Optical Carrier specifications (in use)
OC-1OC-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) usingoptical fiber. This base rate is multiplied for use by other OC-nstandards. For example, an OC-3 connection is 3 times the rate of OC-1.
OC-3 / STM-1x
OC-3 is a network line with transmission speeds of up to 155.52
Mbit/s (payload: 148.608 Mbit/s; overhead: 6.912 Mbit/s, including path
overhead) using fiber optics. Depending on the system OC-3 is also
known as STS-3 (electrical level) andSTM-1(SDH).
When OC-3 is notmultiplexedby carrying the data from a single source, the letterc(standing for concatenated) is appended:OC-3c.
OC-3c
OC-3c ("c" stands for "concatenated") concatenates three STS-1(OC-1)
frames into a single OC-3 look alike stream. The three STS-1 (OC-1)
streams interleaved with each other such that the first column is from
the first stream, the second column is from the second stream, and the
third is from the third stream. Concatenated STS(OC) frames carry only
one column of path overhead because they cannot be divided into finer
granularity signals. Hence, OC-3c can transmit more payload to
accommodate a CEPT-4 139.264 Mbit/s signal. The payload rate is 149.76
Mbit/s and overhead is 5.76 Mbit/s.
OC-12 / STM-4x
OC-12 is a network line with transmission speeds of up to 622.08 Mbit/s (payload: 601.344 Mbit/s; overhead: 20.736 Mbit/s).
OC-12lines are commonly used byISPsasWANconnections. 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 (belowTier 2) internet customers, such asweb hostingcompanies or smaller ISPs buying service from larger ones.
OC-24
OC-24 is a network line with transmission speeds of up to 1244.16Mbit/s(payload: 1202.208 Mbit/s; overhead: 41.472 Mbit/s). Implementations of OC-24 in commercial deployments are rare.
OC-48 / STM-16x / 2.5G Sonet
OC-48 is a network line with transmission speeds of up to 2488.32Mbit/s(payload: 2405.376 Mbit/s; overhead: 82.944 Mbit/s).
With usually cheap interface prices and being faster than OC-3, OC-12 connections, and even surpassinggigabit Ethernet, OC-48 connections are used as the backbones of many regionalISPs. Interconnections between large ISPs for purposes ofpeeringortransitare quite common. As of 2005, the only connections in widespread use that surpass OC-48 speeds areOC-192and10 gigabit Ethernet.
OC-48 is also used as transmission speed for tributaries from OC-192
nodes in order to optimize card slot utilization where lower speed
deployments are used. Dropping at OC-12, OC-3 or STS-1 speeds are more
commonly found on OC-48 terminals, where use of these cards on an
OC-192 would not allow for full use of the available bandwidth.
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).
Implementations of OC-96 in commercial deployments are rare, if ever
used at all.
OC-192 / STM-64x / 10G Sonet
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).
A standardized variant of10 gigabit Ethernet(10GbE), calledWAN-PHY,
is designed to inter-operate with OC-192 transport equipment while the
common version of 10GbE is called LAN-PHY (which is not compatible with
OC-192 transport equipment in its native form). The naming is somewhat
misleading, because both variants can be used on awide area network.
As of 2005, OC-192 connections are most common for use on backbones of large ISPs.
OC-768 / STM-256x
OC-768 is a network line with transmission speeds of up to 39,813.12
Mbit/s (payload: 38,486.016 Mbit/s; overhead: 1,327.104 Mbit/s).
On October 23, 2008, AT&T announced the completion of upgrades
to OC-768 on 80,000 fiber-optic wavelength miles of their IP/MPLS
backbone network.OC-768 SONET interfaces have been available with short-reach optical
interfaces from Cisco since as early as 2006. Infinera made a field
trial demonstration data transmission on a live production network
involving the service transmission of a 40 Gbit/s OC-768/STM-256
service over a 1,969 km terrestrial network spanning Europe and the
U.S. In November 2008, an OC-768 connection was successfully brought up
on theTAT-14/SeaGirttransatlantic cable,with the longest hop being 7,500km.
Optical Carrier specifications (unused)
Note: All of the following OC lines are theoretical. None of these are currently in use.
OC-384
Will be able to provide transmission speeds of around 19.8912 Gbit/s.
OC-1536
Will be able to provide transmission speeds of around 79.62624 Gbit/s.
It is unknown if such standards will be implemented in the near future.
As of 2007, the majority of work beyond 40 Gbit/s is focusing on 100
gigabit Ethernet, in the IEEE's Higher Speed Study Group.
OC-3072
Will be able to provide transmission speeds of around 159.25248 Gbit/s
OC-7144F
Will be able to provide transmission speeds of around 301.33598 Gbit/s
