LAN DESIGN

Functionality - the network must work with reasonable speed and

reliability

Scalability - the network must be able to grow without any major

changes to the overall design

Adaptability - the network should include no element that would

limit use of new technologies as they become available

Manageability - the network must be able to allow ease of

monitoring and managing

Servers can be of two types: enterprise and workgroup

Enterprise servers support ALL users by offering services that

everyone would need

Workgroup servers support only a specific group of users, offering services that only a few groups of

people would need

PLACEMENT OF SERVERS:

• ENTERPRISE - MDF

• WORKGROUP - IDF

When configuring an Intranet (used only by those with access to the LAN) the following should be

considered:

• faster connectivity for desktops

• server privileges for users

• type of data to be accessed

Broadcasts become excessive when there are

• too many client packets looking for services

• too many server packets announcing services

• too many routing table updates

• broadcasts dependent on protocols (e.g.ARP)

Segmentation - the process of splitting a single collision domain into two or more

collision domains. Layer 2 bridges and switches are used

for this process

Bridges and switches forward broadcast traffic; routers do not.

A bandwidth domain is everything associated with one port on a bridge or switch. In

the case of an Ethernet switch, a bandwidth domain is also known

as a collision domain.

When designing a network, the physical cabling is one of the

most important components to be considered

In a simple star topology the HCC patch cables are used to

connect the Layer 1 horizontal cabling with the Layer 2 switch

ports

In an extended star topology, when more wiring closets are

created, multiple catchment areas are also created. (A

catchment area is a zone that falls within an area that can be

served by an internetworking device such as a hub)

The two most common layer 2 devices are bridges and LAN

switches

In an ideal situation, the size of the collision domain is 2 (the

source host and the destination host)

Using Layer 3 devices, such as routers, allows for segmentation

of the LAN into unique PHYSICAL and LOGICAL

networks

Routers provide communication between VLANs

VLANs provide broadcast containment and security

Similarities between hubs and switches

• connection ports

• LAN domain

• connectivity to backbone

• manageable devices

Differences

• Hubs have only an IOS subset image while switches have a full IOS image

• Hubs have a slow CPU while switches have a fast CPU

• Hubs have small memory while switches have buffer memory

• A hub is an indiscriminate repeater while a switch is port-targeted

Do Hubs still play an important part in switched networks?

• YES! Hubs have gotten smarter and cheaper over the years. They continue to be used for enterprise work groups and small companies.