2.5 - WAN technologies Flashcards
Explain Dail-up and it’s speeds
The original copper-based analog using public switched telephone network (PSTN) aka (POTS). Up to 56 Kbp/s.
Explain ISDN
Integrated Services Digital Network. A legacy copper-based network using POTS, breaking the transmission into two channel types: Circuit-switched B channel, and Packet-switched D channel.
Explain DSL
Digital Subscriber Line. A copper-based connection that can use POTS to support multiple voice and data channels. The speeds are comparable to T1 or cable modems, but with degrading strength the farther you are from the Central Office.
Explain ADSL
Asymmetrical DSL. Offers greater download speed than upload speeds.
Explain SDSL
Symmetrical DSL. The speeds are the same, maxing at about 2 Mbit/s
Explain VDSL
Variable DSL. Fastest speeds, up to 50-60 Mbit/s.
Explain Cable Broadband
Uses coaxial cabling to carry TV signals. Speeds can reach up to 10 Gbp/s with fiber as a backbone.
What is HFC?
Hybrid-fiber-copper. When fiber is used as a backbone and copper is used to connect the customer to that fiber line.
Explain the T and E systems.
Provide a high speed always available connection via a dedicated logical circuit. Utilizes TDM (Time-division multiplexing) to allow a single T1 circuit to carry 24 channels.
Give me the stats for T1 and E1
T1 = 24 channels @ 64 Kbps (1.544 Mbps) E1 = 32 channels @ 64 Kbps (2.048 Mbps)
Give me the stats for T3 and E3
T3 = 28 T1 circuits (672 channels) @ 44.736 Mbps E3 = 16 E1 circuits (512 channels) @ 34.368 Mbps
What is SONET?
Synchronous Optical Network. Uses fiber optical cabling to provide fault tolerant high-bandwidth WAN connections. Uses multiplexing to combine multiple T1 lines.
What are the Data rates of OC-3, OC-12, OC-48, and OC-192?
OC-3 = 155.52 Mbps OC-12 = 622.08 Mbps OC-48 = 2.49 Gbps OC-192 = 9.95 Gbps
What is Metropolitan Ethernet?
Metro ethernet was introduced to provide a failsafe for cities and municipalities in case traditional Ethernet failed. It has now eveolved into CET (Carrier Ethernet Transport), through the use of the T-carrier system. CET establishes a virtual tunnel that uses a predetermined path.
Explain satellite transmissions
Over 800 satellites are in geosynchronous orbit, providing non-terrestrial data streams. They are susceptible to cloud obstruction and rain fade. Latency is also an issue, running about 250 ms.
Explain copper transmissions
Fundamental, legacy cabling that uses electrical signals to send transmissions.
Explain fiber transmissions
A transmission medium that uses light (either LED or the more expensive laser) to transmit data at very high speeds. Is currently challenging copper cabling in many aspects.
Explain wireless transmissions
The best example of a wireless WAN is a cellular network.
What is MPLS?
Multiprotocol Label Switching. A connection-orientated method used to route data between nodes on a network over the most efficient route. It allows layer 3 to operate on layer 2. It allows packet-switching over circuit-switching.
What is Frame Relay?
A group of layer 2 protocols were defined as a fast packet-switched network if ISDN connections. A PVC is established by routers and the frames are tagged with DLCI (Data-link connection identifier).
What is ATM?
Asynchronous Transfer Mode. Transmits 53-byte cells (48 for data, 5 for header) to provide predictable, efficient networking.
What is PPP?
Point-to-point protocol. Directly connects to endpoints on WAN. PPP uses headers and trailers to encapsulate packets with an additional 8 to 10 bytes. Supports authentication via protocols such as EAP or MS-CHAPv2.
What is DMVPN?
Dynamic Multipoint VPN. Allows VPN tunnels to be created on demand, reducing the need for static site-to-site tunnels.
What is the Demarcation Point?
Where the provider’s responsibilities end and the customer’s begin. (Phone pedestal, for example). Demarks will be a NID (Network Interface Device) or NIU (Network Interface Unit) placed directly outside or inside the building. Good place to start troubleshooting issues.
