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Hierarchical Design.

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Presentation on theme: "Hierarchical Design."— Presentation transcript:

1 Hierarchical Design

2 Objectives Describe the benefits of using a hierarchical design model
Identify the three layers that make up the hierarchical model Describe the functions typically performed at each layer

3 Three-Layer Model Components
Core Campus Backbone Distribution Building Backbone Access Remote Workgroups Local Workgroups

4 Core-Layer Functions Optimized transport between remote sites
Site A Site C Site B Optimized transport between remote sites Redundant paths Load sharing Rapid convergence Efficient use of bandwidth

5 Distribution-Layer Functions
Campus Backbone Building Backbone Policy-based connectivity Control access to services Define path metrics Control network advertisements

6 Access-Layer Functions
Building Backbone Connect workgroups to backbones Provide logical segmentation Group users with common interests Isolate broadcast traffic from the workgroup Distribute services between multiple CPUs

7 Hierarchical model divide nodes into levels; intra-level nodes talk to each other mostly; level functional independent inter-level communications is summarised adv. : better control, scalability & modularity control - grouping ease network management scalability - traffic contained within region modularity -same cost/method for adding node adding new nodes won’t disturb other levels ; network can grow smoothly & uniformly

8 Hierarchical model (Cont.)
disadv. : address administration overhead recommended for enterprise networks many hierarchical models exist Cisco network model core level :high speed transport for internetwork distribution level :implement management policy access level :connectivity to desktop PCs

9 Benefits of a Hierarchical Design Model
Scalability Ease of implementation Ease of troubleshooting Predictability Protocol Support Manageability

10 Flat model every node is equal and talks to each other
advantage is plug-and-play for small network disadvantage is lack of scalability due to excessive communications and CPU overhead may require a major upgrade at certain point if network continues to grow generally not recommended as an enterprise network architecture

11 One-Layer Design-Distributed
Core WAN Site A Site C Site B

12 One-Layer Design-Hub and Spoke
Central Site Core WAN Remote Site

13 Two-Layer Design SiteB Core WAN Site C Campus Backbone Site A
Building A1 Building A2

14 Redundant Two-Layer Hierarchy
Data Center Remote Site 1 Use for cost-effective LAN redundancy

15 Guidelines for effective deployment
Do not mesh the network within a layer Do not place end stations on backbones Keep 80% of the traffic local to the workgroup Use network features at the appropriate layer

16 Logical topology flat (L2 protocol) hierarchical (L3 protocol)
logical topology may differ from physical choices depend on network protocols used : flat (L2 protocol) hierarchical (L3 protocol) flat logical structure : based on low cost switches; bridges are out plug-and-play; no address administration not scaleable; need to contain broadcast

17 Logical structure (Cont.)
hierarchical logical structure : based on expensive routers or L3 switches need address administration scaleable; better control and manageability several logical structures can co-exist in a multiple protocol network

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