📘 12-02: WAN Technologies¶
📌 Dedicated & Provider Technologies¶
| Technology | Notes |
|---|---|
| Leased line (T1/T3) | Dedicated digital circuit. T1 = 1.544 Mbps; T3 ≈ 44.7 Mbps |
| MPLS | Forwards by labels (not full IP lookups); supports QoS/traffic engineering |
| Metro Ethernet | Ethernet across a provider metro (E-Line, E-LAN) |
| SONET/SDH | High-speed synchronous optical transport (carrier backbones) |
| Frame Relay / ATM | Legacy packet/cell switching — largely replaced |
📌 Broadband Access¶
| Technology | Medium | Notes |
|---|---|---|
| DSL | Copper phone line | Speed drops with distance from DSLAM |
| Cable | Coax/HFC | Uses DOCSIS; shared with neighbors |
| Fiber (FTTH/PON) | Fiber | Highest bandwidth, lowest latency |
📶 Wireless WAN¶
| Technology | Notes |
|---|---|
| Cellular (4G/LTE, 5G) | 5G adds high speed/low latency; used for fixed-wireless and failover |
| Satellite | Coverage anywhere; high latency (esp. geostationary). LEO reduces it |
🌍 Encapsulation on WAN Links¶
- PPP — framing + authentication (PAP/CHAP) on point-to-point links. CHAP hashes the password (secure); PAP sends it in clear text.
- PPPoE — PPP over Ethernet, common on DSL.
Tip
Key idea — Know leased lines (T1/T3), MPLS (label switching), Metro Ethernet, broadband (DSL/cable/fiber), and wireless (cellular/satellite). Fiber wins on bandwidth/latency; satellite trades latency for reach.
See also: WAN Fundamentals, WAN Topologies & Modern WAN
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