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.