ATM Over SONET
By:
Kavitha Sriraman,
CEPE, Dept of ECE, Drexel University,
Email : kavitha@drexel.edu
ATM over SONET~Kavitha Sriraman
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What is ATM over SONET??
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prevalent in the
Computer Networking
for transmitting of
Internet Packets.
optical layer provides
the foundation of
transport services for
both metro and longhaul applications. .
Transporting Layer is
the ATM.
ATM over SONET~Kavitha Sriraman
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SONET??
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Synchronous Optical NETwork.
Synchronous, Asynchronous,
Plesiochronous.
Plesiochronous difference.
Data rate
ATM over SONET~Kavitha Sriraman
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SONET SIGNAL.
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defines a technology for carrying many
signals of different capacities through a
synchronous, flexible, optical hierarchy ~
Byte interleaving.
SONET multiplexing involves the generation
of the lowest level or base signal- STS–1
operates at 51.84 Mbps.
Higher-level signals are integer multiples of
STS–1, creating the family of STS–N signals
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SONET SIGNAL TABLE.
Signal
Bit Rate (Mbps)
Capacity
STS–1, OC–1
51.840
28 DS–1s or 1 DS–3
STS–3, OC–3
155.520
84 DS–1s or 3 DS–3s
STS–12, OC–12
622.080
336 DS–1s or 12 DS–3s
STS–48, OC–48
2,488.320
1,344 DS–1s or 48 DS–3s
STS–192, OC–192
9,953.280
5,376 DS–1s or 192 DS–
3s
Signal
Bit Rate (Mbps)
Channels
DS–0
0.640
1 DS–0
DS–1
1.544
24 DS–0s
DS–2
6.312
96 DS–0s
DS–3
44.736
28 DS–1s
Note: STS = synchronous transport signal; OC = optical carrier
ATM over SONET~Kavitha Sriraman
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SONET FRAME FORMAT
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divided into two main areas: transport overhead
and the synchronous payload envelope (SPE).
SPE divided into two parts: the STS path
overhead (POH) and the payload.
Once the payload is multiplexed into the
synchronous payload envelope, it can be
transported and switched through SONET without
being examined and possibly de-multiplexed at
intermediate nodes ~service-independent or
transparent .
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Transmission Of Signals in
SONET
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signal into containers. Adds the section overhead ~ signal
and the quality of transmission are all traceable.
containers have two names depending on size: virtual
tributary (VT) or a synchronous payload envelope (SPE).
path overhead contains data to control the facility (end to
end) such as for path trace, error monitoring, far-end error,
or virtual container (VC) composition.
packaged in VCs and transported in synchronous transport
vehicles or signals (STS).
ATM over SONET~Kavitha Sriraman
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Transmission Of Signals in
SONET
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Transmission Of Signals in
SONET contd..
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An STS exists on each section (i.e., the link
between two nodes), also contains the line or
section overhead.
This line/section overhead contains data to control
the node-to-node transmission (protection
switching, error monitoring), and, in addition,
provides extra channels (network management and
maintenance phone link).
line transmission rates are 51, 155, and 622 Mbps;
2.5 Gbps; and 10 Gbps.
Line signals can be optical or electrical. Electrical
signals are used for short distances.
ATM over SONET~Kavitha Sriraman
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Transmission Of Signals in
SONET contd..
Bit Rate
(Mbps
)
PDH North America
Name
Bit Rate
PDH Europe
(Mbps
)
Name
SDH
Bit Rate
(Mbps
)
Container
SONET
Transport
Container
Transport
10,000
STM–64
STS/OC–192
2,500
STM–16
STS/OC–48
622
STM–4
STS/OC–12
155
STM–1
STS/OC–3
140
E4
140
VC4
51
STS/OC–1
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Asynchronous Transfer Mode
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A high-performance, cell-oriented switching and
multiplexing technology that utilizes fixed-length
packets to carry different types of traffic.
fixed-length cells consisting of 48 bytes (8 bits per
byte) of payload and 5 bytes of cell header
~ensures that time-critical information such as
voice or video is not affected by long data frames
or packets.
header is organized for efficient switching
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ATM Connections
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virtual path connections (VPCs), which contain virtual
channel connections (VCCs).
A virtual channel connection (or virtual circuit) is the basic
unit, which carries a single stream of cells, in order, from user
to user.
All cells belonging to a particular virtual path are routed the
same way through the ATM network~ faster recovery in case
of major failures.
Virtual circuits can be statically configured as permanent
virtual circuits (PVCs) or dynamically controlled via signaling
as switched virtual circuits (SVCs)~a rich set of service
capabilities.
SVCs are the preferred mode of operation ~ dynamically
established ~ minimizing reconfiguration complexity
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Structure to Carry Data
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ATM cells does not
have the structure.
SONET provides the
VT (containers).
its filled with cells
(ATM ) of 53 bytes.
Higher Data Rate ~
the cells are
concatenated.
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Conclusion….
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high performance via hardware switching
dynamic bandwidth for bursty traffic
class-of-service support for multimedia traffic.
scalability in speed and network size
provide a range of data, image, video and voice
services that take advantage of increasing
insensitivity of the network to distance.
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