We use phones and computers everyday and so we might be curious that how the data is travelling so fast in fractions of Seconds. To carry that data we
need carriers, like we have trains or buses to carry our goods. So there are
different standardized carriers who have the different capacity i.e. at which
rate the data will be transmitted, so depending upon your price range we can
buy the type of carrier. The carriers
can be used to transmit both voice and data
E.g.
In Above Diagram T1C ("C" stands for "concatenated")
Different Type of Carrier
Signals:
T1
1) T1 is a digital
carrier signal that transmits the signal at a data rate of about 1.544
megabits/second.
2) It contains twenty
four digital channels.
3) This technology
makes your modem to have higher speeds and it is an affordable
technology.
4) Basic Unit of
T-Carrier System is DS0(Digital Signal Level 0) having transmission Rate
as
64 k bit/s.
5) The T-1 channel combines 24x64
Kbps(1536 kbps) channels into one single channel
6) The rest 8 k bit/s are used
for framing information
(1536+8 = 1544kbps).
7) T2 and T3 circuit channels carry multiple T1
channels multiplexed, resulting in
transmission rates of 6.312 and 44.736
M bit/s, respectively.
8) The DS designations are used in
connection with the North American(T) hierarchy only.
So DS1 is the data carried
on a T1 circuit so the terms are used interchangeably.
E1
1) E1 is similar to the T1.
2) T1 is the North American term whereas the E1 is the European term
for the transmission 3) E1 is a physical layer protocol, like Ethernet.
It defines a 2Mbps link between two
endpoints.
4) It has 32 channels at the
speed of 64 Kbps.
5) 2 channels among the 32 are reserved for signaling while the other
channel is used for
controlling.
6) The difference between T1 and E1 lies in the number of channels
here. The speed
remains the same. There may be inter – connection between the
E1 and T1 lines. This is
interconnected because it is used for international
purpose.
7) E1 circuits are very common in most telephone exchanges and are used to
connect to
medium and large companies,
OC
1) OC means Optical Carriers.
2) Its standard of transmission bandwidth for
digital signals that can be carried on
Synchronous Optical Networking (SONET) fiber optic networks.
3) The base unit or basic transmission rate is 51.84 Mbit/s.
4) Speed of optical-carrier lines labeled as OC-n is n × 51.84 M bit/s. (OC-4,OC-12
etc.)
The carriers described above
are the basic carries which are used in Networking. Also the exact bandwidth is less
than what you see above because some of the bandwidth is used as an overhead (Signalling
data, Headers etc.)
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