WAN Technology Definition:
WAN Technology is pretty much about a point-to-point (or multi-point) private (represents Bandwidth is exclusively used) leased line Connecting customer’s private LAN to SP or Carrier, or link together separate LANs over a wide area.WAN technology solves the problem about how to allocat the BW that ISP Access Point provided to customers in a high utilization/scalability and cost-effective way without noticeable degradation of the service level.
Large proportion of Bursty traffic in LAN coupled with interface buffer mechanism make relatively low p2p private line adequate to interconnect LANs running on a 10Mbps interface or even higher.
WAN Bandwidth Evolution driven by Traffic Pattern Changing
- BW Roadmap
In the mid-1980s, the most popular and affordable private lines were still analog and ran at speeds that are almost laughable today: 4.8/9.6 Kbps which was suitable for the very old terminal with grey pixel display.
Multi-media traffic introduction coupled with wide range of applications running on terminals drive the WAN BW higher.
When multi-media traffic is transmitted over network in 1984, newer digital private line of 64Kbps is adopted to alleviate that BW pressure.
With LAN interface keeping on upgrading to higher BW driven by multi-applications on terminals, WAN Link is further upgraded to T1, E1, or even higher BW.
- WAN topology evolution
In 1980s, Most private corporate networks had been built to accommodate the IBM SNA environment(client/server model) which is hierarchical, star-shaped WAN topology. Clients running on Remote sites tend to fetch data from the Centralized Server in HQ and each remote site only communicates with HQ. Each remote site needs to be connected to HQ using a physical p2p private line.
As the number of remote sites increase, physical WAN port and related Hardware are required which make this hierarchical Star-shaped topology neither cost-effective nor scalable.
Afterward, instead of communicating only with HQ, remote sites are also required to talk with each other as well. That brought us a full-meshed or partially meshed topology. However, mesh-connected network is relatively expansive to adopt as more peer connection and communication ports are required.