~~~~~ 2nd Lecture - Networking ~~~~

[k2s]

[quote author=ROBO link=topic=232200.msg2880336#msg2880336 date=1314832753]
packet header holds the info about each packet
[/quote]header lo ne ee port info kuda oka part

[k2s]

Ok next we'll learn about the purpose, features, and functions of the following network components:

Hubs

Switches

Bridges

Routers

Gateways

CSU/DSU

Network interface cards (NICs), ISDN adapters, and system area network cards

Wireless access points (WAPs)

Modems

[robo]

[quote author=k2s link=topic=232200.msg2880343#msg2880343 date=1314832806]
header lo ne ee port info kuda oka part
[/quote]ok is there any chance by which we can modify default ports for an application
like ftp with port 2563

[robo]

[quote author=k2s link=topic=232200.msg2880344#msg2880344 date=1314832837]
Ok next we'll learn about the purpose, features, and functions of the following network components:

Hubs

Switches

Bridges

Routers

Gateways

CSU/DSU

Network interface cards (NICs), ISDN adapters, and system area network cards

Wireless access points (WAPs)

Modems
[/quote] yeah

[ToughGuy]

sHa_clap4 sHa_clap4 sHa_clap4 sHa_clap4 sHa_clap4  you rock you rock

[k2s]

[quote author=ROBO link=topic=232200.msg2880356#msg2880356 date=1314832931]
ok is there any chance by which we can modify default ports for an application
like ftp with port 2563
[/quote]

source port can be any for application........but destination port is specific for some applications.......
there are some applications (peer-to-peer) which changes their port #s frequently.

[robo]

[quote author=k2s link=topic=232200.msg2880371#msg2880371 date=1314833042]
source port can be any for application........but destination port is specific for some applications.......
there are some applications (peer-to-peer) which changes their port #s frequently.
[/quote]yeah this is much clear now  you rock you rock you rock you rock

[k2s]

A typical HUB : [img]http://ptgmedia.pearsoncmg.com/images/chap3_0789728303/elementLinks/03fig02.jpg[/img]

Hubs are Layer 1 devices. Most hubs are referred to as active because they regenerate a signal before forwarding it to all the ports on the device. Regeneration of the signal aside, the basic function of a hub is to take data from one of the connected devices and forward it to all the other ports on the hub.

[img width=500 height=247]http://ptgmedia.pearsoncmg.com/images/chap3_0789728303/elementLinks/03fig03.jpg[/img]

[robo]

[quote author=ChittiNaidu link=topic=232200.msg2880394#msg2880394 date=1314833232]
sCo_^Y sCo_^Y  we can force some applications on server side to use different ports..... application default use cheste em cehyalemu kaani...as a server admin we can open such ports kada....
[/quote]source port can be tuned but not destination  sCo_^Y

is it possible to access FTP form different defined port by a server  sCo_^Y sCo_^Y

[k2s]

Switches:

Switches basically  work on Layer2.  on a hub, data is forwarded to all ports, regardless of whether the data is intended for the system connected to the port. This arrangement is very inefficient; however, it requires very little intelligence on the part of the hub, which is why hubs are inexpensive.

Rather than forwarding data to all the connected ports, a switch forwards data only to the port on which the destination system is connected. It looks at the Media Access Control (MAC) addresses of the devices connected to it to determine the correct port. A MAC address is a unique number that is programmed into every NIC. By forwarding data only to the system to which the data is addressed, the switch decreases the amount of traffic on each network link dramatically. In effect, the switch literally channels (or switches, if you prefer) data between the ports.

[img]http://ptgmedia.pearsoncmg.com/images/chap3_0789728303/elementLinks/03fig05.jpg[/img]

[k2s]

[quote author=ChittiNaidu link=topic=232200.msg2880394#msg2880394 date=1314833232]
sCo_^Y sCo_^Y  we can force some applications on server side to use different ports..... application default use cheste em cehyalemu kaani...as a server admin we can open such ports kada....
[/quote]
those are advanced techniques... basics avi cheppi confuse enduku cheyyatam

[robo]

[quote author=ChittiNaidu link=topic=232200.msg2880425#msg2880425 date=1314833533]
yup....  u can force it.... from the applicaiton side....
[/quote] s%H# s%H# yes i am doing it  @3$% @3$%

[k2s]

Bridges :

Bridges also are Layer 2 devices. Bridges are networking devices that divide up networks. A bridge functions by blocking or forwarding data, based on the destination MAC address written into each frame of data. If the bridge believes the destination address is on a network other than that from which the data was received, it can forward the data to the other networks to which it is connected. If the address is not on the other side of the bridge, the data is blocked from passing. Bridges "learn" the MAC addresses of devices on connected networks by "listening" to network traffic and recording the network from which the traffic originates.

[img]http://i51.tinypic.com/2n8wuuw.jpg[/img]

The advantages of bridges are simple and significant. By preventing unnecessary traffic from crossing onto other network segments, a bridge can dramatically reduce the amount of network traffic on a segment. Bridges also make it possible to isolate a busy network from a not-so-busy one, thereby preventing pollution from busy nodes.

[k2s]

A bridge reads the outermost section of data on the data packet, to tell where the message is going. It reduces the traffic on other network segments, since it does not send all packets. Bridges can be programmed to reject packets from particular networks. Bridging occurs at the data link layer of the OSI model, which means the bridge cannot read IP addresses, but only the outermost hardware address of the packet. In our case the bridge can read the ethernet data which gives the hardware address of the destination address, not the IP address. Bridges forward all broadcast messages. Only a special bridge called a translation bridge will allow two networks of different architectures to be connected. Bridges do not normally allow connection of networks with different architectures. The hardware address is also called the MAC (media access control) address. To determine the network segment a MAC address belongs to, bridges use one of:

Transparent Bridging - They build a table of addresses (bridging table) as they receive packets. If the address is not in the bridging table, the packet is forwarded to all segments other than the one it came from. This type of bridge is used on ethernet networks.
Source route bridging - The source computer provides path information inside the packet. This is used on Token Ring networks.

[manjunath455]

k2s  CITI_$D# CITI_$D# CITI_$D# .  naku doubtlu vunte pm seyyocha  sCo_^Y sCo_^Y sCo_^Y