteed minimum bandwidth allocation. The two transmission rate limits are intended to avoid flooding the interface with broadcasts. The actual limit in any second is the first rate limit that is reached. Given the transmission rate restriction, additional buffering is required to store broadcast packets. The broadcast queue is configurable to store large numbers of broadcast packets. The queue size should be set to avoid loss of broadcast routing update packets. The exact size depends on the protocol being used and the number of packets required for each update. To be safe, the queue size should be set so that one complete routing update from each protocol and for each data-link connection identifier (DLCI) can be stored. As a general rule, start with 20 packets per DLCI. The byte rate should be less than both of the following:

N/4 times the minimum remote access rate (measured in bytes per second), where N is the number of DLCIs to which the broadcast must be replicated

1/4 the local access rate (measured in bytes per second)

The packet rate is not critical if the byte rate is set conservatively. In general, the packet rate should be set assuming 250-byte packets. The defaults for the serial interfaces are 64 queue size, 256,000 bytes per second (2,048,000 bps), and 36 pps. The defaults for the High Speed Serial Interfaces (HSSI) are 256 queue size, 1,024,000 bytes per second (8,192,000 bps), and 144 pps.

Example:
A router have too much broadcast in the Frame-relay, adjust FR broadcast queue to 120, 260Kbytes rate per seconds, 240 packet per second.
Edison(config)#interface serial 0/0
Edison(config-if)#frame-relay broadcast-queue 120 260000 240

过去的一段时间，对于备考CCIE的同志们来说，是黑暗的

在这段时间里，我看到了太多的fail

如果有人问我，为什么考CCIE，我想我应该说：“因为有CCIE” 

听到gotoccie即将来北京三考R&S的消息，我是怎么样的感动，我佩服他，佩服他的毅力和精神

其实我们并不在乎CCIE能给我们带来多少经济效益，也不在乎那张纸，那快水晶牌，我们在乎的是和CCIE的情结，还有那个所谓的CCIE光环，我们似乎就是渴望CCIE这几个字母，好像并不太想去深究它的含义

    组播协议分为主机-路由器之间的组成员关系协议和路由器-路由器之间的组播路由协议。组成员关系协议包括IGMP(互连网组管理协议)。组播路由协议分为域内组播路由协议及域间组播路由协议。域内组播路由协议包括PIM-SM、PIM-DM、DVMRP等协议，域间组播路由协议包括MBGP、MSDP等协议。同时为了有效抑制组播数据在链路层的扩散，引入了IGMP Snooping、CGMP等二层组播协议。　　

    IGMP建立并且维护路由器直联网段的组成员关系信息。域内组播路由协议根据IGMP维护的这些组播组成员关系信息，运用一定的组播路由算法构造组播分发树进行组播数据包转发。域间组播路由协议在各自治域间发布具有组播能力的路由信息以及组播源信息，以使组播数据在域间进行转发。

详细内容,已总结成PDF

点击下载: CCIE学习笔记—Multicast

如果需要组播的实验资料,请留下E-mail地址.

把鼠标点到上面看看……

让CISCO唱给你听吧……

NTP—network time protocol，是用来使网络设备时间同步的一个协议。在配置了NTP的网络中，通常都会有一个比较权威的时间源，例如原子钟。NTP就是将从时间源那里获取的时间信息再分发到网络中的其他设备上来使整个网络的时间同步。

NTP使用一个层次（stratum）的概念来描述设备离权威时间源的远近，如层次1时间服务器就是典型的最权威的时间源，如原子钟，GPS时间源。层次2的时间服务器就是通过NTP从层次1那里接受时间信息。

NTP使用两种方法来避免跟时间不准确的设备同步时间。第一，NTP不会去跟自己都还没有同步的设备同步。第二，NTP会比较收到的几个时间信息，并且不会去跟一个与其他的时间信息差别很大的信息同步，哪怕这个信息是从一个层次比较底的设备来的。

在Cisco设备上是不支持层次1的服务器的，因为Cisco认为网络中的设备不太可能连接到原子钟这样的设备上（在特殊的平台上我们还是可以连接到GPS时间服务器上的）。通常都会认为网络中的时间服务器是来自与Internet上的公共服务器。

在不能连上Internet的内网中，我们可以把一台设备配置成NTP服务器使其他的设备来跟这个服务器同步。

详细内容,已总结成PDF

点击下载:CCIE学习笔记—NTP

在"keywords"和"location"里面输入你想找的东西

比如"CCIE","China"

http://www.recruit.net/

Cisco Introduces New CCIE Wireless Certification
Are you interested in greater opportunities for salary increase, differentiation and job advancement??According to Forrester Consulting, 36 percent of the global companies surveyed reported having dedicated wireless specialists in their IT organizations; that number is expected to almost double in the next five years.?The Cisco CCIE Wireless certification assesses and validates wireless expertise. Candidates who pass the CCIE Wireless certification exams demonstrate broad theoretical knowledge of wireless networking and a solid understanding of wireless local area networking (WLAN) technologies from Cisco, the market leader in WLAN technology.?Registration for the written exam will be available February 17th and registration for the lab exam will be available in April.

[Click Here for More Information]