OC12 Connection
An OC12 connection is a high-capacity optical circuit that delivers 622 Mbps of dedicated bandwidth over SONET fiber or dark fiber. Also written OC-12, it carries roughly four times the throughput of an OC3 and is built for large enterprises, carrier backbones, and point to point links between major sites. It provides symmetrical, SLA-backed bandwidth where 155 Mbps is no longer enough.
How an OC12 connection works
An OC12 carries 622 Mbps of dedicated, symmetrical bandwidth over SONET fiber, four times the capacity of an OC3. It can run over the provider's lit SONET ring or over dark fiber that you light with your own optics. An OC-12 supports large-scale dedicated internet access, carrier backbone transport, and private point to point links between major locations.
Typical OC12 pricing
When it fits
✓ Great fit
Large enterprises, carriers, and data centers that need dedicated, symmetrical 622 Mbps with a hard SLA, organizations running backbone transport, and major sites linked over private point to point optical circuits. An OC12 is a strong fit where SONET fiber or dark fiber is available and where 155 Mbps from an OC3 is no longer sufficient.
● Consider instead
If your sites can get modern high-capacity business Ethernet over fiber, it often delivers comparable or greater bandwidth at a lower cost per Mbps than legacy SONET. An OC12 connection makes the most sense when you specifically need SONET, dark fiber, carrier backbone transport, or a long-established optical circuit with a carrier-grade SLA.
How it compares
An OC12 delivers 622 Mbps, four times the 155 Mbps of an OC3, over the same SONET fiber.
An OC48 steps up to roughly 2.5 Gbps, four times an OC12, for the very largest carrier backbones.
Business Ethernet over fiber often scales further per dollar; an OC-12 wins on SONET compatibility and dark fiber control.
What to look for
- ✓SONET or dark fiber. An OC12 can ride the provider's lit SONET ring or dark fiber you light; confirm which is available.
- ✓Point to point capable. An OC-12 can link two sites as a private optical circuit, not just provide internet access.
- ✓Reach and route. Optical pricing scales with distance; a longer OC12 span costs more than a metro one.
- ✓SLA + restoration. SONET supports fast ring restoration; confirm the uptime and repair terms in writing.
Common questions
How fast is an OC12 connection?
An OC12 delivers 622 Mbps of dedicated, symmetrical bandwidth, also written OC-12, over SONET fiber.
What does OC12 stand for?
OC stands for Optical Carrier; OC12, or OC-12, is the 622 Mbps level in the SONET optical hierarchy.
How much faster is an OC12 than an OC3?
About four times faster. An OC-12 carries 622 Mbps versus the 155 Mbps of an OC3 over the same SONET fiber.
Is an OC12 dedicated or shared?
Dedicated. The full 622 Mbps of an OC-12 is reserved for your organization and backed by an SLA.
Can an OC12 run over dark fiber?
Yes. An OC12 can ride a provider's lit SONET ring or dark fiber that you light with your own optics.
Can an OC12 be used point to point?
Yes. An OC-12 can connect two locations as a private, dedicated optical circuit between major sites.
What is the next step up from an OC12?
An OC48, which delivers roughly 2.5 Gbps over SONET, is the next optical tier above an OC-12.
More on OC12 Connection
An OC12 connection, also written OC-12, is a high-capacity optical circuit that delivers 622 Mbps of dedicated, symmetrical bandwidth over SONET fiber. OC stands for Optical Carrier, and OC12 is the 622 Mbps level in the SONET hierarchy, roughly four times the throughput of an OC3. Because the circuit is dedicated and never shared, an OC-12 provides consistent throughput, low latency, and a carrier-grade service-level agreement. That makes an OC12 well suited to large enterprises, carrier backbones, data centers, and private point to point links between major sites. Typical pricing runs from about $30,000 to $150,000 per month depending on reach, route, and term.
An OC12 can ride the provider's lit SONET ring or run over dark fiber that you light with your own optics. The same circuit supports large-scale dedicated internet access, backbone transport, and private site-to-site connections between locations. When 622 Mbps is no longer enough, an OC48 steps the optical model up to roughly 2.5 Gbps; below it, an OC3 covers the 155 Mbps tier.
Types of serviceOptions and variants
What businesses use it for
- ✓Carrier backbone transport. The dedicated 622 Mbps of an OC-12 carries aggregated traffic across carrier and service-provider backbones.
- ✓Large enterprise dedicated internet. An OC12 delivers 622 Mbps of dedicated, symmetrical internet access with a carrier-grade SLA.
- ✓Point to point major site links. An OC-12 connects two major locations as a private optical circuit that never touches the public internet.
- ✓Data center interconnect. The high capacity of an OC12 links data centers and aggregates their high-volume traffic over SONET.
- ✓Campus and metro aggregation. An OC-12 aggregates traffic from many buildings across a campus or metro area over SONET fiber.