Zones & tiers

zone and tier are the load-bearing keys. Almost every "why does my diagram look like that?" traces back to one of them being missing, wrong, or fighting the other.

  zone  →  WHERE something is   →  a spatial container (site, building, VLAN, VPC)
  tier  →  WHAT ROLE it plays   →  a vertical rank (edge → core → dist → access → endpoint)

They are orthogonal. A device can have both, either, or neither.

Tiers

Six values, ranked top to bottom on the page:

endpoint and management share rank 4 — they sit on the same row.

Tiers only take over the layout when every device declares one. A single device without a tier drops the whole topology out of tiered classification. That is the single most common surprise. If your three-tier network came out looking flat, run down the device list looking for the one that's missing tier:.

# this is tiered
- { id: rt-01,  icon: ..., tier: edge }
- { id: sw-01,  icon: ..., tier: core }
- { id: srv-01, icon: ..., tier: endpoint }

# this is NOT tiered — srv-01 has no tier, so the whole diagram falls back to flat
- { id: rt-01,  icon: ..., tier: edge }
- { id: sw-01,  icon: ..., tier: core }
- { id: srv-01, icon: ... }

Zones

A zone is a container drawn as a tinted panel with a title. Its contents are laid out on their own and then packed against the other zones.

zones:
  - id: campus
    name: Campus
    accent: "#7aa2ff"      # tints the panel
    collapse: auto         # auto | open | closed
  - id: bldg-a
    name: Building A
    parent: campus         # nesting

Two or more zones containing devices switches the layout to the zoned mosaic, and that outranks tiers. Inside each zone, tiers still order devices vertically — so zones and tiers compose rather than compete. Zones decide the big shape; tiers decide the shape within.

Use zones for things that are genuinely somewhere: sites, buildings, floors, VLANs, VPCs, OT versus IT, DMZ versus internal. Don't use them as a tagging system — a zone with two devices in it is a box that costs more than it explains.

Nesting

parent nests zones arbitrarily deep. Cycles are an error (MRW-E016).

zones:
  - { id: emea,     name: EMEA }
  - { id: london,   name: London,   parent: emea }
  - { id: ldn-dc1,  name: LDN-DC1,  parent: london }

On a multi-page site, only top-level zones get their own page; a page covers its whole subtree. So the nesting level you choose determines the page granularity of the built site.

Collapse

closed is how you keep a huge but uninteresting zone (500 desktops) from dominating a diagram that's actually about the core.

Choosing between them

Common failures

"My zones didn't render as panels." You need two or more zones that actually contain devices. One zone is not a mosaic; the engine ignores it as a layout signal.

"Everything is in one column." Every device probably landed in the same tier, or none declared a tier and the fallback flat layout kicked in.

"My HA pair is on opposite sides." ha_pair_with needs to be on both devices. Also check they're in the same zone — the engine won't pull a device out of its declared zone to sit next to its partner.

"A zone panel is enormous and empty." An empty zone raises MRW-W102. Either put devices in it or delete it.

Next: how layout is chosen.