Siemens Industrial Training

2012
Siemens Industrial
Training Report
Industrial Training Report
Srinidhi Bheesette

Siemens Industrial Training Report 2012
Srinidhi Bheesette Page 1
Mentor- Mr. Prashant Gavade
Topic-Data Networking
Networking is required to allow multiple computers to connect to each other and share data. There
are some basic components which are used for establishing a network, there are switch, router and
clients (the laptops or computers).
To connect these computers there are two types of cable:
 Straight cable: This is used for connecting non-identical elements.
1. Switch to router
2. Switch to PC or server.
 Crossover cable: This is used for connecting identical elements.
1. Switch to switch
2. PC to PC
3. Hub to hub
4. Router to router
5. Switch to hub
Every client (PC or laptop) is identified using a unique name, here known as IP (Internet Protocol)
address. It is a 32 bit address divided into 4 octaves each, e.g. : 192.168.10.1,168.187.12.42 etc.
There are 5 types of IP addresses:
 Class A-N.H.H.H
 Class B-N.N.H.H
 Class C-N.N.N.H
 Class D-multicasting
 Class E-Research and Development
The table.1 gives the information about the various IP address (its decimal range, octal bits,
network/host ID, subnet mask, number of networks and the no of host per network)
Figure 1: Straight and Cross cable connections

Table.1 Different Category (CAT) cables
Each device also consists of a Network Identification Card (NIC) which is used to connect to a
network through a switch. Every NIC consists of a unique MAC (Media Access Control) number,
e.g.:9C-8E-99-43-56-A7, here the first 4bits (i.e.9C-8E) specify the name of the manufacturer(here
Realtek).
Every data communication over the network takes place over two protocols: TCP/IP and UDP.
TCP/IP stands for Transfer Control Protocol/Internet Protocol. In this type the every time the source
send data it expects an acknowledgement, thus it has control over the data and it decides whether
to transmit more data or not But this feature is not present in UDP (User Datagram Protocol),thus
this protocol does not have control over the data, it sends data even if the receiver does not respond
to it.
Comparing TCP/IP and UDP:
TCP/IP UDP
Sequence Non-sequence
Reliable Non-Reliable
Connection oriented Not connection oriented
Virtual circuit Low overhead
Acknowledge No acknowledgment
Window flowing is present No windowing
DHCP:
DHCP stands for Dynamic Host Control Protocol. It is a device which is connected to the switch in the
network topology which is used to automatically assign a unique IP address to each client connected
in the network. This is used when it is not possible to configure many multiple computers connected
to the network.
The Dynamic Host Configuration Protocol (DHCP) is a network configuration protocol for hosts
on Internet Protocol (IP) networks. Computers that are connected to IP networks must be
configured before they can communicate with other hosts. The most essential information needed is
an IP address, and a default route and routing prefix. DHCP eliminates the manual task by a network
administrator. It also provides a central database of devices that are connected to the network and
eliminates duplicate resource assignments.
In addition to IP addresses, DHCP also provides other configuration information, particularly the IP
addresses of local Domain Name Server (DNS), network boot servers, or other service hosts.
Table.2 TCP/IP vs. UDP

DHCP is used for IPv4 as well as IPv6. While both versions serve much the same purpose, the details
of the protocol for IPv4 and IPv6 are sufficiently different that they may be considered separate
protocols.[1]
Hosts that do not use DHCP for address configuration may still use it to obtain other configuration
information. Alternatively, IPv6 hosts may use stateless address auto configuration. IPv4 hosts may
use link-local addressing to achieve limited local connectivity.
For example:
192.168.10.1..10.2......192.168.10.10 are some set of IPs to be allocated to 10 clients.
Figure 2 : DHCP status in network details
Figure 3: DHCP settings

Types of networks:
 LAN-Local Area Network
 MAN- Metropolitan Area Network
 WAN-Wide Area Network
Local Area Network (LAN):
Local area network is network connecting computers or laptop in a confined area radius of about
100-400m. It is within a community, college, hotel, office etc. A local area network (LAN) is
a computer network that interconnects computers in a limited area such as a home, school,
computer laboratory, or office building using network media.[1]
The defining characteristics of LANs,
in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller
geographic area, and lack of a need for leased telecommunication lines.
ARCNET, Token Ring and other technology standards have been used in the past,
but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently
used to build LANs.
Metropolitan Area Network (MAN):
A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of
buildings to entire cities. MANs can also depend on communications channels of moderate-to-high
data rates. A MAN might be owned and operated by a single organization, but it usually will be used
by many individuals and organizations. MANs might also be owned and operated as public utilities.
They will often provide means for internetworking of local networks.
Wide Area Network (WAN):
As the name suggests this network is spread over several kilometres and is used to communicate
with other countries. In this type of network the data to be communicated is transmitted over a
satellite which broadcasts it in the given direction.
A Wide Area Network (WAN) is a telecommunication network that covers a broad area (i.e., any
network that links across metropolitan, regional, or national boundaries). Business and government
entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various
geographical locations. In essence this mode of telecommunication allows a business to effectively
carry out its daily function regardless of location.

Topologies:
Topology is the pattern in which different computers are connected in the network. The type of
topology should be chosen in such a manner that each computer of the network should be able to
communicate with any other computer.
Types of topologies:
 Bus: A linear bus topology consists of a main run of cable with a terminator at each end (See
fig. 4). All nodes (file server, workstations, and peripherals) are connected to the linear
cable.
 Star: A star topology is designed with each node (file server, workstations, and peripherals)
connected directly to a central network hub, switch, or concentrator. Data on a star network
passes through the hub, switch, or concentrator before continuing to its destination. The hub,
switch, or concentrator manages and controls all functions of the network. It also acts as a
repeater for the data flow. This configuration is common with twisted pair cable; however, it can
also be used with coaxial cable or fibre optic cable.
Figure 3: LAN and WAN layout
Figure 4: Bus topology

 Ring: In Ring Topology, all the nodes are connected to each-other in such a way that they
make a closed loop. Each workstation is connected to two other components on either side,
and it communicates with these two adjacent neighbours. Data travels around the network,
in one direction. Sending and receiving of data takes place by the help of TOKEN. (See fig6)
 Extended Star: A type of network topology in which a network that is based upon the
physical star topology has one or more repeaters between the central node (the 'hub' of the
star) and the peripheral or 'spoke' nodes, the repeaters being used to extend the maximum
transmission distance of the point-to-point links between the central node and the
peripheral nodes beyond that which is supported by the transmitter power of the central
node or beyond that which is supported by the standard upon which the physical layer of
the physical star network is based.
If the repeaters in a network that is based upon the physical extended star topology are
replaced with hubs or switches, then a hybrid network topology is created that is referred to
as a physical hierarchical star topology, although some texts make no distinction between
the two topologies.
Figure 5: Star Topology
Figure 6: Ring Topology

Figure 7: Extended star topology
 Mesh: A network setup where each computer and network device is interconnected with
one another, allowing for most transmissions to be distributed, even if one of the
connections go down. This topology is not commonly used for most computer networks as it
is difficult and expensive to have redundant connection to every computer. However, this
topology is commonly used for wireless networks. Below is a visual example of a simple
computer setup on a network using a mesh topology. See figure 8.
IEEE standard:
IEEE 802 refers to a family of IEEE standards dealing with local area networks and metropolitan area
networks. More specifically, the IEEE 802 standards are restricted to networks carrying variable-size
packets. (By contrast, in cell relay networks data is transmitted in short, uniformly sized units called
cells. Isochronous networks, where data is transmitted as a steady stream of octets, or groups of
octets, at regular time intervals, are also out of the scope of this standard.) The number 802 was
simply the next free number IEEE could assign, though “802” is sometimes associated with the date
the first meeting was held — February 1980.
Figure 8: Mesh Topology

IEEE standard Application
802.1 Bridging (networking) and Network
Management
802.2 OSI
802.3 MAC/Ethernet
802.6 MANs (DQDB)
Table 3: IEE Standard with their applications
CSMA/CD: It stands for Carrier Sense Multiple Access/Collation Detection.
Carrier sense multiple access with collision detection (CSMA/CD) is a Media Access Control method
in which:
 a carrier sensing scheme is used.
 a transmitting data station that detects another signal while transmitting a frame, stops
transmitting that frame, transmits a jam signal, and then waits for a random time interval before
trying to resend the frame.
CSMA/CD is a modification of pure carrier sense multiple access (CSMA). CSMA/CD is used to
improve CSMA performance by terminating transmission as soon as a collision is detected, thus
shortening the time required before a retry can be attempted. The algorithm is show below. (See
figure 9).
Figure 9: The flowchart of CSMA/CA

OSI model:
The Open Systems Interconnection (OSI) model is a product of the Open Systems
Interconnection effort at the International Organization for Standardization. It is a prescription of
characterising and standardising the functions of a communications system in terms of abstraction
layers. Similar communication functions are grouped into logical layers. A layer serves the layer
above it and is served by the layer below it.
For example, a layer that provides error-free communications across a network provides the path
needed by applications above it, while it calls the next lower layer to send and receive packets that
make up the contents of that path. Two instances at one layer are connected by a horizontal
connection on that layer.
Layer 7-Application layer: It deals with the network applications like E-Mail, Web Browser etc. This
layer interacts with software applications that implement a communicating component. Such
application programs fall outside the scope of the OSI model. Application-layer functions typically
include identifying communication partners, determining resource availability, and synchronizing
communication. When identifying communication partners, the application layer determines the
identity and availability of communication partners for an application with data to transmit.
Layer 6-Presentation Layer:
The presentation layer establishes context between application-layer entities, in which the higher-
layer entities may use different syntax and semantics if the presentation service provides a mapping
between them. If a mapping is available, presentation service data units are encapsulated into
session protocol data units, and passed down the stack.
Layer 5-Session Layer:
It talks about the sessions like Simplex, Half duplex or Full duplex.The session layer controls the
dialogues (connections) between computers. It establishes, manages and terminates the
Figure 10: OSI model

connections between the local and remote application. It provides for full-duplex, half-duplex,
or simplex operation, and establishes check pointing, adjournment, termination, and restart
procedures. The OSI model made this layer responsible for graceful close of sessions, which is a
property of the Transmission Control Protocol, and also for session check pointing and recovery,
which is not usually used in the Internet Protocol Suite.
Layer 4-Transport Layer:
The transport layer provides transparent transfer of data between end users, providing reliable data
transfer services to the upper layers. The transport layer controls the reliability of a given link
through flow control, segmentation/desegmentation, and error control. Some protocols are state-
and connection-oriented. This means that the transport layer can keep track of the segments and
retransmit those that fail. The transport layer also provides the acknowledgement of the successful
data transmission and sends the next data if no errors occurred.
Layer 3-Network Layer:
The network layer provides the functional and procedural means of transferring variable
length data sequences from a source host on one network to a destination host on a different
network (in contrast to the data link layer which connects hosts within the same network), while
maintaining the quality of service requested by the transport layer. The network layer performs
network routing functions, and might also perform fragmentation and reassembly, and report
delivery errors. Routers operate at this layer, sending data throughout the extended network and
making the Internet possible.
Layer 2-Data Link:
The data link layer provides the functional and procedural means to transfer data between network
entities and to detect and possibly correct errors that may occur in the physical layer. Originally, this
layer was intended for point-to-point and point-to-multipoint media, characteristic of wide area
media in the telephone system. Local area network architecture, which included broadcast-capable
multi-access media, was developed independently of the ISO work in IEEE Project 802. IEEE work
assumed sub layering and management functions not required for WAN use
Layer 1: Physical Layer:
The major functions and services performed by the physical layer are:
 Establishment and termination of a connection to a communications medium.
 Participation in the process whereby the communication resources are effectively shared among
multiple users. For example, contention resolution and flow control.
 Modulation or conversion between the representation of digital data in user equipment and the
corresponding signals transmitted over a communications channel. These are signals operating
over the physical cabling (such as copper and optical fibre) or over a radio link.

The layers and their functions in a tabular form are shown below:
TCP/IP Layer: The TCP/IP is similar to the OSI model except the fact that the presentation and
Session layer is absent in TCP/IP model, hence it consists of only 4 layers
Table 4: OSI layers and functions in tabular form
Figure 11: OSI and the TCP/IP model

Category cables:
In the context of the 100-ohm UTP (Unshielded Twisted Pair) type of cable used for Ethernet wiring
the only categories of interest are Cat3, Cat4, Cat5, Cat5e, Cat6, and Cat7. CATx is an abbreviation
for the category number that defines the performance of building telecommunications cabling as
outlined by the Electronic Industries Association (EIA) standards. Some specifications for these
categories are shown further down.
Up until the late 1980s thick or thin coaxial cable was typically used for 10-Mbps Ethernet networks,
but around that time, UTP cabling became more commonly used because it was easier to install and
less expensive. UTP CAT3 and CAT4 were used for a quite limited time since the emergence of
100Base-TX networks meant a quick shift to CAT5. By the year 2000, moves to gigabit (1000Base-TX)
Ethernet LANs created a need for another specification, CAT5e. CAT5e is now being superseded by
CAT6 cable and there is a developing standard for CAT7.
Organizations such as the Telecommunication Industry Association (TIA) and Electronic Industries
Association (EIA) set specific product standards, and these guidelines have resulted in cables being
classified into various categories based on their performance levels. These are known as category
cables. Each cable differs from other in terms of the type, Bandwidth and thus application as shown:
Table 6: Specifications of CAT 3, 4, 5, 5e, 6 and 7 cables
CAT5 and CAT5e are pretty much the same,CAT5e specification simply included some additional
limits over the CAT5 specification. The reality is that most CAT5 cable is in fact CAT5e cable just not
certified as such. Here is a comparison of those extra specifications.
Table 5: TCP/IP layers and applications

Table 7: Comparison between CAT 5,5e and 6 cables
Category 6 cable, commonly referred to as Cat 6, is a cable standard for Gigabit Ethernet and other
network physical layers that is backward compatible with the Category 5/5e and Category 3
cable standards. Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications
for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is
suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet)
and 10GBASE-T (10-Gigabit Ethernet).
Whereas Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a
cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien
crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols.
Figure 12: Pin position of a CAT 6 cables

Category 5 cable (Cat 5) is a twisted pair cable for carrying signals. This type of cable is used
in structured cabling for computer networks such as Ethernet. It is also used to carry other signals
such as telephony and video. The cable is commonly connected using punch down
blocks and modular connectors. Most Category 5 cables are unshielded, relying on the twisted pair
design and differential signalling for noise rejection. Category 5 has been superseded by
the Category 5e (enhanced) specification.
Figure 13: Modular connector of cat 5 cable

Virtual Local Area Network (VLAN):
A virtual local area network, virtual LAN or VLAN, is a group of hosts with a common set of
requirements, which communicate as if they were attached to the same broadcast domain,
regardless of their physical location. A VLAN has the same attributes as a physical local area
network (LAN), but it allows for end stations to be grouped together even if not on the
same network switch. VLAN membership can be configured through software instead of physically
relocating devices or connections. Most every Enterprise network today uses the concept of virtual
LANs (VLAN). Without VLANs, a switch considers all interfaces on the switch to be in the same
broadcast domain.
To physically replicate the functions of a VLAN would require a separate, parallel collection of
network cables and equipment separate from the primary network. However, unlike a physically
separate network, VLANs must share bandwidth; two separate one-gigabit VLANs that share a single
one-gigabit interconnection can suffer reduced throughput and congestion. It virtualizes VLAN
behaviours (configuring switch ports, tagging frames when entering VLAN, lookup MAC table to
switch/flood frames to trunk links, and untagging when exit from VLAN.)
VLANs are created to provide the segmentation services traditionally provided by routers in LAN
configurations. VLANs address issues such as scalability, security, and network management. Routers
in VLAN topologies provide broadcast filtering, security, address summarization, and traffic flow
management. By definition, switches may not bridge IP traffic between VLANs as it would violate the
integrity of the VLAN broadcast domain.
This is also useful if someone wants to create multiple layer 3 networks on the same layer 2 switch.
For example, if a DHCP server is plugged into a switch it will serve any host on that switch that is
configured to get its IP from a DHCP server. By using VLANs you can easily split the network up so
some hosts won't use that DHCP server and will obtain link-local addresses, or obtain an address
from a different DHCP server.
VLANs are layer 2 constructs, compared with IP subnets, which are layer 3 constructs. In an
environment employing the VLANs, a one-to-one relationship often exists between VLANs and IP
subnets, although it is possible to have multiple subnets on one VLAN. VLANs and IP subnets provide
independent Layer 2 and Layer 3 constructs that map to one another and this correspondence is
useful during the network design process.
By using VLANs, one can control traffic patterns and react quickly to relocations. VLANs provide the
flexibility to adapt to changes in network requirements and allow for simplified administration.
In cloud computing VLANs and IP addresses on them are resources that can be managed by end
users. Placing cloud-based virtual machines on VLANs may be preferable to directly on the Internet
to avoid security issues.
Configuration of VLANs:
We can configure VLAN on a switch or router using many ways like for example using pocket
tracker, HyperTerminal etc.

The figure below shows how a VLAN is configured using HyperTerminal:
Run HyperTerminal in Windows by going to Start > Programs > Accessories > Communications >
HyperTerminal.
After clicking on the HyperTerminal icon, you will see this window:
HyperTerminal prompts you to create a new connection. Note that this is not required but let’s go
ahead and do it.
Type in the word Cisco for the connection name and click OK.
Connect your Cisco device to your PC’s COM1 port but don’t turn it on yet. On the next window that
appears, make sure that the “Connect Using” field says COM1 and click OK.
Figure 14: HyperTerminal Window
Figure 15: Connect To settings

On the next window, change the Baud rate to 9600 and click OK.
Now, turn on your Cisco device. In the HyperTerminal window, you should see the boot up process
for your device, like this:
Figure 16: COM 1 port properties
Figure 17: Bios and credential window

An example showing port 1 and port 48 of Switch-1 and Switch-2 being configured as VLAN with
untagged and tagged modes is shown below:
VLANs are used to connect to a network even when you are physically present at some distant
location. This allows us to access the network even when we are at home or if we are present
another organization or company. Another way of connected to VLANs is by using softwares likes
putty or SSH client.
Figure 18: Setting up VLAN between two switches for a phone and PC
Figure 19: PuTTY command promt

When do I need a VLAN?
 When we have more than 200 devices on your LAN
 When we have a lot of broadcast traffic on your LAN
 Groups of users need more security or are being slowed down by too many broadcasts?
 Groups of users need to be on the same broadcast domain because they are running the same
applications. An example would be a company that has VoIP phones. The users using the phone
could be on a different VLAN, not with the regular users.
 Or, just to make a single switch into multiple virtual switches.
We could also use subnets in our network but the difference between VLAN and subnet is:
VLAN Subnets
Devices are in different physical locations. All devices must be connected to the same
switch.
A VLAN is a layer 2 term. A subnet is a layer 3 term.
The configuration is done on server side. Based on client side IP configuration.
The client cannot change it. The client can use any subnet he wants.
VLAN is an isolated portion of the network. It allows segmentation of a network.
It allows tagging and un-tagging of data. This feature is not available in subnet.
VLAN is software based. Subnet is hardware based.
Table 8: VLAN vs. Subnets
Spanning Tree:
The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for
any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and
the broadcast radiation that results from them. Loops are formed when two open port in a switch
are connected to each other using an Ethernet cable, this causes uncertainty in the path of the data
transfer and the packet is not transferred to the client efficiently. Spanning tree also allows
a network design to include spare (redundant) links to provide automatic backup paths if an active
link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these
backup links.
Spanning Tree Protocol (STP) is standardized as IEEE 802.1D. As the name suggests, it creates
a spanning tree within a mesh network of connected layer-2 bridges (typically Ethernet switches),
and disables those links that are not part of the spanning tree, leaving a single active path between
any two network nodes.
STP is based on an algorithm invented by Radia Perlman while working for Digital Equipment
Corporation.
The spanning tree algorithm is fed into each switch to automatically prevent the loops.

A series of diagrams explain the spanning tree processes are shown below:
Figure 20: Assume 3 bridges are connected in the network A,B and C. After the connections are set up every bridge
assumes it is the root making its bridge ID the root ID
Figure 21: The bridge C send it Root ID to the other two bridges which check weather their root ID are less or greater.
Depending on this they select their root.

Figure 22: Similarly Bridge A also send it root ID to other bridges and thus they all finalize bridge A as root bridge
Figure 23: The root bridge (Bridge A) chooses the Designated and Non-designated port.

Figure 25: As soon as the flow of BPDUs from Bridge C is interrupted, the Bridge B waits for some duration and
subsequently opens its port 1/2 to forwarding which was blocked earlier. This way spanning tree algorithm is performed.
Figure 24: The BPDUs are sent by Bridge C thus the path is forwarding and the port 1/2.blocked

Mentor-Mr Narayan Bhagwe
Topic-Wireless Local Area Network
A wireless local area network (WLAN) links two or more devices using some wireless distribution
method (typically spread-spectrum or OFDM radio), and usually providing a connection through an
access point to the wider internet. This gives users the mobility to move around within a local
coverage area and still be connected to the network. Most modern WLANs are based on IEEE
802.11 standards, marketed under the Wi-Fi brand name.
Wireless LANs have become popular in the home due to ease of installation, and in commercial
complexes offering wireless access to their customers; often for free. Large wireless network
projects are being put up in many major cities: New York City, for instance, has begun a pilot
program to provide city workers in all five boroughs of the city with wireless Internet access.]
The major IEEE standards for wireless:
Table 9: IEEE 802.11 WLAN standard and their specification
 802.11a
i. The 802.11a standard uses the same data link layer protocol and frame format as the
original standard, but an OFDM based air interface (physical layer). It operates in the 5 GHz
band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields
realistic net achievable throughput in the mid-20 Mbit/s .
ii. Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively
unused 5 GHz band gives 802.11a a significant advantage. However, this high carrier
frequency also brings a disadvantage: the effective overall range of 802.11a is less than that
of 802.11b/g. In theory, 802.11a signals are absorbed more readily by walls and other solid

objects in their path due to their smaller wavelength and, as a result, cannot penetrate as far
as those of 802.11b. In practice, 802.11b typically has a higher range at low speeds (802.11b
will reduce speed to 5 Mbit/s or even 1 Mbit/s at low signal strengths). 802.11a also suffers
from interference, but locally there may be fewer signals to interfere with, resulting in less
interference and better throughput.
 802.11b
i. 802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media access
method defined in the original standard. 802.11b products appeared on the market in
early 2000, since 802.11b is a direct extension of the modulation technique defined in the
original standard. The dramatic increase in throughput of 802.11b (compared to the
original standard) along with simultaneous substantial price reductions led to the rapid
acceptance of 802.11b as the definitive wireless LAN technology.
ii. 802.11b devices suffer interference from other products operating in the 2.4 GHz band.
Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices,
baby monitors, and cordless telephones.
 802.11g
i. In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz
band (like 802.11b), but uses the sameOFDM based transmission scheme as 802.11a. It
operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of forward error
correction codes, or about 22 Mbit/s average throughputs. 802.11g hardware is fully
backward compatible with 802.11b hardware and therefore is encumbered with legacy
issues that reduce throughput when compared to 802.11a by ~21%.
ii. The then-proposed 802.11g standard was rapidly adopted by consumers starting in January
2003, well before ratification, due to the desire for higher data rates as well as to reductions
in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-
band/tri-mode, supporting a and b/g in a single mobile adapter card or access point. Details
of making b and g work well together occupied much of the lingering technical process; in an
802.11g network, however, activity of an 802.11b participant will reduce the data rate of the
overall 802.11g network.
iii. Like 802.11b, 802.11g devices suffer interference from other products operating in the
2.4 GHz band, for example wireless keyboard
 802.11n
i. 802.11n is an amendment which improves upon the previous 802.11 standards by
adding multiple-input multiple-output antennas (MIMO). 802.11n operates on both the
2.4 GHz and the lesser used 5 GHz bands. The IEEE has approved the amendment and it was
published in October 2009. Prior to the final ratification, enterprises were already migrating
to 802.11n networks based on the Wi-Fi Alliance's certification of products conforming to a
2007 draft of the 802.11n proposal.

The other standards summarized in a tabular form are shown below:
Table 10: Universal 802.11 standards
Thus in order to connect to the Local Area Network (LAN) or to the Internet wirelessly we require
Access points. In computer networking, a wireless access point (WAP) is a device that allows wireless
devices to connect to a wired network using Wi-Fi, Bluetooth or related standards. The WAP usually
connects to a router (via a wired network) if it's a standalone device, or is part of a router itself.
There are many companies which manufacture access points. Some of them are listed below.
1. Siemens
2. Aruba
3. Cisco
4. Ruckus
5. TP Link
6. Huwai
7. D Link

The image below shows the access points manufacture by Siemens. The above one is a
antenna less PCB based micro strip antenna access point. And the access point below is
with two external antennas.
The specifications of some of the access points manufacture by Siemens are:
Name Range Price
AP 2610 30m 10000
AP 2620 30m 11000
AP 2630 35m 9500
AP 2640 35m 9500
AP 2650 25m 5600
AP 2660 30m 5500
AP 3610 100m 35000
AP 3620 120m 35000
Table 11: Price and range of some access points manufacture by Siemens
Channel and international compatibility:
802.11 divides each of the above-described bands into channels, analogous to the way radio and TV
broadcast bands are sub-divided. For example the 2.4000–2.4835 GHz band is divided into 13
channels spaced 5 MHz apart, with channel 1 centred on 2.412 GHz and 13 on 2.472 GHz (to which
Japan added a 14th channel 12 MHz above channel 13 which was only allowed for 802.11b). 802.11b
was based on DSSS with a total channel width of 22 MHz and did not have steep skirts. Consequently
only three channels do not overlap. Even now, many devices are shipped with channels 1, 6 and 11
Figure 26: Siemens access points

as preset options even though with the newer 802.11g standard there are four non-overlapping
channels - 1, 5, 9 and 13. There are now four because the OFDM modulated 802.11g channels are
20 MHz wide.
Thus in wireless planning too many companies used access point of channels separated by a factor
of 5. Both the 802.11b and 802.11g have 13 channels and 802.11a has 165 channels. But India we
are allowed to use only 11 channels of every standard. The overlapping of channels other then
channel 1, 6 and 11 is shown below.
Figure 27: Overlapping of channel of 802.11a, 802.11b, and 802.11g standards
Figure 28: Channel 1, 6, and 11 are the non-overlapping channels.

The wireless frequency bands are broadly classified into two band:
1. ISM- Industrial, scientific and medical radio band. The industrial, scientific and medical (ISM)
radio bands are radio bands (portions of the radio spectrum) reserved internationally for the
use of radio frequency (RF) energy for industrial, scientific and medical purposes other than
communications. Examples of applications in these bands include radio-frequency process
heating, microwave ovens, and medical diathermy machines. There frequency range is from
2.40GHz to 2.48GHz In general, communications equipment operating in these bands must
tolerate any interference generated by ISM equipment, and users have no regulatory
protection from ISM device operation.
2. U-NII- Unlicensed National Information Infrastructure radio band is part of the radio
frequency spectrum used by IEEE-802.11a devices and by many wireless ISPs. It operates
over three ranges:
i. U-NII Low (U-NII-1): 5.15-5.25 GHz. Regulations require use of an integrated antenna. Power
limited to 50mW
ii. U-NII Mid (U-NII-2): 5.25-5.35 GHz. Regulations allow for a user-installable antenna, subject
to Dynamic Frequency Selection(DFS, or radar avoidance).Power limited to 250mW
iii. U-NII Worldwide: 5.47-5.725 GHz. Both outdoor and indoor use, subject to Dynamic
Frequency Selection (DFS, or radar avoidance). Power limited to 250mW. This spectrum was
added by the FCC in 2003 to "align the frequency bands used by U-NII devices in the United
States with bands in other parts of the world". The FCC currently has an interim limitation on
operations on channels which overlap the 5600 - 5650 MHz band.
iv. U-NII Upper (U-NII-3): 5.725 to 5.825 GHz. Sometimes referred to as U-NII / ISM due to
overlap with the ISM band. Regulations allow for a user-installable antenna. Power limited
to 1W
Wireless Security:
Wireless security is the prevention of unauthorized access or damage to computers using
wireless networks. The most common types of wireless security are Wired Equivalent Privacy (WEP)
and Wi-Fi Protected Access (WPA). WEP is one of the least secure forms of security. A network that
is secured with WEP has been cracked in 3 minutes by the FBI.[1]
WEP is an old IEEE 802.11 standard
from 1999 which was outdated in 2003 by WPA or Wi-Fi Protected Access. WPA was a quick
alternative to improve security over WEP. The current standard is WPA2; some hardware cannot
support WPA2 without firmware upgrade or replacement. WPA2 uses an encryption device which
encrypts the network with a 256 bit key; the longer key length improves security over WEP.
WPA2 is a WiFi Alliance branded version of the final 802.11i standard. The primary enhancement
over WPA is the inclusion of the AES-CCMP algorithm as a mandatory feature. Both WPA and WPA2
support EAP authentication methods using RADIUS servers and preshared key (PSK).

Most of the world has switched their WAP from WEP to WPA2, since WEP has been proved too
insecure to be used. It is important to note there is a possible security flaw to the WPA protocol. It is
referred to as Hole196. It is a hole in the protocol that exposes the user to insider attacks.
The access point can be made secured by setting up security by using WEP, WPA, WPAv2 and WPA-
PSK encryption keys which are mostly 128 bits, 256 bits or even 2048 bits. An access point being
configured in such manner is shown below:
Figure 29: Security aspects of WLAN
Figure 30: Wireless security configuration

Wireless planning:
Planning is a very important part of wireless network as it helps in configuring the signal strength
and the data rate at a particular area. This is not required in Wired or Ethernet connections as the
PCs or clients are directly connected to the switch using Fast or Giga Ethernet cables like Cat5, Cat6
or Cat 6e.
The process of planning is done by the ISP provider according to the customer needs. The points to
be considered before making a survey are:
 Minimum cost.
 Sufficient bandwidth
 Range
 Capacity
 Output
 Directional characteristics of the access point
 Height of the access point above the floor.
 Access point standard for e.g.:802.11a, g or n.
 The composition of the house like walls, windows, door, furniture, lift shafts etc.
Planning is first performed using software and then accordingly the access points are set up as per
the report obtained by the planning.
One of the popularly used software used by many companies is Ekahau Site Survey. It is developed
by Ekahua Inc based in South Korea.
The steps involved in planning are illustrated as follows:
1. Open the map where the site survey is to be conducted using the Ekahau site survey
software.

2. Now choose the wall type, windows and the door and align them accordingly as shown
below.
We place three access point spaced equally as shown below. The three access point chosen are of 3
different standards 802.11a, 802.11b and 802.11g.Each of three have their own direction, height,
range, power etc.
The signal strength offered by all the three access points must cover the entire the whole are. Thus
the ‘Signal Strength’ parameter helps in understanding the intensity of the signal coverage. This is
illustrated below:
Brick wall (attenuation-10db)
Dry wall (attenuation-3db)
Concrete wall (attenuation-12db)
Figure 31: Ekahau site survey software loaded with sample map
Figure 32: Different types of wall types, window and door frames which can be selected
Figure 33: Signal strength visualization
Access points

The interference between different access points is another major disadvantage which should be
minimized if not nullified.
As discussed earlier interference is avoided is we choose access points with their channels separated
by a factor of 5. Thus we have used the access point with channel 26, 1 and 11.The interference can
be visualized by using the visualization option and selecting interference in the view menu.
Each type of access point conforming to different standards like 802.11 a, b and g provides different
data rate (bits/sec). The access point of standard b and g provide a data rate of 11 Mbps and
802.11g provides a Data rate of 54Mbps. The image below shows the visualization of the data rate.
The green portion indicates a speed of 11Mbps and the pink portion a speed of 54Mbps. Note that
all the above values are theoretical and practically much lesser.
No interference
Figure 34: Interference visualization for the three access points fixed

Figure 35: Data rate visualization (Legend-Pink portion-54 Mbps; Green portion-11 Mbps)
Thus in this way the access points are configured and placed to give maximum coverage of the area
and meet the needs of the customer.

Mentor- Mr. Sagar Punyarthi
Topics-Video Conferencing
Video conferencing is the process by which two parties at any distant location can communicate
with each other through audio as well as video. This help to save time in commuting from one place
and also helps in reducing the carbon footprint.
Video conferencing is the integration of video, audio and peripherals to enable two or more people
to communicate simultaneously over some type of telecommunications lines. By video conferencing
you are transmitting synchronized images and verbal communications between two or more
locations in lieu of them being in the same room.
The main ingredients of video conferencing are video cameras, microphones, appropriate computer
software and computer equipment and peripherals that will integrate with the transmission. The
analogue information recorded by the microphones and cameras is broken down into discreet units,
translating it to ones and zeros. A Codec encodes the information to a digital signal that can then be
transmitted to a codec at the other end, which will retranslate these digital signals back into
analogue video images and audio sounds.
This is now widely used by many companies, organization and even school and colleges for
education, meeting and conferences.
The most popular companies which offer the video conferencing technology equipments are
Polycom, Tandberg, Radvision , Aethra, Huwaie, Life Size and Genesys.
Video conferencing standards:
Like Ethernet and wireless networks, video conferencing also has some defined standards. These
standards are defined by the International Telecommunication Union (ITU) founded in the year
1865.The union developed the standards for video conferencing in the year 1996. They established
Standard H.263 to reduce bandwidth for transmission for low bit rate communication. Other
standards were developed, including H.323 for packet-based multi-media communications. These
are a variety of other telecommunications standards were revised and updated in 1998. In 1999, the
Moving Picture Experts Group as an ISO standard for multimedia content developed Standard
MPEG-4.
ITU standards for video conferencing:
 H.320 (synchronous networks)
a. -Video: H.261, H.263, H.264, etc.
b. -Audio: G.711, G.722, G.722.1, G.728.
c. -Data: T.120.

d. -Call control: H.221.
 H.323 (for packet switched networks) H.323 is a multimedia conferencing protocol, which
includes voice, video, and data conferencing, for use over packet-switched networks
a. -Video: H.261, H.263, H.264, etc.
b. -Audio: G.711, G.722, G.729, G.728.
c. -Call setup: H.245, Q.931, RAS.
 H.235 for security and encryption.
 H.350 (directory based protocol).
 H.225 for call signalling.
 H.245 for call control.
 H.332 for large conferences.
 H.450.X is used for supplementary services.
 H.235 is used for security and encryption.
 H.246 is popularly used for interoperability.
Codecs used for video conferencing:
Video codecs:
1. H.261:
 H.261 is a ITU-T video coding standard, ratified in November 1988.[1][2]
It is the first member
of the H.26x family of video coding standards in the domain of the ITU-T Video Coding
Experts Group (VCEG), and was the first video codec that was useful in practical terms.
 H.261 was originally designed for transmission over ISDN lines on which data rates are
multiples of 64 Kbit/s. The coding algorithm was designed to be able to operate at video bit
rates between 40 kbit/s and 2 Mbit/s. The standard supports two video frame
sizes: CIF(352x288 luma with 176x144 chroma) and QCIF (176x144 with 88x72 chroma) using
a 4:2:0 sampling scheme. It also has a backward-compatible trick for sending still picture
graphics with 704x576 luma resolution and 352x288 chroma resolution (which was added in
a later revision in 1993).
 The LGPL-licensed libavcodec includes a H.261 encoder and decoder. It is supported by the
free VLC media player and MPlayermultimedia players, and in ffdshow and FFmpeg decoders
projects
2. H.263:
 H.263 is a video compression standard originally designed as a low-bit rate compressed
format for videoconferencing. It was developed by the ITU-T Video Coding Experts
Group (VCEG) in a project ending in 1995/1996 as one member of the H.26x family of video
coding standards in the domain of the ITU-T.

 H.263 has since found many applications on the internet: much Flash Video content (as used
on sites such as YouTube, Google Video, MySpace, etc.) used to be encoded in Sorenson
Spark format (an incomplete implementation of H.263), though many sites now
use VP6 or H.264 encoding. The original version of the RealVideo codec was based on H.263
up until the release of RealVideo 8.
 H.263 is a required video codec in ETSI 3GPP technical specifications for IP Multimedia
Subsystem (IMS), Multimedia Messaging Service (MMS) and Transparent end-to-end Packet-
switched Streaming Service (PSS). In 3GPP specifications, H.263 video is usually used
in 3GP container format.
 The block layout of the H.263 system is shown below:
Figure 36: The block layout of a H.263 system
3. H.264:
 The H.264 and the MPEG-4 Part 10, also named Advanced Video Coding (AVC), is
jointly developed by ITU and ISO. H.264/MPEG-4 supports video compression
(coding) for video-conferencing and video-telephony applications. The H.264 video
codec has a very broad range of applications that covers all forms of digital
compressed video from, low bit-rate Internet streaming applications to HDTV
broadcast and Digital Cinema applications with nearly loss less coding.

APPLICATIONS:
This new standard is designed for technical solutions including the following applications areas:
 Broadcast over cable, satellite, Cable Modem, DSL, terrestrial, etc.
 Interactive or serial storage on optical and magnetic devices, DVD, etc.
 Conversational services over ISDN, Ethernet, LAN, DSL, wireless and mobile networks,
modems, etc. or mixtures of these.
 Video-on-demand or multimedia streaming services.
 Multimedia Messaging Services (MMS).
BENEFITS
 H.264 / MPEG-4 is designed as a simple and straightforward video coding, with enhanced
compression performance, and to provide a “network-friendly” video representation.
 H.264/MPEG-4 has achieved a significant improvement in the rate-distortion efficiency –
providing a factor of two in bit-rate savings compared with MPEG-2 Video, which is the most
common standard used for video storage and transmission. The coding gain of H.264 over
H.263 is in the range of 25% to 50%, depends on the types of applications.
Another popular protocols used for video conferencing are SIP and the H.323 protocols.
Figure37: Improved picture quality due to the use of H.264

H.323 provides a greater Bandwidth and it is used for security and encryption. It has improved
reliability, ad-hoc convenience and centralized management.
Figure 38: H.323 components required for video conferencing
SIP (Session Initiation Protocol):
The Session Initiation Protocol (SIP) is an IETF-defined signaling protocol widely used for
controlling communication sessions such as voice and video calls over Internet Protocol (IP). The
protocol can be used for creating, modifying and terminating two-party (unicast) or multiparty
(multicast) sessions. Sessions may consist of one or several media streams.
Other SIP applications include video conferencing, streaming multimedia distribution, instant
messaging, presence information, file transfer and online games.
The SIP protocol is an Application Layer protocol designed to be independent of the
underlying Transport Layer; it can run on Transmission Control Protocol (TCP), User Datagram
Protocol (UDP), or Stream Control Transmission Protocol (SCTP). It is a text-based protocol,
incorporating many elements of the Hypertext Transfer Protocol (HTTP) and the Simple Mail
Transfer Protocol (SMTP).

Figure 39: SIP layout
Table 12: Comparison between SIP and H.323

Polycom provides many types of hardware equipments and software applications for video
conferencing like Polycom PVX and Telepresence.
Polycom PVX:
This software provides features like Picture in
Picture, Desktop sharing, Speed dial and
directory.
Polycom PVX is a full-featured H.323 compliant desktop videoconferencing solution for Microsoft
Windows PCs. There is no client currently available for Mac or Solaris. The strength of this package is
its quick set-up, ease-in-use and compability with other H.323 clients.
Polycom PVX is not a free client (average cost ~$110). A free demo version of the Polycom PVX client
is available here. This will allow a user to connect to a videoconference for up to 5 minutes.
Figure 40: Polycom PVX software
Figure 41: Polycom PVX welcome screen
Figure 42: Functions of each key

Polycom Telepresence m100:
The Telepresence m100 solution is perfect for small and medium businesses that need a cost-
effective way to add video to their communication tools
The Polycom Telepresence m100 business-class video conferencing software application delivers
HD-quality audio, video, and content sharing to users of Microsoft Windows OS. Its intuitive and
simplified interface lets users search directories for colleagues or friends and click a name to call,
discuss projects, and share virtually anything from their desktop with remote participants and
teams.
Figure 43: Polycom Telepresence m100 software

Telepresence:
Telepresence refers to a set of technologies which allow a person to feel as if they were present, to
give the appearance of being present, or to have an effect, via tele-robotics, at a place other than
their true location.
Telepresence requires that the users' senses be provided with such stimuli as to give the feeling of
being in that other location. Additionally, users may be given the ability to affect the remote
location. In this case, the user's position, movements, actions, voice, etc. may be
sensed, transmitted and duplicated in the remote location to bring about this effect.
Therefore information may be travelling in both directions between the user and the remote
location.
Telepresence via video deploys greater technical sophistication and improved fidelity of both sight
and sound than in traditional videoconferencing. Technical advancements in mobile
collaboration have also extended the capabilities of videoconferencing beyond the boardroom for
use with hand-held mobile devices, enabling collaboration independent of location.
Polycom offers a complete portfolio of high definition telepresence solutions over IP networks
ranging from personal telepresence solutions to immersive telepresence solutions. It provides
mainly two services which are the:
 Polycom Real Presence Experience (RPX) Series:
Features:
i. HD quality for up to 50% less bandwidth with industry-leading H.264 High Profile support
ii. Ideal for executive meetings, board meetings, trainings, education, project management, and
organizations with dispersed workgroups
iii. Full screen, cinematic view and seating capacity for 4 to 28 participants creates an immersive
face-to-face meeting experience
iv. Transparent technology eliminates distractions and results in more productive meetings
v. True-to-life dimensions allow participants to see facial expressions, make eye contact, and
read body language
Figure 44: A telepresence process in progress

 Polycom Open Telepresence Experience (OTX) 100 and 300:
Features:
i. Experience the most stunning HD quality for up to 50% less bandwidth with industry-leading
H.264 High Profile support
ii. Transform team collaboration with a unique design and hidden technology for a variety of
room uses and "true to life" telepresence meetings
iii. Introduce your organization to real investment protection from standards-based
interoperability; connect your teams, your customers, and your partners
iv. Extend the power, performance, and simplicity of native integration with industry-leading
UC environments as part of the Polycom Open Collaboration Network strategy
Polycom RMX Platforms
The Polycom RMX 4000, The Polycom RMX 2000 and RMX 1500 are the 3 multi conferencing units
manufactured by Polycom which deliver a powerful range of collaboration tools suited to unique
individual and team requirements, with open architecture and standards-based designs that provide
long-term investment protection and a rational migration path to the future.
Polycom RMX 4000:
The Polycom RMX 4000 Conference Platform allows organizations to unite teams over distance in
any media. From users in immersive telepresence suites to remote audio callers, the RMX 4000
delivers high quality group communication for increased knowledge sharing and faster team decision
making at large organizations.
The highest capacity platform in the RMX series, the RMX 4000 natively supports multiple network
types to extend the power of unified collaboration within — and beyond — the enterprise. For
managing wide-scale conference deployments, the Polycom Distributed Media Application™ (DMA)
7000 pairs with the RMX 4000 and Polycom RMX 2000® to deliver unmatched redundancy, scale,
flexibility, and control for conferencing.
Figure 45: Polycom RMX 4000 MC unit

Polycom RMX 2000 MCU:
Delivers industry-firsts in quality, scale, and flexibility. Unsurpassed scale in a flexible, and future-
proof platform. Unrivalled multi-party video quality with support for 1080p and 720p 60fps. Best
value per call with flexible or fixed performance capacities. New ease-of-use features simplify
conference management. The Polycom RMX 2000 Real-Time Media Conferencing Platform is an
advanced IP-based platform for simplified multipoint conferencing.
Built upon the Advanced Telecommunications Computing Architecture (Advanced TCA), the
standards-based RMX 2000 conferencing platform provides ultra high-speed connectivity, extreme
low latency, and the utmost in reliability and serviceability. The RMX 2000 conferencing platform
also incorporates a modular, IP Multimedia Subsystem (IMS)-ready design to support highly scalable,
next generation deployments of conferencing applications.
Polycom RMX 1500:
A simplified, flexible, mid-range conferencing platform
The Polycom RMX 1500 conferencing platform is designed with intelligence built in—including
dynamic resource allocation, network flexibility and reliability, and cost-effective scalability, all
tightly integrated with major UC partners. Built on the award-winning Polycom RMX platform, the
RMX 1500 extends the power of video, audio, and content collaboration to the network edge.
Figure 46: Polycom RMX 2000 MC unit

Video Conferencing Management Applications
For every video conferencing terminal setup one also requires some video conferencing
management applications. These are known as Conveyed management application (CAM). Some o
the applications which are provided by Polycom are shown below.
Polycom CMA 5000/4000:
Centrally manage and deploy visual communications across your entire organization — desktop to
conference room. Centrally deploy, manage and provision personal and room-based
endpoints. Provide corporate directory services to video enabled users
Integrated presence-awareness allows users to verify contact availability with status icons
The Polycom Converged Management Application (CMA) delivers and manages real-time video
conferencing throughout the enterprise. With Polycom CMA, organizations can video-enable
individuals and groups in conference rooms, personal workspaces, desktops, and mobile devices
using a single highly scalable application. The enterprise benefits from improved communication
that speeds decision making and seamlessly extends the power of video to all parts of the
organization.
Figure 47: Polycom Conveyed management application
Comparison of CMA 4000 and CMA 5000:
CMA 4000 CMA 5000
1 CPU 2 CPUs
4GB memory 8 GB memory
Single Hard disk RAID (Multiple) Hard disks
Table 13: CMA 4000 v. CMA 5000

An overview of videoconferencing
Figure 48: MCU connections for video conferencing

References:
 Spanning tree-http://www.cisco.com/image/gif/paws/10556/spanning_tree1.swf
 www.wikipedia.com
 Polycom CMA 5000/4000 and CMA Desktop and Polycom Video Conferencing (VTC)
 www.ivci.com
 Polycom® OpenTelepresence Experience™ (OTX™) - Products - Polycom ; Polycom
Telepresence Solutions; Polycom® RealPresence® Immersive Theater Solutions - Products -
Polycom
 www.polycom.com
 www.seimens.in
 www.cisco.com
 Introduction to VC- Mr. Sagar Punyarthi
 Switching NMS-Enterasys

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