WAN Technologies Overview

1. What Is a WAN and Why Does It Matter?

A Wide Area Network (WAN) connects geographically separated networks — branch offices, data centres, cloud providers, and remote workers — across distances that range from a few kilometres to intercontinental spans. Unlike a LAN, which an organisation owns and operates entirely, a WAN typically involves service provider infrastructure: leased circuits, shared provider backbones, or internet-based overlays.

Choosing the right WAN technology is one of the most consequential network design decisions an organisation makes. The wrong choice leads to either overspending (paying for premium MPLS when broadband internet with VPN would suffice) or underdelivering (using best-effort broadband for latency-sensitive voice and video). The key evaluation axes are cost, bandwidth, latency, reliability, security, and scalability.

WAN Technology	Provider Type	Typical Bandwidth	Latency	Cost	Best For
Leased Line	Telco	1.5 Mbps – 10 Gbps	Very low — guaranteed	Very high	Mission-critical point-to-point links
MPLS	Carrier	1 Mbps – 10 Gbps	Low — SLA-backed	High	Enterprise multi-site, voice/video, QoS
Metro Ethernet	Carrier / CLEC	10 Mbps – 100 Gbps	Low – medium	Medium – high	Metropolitan area connectivity, campus WAN
DSL	Telco (copper)	1 – 100 Mbps	Medium	Low	Small offices, home workers, backup links
Cable (HFC)	Cable operator	10 Mbps – 1+ Gbps	Low – medium	Low – medium	SMB, home offices, backup links
SD-WAN	Software overlay (any transport)	Depends on transport	Variable (managed intelligently)	Medium (saves vs MPLS)	Modern multi-site enterprise, cloud access

2. WAN Fundamentals — Key Concepts

2.1 Circuit-Switched vs Packet-Switched

WAN technologies historically fall into two categories based on how data is transported across the provider network.

Model	How It Works	Bandwidth	Examples	Status
Circuit-Switched	A dedicated physical path is established between endpoints for the duration of the call or session. Bandwidth is reserved end-to-end regardless of whether data is being sent.	Fixed, dedicated — always available, never shared	PSTN (phone network), ISDN, traditional T1/E1	Legacy — largely replaced
Packet-Switched	Data is divided into packets, each routed independently through shared provider infrastructure. No dedicated path — packets may take different routes.	Shared — bandwidth is used only when packets are in transit	MPLS, internet, Frame Relay (legacy), ATM (legacy)	Current — dominant model

2.2 CPE, CE, and PE Routers

Three device roles define the boundary between the customer and the service provider in a WAN. The CE router peers with the PE router using routing protocols such as OSPF, EIGRP, BGP, or static routes. See also: Routers.

2.3 WAN Serial Interfaces and Common Physical Standards

  Common WAN interface types on Cisco routers:

  Serial interfaces (for leased lines / frame relay / legacy WAN):
  → Serial0/0/0 — supports T1, E1, T3, E3 speeds
  → Clock rate configured on the DCE end (provider or simulated in lab)
  → Encapsulations: PPP, HDLC (Cisco default), Frame Relay

  Modern WAN interface types:
  → GigabitEthernet — Metro Ethernet handoff
  → Dialer/Virtual interfaces — DSL (PPPoE), VPN tunnels
  → Cellular interfaces — 4G/LTE backup WAN

  Lab simulation:
  Router(config)# interface Serial0/0/0
  Router(config-if)# ip address 10.0.0.1 255.255.255.252
  Router(config-if)# clock rate 2000000   (DCE side only — sets line speed)
  Router(config-if)# encapsulation ppp    (or hdlc / frame-relay)
  Router(config-if)# no shutdown

3. Leased Lines — Dedicated Point-to-Point Circuits

A leased line (also called a dedicated circuit or private line) is a permanently established, dedicated point-to-point connection between two sites, provided by a telecommunications carrier. The full bandwidth of the circuit is exclusively available to the customer at all times — it is never shared with other customers.

Leased Line Characteristics

Characteristic	Detail
Bandwidth	Fixed — the leased speed is always available, never contended with other customers
Latency	Very low and predictable — no shared queuing in the provider network
Reliability	Very high — SLA-backed with carrier-grade uptime guarantees (typically 99.9% or better)
Security	Inherently private — traffic is physically isolated from other customers; no encryption needed
Cost	Very high — customers pay a flat monthly rate for the full circuit regardless of actual utilisation
Scalability	Poor — each new site requires a new physical circuit; long provisioning times (weeks to months)
Topology	Point-to-point only — one circuit connects exactly two sites

Leased lines today: Traditional leased lines are used for mission-critical links where guaranteed bandwidth and lowest latency are non-negotiable — financial trading connections, core backbone links, and last-resort backups. For general branch connectivity, MPLS and SD-WAN have largely replaced dedicated leased lines due to their lower cost and greater flexibility.

4. MPLS — Multiprotocol Label Switching

MPLS (Multiprotocol Label Switching) is a high-performance packet-forwarding technology used by service providers to build scalable, QoS-capable private WANs for enterprise customers. Instead of routing packets based on IP destination address at every hop (which is CPU-intensive), MPLS routers forward packets based on short fixed-length labels — making forwarding decisions extremely fast.

From the customer's perspective, an MPLS WAN behaves like a private Layer 3 network: all branch sites are connected as if they share a single routing domain, with the provider's network acting as a transparent cloud. Customers do not see or manage the MPLS label infrastructure — that is entirely within the provider's domain.

MPLS Key Characteristics

Characteristic	Detail
Traffic separation	Each customer gets a separate VRF — traffic is logically isolated even though the physical infrastructure is shared
QoS support	MPLS providers offer QoS classes — voice, video, and data can receive different treatment across the provider backbone; SLA-backed latency and jitter for real-time traffic
Any-to-any connectivity	All customer sites are part of the same VPN — any site can communicate directly with any other without traffic flowing through HQ (unlike hub-and-spoke VPN)
Routing	CE routers peer with PE routers using OSPF, EIGRP, BGP, or static routes; CE does not see MPLS internals
Bandwidth	1 Mbps to 10+ Gbps; committed rates with burst capabilities
Cost	High — premium over broadband internet, but lower than individual leased lines for multi-site connectivity
Provisioning time	Weeks — physical circuit provisioning still required per site
Security	Traffic is logically private (VRF separation) but not encrypted — MPLS is not inherently encrypted

CCNA exam tip: Remember that MPLS provides logical traffic separation via VRFs — not encryption. If a customer requires confidentiality, IPsec must be added on top of MPLS. Also know: CE routers connect to PE routers; P (Provider core) routers only switch labels and are never directly visible to customers.

See full detail: MPLS Deep Dive

5. Metro Ethernet — Carrier Ethernet WAN

Metro Ethernet (Metropolitan Area Ethernet) extends standard Ethernet technology beyond the LAN into the WAN, across a metropolitan or regional area using a carrier's fibre infrastructure. From the customer's perspective, the WAN connection looks and behaves like an Ethernet interface — familiar, simple, and interoperable with existing LAN equipment.

The Metro Ethernet Forum (MEF) defines standardised service types. The two most common for enterprise WAN use are:

MEF Service	Also Called	Description	Use Case
E-Line	Ethernet Private Line (EPL) / Ethernet Virtual Private Line (EVPL)	Point-to-point Ethernet connection between two sites. Effectively a leased line replacement using Ethernet framing over carrier fibre.	Replacing T1/E1 leased lines; data centre interconnect; high-bandwidth point-to-point links
E-LAN	Ethernet LAN / VPLS (Virtual Private LAN Service)	Multipoint-to-multipoint Ethernet service. All sites share a common Ethernet broadcast domain — they appear to be on the same LAN even across the provider network.	Multi-site enterprise LANs, campus extension, replacing Frame Relay/ATM multipoint WANs

Metro Ethernet Characteristics

Characteristic	Detail
Bandwidth	10 Mbps to 100 Gbps; highly scalable — often just a contract change to upgrade
Interface type	Standard Ethernet (802.3) — no special WAN hardware needed on the customer side
Latency	Low — fibre-based, minimal provider-side processing
Geographic scope	Metropolitan or regional — not suitable for wide geographic separation (that requires MPLS or internet VPN)
Cost	Medium to high — lower than traditional leased lines for equivalent bandwidth; fibre infrastructure investment required
QoS	Supported via 802.1p CoS marking within provider network; some providers offer SLA-backed classes of service

6. DSL — Digital Subscriber Line

DSL (Digital Subscriber Line) delivers broadband internet access over the existing copper telephone (PSTN) infrastructure. DSL uses frequencies above the voice band on the copper pair, allowing voice and data to share the same physical line simultaneously.

DSL Variants

Type	Full Name	Download	Upload	Notes
ADSL	Asymmetric DSL	Up to 24 Mbps	Up to 3.5 Mbps	Most common residential DSL; asymmetric (download > upload)
ADSL2+	ADSL2+	Up to 24 Mbps	Up to 3.5 Mbps	Extended range and improved noise tolerance over ADSL
VDSL	Very High Speed DSL	Up to 52 Mbps	Up to 16 Mbps	Requires shorter copper loop; often combined with fibre-to-the-cabinet (FTTC)
VDSL2	Very High Speed DSL 2	Up to 100+ Mbps	Up to 100 Mbps	Short copper loop required (<500m); basis for "Fibre to the Node" broadband
SDSL	Symmetric DSL	Up to 2 Mbps	Up to 2 Mbps	Equal upload/download; suited for small offices hosting servers

DSL Architecture — PPPoE

Most DSL deployments use PPPoE (PPP over Ethernet) to carry the DSL connection from the customer's router to the ISP's BRAS (Broadband Remote Access Server). PPPoE allows authentication (username/password) and IP address assignment over the Ethernet-like DSL connection.

DSL Characteristics

Characteristic	Detail
Cost	Low — among the cheapest broadband options; uses existing copper infrastructure
Bandwidth	Up to ~100 Mbps (VDSL2); speed is distance-dependent
Contention	Shared at the DSLAM and ISP level; not a dedicated circuit
Reliability	Best-effort — no SLA for most consumer/SMB DSL products
Typical WAN use	Small office/home office (SOHO) primary or backup WAN; internet access; IPsec/SSL VPN endpoint

7. Cable Broadband — HFC Networks

Cable broadband uses the Hybrid Fibre-Coaxial (HFC) infrastructure originally deployed for cable television. Fibre runs from the cable operator's headend to neighbourhood nodes; coaxial cable carries the signal the final distance to each home or business. The DOCSIS (Data Over Cable Service Interface Specification) standard governs how data is transmitted over cable TV infrastructure.

Cable vs DSL Comparison

Feature	Cable (HFC)	DSL (ADSL/VDSL)
Physical medium	Fibre + coaxial cable	Copper telephone wire
Typical speeds	100 Mbps – 1+ Gbps	1 – 100 Mbps (distance dependent)
Shared medium?	Yes — coaxial segment is shared by neighbours	Partially — dedicated copper loop to DSLAM; shared at ISP level
Distance sensitivity	Low — fibre extends deep into neighbourhood	High — speed degrades significantly with distance from DSLAM
Typical WAN use	SMB primary or backup internet; home office	SOHO; backup link; internet access for small branches
Reliability	Best-effort; no SLA for most consumer plans	Best-effort; no SLA for most consumer plans

Broadband for enterprise WAN: Both DSL and cable are best-effort services with no SLA guarantees. They are appropriate for internet access, IPsec VPN overlays, and backup WAN links — but not for primary voice/video traffic that requires guaranteed QoS. SD-WAN can intelligently steer QoS-sensitive traffic away from degraded broadband paths.

8. SD-WAN — Software-Defined Wide Area Networking

SD-WAN (Software-Defined WAN) is a modern approach that separates the WAN control plane (intelligence) from the data plane (packet forwarding), using software to manage and optimise traffic across multiple underlying WAN transports simultaneously — MPLS, internet broadband, LTE/5G, or any combination. SD-WAN is not a physical WAN technology itself; it is an overlay that runs on top of existing transports.

SD-WAN Key Capabilities

Capability	Description
Transport-agnostic	Works over any WAN transport — MPLS, internet, LTE/5G, satellite — simultaneously
Application-aware routing	Identifies applications (Salesforce, Office 365, VoIP) and steers them to the optimal WAN path based on real-time performance metrics (latency, jitter, loss)
Centralised policy management	All routing and security policies are defined centrally (via vManage) and pushed to all edge devices automatically
Zero-touch provisioning	New branch devices connect to the SD-WAN fabric and download their configuration automatically — no truck roll required
Built-in encryption	All overlay tunnels are IPsec-encrypted — data security over internet transports without separate VPN infrastructure
WAN optimisation	Some SD-WAN solutions include compression, deduplication, and TCP optimisation to improve application performance
Cloud-friendly	Direct cloud breakout — traffic to SaaS (Office 365, Salesforce) can be sent directly to the internet from the branch rather than backhauling through HQ

SD-WAN vs Traditional MPLS

Factor	MPLS WAN	SD-WAN (over broadband + MPLS)
Cost	High — MPLS circuits are expensive	Lower — can use cheap internet broadband for most traffic
QoS	SLA-backed across provider backbone	Application-aware steering + path quality monitoring
Agility	Low — weeks to provision new sites	High — zero-touch provisioning; branch up in hours
Cloud access	Traffic must backhaul to HQ then out to internet	Direct cloud breakout from branch
Encryption	Not native — requires additional IPsec overlay	Built-in IPsec for all paths
Vendor lock-in	Tied to one MPLS provider	Multi-transport; can mix providers

See full detail: SD-WAN Overview | Cisco SD-WAN / Viptela Overview Lab

9. VPN Overlays on WAN — IPsec, GRE, and DMVPN

When organisations use internet broadband (DSL, cable, LTE) as their WAN transport, they need to secure traffic and create private connectivity between sites. This is achieved using VPN overlays — encrypted tunnels that run across the public internet, making it behave like a private WAN.

VPN Technology	Description	Best For
Site-to-Site IPsec VPN	Encrypted tunnel between two fixed sites using IKE/IPsec. Static tunnels — each site-pair needs its own tunnel configuration.	Small number of branch sites; simple hub-and-spoke topologies
GRE Tunnel	Generic Routing Encapsulation — creates a virtual point-to-point link that can carry multicast and routing protocol traffic. Not encrypted by itself — usually combined with IPsec.	Routing protocol extension across WAN; carrying multicast over internet paths
DMVPN	Dynamic Multipoint VPN — combines mGRE (multipoint GRE) with NHRP to allow spoke sites to build dynamic direct spoke-to-spoke tunnels on demand, without going through HQ.	Large-scale branch networks; spoke-to-spoke traffic without backhauling through hub
SSL/TLS VPN	Remote access VPN using HTTPS — works through firewalls and NAT without special ports. Used for individual remote workers, not typically site-to-site.	Remote user access; BYOD; clientless web-based access — see Site-to-Site vs Remote Access VPN

10. Choosing the Right WAN Technology

Technology	Cost	Scalability	QoS/SLA	Security	Setup Time	Ideal Use Case
Leased Line	★★★★★	★☆☆☆☆	★★★★★	★★★★★	Weeks–months	Mission-critical P2P; backbone links
MPLS	★★★★☆	★★★☆☆	★★★★★	★★★★☆	Weeks	Enterprise multi-site; real-time traffic
Metro Ethernet	★★★☆☆	★★★★☆	★★★★☆	★★★★☆	Days–weeks	Metro area; campus WAN; DC interconnect
DSL	★☆☆☆☆	★★☆☆☆	★☆☆☆☆	★★☆☆☆	Days	SOHO; backup WAN; internet access
Cable	★★☆☆☆	★★★☆☆	★☆☆☆☆	★★☆☆☆	Days	SMB; home office; backup WAN
SD-WAN	★★★☆☆	★★★★★	★★★★☆	★★★★★	Hours	Modern enterprise; cloud-first; branch agility

Test Your Knowledge — WAN Technologies Quiz

What is the fundamental difference between circuit-switched and packet-switched WAN technologies?

A. Circuit-switched networks use IP addressing; packet-switched networks use MAC addresses B. Circuit-switched dedicates a fixed physical path for the duration of a session with reserved bandwidth; packet-switched shares provider infrastructure and routes each packet independently with no dedicated path C. Packet-switched networks are only suitable for voice; circuit-switched networks are only suitable for data D. Circuit-switched networks are always faster than packet-switched

Correct answer is B. In circuit-switched networks (e.g., traditional PSTN, ISDN), a dedicated path is established end-to-end before communication begins, and bandwidth is reserved for the duration of the session — even during silence. In packet-switched networks (MPLS, internet), data is broken into packets that share provider infrastructure, taking independent paths, and bandwidth is only consumed when packets are in transit. Virtually all modern WANs are packet-switched.

In an MPLS WAN, what is the role of the CE router, and what does it know about the MPLS provider network?

A. The CE router applies MPLS labels to packets and manages VRF tables for each customer B. The CE router is part of the provider core and switches packets based on MPLS labels only C. The CE (Customer Edge) router is the customer's router at the site boundary. It peers with the provider's PE router using standard routing protocols (OSPF, BGP, static) but has no visibility into the MPLS label infrastructure inside the provider network D. The CE router is owned by the provider and configured remotely by the carrier

Correct answer is C. The CE (Customer Edge) router is the customer's own router, located at each site, that connects to the provider's PE (Provider Edge) router. The CE runs normal IP routing with the PE — it knows nothing about MPLS labels, VRFs, or the provider's internal topology. From the CE's perspective, the MPLS network is a transparent cloud connecting all its remote sites. The PE router handles all MPLS functionality. See: MPLS Deep Dive

A company uses DSL broadband as its branch WAN connection. DSL speed drops from 80 Mbps to 12 Mbps after the branch moves to a new building. What is the most likely cause?

A. The new location is farther from the telephone exchange (DSLAM). DSL performance degrades significantly with longer copper loop distances. B. The DSL router's firmware needs to be updated to support the new address C. The DOCSIS version on the new coaxial segment is older D. Too many users are simultaneously using the same PPPoE session

Correct answer is A. DSL speed is highly sensitive to the distance between the customer and the DSLAM (telephone exchange or street cabinet). Signal attenuation on copper wire increases with distance — at 300m a customer may get near-maximum speeds, while at 3 km speeds may drop to a few Mbps regardless of the ADSL/VDSL variant. Moving to a building further from the exchange is a classic cause of DSL speed degradation. DOCSIS is a cable technology, not DSL.

What makes MPLS suitable for carrying real-time voice and video traffic across a multi-site enterprise WAN?

A. MPLS encrypts all voice packets using AES, protecting them from interception B. MPLS uses circuit switching, dedicating a physical path per call C. MPLS routes packets faster because it uses larger MTU values than standard IP routing D. MPLS providers offer SLA-backed QoS classes with guaranteed latency and jitter across the provider backbone, allowing voice (EF/DSCP 46) to receive priority treatment end-to-end

Correct answer is D. MPLS providers offer differentiated QoS classes tied to SLAs — voice traffic marked DSCP EF receives strict priority queuing through the provider backbone with guaranteed maximum latency and jitter. This is fundamentally different from best-effort internet, where packets compete equally. MPLS is packet-switched (not circuit-switched) and does not natively encrypt traffic. See: QoS Marking

What is Metro Ethernet E-LAN, and how does it differ from E-Line?

A. E-LAN is a point-to-point service; E-Line connects multiple sites in a hub-and-spoke topology B. E-Line is a point-to-point service between two sites; E-LAN is a multipoint-to-multipoint service where all connected sites share a common Ethernet broadcast domain, as if on the same LAN C. E-LAN uses fibre; E-Line uses copper D. E-Line supports higher speeds than E-LAN

Correct answer is B. The MEF defines two primary Metro Ethernet service types: E-Line (Ethernet Line Service) provides a point-to-point Ethernet connection between exactly two sites — a leased-line replacement using Ethernet framing. E-LAN (Ethernet LAN Service / VPLS) provides multipoint-to-multipoint connectivity where all sites appear on the same Ethernet broadcast domain, allowing any-to-any Layer 2 communication across the provider network.

What is the primary advantage of SD-WAN over a traditional MPLS-only WAN for a modern cloud-first enterprise?

A. SD-WAN provides higher physical bandwidth than MPLS circuits B. SD-WAN eliminates the need for any WAN routers at branch sites C. SD-WAN allows multiple transports (MPLS, internet, LTE) to be used simultaneously with intelligent application-aware routing, lower cost than MPLS-only, built-in encryption, and direct cloud breakout from branch sites without backhauling through HQ D. SD-WAN provides dedicated circuits like leased lines but managed through software

Correct answer is C. SD-WAN's key advantages over MPLS-only WANs are: simultaneous use of multiple transports (cheap broadband + MPLS), intelligent steering of applications to the best path in real time, built-in IPsec encryption, zero-touch branch provisioning, and direct cloud/SaaS access from branches without backhauling through HQ. These capabilities make SD-WAN particularly compelling for organisations with heavy cloud usage (Office 365, Salesforce, AWS). See: SD-WAN Overview

A branch office has DSL broadband as its only WAN connection. Which technology provides secure private connectivity to the corporate headquarters over this internet connection?

A. Site-to-site IPsec VPN — creates an encrypted tunnel over the internet between the branch router and the HQ firewall/router, making the DSL internet connection behave as a private WAN link B. MPLS — the ISP automatically encrypts DSL traffic using MPLS labels C. Metro Ethernet E-Line — extends the corporate LAN over the DSL connection D. VDSL2 — upgrading to VDSL2 automatically provides private connectivity

Correct answer is A. When broadband internet (DSL, cable) is the only WAN transport, a site-to-site IPsec VPN provides the security and privacy of a private WAN over the public internet. The branch router establishes an encrypted IPsec tunnel to the HQ router or firewall — all traffic between sites is encrypted and authenticated. MPLS is a separate provider service, not something layered on top of DSL. See: IPsec VPN

Why is cable broadband described as a "shared medium" and what does this mean for enterprise use?

A. Cable broadband shares its IP address pool with DSL subscribers in the same area B. The cable operator shares its billing infrastructure with multiple ISPs C. Cable uses shared radio spectrum, like Wi-Fi D. The coaxial cable segment from the neighbourhood node to each home is shared among all subscribers — total bandwidth is divided among them, so speeds vary with local contention. This means no bandwidth guarantee, making cable unsuitable as a primary SLA-backed enterprise WAN

Correct answer is D. In HFC cable networks, the coaxial segment from the neighbourhood node to individual premises is a shared medium — all subscribers on that segment share the available bandwidth. During peak hours (evenings), when many users stream video simultaneously, individual speeds can drop significantly. This contention-based model means cable provides no bandwidth guarantees, making it appropriate for backup WAN or non-critical internet access but not as a primary link for latency-sensitive voice and video with SLA requirements. For secure WAN over cable, add an IPsec VPN overlay; use SD-WAN to intelligently manage path quality.

How does DMVPN improve on a standard hub-and-spoke IPsec site-to-site VPN for a large branch network?

A. DMVPN eliminates the need for encryption between spoke sites B. DMVPN uses NHRP to allow spoke sites to discover each other's real IP addresses and build direct encrypted tunnels on demand — spoke-to-spoke traffic does not need to backhaul through the hub, and new spokes can be added without changing hub configuration C. DMVPN uses MPLS labels to forward traffic instead of IP routing D. DMVPN requires a leased line between the hub site and each spoke

Correct answer is B. In a standard hub-and-spoke IPsec VPN, all traffic between spoke sites must travel through the hub — even if two spokes are geographically close. DMVPN uses NHRP (Next Hop Resolution Protocol) to allow spokes to dynamically discover each other's public IP addresses and build direct spoke-to-spoke tunnels on demand. New branches are added by configuring them to connect to the hub; no changes are needed to existing spoke or hub configs. See: DMVPN

A company runs a multi-site MPLS WAN for voice and video, but wants to reduce costs and enable direct cloud access for Office 365 and Salesforce from branches. Which approach best addresses both goals?

A. Upgrade all MPLS circuits to higher bandwidth — this will handle cloud traffic without any architecture change B. Replace MPLS entirely with DSL broadband and site-to-site IPsec VPNs C. Implement SD-WAN — retain MPLS for voice/video (SLA traffic), add cheap internet broadband for data and cloud access, use application-aware routing to steer SaaS traffic directly to the internet from branches while keeping voice on MPLS D. Deploy Metro Ethernet E-LAN across all sites to replace both MPLS and internet access

Correct answer is C. This is the classic SD-WAN use case. SD-WAN allows organisations to augment (not fully replace) their MPLS with cheaper internet broadband, using application-aware policies to keep latency-sensitive voice on MPLS while sending Office 365 and Salesforce directly to the internet from branches (direct cloud breakout) rather than backhauling through HQ. This reduces MPLS bandwidth requirements and cost while improving cloud application performance. See also: QoS Overview. See: SD-WAN Overview

WAN Technologies Overview

1. What Is a WAN and Why Does It Matter?

2. WAN Fundamentals — Key Concepts

2.1 Circuit-Switched vs Packet-Switched

2.2 CPE, CE, and PE Routers

2.3 WAN Serial Interfaces and Common Physical Standards

3. Leased Lines — Dedicated Point-to-Point Circuits

Leased Line Characteristics

4. MPLS — Multiprotocol Label Switching

MPLS Key Characteristics

5. Metro Ethernet — Carrier Ethernet WAN

Metro Ethernet Characteristics

6. DSL — Digital Subscriber Line

DSL Variants

DSL Architecture — PPPoE

DSL Characteristics

7. Cable Broadband — HFC Networks

Cable vs DSL Comparison

8. SD-WAN — Software-Defined Wide Area Networking

SD-WAN Key Capabilities

SD-WAN vs Traditional MPLS

9. VPN Overlays on WAN — IPsec, GRE, and DMVPN

10. Choosing the Right WAN Technology

Test Your Knowledge — WAN Technologies Quiz

What is the fundamental difference between circuit-switched and packet-switched WAN technologies?

In an MPLS WAN, what is the role of the CE router, and what does it know about the MPLS provider network?

A company uses DSL broadband as its branch WAN connection. DSL speed drops from 80 Mbps to 12 Mbps after the branch moves to a new building. What is the most likely cause?

What makes MPLS suitable for carrying real-time voice and video traffic across a multi-site enterprise WAN?

What is Metro Ethernet E-LAN, and how does it differ from E-Line?

What is the primary advantage of SD-WAN over a traditional MPLS-only WAN for a modern cloud-first enterprise?

A branch office has DSL broadband as its only WAN connection. Which technology provides secure private connectivity to the corporate headquarters over this internet connection?

Why is cable broadband described as a "shared medium" and what does this mean for enterprise use?

How does DMVPN improve on a standard hub-and-spoke IPsec site-to-site VPN for a large branch network?

A company runs a multi-site MPLS WAN for voice and video, but wants to reduce costs and enable direct cloud access for Office 365 and Salesforce from branches. Which approach best addresses both goals?

Related Topics & Step-by-Step Tutorials