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CSE 550 Computer Network Design


Not generally created in a modular fashion ... Should be aware of latest news on hacker activity & threats to your network systems ... – PowerPoint PPT presentation

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Title: CSE 550 Computer Network Design

CSE 550 - Computer Network Design
  • Dr. Marwan Abu-Amara
  • 2nd Semester (T052)

Network Topologies
  • Questions to determine network topology
  • Is a small LAN with a few workstations?
  • Is a campus LAN or a massive enterprise
  • Is scalability important?
  • How about network management?
  • What about cost?

Network Topologies (cont.)
  • No one topology is right for every network
  • Each network topology can be an integral part of
    another topology design
  • Redundant and secure topologies should be part of
    every network design

Network Topologies (cont.)
  • Network topologies covered
  • Flat network topology
  • Hierarchical network topology
  • Mesh network topology
  • Redundant network topology
  • Campus/LAN network topology
  • Enterprise/WAN network topology
  • Secure network topology

Flat Network Topology
  • Generally used for very small networks
  • Each network device (e.g. hub, switch, …) is used
    for a general rather than specific purpose
  • Most network components are used for simple
    broadcasting and providing limited switching
  • Based on a common broadcast domain
  • Not generally created in a modular fashion
  • Provide a consistent and easy-to-manage network
  • Scalability is not usually an important design

Flat Network Topology (cont.)
  • Advantages
  • Lower cost lower in initial cost due to the
    smaller size of network and lower equipment costs
    (special routing switching components are not
    used to a wide extent)
  • Reliability due to the simplistic design
    general static nature of the topology
  • Easy to design due to the lack of need for
    modularity scalability
  • Easy to implement due to the lack of
    specialized switching equipment

Flat Network Topology (cont.)
  • Disadvantages
  • Not modular changes to the environment will
    usually affect all internetworking devices
  • Bandwidth domain most if not all devices are
    usually in the same bandwidth domain (i.e. share
    the same bandwidth)
  • Broadcast domain same broadcast domain that can
    lead to congestion

Hierarchical Network Topology
  • Created in layers to allow specific functions
    features to be implemented in each of the layers
  • Each component is carefully placed in a
    hierarchical design for maximum efficiency
    specific purpose
  • Routers, switches, and hubs all play specific
    role in routing distributing data packet info
  • Incorporates 3 key layers
  • Core layer
  • Distribution layer
  • Access layer

Hierarchical Network Topology (cont.)
  • Core layer
  • Provides the backbone, or high-speed switching
    component to the network
  • Provides only the specialized task of switching
  • Distribution layer
  • Demarcation point between core layer end-user
    access layer
  • Provides packet manipulation, filtering,
    addressing, policy enforcement, and other
    data-manipulation tasks

Hierarchical Network Topology (cont.)
  • Access layer
  • Provides end-user access to network
  • Prioritization bandwidth switching can also be
    configured at the access layer to optimize use of
    network resources
  • With modularity, hierarchical networks can limit
    the effect of each component change to the
    immediate area of change only
  • Hierarchical networks are created to be scalable

Hierarchical Network Topology (cont.)
Hierarchical Network Topology (cont.)
  • Advantages
  • Scalable allows addition of routers, switches,
    …, when needed with minimum impact to design
  • High availability due to redundancy, alternate
    paths, optimization, and filtering
  • Low delay routers delineating broadcast
    domains, and multiple paths for switching
  • Fault isolation can facilitate change and
    improve fault isolation

Hierarchical Network Topology (cont.)
  • Advantages (cont.)
  • Modular allows each component to perform a
    specific purpose in the internetwork leading to
    easier more organized network management
  • Cost efficient due to ability to optimize
    tune switching routing paths
  • Network management more automated easier to
  • Disadvantages
  • Cost due to redundancy that is often integrated
    into the network topology switching equipment

Mesh Network Topology
  • Constructed with many different interconnections
    between network nodes
  • 2 types
  • Fully meshed
  • Typically the backbone of the enterprise network
  • Provides excellent redundancy reliability
  • Frequently runs mission-critical services
  • Partially meshed
  • Similar to fully meshed except that each network
    node or switch does not necessarily have
    immediate connection to each other network node
    or switch

Mesh Network Topology (cont.)
  • Fully Meshed
  • Each network node or switch will have a direct
    path to every other network node or switch
  • Nodes are typically located at core level or
    backbone level of network
  • Not a cost-effective solution
  • Cant guarantee that server or application
    failures will be redundant with just a fully
    meshed backbone

Mesh Network Topology (cont.)
Mesh Network Topology (cont.)
  • Partially Meshed
  • Can still provide redundancy through alternate
    paths, and, therefore, allowing mission critical
    application to continue processing
  • If a network connection fails, the network will
    remain operational with reduced bandwidth and
    service levels
  • More likely to be implemented in an enterprise

Mesh Network Topology (cont.)
Mesh Network Topology (cont.)
  • Advantages
  • Redundancy provided by having multiple links
    connecting each network site
  • Disadvantages
  • Cost due to redundancy high circuit cost

Redundant Network Topology
  • Should be incorporated into all network designs
  • Can be incorporated in transmission media,
    routers, servers, and workstations
  • Extremely important at the core or backbone layer
  • As an alternative to using multiple data circuits
    or multiple network providers, you can select 2
    media types to provide redundancy (e.g. satellite
    data circuits)
  • Need to consider redundancy in routers,
    workstations, and servers

Redundant Network Topology (cont.)
Redundant Network Topology (cont.)
  • Advantages
  • Provides high network availability
  • Secures data transactions from hardware failures
  • Allows easier more cost-effective network
    management of redundant nodes
  • Disadvantages
  • Could be costly if not well designed

Redundant Network Topology (cont.)
  • Must include a backup path consisting of routers,
    switches, and individual backup links
  • Must take into account
  • How much capacity does the backup path support?
  • How quickly will network begin to use backup
  • Can use backup path for load balancing
  • Some protocols dont support load balancing (e.g.
    running RIP on IPX)

Campus/LAN Network Topology
  • Uses more specific technology that is not
    necessary broadcast based
  • Progression of network complexity
  • Traditional networks
  • Examples Netware Windows NT
  • Share data within an office, building, or smaller
    internetworking environments
  • Topologies Ring (Token Ring FDDI), Bus
    (Ethernet), Star
  • Switched LANs
  • Can provide dedicated bandwidth to specific users
  • VLANs

Campus/LAN Network Topology (cont.)
  • Common practice to design redundant links between
    LAN switches
  • Most LAN switches implement IEEE 802.1d spanning
    tree algorithm ? Loops in network traffic can be
  • Algorithm guarantees that there is 1 active path
  • No load balancing!
  • Can combine IEEE 802.1d VLANs in some switches
    to implement one spanning tree per VLAN ? Can
    offer load balancing

Campus/LAN Network Topology (cont.)
Campus/LAN Network Topology (cont.)
  • Advantages
  • Can provide dedicated bandwidth to the desktop
  • More efficient use of network resources at LAN
  • Cost due to easier physical implementation
  • Disadvantages
  • Possibility that newer technologies are
    implemented too early dont take full advantage
    of network components that are already in place
    (may cause interoperability issues)

Enterprise/WAN Network Topology
  • Should be built to serve the applications that
    are needed to support the business, not the other
    way around!
  • 3 main types
  • Remote Access Networks
  • Driven by telecommuters business travel
  • Uses dialup, ISDN, cable access, and DSL
  • Intranet/Internet
  • Tracking security is of extreme importance
  • WAN
  • Combines intranet services, Internet access, and
    remote access to allow corporations to
    communicate with distributors, clients, and
  • Technologies used include ATM Frame Relay

Enterprise/WAN Network Topology
  • VPNs
  • Network design alternative
  • Can connect business suppliers distributors
    through a third-party proprietary network
  • Cost saving no need for support staff on
    backbone infrastructure, and less equipment to
    purchase maintain
  • Keeps up on latest technology for backbone
  • Control of network infrastructure is not in your

Enterprise/WAN Network Topology
  • Advantages
  • Must have for enterprises!
  • Disadvantages
  • Staffing support to implement maintain the
    network (can be solved by outsourcing)

WAN Link Options
WAN Topologies
Star or Hub-and-Spoke
Three-layer design model (WAN version)
Secure Network Topology
  • 3 main areas
  • Policy Standardization
  • Allow network users freedom to use network
    services securely
  • Access management (different levels for different
  • Remote access management
  • Data encryption authentication
  • Firewalls
  • Physical security!
  • Implementation
  • Firewalls are commonly used
  • Not everyone needs to know what level of security
    is implemented!

Secure Network Topology
  • 3 main areas (cont.)
  • Audit Review
  • Review audit of network security is critical
  • Should be aware of latest news on hacker activity
    threats to your network systems
  • Stay current on new technologies as well as
    latest software patches, security holes, and

Secure Network Topology (cont.)
  • Advantages
  • Business can be conducted electronically
    quicker than in non-secure environment
  • Disadvantages
  • Cost
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