1 CCNA 3 v3.1 Module 5

2 CCNA 3 Module 5 Switches/LAN Design

333 LAN Spans a single room Building set of buildings that are close together Campus Group of buildings on a site and belong to a single organization

444 Network Design Requirements Functionality of the network It must work with reasonable speed and reliability It must allow users to meet their job requirements Scalability of the network Must be able to grow without any major changes to design Adaptability of the network Designed with a vision toward future technologies Manageability of the network It should facilitate network monitoring and management to ensure ongoing stability of operation

555 Why have LANs Expanded Development of high-speed technologies E.g., Asynchronous Transfer Mode (ATM) Complex LAN architectures LAN switching Virtual LANs (VLANs)

666 Design consideration to maximize available LAN bandwidth and performance 1.The function and placement of servers 2.Collision detection issues 3.Segmentation issues 4.Broadcast domain issues

777 LAN Servers Provide File sharing, Printing, Communication, Application services Do not function as workstations Run specialized operating systems NetWare, Windows NT, UNIX, and Linux Usually dedicated to one function E.g., or file sharing Categorized into two distinct classes Enterprise servers Workgroup servers Layer 2 LAN switches located in the MDF and IDFs should allocated 100 Mbps to these servers

888 Enterprise Server Supports all the users on the network service that everyone in an organization would need (centralized function) Offers services such as Domain Name System (DNS) Placed in the Main Distribution Facility (MDF)

999 Workgroup Server Supports a specific set of users services such as word processing file sharing Print services Placed in the Intermediate Distribution Facilities (IDFs) Closest to users accessing the applications

10 Bridging and Switching Excessive collisions reduce available bandwidth by 35% or 40% Segmentation with bridges and switches Splits 1 collision domain into 2 or more collision domains Create multiple collision domains Create a single broadcast domain Stations can get dedicated bandwidth (microsegmentation) Broadcast MAC address FF:FF:FF:FF:FF:FF Bridges and switches pass broadcast on Routers filter broadcasts

11 LAN Design Methodology 1.Gather requirements and expectations Identify any current network problems Information includes Organization's history Current status Projected growth Operating policies Management procedures Office systems and procedures Viewpoints of the people using the LAN requirements allow for an informed estimate of costs and timelines for projected LAN design implementation

12 Availability measures the usefulness of the network and is affected by Throughput Response time Access to Resources 2.Analyze requirements and data User requirements constantly change Increased need for bandwidth due to voice and video-based network applications Assess user requirements LAN must provide prompt and accurate information

13 3.Design the Layer 1, 2, and 3 LAN structure Star topology or Extended Star topology Use Ethernet CSMA/CD technology LAN topology design can be broken into Network layer Data link layer Physical layer

14 4.Document the logical and physical network implementation Physical topology is the way the various LAN components are connected together Logical design is the flow of data in a network and the naming and addressing schemes used in the implementation of the LAN design solution. Specify the locations of the MDF and IDF Document the type and quantity of cabling Document spare cables Useful for troubleshooting

15 LAN Design Documents OSI layer topology map LAN logical map LAN physical map Cut sheets VLAN logical map Layer 3 logical map Addressing maps

16 OSI Layer Topology MAP Extended Star Topology in a Multi-campus Building

17 Cut Sheet Provide detailed documentation of all cable runs Identification numbers Port the run is terminated on at the HCC or VCC

18 VLAN Logical MAP Group users by department, team or application Provides broadcast containment and security Routers provide communication between VLANs Combines L2 & L3 technology to limit collisions and broadcasts Communicates between VLANs

19 Layer 3 Logical MAP

20 Addressing Map Used in troubleshooting

21 Layer 1 Design Physical Cabling Fast Ethernet 100 Mbps, can be full-duplex Fiber-optic backbone Cat 5e UTP horizontal runs TIA/EIA-568-A specifications

22 TIA/EIA-568-A Every device connected to the network should be linked to a central location with horizontal cabling Main wiring closet MDF IDF needed for every 100 m Vertical cable connects IDF and MDF (normally fiber cable)

23 Layer 2 Design Provide flow control, error detection, error correction, and to reduce congestion in the network Layer 2 devices are bridges and switches Provide microsegmentation of the network Reduces the size of collision domains and reduces collisions Boost performance for a workgroup or a backbone Asymmetric Switching can allocate bandwidth on a per-port basis (10-Mbps and 100-Mbps ports ) Provide more bandwidth to vertical cabling, uplinks, and servers

24 Asymmetric Switching In a pure switched LAN the size of the collision domain is 2

25 All hosts connected to the shared LAN hub share the same collision domain and bandwidth

26 Layer 3 Design Router is a layer 3 device create unique LAN segments dividing networks into subnetworks, or subnets (scalability) Allow communication between segments based on Layer 3 addressing (IP addressing) Forwards data packets based on destination addresses Does not forward LAN-based broadcasts (e.g., ARP requests) Entry and exit point of a broadcast domain Stops broadcasts from reaching other LAN segments Serve as firewalls for broadcasts Allows for segmentation of the LAN into unique physical and logical networks Allow for connectivity to wide-area networks (WANs), such as the Internet

27 Addressing Scheme should be constant throughout the network Physical port is used to implement VLAN assignment VLAN 1 - Ports P1, P4, P6 VLAN 2 – Ports P2, P3, P5 Router allows communication between VLANs

28 Hierarchical Design Model 1.Access layer Connects end users into the LAN (closest to end user) Host switches Workgroup servers Access layer services provides services such as VLAN membership 2.Distribution layer Packet manipulation and Interconnecting workgroups Layer 3 switches Enterprise servers 3.Core layer Provides the fastest connection between the distribution points – no packet manipulation Backbone Optimal transport between sites

29 Hierarchical Design Model

30 Access Layer Entry point for user workstations and servers to the network Access Layer devices are a switch or a hub Shared bandwidth - Hub Switched bandwidth - Switch - bandwidth is dedicated Access layer functions include MAC layer filtering - direct frames only to the switch port that is connected to the destination device Microsegmentation – 2 devices in collision domain

31 Distribution Layer Provide boundary definition in which packet manipulation can take place Networks are segmented into broadcast domains Policies can be applied Access Control Lists can filter packets Isolates network problems to workgroups they occur Prevents these problems affecting the core layer Operate at Layer 2 and Layer 3 Functions Aggregation of the wiring closet connections Broadcast/multicast domain definition Virtual LAN (VLAN) routing Any media transitions that need to occur Security

32 The Core Layer High-speed switching backbone Interconnects distribution layers Router is used for the Layer 3 function Should not perform any packet manipulation Use Layer 2 or Layer 3 switching Asynchronous Transfer Mode (ATM) or Ethernet switches can be used