Core: Transport technologies
In one line The physical layer sets the distance, bandwidth, and resilience ceiling that every higher layer inherits - and cabling outlives the electronics plugged into it. Copper Twisted pair (Cat5e/6/6A), ~100 m channel limit, carries PoE / PoE+ / PoE++ for powering APs/phones/cameras, but is susceptible to EMI
Core: Transport technologies
In one line Ethernet is the universal L2 framing from the access edge to 400G+ and out into the WAN as Carrier / Metro Ethernet. Speeds, lanes, and optics 1 / 10 / 25 / 40 / 100 / 400G. Higher speeds use multiple lanes (40G = 4x10G, 100G = 4x25G, 400G = 8x50G PAM4), enabling breakout. At 25G
Core: Transport technologies
Requirement / business driver Carry capacity across distance - campus/metro links, data-centre interconnect (DCI), or fibre-exhaust relief - as cost-effectively as the growth curve allows. Constraints Number of wavelengths needed now and later, distance (amplification?), budget, own vs leased fibre, and operational capacity. Options * Grey optics over dark fibre
Core: Transport technologies
Requirement / business driver Choose the access / transport methods for sites and the WAN, balancing bandwidth, cost, availability/SLA, latency, and reach across very different site profiles. Options Leased line / private circuit, MPLS access or Metro Ethernet, broadband (xDSL / DOCSIS / FTTx), cellular (4G / 5G, incl. fixed-wireless and backup), satellite (high-
Core: Transport technologies
In one line Physical-layer protection and path diversity decide whether higher-layer convergence ever gets tested - and legacy transports must be migrated cleanly. Physical resiliency 1+1 / 1:1 protection, optical rings with protection switching, or mesh; dual entrance and diverse fibre paths. The trap is SRLG / fate-sharing: