Today I am going to be discussing WAN (Wide Area Network) architectures. A WAN is a large-scale telecommunications network that spans large geographic distances and interconnects multiple LANs (Local Area Networks) across cities, regions, countries, and continents. A WAN allows hosts in one private LAN to communicate with hosts in a completely different LAN. When corporations or service providers use WAN to communicate there are many different technologies that can be used to transport packets over the shared network. WAN technologies include leased lines, DSL (Digital Subscriber Line) , CATV, MPLS (Multi Protocol Label Switching) and VPNs (Virtual Private Network).
Leased Lines – The first WAN technology I am going to talk about is leased lines. Leased lines are dedicated, private, point to point communication WAN circuits that establish a permanent connection between two geographically separate locations such as a corporate headquarters and a branch site. Leased lines differ from other technologies such as DSL, because the connection is not shared with other subscribers. Leased lines provide dedicated bandwidth reserved exclusively for the customers, which ensures consistent performance regardless of traffic from other subscribers on the provider network. Leased lines are known for delivering “symmetric speeds,” meaning that the upload and download bandwidth are nearly identical. Leased line services are also typically backed by an SLA (Service Level Agreement), which provides a contractual guarantee of uptime, availability, and specific performance metrics such as latency, jitter, packet loss, or repair response times.
DSL- Another WAN technology is DSL, DSL provides high speed digital data transmission over existing twisted pair copper wiring of the plain switched telephone network (PSTN). It operates by using the higher frequency bands on the twisted pair. Voice in DSL typically only uses a limited (lower) frequency range (0 to 4 kHz), so this leaves the higher frequency bands unused. This allows internet data and voice signals to function simultaneously over the same physical connection without interfering with each other.
CATV- The next type of WAN technology is CATV, CATV refers to the use of existing cable TV infrastructure to provide internet access over a WAN. It delivers data over the same coaxial cable system originally designed for television services, enabled by technologies such as DOCSIS. Internet data and TV channels are able to coexist on the same coaxial cable because they use different frequency bands.
MPLS- Another WAN technology is MPLS, MPLS is used by service providers to forward traffic efficiently across large networks using MPLS labels instead of performing a traditional IP routing table look up at each hop. This is mainly used by service providers such as ISPs, and it supports numerous protocols such as IPv4, IPv6, Ethernet, voice and VPN data across the same infrastructure.
VPN- The last WAN technology I will discuss is VPNs, VPNs are a WAN technology that creates a secure and encrypted connection over a shared network such as the internet, so hosts in different locations can send and receive data as if they were directly connected to the same private network. The main role or purpose of a VPN is to provide secure communication over the public internet through data confidentiality, integrity, and authentication, while securely extending private network connectivity across public infrastructure.
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