Data Center Operators L1-L7
Data Centers — 6 vendors and operators, each broken down by layer L1 to L7: what they sell at that layer, and which layer is their home turf.
Equinix
Home turf: L1
L1 Physical
This layer is the product itself in this domain, which makes it the thickest L1 on the site. Four things matter. IBX facilities and coverage: Equinix's asset is a footprint on the order of two hundred-odd data centres across dozens of countries (confirm against current disclosures), and its value depends heavily on whether the party you want to reach is insi…
L2 Data Link
This is the most valuable part of the domain after the physical layer, because interconnection is where Equinix's real margin lives. Three product lines and one comparison matter. Equinix Fabric: on top of existing physical attachment, software-provisioned virtual connections to clouds, other facilities and service providers — mechanically very close to Mega…
L3 Network
This layer holds one value no other domain can offer, plus a set of products that overlap heavily with Megaport, and the two deserve separate treatment. The distinctive part is multi-homing: an IBX concentrates carriers and exchange members, which makes this the easiest place on the whole site to be genuinely multi-homed — one cross connect to each of two or…
L4 Transport
This layer is explicitly empty — no product or service. This domain sells space, power, cooling, physical security and cross connects (see the earlier layers), not equipment or network services — it has no layer-4 product like load balancing or session management; that capability belongs to the equipment vendors and cloud domains that colocate in its facilit…
L5 Session
The application-session part of this layer is empty (the fabric and cross connects are entirely transparent to sessions above them), but the control plane has real content, and this domain has a hybrid character no other domain shares: it operates on two cadences at once.
L6 Presentation
This layer is explicitly empty — no product or service. A cross connect (see L1) is a physical-layer line — it has no involvement in what bits it carries or whether they're encrypted; encryption is decided entirely by the equipment at each end of the cross connect, something this domain neither provides nor participates in.
L7 Application
Under the reading established at L4 this layer is thin: Equinix performs no application-layer traffic processing — no WAF, no API gateway, no DNS service, no CDN, no application delivery and no global load balancing. But it has two substantial pieces, one of them unique to this domain.
Cross-layer / Operations
This layer states plainly something that recurs across the previous seven without being addressed head on: this domain's operating model differs from every other domain on this site — it is not operated by editing configuration but by signing contracts, raising tickets and sending people on site.
21Vianet
Home turf: L1
L1 Physical
This layer is this domain's entire business, which is why it's flagged here — what it sells is cabinets, power, cooling and physical interconnect, not network services. The entry point for understanding this domain is the word neutral, and its meaning only makes sense set against the Chinese context: in mainland China, each of the three state carriers runs i…
L2 Data Link
This layer needs its weight stated honestly up front: it's thinner than L1, because this domain's core business is physical space, and network services are an adjacent business grown on top of the physical facility, not the core.
L3 Network
This layer is the most distinctly Chinese layer in this domain, with two blocks of content that have no equivalent in any other domain on this site. Multi-line BGP access: the fundamental reason it exists is a structural problem unique to China — cross-carrier access quality has long been noticeably worse than access within the same carrier (interconnection…
L4 Transport
This layer needs one thing stated up front, and it's a real difference between this domain and the H3C domain on this site: server load balancing is not one of its product lines. The Arista, Juniper, Palo Alto and Ruijie domains and several carrier domains on this site have the same gap at this layer, while the H3C domain has its own load-balancing product —…
L5 Session
At this layer, colocation takes a very specific shape: your equipment sits inside someone else's building, so how do you actually issue it a command becomes a layer that has to be designed in its own right. Three blocks, split by technology, people and process.
L6 Presentation
This layer needs to dismantle a very common misunderstanding in domestic IDC procurement, and doing so is the most valuable thing at this layer: a facility that has passed MLPS classified protection does not mean your system has passed MLPS classified protection.
L7 Application
There's one block of content at this layer that's unique to this domain, with no equivalent anywhere else on this site: its affiliated entity holds the licence to operate a foreign public cloud's China instance.
GDS Holdings
Home turf: L1 / L7
L1 Physical
This layer is this domain's entire business, the same neutrality logic and the same hard energy-quota constraint as this page's Vianet domain (cabinets, power, cooling, cross connects, energy quotas — mechanics not repeated here; see Vianet domain L1).
L2 Data Link
In-facility patch panels and cross connects, mechanics identical to this page's Vianet domain (the technical expression of neutrality — see Vianet domain L2), not repeated here.
L3 Network
Physical onboarding of multiple carriers' circuits and multi-carrier access, mechanics identical to this page's Vianet domain (see Vianet domain L3), not repeated here. The audit checklist is the same too: confirm the carrier you need is actually onboarded in the target building, not just 'present somewhere in the campus.'
L4 Transport
Bandwidth-pool and burst-allowance billing, mechanics identical to this page's Vianet domain (see Vianet domain L4), not repeated here.
L5 Session
Out-of-band management, portal and ticketing workflow, mechanics identical to this page's Vianet domain (see Vianet domain L5), not repeated here.
L6 Presentation
MLPS (等保) assessment and the compliance-responsibility boundary, mechanics identical to this page's Vianet domain (see Vianet domain L6), not repeated here.
L7 Application
This layer has one piece unique to this domain: DayOne, its international brand for the Southeast Asian market (Indonesia, Malaysia and others). This is the mirror image of this page's Vianet domain's unique L7 content — the Vianet domain's story is a foreign cloud provider's China instance operated by a locally licensed entity (capital and capability flowin…
CoreSite
Home turf: L1 / L3
L1 Physical
This layer is this domain's product itself. Like this page's Equinix domain, cabinet floor space isn't the truly scarce resource — power is; the monthly fee is driven mainly by committed power.
L2 Data Link
This layer is explicitly empty — no product or service. This domain builds no switches and manages no VLANs — layer-2 switching inside a facility is the colocated customer's own equipment's job; its software-defined interconnection capability (Open Cloud Exchange) as a whole productizes 'connecting to clouds and other customers,' which reads more completely…
L3 Network
This is this domain's second star layer: Open Cloud Exchange, its software-defined interconnection platform, and the direct counterpart to this page's Equinix domain's Fabric and Megaport domain's VXC — on top of an existing physical connection, it opens virtual connections to cloud providers and other colocated customers on demand via software, without need…
L4 Transport
This layer is explicitly empty — no product or service. This domain sells space, power and physical/virtual interconnection, not equipment or network services — it has no layer-4 product like load balancing or session management; that capability belongs to the equipment vendors and cloud domains that colocate in its facilities.
L5 Session
The application-session portion of this layer is blank (interconnection is fully transparent to sessions above it), but there's real content in operational tempo: like this page's Equinix domain, this domain runs two operational modes at once.
L6 Presentation
This layer is explicitly empty — no product or service. Both cross connects and virtual connections are transparent physical/link-layer paths — they have no involvement in what bits they carry or whether they're encrypted; encryption is decided entirely by the equipment at each end of the connection.
L7 Application
This layer is thin, consistent with this page's Equinix domain: it does no application-layer traffic processing of its own — no WAF, no CDN, no application delivery. But there are two genuine pieces.
Colt DCS
Home turf: L1
L1 Physical
This layer is almost this domain's entire business, but in a completely different shape from this page's Equinix and CoreSite domains: what it sells isn't retail cabinets, but whole floors and whole buildings of wholesale space with power capacity delivered ready to use (powered shell / build-to-suit), and its customers are almost entirely hyperscale cloud p…
L2 Data Link
This layer is explicitly empty — no product or service. This domain doesn't do retail colocation — customers get a whole floor or building of dedicated space, with no layer-2 network shared with other tenants for it to manage; networking inside the facility is the customer's own equipment's job.
L3 Network
This layer is explicitly empty — no product or service. This is the most consequential difference between this domain and this page's Equinix and CoreSite domains: it has no software-defined interconnection product — no interconnection marketplace comparable to Equinix Fabric or CoreSite's Open Cloud Exchange — because its customer structure is a small numbe…
L4 Transport
This layer is explicitly empty — no product or service. This domain sells wholesale space, power and cooling, not equipment or network services.
L5 Session
This layer is explicitly empty — no product or service. Wholesale customers manage operations within their own whole-floor space directly, without depending on a portal or ticketing system from this domain for day-to-day connection management — different from this page's Equinix and CoreSite domains' portal/ticket-driven operational model aimed at a large re…
L6 Presentation
This layer is explicitly empty — no product or service. It has no involvement in any application or encryption scheme a customer runs within its own dedicated space.
L7 Application
This layer is explicitly empty — no product or service. It does no application-layer traffic processing, and there's no publicly documented customer-portal/telemetry product to confirm — unlike this page's Equinix and CoreSite domains' portal and facility-telemetry applications aimed at retail tenants, wholesale customers' facility monitoring is typically fo…
Digital Realty
Home turf: L1 / L3
L1 Physical
This layer is this domain's product itself; like this page's Equinix domain, cabinet floor space isn't the truly scarce resource — power is. What's most worth covering separately about this domain is that it spans both wholesale and retail at once — unlike any other data-centre domain on this page: this page's Colt DCS domain is pure wholesale (whole floors…
L2 Data Link
This layer is explicitly empty — no product or service. This domain builds no switches and manages no VLANs — layer-2 switching inside a facility is the colocated customer's own equipment's job; its software-defined interconnection capability (PlatformDIGITAL / ServiceFabric) as a whole productizes 'connecting to clouds and other customers,' which reads more…
L3 Network
This is this domain's second star layer: PlatformDIGITAL, the collective name for its data-centre platform ecosystem, within which the specific software-defined interconnection product is ServiceFabric — on top of an existing physical connection, it opens virtual connections to cloud providers and other colocated customers on demand via software, the same ca…
L4 Transport
This layer is explicitly empty — no product or service. This domain sells space, power and physical/virtual interconnection, not equipment or network services — it has no layer-4 product like load balancing or session management; that capability belongs to the equipment vendors and cloud domains that colocate in its facilities.
L5 Session
The application-session portion of this layer is blank (interconnection is fully transparent to sessions above it), but there's real content in operational tempo, consistent with this page's Equinix and CoreSite domains: this domain runs two operational modes at once.
L6 Presentation
This layer is explicitly empty — no product or service. Both cross connects and virtual connections are transparent physical/link-layer paths — they have no involvement in what bits they carry or whether they're encrypted; encryption is decided entirely by the equipment at each end of the connection.
L7 Application
This layer is thin, consistent with this page's Equinix and CoreSite domains: it does no application-layer traffic processing of its own — no WAF, no CDN, no application delivery. But there are two genuine pieces.