CCDA Group 1.ppt

1、1,Cisco Certified Design Associate,CCDA Prep,Cisco Certified Design Associate (CCDA),The Cisco Certified Design Associate individual certification denotes proficiency in designing simple routed LAN, routed WAN and switched LAN networks. Recommended courses: Internetworking Technology Handbook Cisco

2、Routing & LAN Switching (ICND) Cisco Certified Design Associate course Exam #640-441,Cisco Career CertificationsRouting and Switching,Network Support,Network Design,For more information about Ciscos Career Certifications: ,Class Objectives,Upon completion of this class, you will be able to do the fo

3、llowing: Design a network that meets a customers requirements for performance, security, capacity, and scalability. Assemble Cisco product lines into an end-to-end solution for customers.,Class Modules,Introduction - A Small- to Medium-Sized Solutions Framework Module 1 - Identify Customer Needs Mod

4、ule 2 - Design the Network Structure Module 3 - Build a Prototype or Pilot the Network Structure,7,A Small-to Medium-Sized Business Solutions Framework,Section Objectives,Upon completion of this introduction, you will be able to recognize a framework you can use to simplify the complexities associat

5、ed with analyzing customer network problems and creating Cisco scalable solutions.,CCDA Role,Network Design Consultant Build Comprehensive Designs that: Solve your customers internetworking problems Functionality, Performance and Scalability,OSI Reference Model Layers,Layer 2 - data link layer opera

6、tes within a specific LAN or WAN segment. Layer 3 - network layer operates between and across segments.,Layer 2 Switching,Last two years have shown significant growth in the use of LAN switching at Layer 2 LAN switches provide performance by increasing bandwidth and throughput,Layer 3 Routing,Interc

7、onnects the switched workgroups and provides services such as: security quality of service (QoS) traffic management,Integration of Layers,Traditionally, Layer 2 switching has been provided by LAN switches, and Layer 3 networking has been provided by routers. Increasingly, these two networking functi

8、ons will be integrated into common platforms.,A Small- to Medium-Sized Business Solutions Framework,The decision to use Layer 2 or Layer 3 functionality in a network design depends on what problems you are trying to solve for your customer. These problems can be any of the following: Media Problems,

9、 Protocol Problems, and the need to transport large payloads.,Basic Framework,Media problems,Media problems refer to an excessive number of collisions on Ethernet and long waits for the token in Token Ring or FDDI. Media problems are caused by too many devices, all with a high offered load for the n

10、etwork segment. Media problems can be solved by dividing a network into separate segments using one or more switches.,The Need to Transport Large Payloads,This category includes the need to offer voice and video network services. These services may require much more bandwidth than is available on a

11、customers network or backbone. Transport problems can be solved by using high-bandwidth technologies, such as Fast E, GigE or ATM.,Protocol problems,Protocol problems are caused by protocols that do not scale well, for example, protocols that send an excessive number of broadcasts. Protocol problems

12、 can be solved by dividing a network into separate segments using one or more routers.,Steps for Designing Scalable Networks,Identifying Customer Needs Design the Network Structure Build a Prototype or Pilot the Network Structure,20,Module 1 - Identify Customer Needs,Characterize the Existing Networ

13、k,Section Objectives,Recognize all the data you should gather to characterize the customers existing network Document the customers current applications, protocols, topology, and number of users Document the customers business issues that will be relevant to the network design project Assess the hea

14、lth of the customers existing network and make conclusions about the networks ability to support growth,Goals of characterizing a customers network,Identify any bottlenecks Determine if anticipated growth may cause problems Recognize legacy systems that must be incorporated into the new design Recog

15、nize business constraints,Gathering Data,Administrative - corporate structure, business goals, staffing, policies, politics Technical - applications, protocols, internetworking devices, performance,Characterizing the Customers Network,Has a new design been tried before and failed? Are there people o

16、n the project who do not want to implement changes? Who will help you design the internetwork? Will the new design cause changes in job functions or possibly eliminate jobs? How much in-house expertise is there?,Tools That Help You Characterize a Customers Network,CiscoWorks/NMS Protocol analyzers/S

17、niffers,CiscoWorks 2000,A set of SNMP-based tools for characterizing a customers network, monitoring the status of devices, maintaining configurations, and troubleshooting problems.,Protocol Analyzers,Capture and analyze network traffic, providing both protocol analysis and statistics. Some analyzer

18、s, such as the Network Associate Corporations Sniffer, incorporates artificial intelligence & expert capabilities to simplify and enhance performance management.,28,Module 1, Section 2 Identify Customer Needs,Extract New Customer Requirements,Section Objectives,Extract the customers requirements for

19、 new applications, protocols, number of users, peak usage hours, security, and network management. Diagram the flow of information for new applications. Isolate the customers criteria for accepting the performance of a network. List some tools that will help you characterize new network traffic. Pre

20、dict the amount of traffic and the type of traffic caused by the applications mentioned in the case study, when given charts that characterize typical network traffic.,Steps for Extracting a Customers Requirements,Identify business constraints Identify security requirements Identify manageability re

21、quirements Extract application requirements Characterize new network traffic Identify performance requirements Create a customer needs specification document (optional),Identify business constraints,Document the budget and resources available for this project Document the time line for this project

22、Identify any staffing requirements such as hiring or training,Identify Security Requirements (Security Policy),Appraise security risks and determine how much security will be needed and of what type Determine requirements for outsiders to access data Determine the authorization and authentication re

23、quirements for corporate branch offices, mobile users, and telecommuters Identify any requirements for authenticating routes received from access routers or other routers Identify any requirements for host security such as physical security of hosts, user accounts, dated software, access rights on d

24、ata, etc.,Identifying Manageability Requirements,Isolate any requirements for fault management Isolate any requirements for accounting management Isolate any requirements for configuration management Isolate any requirements for performance management Isolate any requirements for security management

25、,Extracting Application Requirements,Document the names and types of new applications Document the names and types of new protocols Document the number of users who will use new applications and protocols Diagram the flow of information when new applications are introduced Diagram the flow of inform

26、ation of existing applications Identify peak hours of usage of new applications,Characterizing New Network Traffic,Characterize traffic load Characterize traffic behavior Use tools such as the NETSYS Enterprise/Solver Performance Tools Use other tools that we discussed earlier, such as CiscoWorks, e

27、tc.,Identifying Performance Requirements,Response time Accuracy Availability Maximum network utilization Throughput Efficiency Latency,Create a Customer Needs Specification Document,Record the customers requirements, business constraints, and the characteristics of the existing network,Characterizin

28、g Network Traffic,One of the most difficult aspects of extracting a customers requirements is to gain an understanding of how the customers protocols behave. Characterizing network traffic and protocols requires you to understand broadcast behavior, frame size, windowing and flow control, and error

29、recovery mechanisms.,Broadcast Behavior,Desktop protocols such as AppleTalk, NetWare, NetBIOS, and TCP/IP require broadcast and multicast packets to find services and check for uniqueness of addresses and names Routing and bridging protocols, also use broadcasts and multicasts to share information a

30、bout the internetwork topology.,Broadcast Behavior,Layer 2 switches forward broadcasts and multicasts, which becomes a scalability issue as flat switched networks become larger. CPU Utilization. The network interface cards in a network station pass broadcasts and relevant multicasts to the CPU of th

31、e station.,Scalability Constraints for (Switched/Bridged) Flat Networks,Protocol Maximum Number of Workstations IP 500 IPX 300 AppleTalk 200 NetBios 200 Mixed 200,Frame Size,Using a frame size that is the maximum supported for the medium has a positive impact on network performance that is significa

32、nt. Avoid increasing the MTU to larger than the maximum supported for the media traversed by the frames, in order to avoid fragmentation and reassembly of frames. Ethernet : 1500, Serial : 1500, Token Ring : 4464, ATM : 4470, FDDI : 4470, HSSI (HSA) : 4470,802.3 Efficiency Depending on Frame Size,So

33、urce: Breyer and Riley, Switched and Fast Ethernet: How It Works and How to Use It, Ziff-Davis Press, 1995.,Windowing and Flow Control,In addition to characterizing a protocols broadcast behavior and frame sizes, you should also characterize the windowing and flow control. Novells NCP - Ping Pong vs

34、. Burst Mode In the IP suite, Transmission Control Protocol (TCP) supports windowing and flow control User Datagram Protocol (UDP) does not offer windowing and flow control (connectionless),Error Recovery,Connectionless protocols usually do not implement error recovery (Best-effort) Most data link-l

35、ayer and network-layer protocols are connectionless Some transport-layer protocols, such as UDP, are connectionless Error recovery mechanisms for connection-oriented protocols vary,46,Module 2 - Design the Network Structure,Agenda for Module II,Section 1 - Design the Topology Section 2 - Provision H

36、ardware and Media for the LAN Section 3 - Provision Hardware and Media for the WAN Section 4 - Design a Network-Layer Addressing and Naming Model,Section 5 - Select Routing and Bridging Protocols Section 6 - Provision Software Features Section 7 - Select a Network Management Strategy Section 8 - Wri

37、te a Design Document,48,Module 2 - Design the Network Structure,Design the Topology,Section Objectives,Recognize the advantages, disadvantages, scalability issues, and applicability of standard internetwork topologies. Draw a topology map that meets the customers needs and includes a high-level view

38、 of internetworking devices and interconnecting media.,Hierarchical Models,Hierarchical models for internetwork design let you design internetworks in layers. Hierarchical models for internetwork design also use layers to simplify the tasks required for internetworking.,Hierarchical Models,Control t

39、raining and staff costs Control management costs Hierarchical design facilitates changes Improved fault isolation,Hierarchical Network Design,The Core Layer provides optimal transport between sites. The Distribution Layer provides policy-based connectivity. The Access Layer provides workgroup/user a

40、ccess to the network.,Core Layer,Provides redundancy and fault tolerance Adapts to changes quickly Low latency and good manageability Limited and consistent diameter,Distribution Layer,The distribution layer of the network is the demarcation point between the access and core layers of the network. T

41、he distribution layer can have many roles, including implementing the following functions: Policy, Security, Address or area aggregation, Departmental or workgroup access, and Broadcast/multicast domain definition Several Cisco IOS software features can be used to implement policy at the distributio

42、n layer: Filtering by source or destination address, and Static Routing,Access Layer,The access layer provides users on local segments access to the network Characterized by switched and shared-bandwidth LANs in a campus environment For SOHO environments, the access layer provides access for remote

43、sites into the corporate network,Redundant Models,There are four types of redundancy to consider during the design phase: Workstation-to-router redundancy Server redundancy Route redundancy Media redundancy,Workstation-to-Router Redundancy,When a workstation has traffic to send to a station that is

44、not local, it has many possible ways to discover a router on its network segment: Address Resolution Protocol explicit configuration Router Discovery Protocol routing protocol.,Router Redundancy,Hot Standby Router Protocol (HSRP) Provides a way for IP workstations to keep communicating on the intern

45、etwork even if their default router becomes unavailable.,HSRP Example,Server Redundancy,In some environments, fully redundant (mirrored) file servers should be recommended If complete server redundancy is not feasible due to cost considerations, mirroring or duplexing of the file server hard drives

46、is a good idea,Route Redundancy,Designing redundant routes has two purposes: Load balancing Minimizing downtime,Load Balancing,By default AppleTalk and IPX do not support load balancing To support load balancing, keep bandwidth consistent within a layer of the hierarchical model so that all paths ha

47、ve the same cost,Minimizing Downtime,In addition to facilitating load balancing, another reason to design redundant routes is to minimize network downtime. Routing protocols converge much faster if multiple equal-cost paths to a destination network exist. By using redundant, meshed network designs,

48、you can minimize the effect of link failures,Meshed networks,A network can be designed as a full mesh or a partial mesh A full-mesh network provides: complete redundancy good performance $,Full Mesh Diagram,The number of links in a full mesh is n(n-1)/2 (n=device),Partial Mesh,Media Redundancy,In switched network