1.2 Explain the characteristics of network topologies and network types. Flashcards
Network Topologies
- Useful in planning a new network
– Physical layout of a building or campus - Assists in understanding signal flow
– Troubleshooting problems
Star
- Hub and spoke
- Used in most large and small networks
- All devices are connected to a central device
- Switched Ethernet networks
The switch is in the middle
Ring
- Used in many popular topologies
– Token Ring is no longer with us - Still used in many Metro Area Networks (MANs) and
Wide Area Networks (WANs)
– Dual-rings
– Built-in fault tolerance
!!! for the test they always mean FDDI ring. So think Redundancy. Ring = Redundant !!!
Bus
- Early local area networks
– Coaxial cable was the bus - Simple, but prone to errors
– One break in the link disabled the entire network - Controller Area Network
– CAN bus
Mesh
- Multiple links to the same place
– Fully connected
– Partially connected - Redundancy, fault-tolerance, load balancing
- Used in wide area networks (WANs)
– Fully meshed and partially meshed
Hybrid
- A combination of one or more physical topologies
– Most networks are a hybrid
Wireless topologies
Infrastructure
– All devices communicate through
an access point
– The most common wireless
communication mode
* Ad hoc networking
– No preexisting infrastructure
– Devices communication amongst themselves
* Mesh
– Ad hoc devices work together
to form a mesh “cloud”
– Self form and self heal
Peer-to-peer
- All devices are both clients and servers
– Everyone talks to everyone - Advantages
– Easy to deploy, Low cost - Disadvantages
– Difficult to administer
– Difficult to secure
Client-server
- Central server
– Clients talk to the server - No client-to-client communication
- Advantages
– Performance, administration - Disadvantages
– Cost, complexity
LAN - Local Area Network
- A building or group of buildings
– High-speed connectivity - Ethernet and 802.11 wireless
– Any slower and it isn’t “local”
MAN - Metropolitan Area Network
- A network in your city
– Larger than a LAN, often smaller than a WAN - Common to see government ownership
– They “own” the right-of-way
WAN - Wide Area Network
- Generally connects LANs across a distance
– And generally much slower than the LAN - Many different WAN technologies
– Point-to-point serial, MPLS, etc.
– Terrestrial and non-terrestrial
Cus
WLAN - Wireless LAN
- 802.11 technologies
- Mobility within a building or geographic area
- Expand coverage with additional access points
PAN - Personal Area Network
- Your own private network
– Bluetooth, IR, NFC - Automobile
– Audio output
– Integrate with phone - Mobile phone
– Wireless headset - Health
– Workout telemetry, daily reports
CAN - Campus Area Network
- Corporate Area Network
- Limited geographical area
– A group of buildings - LAN technologies
– Fiber connected, high speed Ethernet - Your fiber in the ground
– No third-party provider
NAS vs. SAN
- Network Attached Storage (NAS)
– Connect to a shared storage device
across the network
– File-level access - Storage Area Network (SAN)
– Looks and feels like a local storage device
– Block-level access
– Very efficient reading and writing - Requires a lot of bandwidth
– May use an isolated network and
high-speed network
MPLS
- Learning from ATM and Frame Relay
- Packets through the WAN have a label
– Routing decisions are easy - Any transport medium, any protocol inside
– IP packets, ATM cells, Ethernet frames
– OSI layer 2.5 (!) - Increasingly common WAN technology
– Ready-to-network
MPLS pushing and popping
- Labels are “pushed” onto packets as they enter the MPLS cloud
- Labels are “popped” off on the way out
mGRE
- Multipoint Generic Router Encapsulation
– Used extensively for Dynamic Multipoint VPN (DMVPN)
– Common on Cisco routers - Your VPN builds itself
– Remote sites communicate to each other - Tunnels are built dynamically, on-demand
A dynamic mesh
SD-WAN
- Software Defined Networking in a Wide Area Network
– A WAN built for the cloud - The data center used to be in one place
– The cloud has changed everything - Cloud-based applications communicate directly to the cloud
– No need to hop through a central point
Demarcation point
- The point where you connect with the outside world
– WAN provider
– Internet service provider
– The demarc - Used everywhere
– Even at home - Central location in a building
– Usually a network interface device
– Can be as simple as an RJ-45 connection - You connect your CPE
– Customer premises equipment or “customer prem”
Smartjack
- Network interface unit (NIU)
– The device that determines the demarc
– Network Interface Device,
Telephone Network Interface - Smartjack
– More than just a simple interface
– Can be a circuit card in a chassis - Built-in diagnostics
– Loopback tests - Alarm indicators
– Configuration, status
Virtual networks
- Server farm with 100 individual computers
– It’s a big farm - All servers are connected with enterprise
switches and routers
– With redundancy - Migrate 100 physical servers to one physical server
– With 100 virtual servers inside - What happens to the network?
Network function virtualization (NFV)
- Replace physical network devices with virtual versions
– Manage from the hypervisor - Same functionality as a physical device
– Routing, switching, load balancing, firewalls, etc. - Quickly and easily deploy network functions
– Click and deploy from the hypervisor - Many different deployment options
– Virtual machine, container,
fault tolerance, etc.