MAN
A metropolitan network: a city-scale fabric, often provider-owned fiber.
Level: beginner
What is it?
A Metropolitan Area Network (MAN) connects multiple local networks across a city or metropolitan region. It may use provider-operated fiber, Ethernet services, or routed links to connect campuses, offices, and facilities.
Why does it matter?
A MAN fills the gap between a local-site network and a wide-area network spanning larger regions. It allows nearby sites to share services while keeping local network design and routing boundaries.
Mental model
Think of a city-scale network backbone linking several LANs. Each site still has its own local switching and addressing; the MAN transports traffic between site gateways.
How it works
- MAN describes geographic and administrative scale rather than one specific protocol or topology.
- Provider Ethernet, metropolitan fiber rings, and routed IP services are common implementation choices.
- Resilience may come from rings, redundant paths, diverse fiber routes, and fast failover mechanisms.
- Security still depends on encryption, segmentation, routing policy, and provider configuration.
- A MAN can be managed by one organization or delivered as a service by a carrier.
Steps
- Each campus or office runs its own LAN and sends remote-site traffic to a gateway.
- The gateway forwards packets over the metropolitan service toward the destination site.
- The destination gateway routes the packets to the intended local network.
- Operators monitor route availability, link capacity, latency, and redundant paths.
Real-world usage
- Connecting university campuses or offices across a city.
- Planning regional connectivity between data centers and branch sites.
Common mistakes
- Assuming every MAN uses the same technology or is automatically one broadcast domain.
- Confusing a provider's geographic service label with an IP addressing design.
Interview questions
How does a MAN differ from a LAN?
A LAN normally serves one site or local area; a MAN connects multiple local networks across a city-scale region.
What matters when designing a resilient MAN?
Diverse paths, route convergence, capacity, latency, monitoring, and a tested failover plan.