LAN design. Chapter 1

Transcription

1 LAN design Chapter 1 1

2 Topics Networks and business needs The 3-level hierarchical network design model Including voice and video over IP in the design Devices at each layer of the hierarchy Cisco switches for each layer 2

3 CIS 153 Course Design LAN Design Basic Switch Concepts Wireless VLANs STP VTP Inter-VLAN routing 3

4 Hierarchical design model 4

5 Hierarchical design model High speed backbone. 5

6 Hierarchical design model Subnets, VLANs, routing, flow control, security. 6

7 Hierarchical design model Connects end devices. Controls which devices connect. 7

8 Collapsed core Small network: merged core and distribution 8

9 Logical and physical layout Logical how they connect. Physical where they are. Logical connections not obvious from looking. 9

10 Benefits of Hierarchical Network Scalability easy to expand Redundancy at core and distribution layers Performance route packets through fast devices Security at access and distribution layers Manageability similar functions within layer Maintainability - modular 10

11 Design principles Network diameter how many devices must packet pass through? Keep it low. Bandwidth aggregation combine ports where high bandwidth is needed. Redundant links/devices in core and distribution layers. Too expensive for access. Start design at the access layer. How many devices, how much bandwidth needed? 11

12 Converged network Combines data, voice, video. (Not converged as in all routers have consistent information. Same word used.) Needs quality of service (QoS) to give priority to voice and video. Was very expensive, needed expertise, needed to replace legacy equipment. Now more affordable. 12

13 Advantages of converged network One network to manage/ keep up to date One set of cabling and networking devices One group of people to run it One service provider Can have voice and video on PC using headset, webcam and software no separate equipment. 13

14 Choosing switches Carry out Traffic Flow Analysis using software to monitor amount and source of traffic. Allow for growth. Carry out User Communities Analysis. Group by job function. How many ports? How much bandwidth? Allow for growth. Carry out Data Stores and Data Servers analysis. Traffic to, from, between. 14

15 Topology Diagram Ports? Bandwidth? Bottlenecks? Layers? Routes? Redundancy? 15

16 Topology Diagram Ports? Bandwidth? Bottlenecks? Document it now Layers? Routes? Redundancy? 16

17 Choosing switches Form factor Fixed configuration ports on chassis Modular ports on cards Stackable act as one switch, linked by special ports. 1 rack unit (1U) 17

18 Choosing switches (cont) Port density how many ports? (Allow for links between switches.) Forwarding rate How many Gbps can it process? Can all ports work simultaneously at maximum speed? Link aggregation (EtherChannel) up to 8 ports bound together, acting as one, with combined bandwidth can it do this? 18

19 Choosing switches (cont d ) Power over Ethernet (PoE) for IP phones, network access points. Do you need it? It adds to the cost. Multilayer switch needed? Typical switch works at Data Link layer (2), uses MAC addresses. Multilayer also works at Network layer (3), routes between subnets. 19

20 Access Layer Switch Features Port security choose which devices may connect. All Cisco switches support this. VLANs connected devices on different subnets. Speed Fast Ethernet (100Mbps) or Gigabit. Power over Ethernet (PoE) expensive Link aggregation for uplinks Quality of service (QoS) if needed 20

21 Distribution Layer Switch Features Layer 3 support route between VLANs High forwarding rate (processing) Port speed Gbps, 10Gbps ports Redundancy Security Access control lists Link aggregation Quality of service Availability. Hot swappable power supply? 21

22 Core Layer Switch Features Support for Network layer (3) - routing Very high forwarding rate Very high port speed (1Gbps, 10Gbps) Redundancy Link aggregation Quality of service Avoid security and other distractions here. Go for speed. 22

23 Catalyst Switch product lines 23

24 Catalyst Switch product lines Concentrate on general features 24