Cisco Certified Design Associate (CCDA) Quick Reference Sheet Exam

Transcription

1 Cisco Certified Design Associate (CCDA) Quick Reference Sheet Exam

2 Chapter 1. Network Design Methodologies Basic Network Design Considerations Business Driven: Business Requirements must exclusively consider in the design process of network. Business strategies, requirements and demands must satisfy in a successful network design. Modular: Entire Network infrastructure is segregated and designed independently so that each part remains isolated in situations of network failure yet integrated to complete connectivity. Adaptable: Future expansion of business is a reality that should keep in mind while design a corporate network. Flexible: Network design should be planned to add or remove components easily without effecting the overall network structure. OSI Reference Model What? 7-layer hierarchal design. Data has to pass through each layer at both ends (sender and receiver). Sender device attach control bits at each layer that would detach at receiver s side over the corresponding layer. 7-layers: layers are broadly classified into upper and lower layers. Upper (Host) Layer: Application, Presentation and Session layer Lower (Media) Layer: Transport, Network, Data-Link and Physical layer. Application Layer: Network services are requested by this layer. Example: HTTP, FTP, DNS etc. Presentation Layer: Data representation and organization is performed at this layer. Example: JPEG, ASCII etc Session Layer: Establishment and maintenance of communication sessions. Example: NetBIOS etc Transport Layer: Assembly, disassembly and delivery of data segments is performed over this layer. Example: TCP, UDP etc Network Layer: Routing and addressing decisions are implemented over this layer. Example: IP, IPsec etc Data Link Layer: This layer is combination of two sub-layers: Media Access Control Layer: Control and access of devices to the network is supported by this sub-layer. Logical Link Control Layer: Packet synchronization, error detection and fixation are implemented on this sub-layer. Example: Ethernet, Frame relay, PPP etc. Physical Layer: Implement medium specific functionalities to make bits compatible travel through the channel. Example: RJ.45, etc TCP/IP REFERENCE MODEL What? 4 Layers. TCP protocol ensures for the reliable and error free and acknowledged transmission of data. IP protocol dictates path packet has to take from sender to receiver. Application Layer: Represent end-points from which transmission and reception take place Transport Layer: Management and monitoring of data is carried out at this layer. Internet Layer: Manages and perform functionalities for the movement of data packet over routed environment. Network Interface Layer: Manages physical connectivity of data associated with IP protocol TCP Three-Way Hand Shake Process For the establishment of dedicated connection between two devices (i.e. client, server), transmission control protocol (TCP) performs three-way exchange and acknowledgement mechanism. SYNC Client Client Client SYNC + ACK ACK Server Server Server Application Requirements Following are emerging requirement of almost every organization: E-commerce E-banking Video-conferencing Network Must Provide High Availability Services Access and Mobility Services Application Optimization and Protection Services Virtualization Services Security Services Operational and Management Services Network Design Drivers Return on Investment Compliance to Regulations and Standards Enhance Productivity Applications Cisco Life Cycle Approach Provide platform to logically build and maintain network infrastructure for complete resource utilization. This approach consists of three broad phases: 1. Plan Phase: Network strategy, roadmap and design are developed and analyzed using Cisco s smart tools. 2. Build Phase: Implementation, validation and migration of application are services are executed over this step. 3. Manage Phase: optimized solutions for the application, infrastructure and services are managed over this phase. Network Design Methodology Recommended Design Approach: Top-Down Approach is suggested over Bottom-up Approach. Why? Because customer requirements are given foremost priority in network design and Top-Down approach is focused to implement customer desires. How? Clients reside on the access layer (top) of the network. Design Consideration Scalability Availability Security Manageability Customer Requirements Identification Focused, structured and comprehensive analysis of customer requirements is first and the most essential step in network design. Customer s business, functional and technical requirements are analyze through arranging meetings and workshops with customers before building network design. Formal proposal report of design must deliver to customer before implementation to prevent end up with ineffective and unserviceable network. Network Structure must be Self-healing Self-defending Self-optimizing Self-aware Factors Effecting Design Process Price Time Lines Site Constraints Resources Building Blocks of Network Design Reliability: This factor is influenced by choice of transport mechanism. TCP and UDP are commonly used mechanism to provide transport services. TCP: Connection oriented, reliable data transfer. Example: HTTP, HTTPs, SMT FTP, Telnet UDP: Connection-less and fast data transfer. Example: DNS, DHCP etc. Availability: Basic network performance is measured by network availability. Availability (%) = Uptime/Total time Total time= Uptime + downtime Modularity: Addition and separation of network section does not affect the complete construction. Following are the advantages of modular network: Scalability Manageability Flexibility Simplicity Manageability: Five functional areas are considered to manage overall network. Fault Management Configuration Management Performance Management Security Management Accounting Management

3 Chapter 2. Network Design Objectives Design Objectives Following are the required design parameters that must be consider in the design process: Modularity Hierarchy Scalability Resiliency Fault domains Enterprise Campus Design What? Collection of devices (end-point) over wired or wireless link create campus network environment. Network Modularity Entire network structure is divided into small network sections. Modular design supports: Future growth and flexibility Easier customization Easy troubleshooting Simplifies design Network Hierarchy Specified functions can be implemented in hierarchal design. Access Layer: Users and end-points are connected to network over this layer. Functionalities supported: Maintain device connectivity Support various logical networks simultaneously Supported resiliency and provide security Support advanced technologies Distribution Layer: Aggregates access and core layer. Supported functionalities: Filtering Quality of Service (Qos) Summarization Layer-3 services Supported scalability Reduced complexity and introduce resiliency Core Layer: The most efficient, simple and fast layer of the network. This layer glues together various elements of network architecture. Datacenter: Internal and corporate servers are supported over this module. Data center design must be: Resilient Scalable Flexible Data center holds the following features: Monitoring modules Logging modules Security modules Enterprise WAN: The WAN module provides connectivity between remote sites and the main site over various WAN technologies. Example: Frame-relay, MPLS etc Internet Edge: This module connects to the internet world through service provider network. Internet edge is the vulnerable portion of network. Firewalls, IPS, Filtering and other security mechanism have implemented to secure internal network from outside world. Enterprise Branch: The enterprise branch module extends the enterprise by providing each location with resilient network architecture with integrated security. Enterprise Tele-worker: Highly secure and protected access to the network resources is provided over this module to remote locations. VPN tunnel mechanism is used to establish connection. Network Scalability Expansion and expected future growth must consider in the network design along with maintaining high network performance includes: Availability Reliability Responsive Efficient Adaptable Network Resiliency Availability of network throughout is must in every condition. Following are the levels over which resiliency is incorporated: Network Resiliency Device Resiliency Operational Resiliency Network Fault Domains Potential fault domain must be located and analyzed in the design process. Following are the two types of network failure: Planned Failure: Deliberately down for a scheduled event Unplanned Failure: Caused by internal failure of hardware or software

4 Chapter 3. Addressing and Routing Protocols in an Existing Network Fundamentals of IP Addressing Internet Protocol version 4 (IPv4): 32-bit address space Public Addresses: Internet routable addresses Private Addresses: Specific range of address only employed for private use, they are not routable on internet. Class full Addressing: Class A, B, C, D and E are demarcated by IP address range so as defined amount of networks and host are associated with each class. Class-less Addressing: Customized network and host addresses can be formed. Internet Protocol version 6 (IPv6): 128-bit address space Scalable IP Addressing Plan Following factors directly influence scalability: Hierarchy: Identification of various levels and sections in a network introduce efficient addition or subtraction of a particular block without effecting other portions improves scalability. Summarization: Summarized routes exchange greatly improves network scalability. Efficiency: Efficient and sophisticated network structure enhances the chance of easy expansion. Consideration for Effective IP Address The parameters need to consider designing an effective IP address scheme for a network are: Sub-netting: Introduce multiple logical networks within a network. NAT: Modify private addresses by mapping them with public address to route private data over public network. Scalability: This is enabled by implementing other features such as hierarchy, summarization etc. Routing Protocol What? Routing protocol dictates the process of establishment of communication between/among network devices Static Routing Protocol: Static routing protocol need to statically implement changes and transitions. Fit for small network AD = 1 Easy to configure and implement Low Bandwidth and processing Dynamic Routing Protocol: Dynamic routing protocols are designed to learn and implement changes by themselves. Suitable for large networks Complex design and configuration AD > 1 High BW and processing required Less AD values are preferred while routing decisions are taken. Autonomous System represent single routing domain. Dynamic Routing Categories Interior Gateway Protocols (IGP): It is designed to exchange information within autonomous system. IGPs has two broad categories: Link state Routing Protocol: Link state Routing Protocol follows: Hello Packets are collected from each node Update transitions Calculate best route using dijkstra's algorithm Complete information of topology is known. Example: OSPF, IS-IS Distance Vector Routing Protocol: Also called at Routing by Rumor protocol. DVRP follows: Information is collected from direct neighbors only Update periodically Hop Count is used for the calculation of best route Complete topology is not known. Example: RIP v1, RIP v2 Exterior Gateway Protocol (EGP): EGP is employed the exchange information between autonomous system. Example: BGP, EGP Hierarchiel and Flat Routing Protocol In Hierarchiel, network is segmented into various sections Example: OSPF IS-IS In Flat, each network device lies on same level. Example: RIP, EIGRP Selection of Routing Protocol Static Routing not suitable RIP v1 & v2 not efficient OSPF/IS-IS Suitable, complex to design EIGRP Suitable, Cisco Proprietary Open Shortest Path First OSPF deployments hold: Area specification are assigned with a backbone area, Area0 All other areas, non-backbone areas, are connected to Area0 Routers share backbone and non-backbone area assigned as Area Border Router (ABR) For compatibility between OSPF and other routing protocol, Autonomous System Boundary Router (ASBR) is used Enhanced Interior Gateway Protocol EIGRP holds: Diffusing Update Algorithm (DUAL) is used for the best route calculation It maintains backup routes information Feasible Successor enable in case of unavailability Feasible condition must be followed to become a feasible successor i.e. the reported distance (RD) from the neighboring router must be lower than the current feasible distance (FD) Border Gateway Protocol (BGP) Follows path vector protocol Path factor along with path attribute are used for the calculation of best route ibgp: BGP running between router of same AS is interior BGP (ibgp). ibgp neighbors are not directly connected. ebgp: BGP running between routers of different AS is exterior BGP (ebgp). ebgp routers are directly connected. Routing Protocol Deployment Routing protocol selection is mainly influence by IP addressing employed, topological structure of network etc. The suggested routing protocol for each layer is: Distribution Layer: Aggregate core and access layer so this layer must support the functionality of both layer s protocol Core Layer: Fast convergence and high availability are the fundamental requirements Edge Layer: OSPF LAN, Non-Broadcast multiple access network (NBMA) and dialups EIGRP NBMA with split horizon (such as ATM and Frame relay) Remote Access and VPN: Static BGP Single exit point, IPsec VPN Multiple exit point with/without multi homing Advanced Routing Strategies Route Redistribution: Route redistribution is implemented to enforce different routing protocols compatibility. 1-Way Route Redistribution: Enabled on only one direction 2-Way Route Redistribution: Enabled on both directions Route Filtering: Prevent certain routing advertisement to flood into specific portion of the network. Route Summarization: Also called as Route Aggregation and Supernetting, implement to reduce the size of routing entries to efficiently use processing resource of network.

5 Chapter 4. Enterprise Network Design Basic Campus Design Campus network generally consist of two network modules: Local Area Network Module Datacenter Module Campus overall design is divided into two design consideration steps: Network Design Consideration Infrastructure Design Consideration Network Design Consideration The design parameters which are considered at this level are: Applications considerations includes: Peer-Peer, Client-Local Server, Client- Datacenter, Client-Enterprise Edge server Devices selection is effected by the size, density of users and topology. Choices includes: Shared Media segment: Same speed with fixed (portion of total) Bandwidth to each node Switched Media Segment: Dynamic speed with full Bandwidth allocation. Environment characteristics that effects design are: Distance between the node (Nodes Location) Type of connection used between the nodes (Connection Medium) Selection of Medium is decided upon how nodes are connected. Medium can be selected from two broad categories includes: Wired Medium Wireless Medium Infrastructure Design Consideration Modular and reliable design is implemented. The design consideration for each module is: Access Layer Design Considerations: Access layer utilizes following facilities and protocols: Layer-2 Protocol & VLAN Spanning Tree Protocol (STP) Cisco STP Tool Kit Ether Channels Trunk Management Campus Distribution Layer Design Consideration: Aggregation of core and access layer is implemented over this layer including following feature for fast convergence: First Hop Redundancy Protocols Layer-2/Layer-3 Demarcation Virtual Switching System (VSS) Campus Core Layer Design Considerations: High availability and fast convergence with simplified structure are basic design requirements of core layer. Edge Distribution must also implement on core layer to secure internal network from outside. Campus Data Center Design Considerations: Design of data center must follow fast allocation of resources. Cisco Datacenter Architectural Framework is used that supports: Virtualization Unified Computing Unified Fabric Data center infrastructure also follows modular design approach. Each layer holds the similar functions as campus network layer with listed slight modifications: Access Layer: Switches must support high performance, low latency and dense port requirements. Distribution Layer: Multi-layer distribution switches are recommended with layer2/layer3 demarcation. Design to support high speed STP calculations, Firewalls, security policies etc. Core Layer: High speed layer-3 devices are suggested. Basic Enterprise Design Enterprise design requires some additional modules includes: Enterprise Edge Module ServiceProvider Tele-Worker Module LAN is extended to wide area network (WAN) in enterprise. WAN additional requirements must thoroughly analyze to design enterprise network. WAN Technologies: TDM, ISDN, Frame-relay, ATM, MPLS, Metro-Ethernet, DSL, Cable, Wireless and SONET/SDH WAN Link Categories: Private, Leased and Shared WAN WAN Design Considerations Following are the list of parameters over which a comprehensive network can be built: Layer-3 Protocols & Redistribution is implemented to establish communication with outer network (internet) WAN Connectivity is a collective term that includes: WAN Topology: list of standard topological. Includes: Hub and Spoke Spoke to Spoke Point to Point Partial Mesh Full Mesh WAN Connectivity Methods: Following are conventional connectivity methods available to connect remote locations to the central office: DMVPN, get VPN, MPLS Layer-3 VPN, Static IPsec, GRE, VTI Resiliency: Network must design to recover itself from unwanted situation. Following factor influences and improved resiliency: Service Level agreements (SLAs): official agreement of quality of expected service with ISP. Backup Links: backup links installation improves performance. Following methods can be employed to backup WAN link: Dial Backup Routing Permanent Secondary WAN Link IPsec Internet as a Backup Quality of Service (QoS): QoS criteria are selected according to the requirements and traffic type. Connectivity to Edge Module: Module bridges between external and internal network is edge module. Following facilities must be implemented over this module: Internet Connectivity: For the establishment of connection between internal &external networks. ACL & Firewall Placement: To prevent unwanted and heavy traffic extension to internal sensitive network. NAT Placement: To facilitate inside traffic movement to outside world Enterprise Tele-Worker Network Cisco Virtual Office Solution is implemented to allow access to the network for remote users. Basic Branch Design Functional individual network over each branch along with concurrent connectivity is the basic idea of branch network design. Design is influences by the size of branch offices. Following is the approach for each size of branch offices: Small (up to 50 users) Medium ( users) Large ( users) Additional Design Considerations Redundant deployments of hardware and links Service Provider managed MPLS Suitable capacity of Link Single-tier design Dual-tier Three-tier

6 Chapter 5. Considerations for Expanding an Existing Network Wireless Considerations Deployments of wireless can be implemented by two ways: Autonomous Deployment: Access Point independently establishes connection. Cisco Unified Deployment: Controller and Access Point (AP) collectively establish connection Protocol used: CAPWAP (Control & Provisioning of Wireless Access Point) LWAPP (Light-weight Access Point Protocol) Cisco Unified WLAN Architecture Client Devices Access Points Network Unification Module World Class Network Management Mobility Services Design Consideration of WLAN RF Site Survey: Formal & comprehensive site survey is performed and reported utilizing efficient survey tool. Campus Network: Numbers of APs, controllers and power requirements are considered Controller Deployment Options Physical Controller: Placed over network and access APs. Virtual Controller: Software applications (8.2 and later version). Centralized Controller: Placed centrally in core layer. De-centralized Controller: Placed in each distributions module. Branch Network: Design must support efficiency, speed and reliability. H- REAP mode enabled Access Points are placed. Guest Services: Following step are taken to enable guest services: Path isolation is implemented to segregate internal traffic from guest Guest traffic is directed to DMZ, over which guest use guest controller to access network Certain number of network access is incorporated to improve security Outdoor Network: Following deployment structures are used: Point to Point Point to Multipoint Mesh Connection Integration of WLAN over Existing Network Integration solutions take in to account following parameters: Traffic Flows: Roaming capability in WLAN network supported network access to moving devices. Bandwidth Consumption: Bandwidth must be considered according to the intended user requirements. Controller & AP Connectivity: AP undergo discovery of controller process to discover neighboring WLAN controller using CAPWAP protocol first. If controller found unavailable for 60 seconds, scanning process is re-started using LWAPP protocol. Quality of Service: Implementation of QoS policies is very important especially when medium is both wireless and remote. Security Considerations Identification of potential risks and threats Locate vulnerable network sections Enforce security policies accordingly Solution: Cisco SAFE Architecture. Traffic filtering and Inspection: is carried out over vulnerable points of network. Cisco Intrusion Prevention System (IPS) is deployed for controlled detection and filtration of unwanted traffic. Firewall and IPS placement: Firewall and IPS are placed on each network device such as routers, switches etc. according to the level of vulnerability. Security Policies Deployments Following are the security policies along with the technologies by which they are implemented and enforced over campus and datacenter module: Identity and Access Control Security Policies: IEE 802.1x, NAC, Firewalls, ACLs Threat Detection and Mitigation Security Policies: SNMP, NetFlow, Syslog, Cisco security MARS Security Policies over Infrastructure Security Policies: SNMP, AAA, Layer-2 security, MD5, SSH, IGP/EGP Client Access Methods: Trust and identity are managed to decide client access. Trust and identity are managed by: IEE 802.1x, Cisco IBNS, ACL, NAC, Firewall Network Access Control Following conventional structure is used to deploy access control: Source Specific Rules: Apply closer to source Destination Specific Rules: Apply closer to destination Mixed Rules: Apply closer to source node Collaboration Considerations Integration of Voice and Video over Existing Network: Voice is traditionally transmitted over PSTN network which is not feasible medium for video transfer. Unified approach fits well for the transportation irrespective of type of the data. IP infrastructure provides an integrated platform over which each data type is modified into packets. Voice and Video Standards H.323 (Multimedia Transfer Protocol) H.264 (Video Compression Protocol) Real Time Transport Protocol (RTP) Skinny Client Control Protocol (SCCP) Session Initiation Protocol (SIP) Media Gateway Control Protocol (MGCP) Requirement of Voice and Video Technologies Following parameters need to specifically consider for an integrated network design: Quality of Service, Trust Boundaries, Delay, Loss, Capacity Convergence Time, Service Placement Virtualization Considerations What? Virtualization introduces efficient utilization of network resources. Network or devices of the network can be virtualized to efficiently and cost-effectively use network resources. Virtualization can be used to split single device in to multiple devices or aggregate multiple devices into single. Following are the network resources that can e virtualized: Switches: VLAN, VSS, Chassis, VDC Appliances: Context Routers: VRFs. routing elements Tunnels: Tunnel is itself a logical concept, virtualized to utilize it more efficiently Programmability Considerations Programmable network is progressive concept in which customized and controlled operation of network is accomplished, often called as Software Defined Network (SDN). The composition of SDN includes: Application Program Interfaces (APIs): The interfaces which interact to network layers are API. Two type of API includes: South-Bound API: Controller to Network Devices (lower) North-Bound API: Controller and Application layer (upper) Controllers: control and management policies of network devices are de-coupled and starched to controller. Application Centric Infrastructure (ACI): Network devices are placed over ACI. Datacenter Components Datacenter requires all time high availability and connectivity. Bandwidth requirement must analyze in data center design along with suitable devices and protocol implementation at each layer to use datacenter for the designed purpose. Following are the advance strategies implemented on data center for better efficiency: Server Load-Balancing: Traffic is controlled to take clear path rather than congested with the distribution of traffic over redundant paths. Blocking Vs Non-Blocking: Blocking is introduced by applying STP protocols to prevent looping. Non-Blocking is the cost effective method and by default switches are in non-blocking mode. Layer-2 Extension: Implement Layer-2 switching over layer-3 to improve efficiency, reliability and compatibility.

7 About this Quick Reference Sheet IPSpecialists Quick Reference Sheets are summarized collection of the condensed notes taken from our technology workbooks that are prepared keeping the exam blueprint in mind. It s an ideal handy document to help you remember the most important technology concepts.