Internet Connectivity. Computer and Network Examples

"There are two definitions for wireless LAN roaming:
Internal Roaming (1): The Mobile Station (MS) moves from one access point (AP) to another AP within a home network because the signal strength is too weak. An authentication server (RADIUS) performs the re-authentication of MS via 802.1x (e.g. with PEAP). The billing of QoS is in the home network. A Mobile Station roaming from one access point to another often interrupts the flow of data among the Mobile Station and an application connected to the network. The Mobile Station, for instance, periodically monitors the presence of alternative access points (ones that will provide a better connection). At some point, based on proprietary mechanisms, the Mobile Station decides to re-associate with an access point having a stronger wireless signal. The Mobile Station, however, may lose a connection with an access point before associating with another access point. In order to provide reliable connections with applications, the Mobile Station must generally include software that provides session persistence.
External Roaming (2): The MS (client) moves into a WLAN of another Wireless Internet Service Provider (WISP) and takes their services (Hotspot). The user can independently of his home network use another foreign network, if this is open for visitors. There must be special authentication and billing systems for mobile services in a foreign network." [Wireless LAN. Wikipedia]
This Cisco roaming wireless local area network diagram example was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Cisco Network Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.

This infographic sample visualizes the Conventional and wireless ad hoc network. It was designed on the base of the Wikimedia Commons file: Běžná bezdrátová síť a ad hoc síť.png.
[commons.wikimedia.org/ wiki/ File:B%C4%9B%C5%BEn%C3%A1_ bezdr%C3%A1tov%C3%A1_ s%C3%AD%C5%A5_ a_ ad_ hoc_ s%C3%AD%C5%A5.png]
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. [creativecommons.org/ licenses/ by-sa/ 4.0/ deed.en]
"A wireless ad hoc network (WANET) is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, so the determination of which nodes forward data is made dynamically on the basis of network connectivity. In addition to the classic routing, ad hoc networks can use flooding for forwarding data.
Wireless mobile ad hoc networks are self-configuring, dynamic networks in which nodes are free to move. Wireless networks lack the complexities of infrastructure setup and administration, enabling devices to create and join networks "on the fly" – anywhere, anytime." [Wireless ad hoc network. Wikipedia]
The infographic example "Conventional and wireless ad hoc network" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Computers and Communications solution from the Illustration area of ConceptDraw Solution Park.

This diagram sample illustrates the cooperative vehicular delay-tolerant network operation.
"Delay-tolerant networking (DTN) is an approach to computer network architecture that seeks to address the technical issues in heterogeneous networks that may lack continuous network connectivity. Examples of such networks are those operating in mobile or extreme terrestrial environments, or planned networks in space.
Recently, the term disruption-tolerant networking has gained currency in the United States due to support from DARPA, which has funded many DTN projects. Disruption may occur because of the limits of wireless radio range, sparsity of mobile nodes, energy resources, attack, and noise." [Delay-tolerant networking. Wikipedia]
"Routing in delay-tolerant networking concerns itself with the ability to transport, or route, data from a source to a destination, which is a fundamental ability all communication networks must have. Delay- and disruption-tolerant networks (DTNs) are characterized by their lack of connectivity, resulting in a lack of instantaneous end-to-end paths. In these challenging environments, popular ad hoc routing protocols such as AODV and DSR fail to establish routes. This is due to these protocols trying to first establish a complete route and then, after the route has been established, forward the actual data. However, when instantaneous end-to-end paths are difficult or impossible to establish, routing protocols must take to a "store and forward" approach, where data is incrementally moved and stored throughout the network in hopes that it will eventually reach its destination. A common technique used to maximize the probability of a message being successfully transferred is to replicate many copies of the message in hopes that one will succeed in reaching its destination." [Routing in delay-tolerant networking. Wikipedia]
The example "Cooperative vehicular delay-tolerant network diagram" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Vehicular Networking solution from the Computer and Networks area of ConceptDraw Solution Park.

The vector stencils library "Cisco products additional" contains 141 symbols of computer network devices and equipment.
"Cisco's products and services focus upon three market segments—Enterprise and Service Provider, Small Business and the Home. ...
Corporate market refers to enterprise networking and service providers.
Borderless networks ... routers, switches, wireless systems, security systems, WAN acceleration, energy and building management systems and media aware networks.
Collaboration ... IP video and phones, TelePresence, HealthPresence, Unified Communications, Call Center systems, Enterprise social networks and Mobile applications.
Datacenter and Virtualization ... Unified Computing, Unified Fabric, Data Centre Switching, Storage Networking and Cloud Computing services.
IP NGN (Next Generation Networks) ... High-end routing and switching for fixed and mobile service provider networks, broadcast video contribution/ distribution, entitlement and content delivery systems. ...
Small businesses include home businesses and (usually technology-based) startups.
Home user refers to individuals or families who require these kinds of services." [Cisco Systems. Wikipedia]
Create the computer network toplogy diagrams using the ConceptDraw PRO diagramming and vector drawing software with the design elements library "Cisco products additional".
The example "Design elements - Cisco products additional" is included in the Cisco Network Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.