Optical Carrier
Encyclopedia : O : OP : OPT : Optical Carrier
Optical Carrier levels are used for the categories of bandwidth in a SONET fiber optic network.[IEC online study material, SONET introduction]
The general rule for calculating the speed of Optical Carrier lines is when a specification is given as OC-n, that the speed will equal n × 51.8 Mbit/s.
Optical Carrier Specifications (In Use)
OC-1
OC-1 is a SONET line with transmission speeds of up to 51.84 Mbit/s (payload: 50.112 Mbit/s; overhead: 1.728 Mbit/s) using optical fiber. This base rate is multiplied for use by other OC-n standards. For example, an OC-3 connection is 3 times the rate of OC-1.OC-3
OC-3 is a network line with transmission speeds of up to 155.52 Mbit/s (payload: 150.336 Mbit/s; overhead: 5.184 Mbit/s) using fiber optics. Depending on the system OC-3 is also known as STS-3 (electrical level) and STM-1 (SDH).When OC-3 is not multiplexed by carrying the data from a single source the letter c (standing for concatenated) is appended: OC-3c.
OC-12
OC-12 is a network line with transmission speeds of up to 621.84 Mbit/s (payload: 601.344 Mbit/s; overhead: 20.736 Mbit/s).OC-12 lines are commonly used by ISPs as WAN connections. While a large ISP would not use an OC-12 as a backbone (main link), it would for smaller, regional or local connections. This connection speed is also often used by mid-sized (below Tier 2) internet customers, such as web hosting companies or smaller ISPs buying service from larger ones.
OC-24
OC-24 is a network line with transmission speeds of up to 1243.68 Mbit/s (payload: 1202.208 Mbit/s; overhead: 41.472 Mbit/s).OC-48
OC-48 is a network line with transmission speeds of up to 2488.32 Mbit/s (payload: 2405.376 Mbit/s; overhead: 82.944 Mbit/s).OC-48 connections are some of the fastest data connections in use today. Faster than OC-3, OC-12 connections, and even surpassing gigabit ethernet, OC-48 connections are used as the backbones of many regional ISPs. Interconnections between large ISPs for purposes of peering or transit are quite common. As of 2005, the only connections in widespread use that surpass OC-48 speeds are OC-192 and 10 gigabit ethernet.
OC-96
OC-96 is a network line with transmission speeds of up to 4976.64 Mbit/s (payload: 4810.752 Mbit/s; overhead: 165.888 Mbit/s).OC-192
OC-192 is a network line with transmission speeds of up to 9953.28 Mbit/s (payload: 9621.504 Mbit/s; overhead: 331.776 Mbit/s). This is the fastest connection commonly available to the Internet.A standardized variant of 10 Gigabit Ethernet, called WAN-PHY, is designed to inter-operate with OC-192 transport equipment while the common version of 10GE is called LAN-PHY. The naming is somewhat misleading, because both variants are suitable for use on a wide area network.
As of 2005, OC-192 connections are the most common for use on the backbones of large ISPs.
OC-768
OC-768 is a network line with transmission speeds of up to 39,813.12 Mbit/s (payload: 38,486.016 Mbit/s; overhead: 1327.104 Mbit/s).As of 2006, use of OC-768 connections outside of research or testing networks is quite rare, because of the high cost as opposed to link-bundled OC-192 and sheer lack of need for such speeds. However many large multi-nationals are developing their NGN with the ability to handle speeds up to OC-768 for future converged service operation.
However, Cisco Systems has an single OC-768 port line card for its CRS-1 NGN platform. Juniper Networks has OC-768 interface cards in production for its T-640 core routers. Also, Avici Systems has committed to developing an OC-768 line card for AT&T.
Optical Carrier Specifications (Not Used)
OC-256
OC-256, when launched will theoretically be able to provide transmission speeds of around 13 Gbit/s.OC-384
OC-384, when launched will theoretically be able to provide transmission speeds of around 20 Gbit/s.OC-1536 & beyond
The two AACarrier standards remaining (OC-1536 & OC-3072) will theoretically be able to provide transmission speeds of around 80 Gbit/s & 160 Gbit/s respectively. It is unknown if such standards will be implemented in the near future, and is considered unlikely.References
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