Chapter 2 - Networking Administration

CYBER 260

network topology

Network Topology: The ________ refers to the arrangement or layout of the interconnected devices in a computer network. It defines how the devices are connected and the paths through which data flows. Common types include bus, star, ring, mesh, and hybrid topologies.

physical topology

high level overview of where the network devices exists

logical topology

how the data flows over the physical network, including IP addresses and schemes

bus topology

* older tech
* used with Shared Ethernet
* each message sent to a specific MAC address
* multiple simultaneous transmissions resulted in collisions and retries
* no redundancy if network cable fails

ring topology

* older tech where messages travel in a logical “ring”
* dual ring provides redundancy
* fails more “gracefully” than Bus … however slower if fewer devices are transmitting

star topology

* common topology in most organizations
* switch connects all devices
* hosts send messages through the switch
* if no redundancy planned and switch goes down, so do all communications
* switches can connect to other switches to extend the network

mesh topology

* commonly used to connect routers in internal networks
* creates redundant paths
* full mesh connections are expensive
* five devices mean there are 10 links (s N(N-1)/2)

hybrid topology

* mixture of topologies interconnected to create a unified network
* exa: star and ring

hub and spoke topology

* interconnects different locations
* no direct communications between spokes

peer to peer networks

* no centralized management - so security is an issue
* OK for small networks (>10 hosts)
* ex: a torrent - allowing users to share files across a network, aka internet

client - server model

* dedicated, distributed services
* ex: email, databases
* easy to expand

personal area network (PAN)

* personal network that communicates over short distances
* ex: bluetooth connections with smartphone and printer

local area network (LAN)

* LANs exist within single geographic location
* interconnects devices to share resources (ex: printers, computers)
* router functions as the default gateway to forward traffic from one network to another

metropolitan area network

* located within a metropolitan area
* connected by common carriers or ISP

wide area network

* extends to larger geographic distances

wireless LAN

* hosts connect to Access Point (AP), which connect to a network switch and into the router

campus area network

* LANs connected by high-speed connections

storage area network (SAN)

* shared network storage connected by high speed, fiber optic switches an cables
* redundancy is key

software-defined networks / SD-WAN

**SDN** - centralized controller makes routing decisions

**SD-WAN -** allows software to automatically configure the WAN solution

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multiprotocol label switching (MPLS)

* switching tech that connects networks over large geographic distances
* interface independent (could use Metro Ethernet (MetroE), fiber optic, DSL, etc)
* offers Quality of Service (QoS) to prioritize by traffic type
* packets into the network are tagged by the Label Edge Router (LER) on the Provider Edge (PE) of the service provider’s network

generic routing encapsulation vs multipoint generic routing encapsulation (mGRE)

**GRE**

* tunneling tech that allows a tunnel between one site to another over the Internet
* traditional tunnels aren’t as scalable

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**mGRE**

* both hub router and each branch router can be configured to automatically establish a GRE tunnel to another branch

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service related entry points

* demarcation points - location where the customer network and provider’s network meet
* Fiber Access Terminal (FAT).- fiber connection option to the customer premise (fiber-to-the-hom / FTTH)

digital subscriber line (DSL)

**Symmetric DSL (SDL)**

* upload and download rates are the same.
* very expensive and limited in distance from the TelCo’s Central Office due to **attenuation**

**Asymmetric DSL (ADSL)**

* faster downloads than load speeds
* connect over Public Switched Telephone Network (PSTN) / Plain Old Telephone Service (POTS) using a DS Line Access Multiplexer (DSLAM)

leased lines

* leased from a service provider
* always “on”, guaranteed, dedicated bandwidth
* expensive

metro optical

* suitable for Internet access and WAN solutions
* consists of fiber optic cables that provide high-speed network connectivity between the customer and ISP
* works with Ethernet tech so a less expensive solution