2/10/2003 --

	Exam #640-861: Designing for Cisco Internetwork Solutions (CCDA) Vendor Cisco Status Live Reviewer's Rating "The CCDA exam has finally been updated and it includes all the latest technologies and design methodologies, which adds difficulty to this entry-level exam.." Test Information Apx. 58 questions, 75 minute exam. Cost: $125 (U.S.). . Who Should Take This Exam? Candidates for CCDA and CCDP. Test Objectives Click here

The Cisco Certified Design Associate (CCDA) certification was released by Cisco in 1998 and is used as the first step towards a career in designing Cisco networks. The previous version of the CCDA exam was in desperate need of a refresh and Cisco has accomplished that with this new exam. The CCDA certification is a requirement if you choose to pursue the Cisco Certified Design Professional (CCDP).

The CCDP certification requires you to pass three core exams from the CCNP track and the Cisco Internetwork Design (CID) exam which was also refreshed earlier this year. More information can be found here.

The main objectives of the CCDA exam are analysis, modeling and planning small to medium size networks. You'll find a primer from Cisco here.
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Beyond this information, to increase your chances of success, you can take the official Cisco DESGN course for instructor-led training or try one of several self-study guides. For my original exam study I used Designing Cisco Networks from Cisco Press for study, but this book doesn't have everything you'll need for the new exam.

To update yourself, make sure to check these resources on Cisco.com:

· SAFE design guide
· VoIP design guide
· IPv6 fundamentals

Although study guides are still in development at the time of this writing, you can expect new books from Cisco Press, Sybex and others. One of the more popular books on Cisco network design is Priscilla Oppenheimer's Top-Down Network Design from Cisco Press. This book comes close to the exam but is lacking the detail for SAFE, VoIP and IPv6.

The CCDA certification requires knowledge of many fundamental design concepts and methods using Cisco products and technologies. The CCDA exam covers these topics from a business and implementation perspective. In this article, I address some of the high points to study for the new exam by mapping to the official exam objectives, which you'll find here.

Analysis
Some of the sub-objectives in this category include gathering and evaluating information on the existing social, data, and voice requirements of the owner's current network. This exam topic requires you to demonstrate your ability to dissect a fictitious network scenario and identify the current and future needs to aid in the new design. These scenario case studies aren't new to IT certification exams (Microsoft exams use them) and you'll need to eliminate the fat thrown at you and find the meat of the information that will help you answer the question. This type of question requires careful reading.

Tip: I find it helpful to read the case study, review the questions and reread the case study to locate the answers.

Learning how to analyze an existing network requires practice and skill. The first thing you need to do is ask many questions of the decision makers, management and IT staff. These questions should be used to solicit answers that can be applied by the network designer for a scalable, verifiable and secure network design. Sometimes the network designer doesn't have the necessary people or business skills to be successful when dealing with the company's staff, and this is where a good project manager can make the difference. Regardless of who collects the necessary information, most design work is performed on existing networks, and the information is crucial.

The type of information that must be gathered includes business goals, social requirements, current data and voice network and future needs, possibilities for network improvement along with validation of the information and documentation. Business goals can include an increase in revenue and profit, improving communications, business partnerships, business expansion into worldwide markets and the ability to offer new or improved customer support services. Social requirements define the use of the network based on the company's business goals by its users and can include locations, market position, investors, vendors and customers.

Analyzing the customer's requirements for data and voice can be more complex, but the best place to start is by sampling the traffic patterns with a network analyzer tool to create baselines. With the collected baselines, you can begin the planning and modeling design work by identifying solutions and developing an implementation. For the data portion of the collection, give consideration to the different protocol types and network operating systems in use. Many protocols are broadcast-based, such as Microsoft's NetBIOS. These types of protocols can present a unique challenge to the network designer if hierarchical design methodologies aren't followed. For more information and a detailed baseline "best practices" white paper, click here.

Cisco's three-layer hierarchical design model includes the Core, Distribution and Access layers. Understanding the application, benefits and limitations of this design model are crucial to passing this exam. The Core layer is the backbone of the network and should only switch traffic at a high rate of speed with no changes being made in the design at this layer. The Distribution layer is where traffic control occurs with access lists, firewall design, address or area aggregation, broadcast domain definition, vLAN routing and security. The Access layer may include shared and switched bandwidth client connections with support for MAC layer filtering. You can find more information on the three-layer model and many other network design basics in the Cisco Internetworking Design guide found here.

Validation and documentation includes the need through pilot or prototype testing to show that a design will meet the customer's business, technical, and budget goals. Documenting the finding of testing, the designer and customer will have a record of the solutions showing the design details, which can then be passed on to the network engineers for implementation. Understanding exactly which design details need to be communicated to the network engineers is a requirement of this exam, and you need to know just how much to include. Relevant information includes the justification for design, an overview with specific steps with clear concise details to avoid confusion.

Modeling
Network design modeling is the core topic of this exam, and it's no wonder since this is where specific design issues need to be brought to the table to identify available solutions. Sub-objectives in this category include: solutions for IP addressing needs, routing protocols, network management, equipment and technology for Campus and Enterprise Edge design, Enterprise Composite Network Model and voice traffic over a data network.

Solutions for IP addressing include: NAT, private IP addresses and VLSM. This exam includes the standard subnetting questions and design considerations for network address translation and private IP addressing. You also need to demonstrate an understanding of VLSM with routing protocol support. VLSM is often referred to as subnetting a subnet. It is a design solution that reduces the network's routing tables at the edges and is very scalable.

Tip: Practice VLSM addressing calculations just like you did for standard subnetting to prepare for this exam RIP version 1 and IGRP are classful routing protocols, and they don't support VLSM. Remember that VLSM requires the subnet mask to be sent with all routing updates.

Private IP addressing solutions conserve Internet IP addresses but require NAT and sometimes proxy servers to perform the translation between private and public addresses and vice versa. This new exam does include IPv6 questions and you should be ready to demonstrate your understanding of address formats, abbreviations, subnetting and loopback addressing. Take the time to review the IPv6 fundamentals reference material earlier in this article.

Network Management solutions can include SNMP, CDP and CiscoWorks 2000. SNMPv3 is the latest Simple Network Management Protocol. It includes support for security features such as authentication and encryption, which has been highly anticipated by the network management community. The first half of this document will give you all that you need to prepare for this exam (click here to access.)

CDP or Cisco Discovery Protocol is a Cisco proprietary network management tool that can be useful for documenting and troubleshooting your Cisco network. The limitation of CDP is reporting features on neighboring devices; but its greatest feature is that it is media- and protocol-independent and operates at the data link layer. CiscoWorks 2000 is a suite of management tools for the LAN and WAN. Service Level Manager is a plug-in to CiscoWorks 2000. You should be familiar with its operation for this exam. More information can be found here.

Equipment and technology for Campus and Enterprise Edge design includes identification of the right Cisco device for the application. Most CCNA and CCDA study guides include the proverbial Cisco product chart for both routers and switches. This exam references the latest and greatest, such as the 3600 series of routers and 6500 series of switches. You should be comfortable with the Cisco product chart. Learn more here.

The Enterprise Composite Network Model includes various modules of a network security design as outlined in this document, titled, "Extending the Security Blueprint to Small, Midsize, and Remote-User Networks." For this exam it's imperative that you understand the design philosophy behind Cisco's SAFE security architecture design. The ECNM allows network designers to focus on each area of the enterprise and campus design for a layered approach to security. Each network device and module such as the campus, edge or WAN can be secured against attacks from the outside and inside. A layered approach to security design is highly recommended in all cases.

I briefly mentioned voice traffic over a data network or VoIP and referenced a fundamentals document earlier in this article. There are also a few implementation details on this exam that you should be familiar with. Much of the fundamental information can be found here.

Cisco Press also has a great book on the topic, Voice over IP Fundamentals, by Jonathan Davidson and James Peters.

The exam covers various trunking, PBX and Centrex line basics. T1 digital trunks have become a popular choice in North America as the need for bandwidth increases. The PBX switch offers many features such as integrated voice mail, local lines and PSTN trunks. The Centrex line provided and managed by the LEC (Local Exchange Carrier) offers additional services similar to the PBX switch such as call transfer, three-way calling and a closed user-dialing plan.

Silence suppression is another challenge for VoIP networks, and it's often circumvented on the switch by VAD (Voice Activity Detection) configuration.

Remember that finding the correct Cisco solution is elementary to passing this exam since it's vendor specific and vendor sponsored.

Planning
This is the final exam topic. The sub-objectives in this category include developing an implementation, prototype testing and verification plan. When it comes to planning, the old rules still apply; successful projects include 99 percent planning and one percent perspiration. The exam includes scenarios that ask you to identify the correct order of steps, identified as implementation, prototype testing and verification. You may also see questions asking you what step or steps should follow the initial technical design phase prior to the hand-off of the design to the network engineers.

Knowing when to develop an implementation plan is crucial to a successful design if you want to keep your job or be invited back to a customer's site. The implementation plan is usually one the final responsibilities of the network designer and can include the detailed steps relayed to the engineers as noted earlier. In most cases, prototype testing is completed prior to implementation and this is followed by a verification plan.

You should understand the reasons for prototype testing, which include proof of design both technical and non-technical, knowledge of a competitor's design, and user and support staff consensus with the design for usability and management included. Prototype testing may be performed on a test network in a lab, integrated into a production network for off-hours testing or integrated into a production network and tested during normal business hours. When using a production network for prototype testing, you should warn the users, administrators and network managers in advance. Also included in prototype testing is a test plan, which should spell-out the objectives, types of tests, resources required, scripts and timeline milestones. Objectives can include various measurements of response time against the baseline information gathered in the analysis phase. The tests to be run during the prototype are application response, throughput and network availability. Resources required will include a list of hubs, switches, routers, workstations, servers, simulators and cables. Test scripts will generally include the steps taken to meet a particular test objective and acceptance criteria.

Verification plans usually include documented findings to support your network design for a prototype or implementation.

The CCDA certification is the first step in the right direction if you choose a career in designing Cisco network solutions. This new version of the exam could help you decide if you have what is takes to be successful. If you pass it, you'll have a greater understanding of Cisco's network design philosophies. Good luck!