solaris some useful commands-1

    Explain the boot process?

    Boot process dived into 4 phases.

    1. POST

    2. OBPROM

    3. KERNEL INITIALIZATION

    4. INIT PHASES

    5.SVC statd

    POST: Power on self test, It will detect hardware, machine host ID,serial No, architecture type, memory and Ethernet address and it will load the primary program called bootblk.

    OBP: Open boot programmable,

                1.Diagnosing all the system hardware and memory.

                2.Initializing the boot parameter.

                3.Creating device trees and load the boot block from (0-15 sector), it is called as

                   secondary boot programmable ufsboot.

    KERNEL

    INITIALIZATION: ufsboot load the kernel (generic unix), kernel will load all the necessary

                             devices modules to mount the root partition to continue the booting process.

    Init Phase : It will started by executing of /etc/init program and start other process reading the

                       /etc/inittab files, as the directory in the /etc/inittab files.

    Svc startd : It will read the rcp data and start the services

    What is the difference between init 1 and init s ?

    If you switch from multiuser mode to init s and switch it back to multiuser mode.then remote useres automatically reconnects to the system.

    where as in the case of init 1. they have to reconnect manully means they have to relogin

    Explain about init phases

    There are 8 run level.

    Init0: Shutting down the system and bring back the system to OBP prompt (OK)

    Init1: Single user mode for administrative

    Init2: Multi user mode without resource sharing

    Init3: Multi user mode with resource sharing

    Init4: Not in use

    Init5: Shutdown and power off the system

    Init6: Reboot the system to default run level

    Inits: Single user mode but user login are disabled

    Explain rc script and run level

    Rc script : check and mount the file system, start and stop the various process.

    Run level: Base on the init phases 8 run level

    Which file will take place while booting.

    # /etc/inittab

    How many file to modify the host name to be changed without rebooting the system.

    There are 6 files.

    #vi /etc/hosts

    #vi /etc/nodename

    #vi /etc/hostname.hme

    #vi /etc/net/ticlts/hosts

    #vi /etc/net/ticosts/hosts

    #vi /etc/net/ticotsord/hosts

    Where the ip address will be stored

    # /etc/hosts

    # /etc/hosts.equi

    # /etc/hosts.hme

    How to configure the network card

    # ifconfig hme0 plumb

    # ifconfig hme0 192.9.200.10 netmask 255.255.255.0 up

    # vi /etc/hosts ( update the ip address )

    # vi /etc/hosts.hme0 ( update the ip address ) --> to bring the interface along with the ipaddress during boot time.

    How to configure the virtual ip address

    Infinity virtual ip address can be created.

    # ifconfig hme0:1 plumb

    # ifconfig hme0:1 192.9.200.10 netmask 255.255.255.0 up

    # vi /etc/hosts ( update the ip address )

    # vi /etc/hosts.hme0:1 ( update the ip address ) --> to bring the interface along with the ipaddress during boot time.

    How to find the network card speed

    # ndd –get /dev/hme link_speed          

    1 = 100mbps

    0 = 10mbps

    How to modify network card speed

    # ndd –set /dev/hme instance 0

    # ndd –get /dev/hme link_status

    # ndd –get /dev/hme link_mode

                 To modify

    # ndd –set /dev/eri instance 0

    # ndd –set /dev/eri adv_100T4_cap0

    # ndd –set /dev/eri adv_100fdx_cap1

    # ndd –set /dev/eri adv_100hdx_cap0

    # ndd –set /dev/eri adv_10fdx_cap0

    # ndd –set /dev/eri adv_10hdx_cap0

    # ndd –set /dev/eri adv_autoneg_cap0

    How to find the hardware configuration

    OK banner --> from the open boot prompt

    # prtconf

    # sysdef

    # /use/platform/sun4u/sbin/prtdiag

   How will you find the number of hard disk

    # format

    #dmesg  --> this will not give the correct answer

    #sysdef

    #iostat –En  --> it wont show the Fibre channel

    OK show-devs --> it will show the device scsi bus channel

    OK probe-scsi-all --> This will deteck all the scsi bus channel, it will show CD-ROM/DVD-ROM also

    Difference between probe-scsi-all and probe-scsi

    OK probe-scsi-all: it will show all the scsi devices connected internal and external

    OK probe-scsi: it will show only internal scsi devices connected

    How to create core dump and crash dump

    #coreadm

    Procedure for Firmware upgrade Shutdown root cron on csslu377 servers  #./etc/init.d/cron stop

    Reset the system controller from the console.# resetsc -y Upgrade the firmware on the system controller  > cd /114527-04 > lom -G ./sgrtos.flash> lom -G ./sgsc.flash Escape to lom> and reset the SC:  lom> resetsc -y Upgrade the firmware on the system boards:> lom -G ./lw8cpu.flash> lom -G ./lw8pci.flash Shutdown the Operating System. #shutdown –i0 –g0 –y

    This may take a while for the server to come up

    > poweroff> poweron

    Which file to be configuring the logs messages (like: /var/adm/message etc…)

    #/etc/syslog.conf

  Which file maintain the kernel

    # /etc/path_to_inst

  This will be quite complicative, because kernel is the core of the operating system, its an image of the OS. whereas /etc/path_to_inst are the drivers are stored for the enabled hardware.

    How will see the kernel version

    Ok banner --> This will not show the Kernel

    Ok .version  --> This will tell the open boot prompt version otherwords, FIRMWARE

    # prtconf –V

    # showrev --> will show the installed patches

    # uname –x

List LUNs attached to HBA / Disk controllers in Solaris 10

As a system administrator you may come across situations where in your SAN admin presents you some storage (LUNS) and you can’t find where the hell has it gone. The following are some of the ways to list the LUNS presented on a controller or all the controllers on the server.

1. Using fcinfo

In Solaris 10, you can use the “fcinfo” utility which is a 2 step process to identify the Luns presented to the server.

1. Find the HBA port WWN number on the server:

# fcinfo hba-port

This command will show the HBA Port WWN (world wide Node ) among other information like the Node WWN, Device name, manufacturer, firmware, driver details etc.

root@myserver:/root # fcinfo hba-port
HBA Port WWN: 21000022ff0553e9
OS Device Name: /dev/cfg/c5
Manufacturer: QLogic Corp.
Model: 371-4324-02
Firmware Version: 05.03.02
FCode/BIOS Version: BIOS: 2.02; fcode: 2.03; EFI: 2.01;
Serial Number: 0402R00-1102885753
Driver Name: qlc
Driver Version: 3.00p
Type: L-port
State: online
Supported Speeds: 2Gb 4Gb 8Gb
Current Speed: 4Gb
Node WWN: 20000022ff0553e9

Here 21000022ff0553e9 is the WWN number for the HBA port.

2. List SCSI targets for the remote port attached to the HBA port attached to the above.

# fcinfo -sl -p HBA-Port-WWN

root@myserver:/root # fcinfo remote-port -sl -p 21000022ff0553e9
Remote Port WWN: 202400a0b8744072
Active FC4 Types:
SCSI Target: yes
Node WWN: 200400a0b8744072
Link Error Statistics:
Link Failure Count: 1
Loss of Sync Count: 2
Loss of Signal Count: 72
Primitive Seq Protocol Error Count: 0
Invalid Tx Word Count: 0
Invalid CRC Count: 0
LUN: 0
Vendor: SUN
Product: LCSM100_F
OS Device Name: /dev/rdsk/c5t202400A0B8744072d0s2
LUN: 2 Vendor: SUN
Product: LCSM100_F
OS Device Name: /dev/rdsk/c5t202400A0B8744072d2s2
LUN: 31 Vendor: SUN
Product: Universal Xport
OS Device Name: /dev/rdsk/c5t202400A0B8744072d31s2

Here, LUN0 and LUN2 are the actual disks and LUN31 is the Command device for the Storage controller
2. Using cfgadm

You can also find the above information using the “cfgadm” utility. One of the following commands should reveal the LUNS attached to the controller. Although the later works only on Solaris 10.

# cfgadm -al -o show_FCP_dev c5
 
or
 
# cfgadm -al -o show_SCSI_LUNS c5

where c5 is the controller. If you do not mentioned the controller, it then displays for every single disk controller on the server.

root@myserver:/root # cfgadm -al -o show_FCP_dev c5
Ap_Id Type Receptacle Occupant Condition
c5 fc-private connected configured unknown
c5::202400a0b8744072,0 disk connected configured unknown
c5::202400a0b8744072,2 disk connected configured unknown
c5::202400a0b8744072,31 disk connected configured unknown

root@myserver:/root # cfgadm -al -o show_SCSI_LUN c5
Ap_Id Type Receptacle Occupant Condition
c5 fc-private connected configured unknown
c5::202400a0b8744072,0 disk connected configured unknown
c5::202400a0b8744072,2 disk connected configured unknown
c5::202400a0b8744072,31 disk connected configured unknown

                      thanks for Reading.. 

DISK QUOTA PERMISSIONS IN SOLARIS 10

verify before prceeding.

SUN#df -k or df -h
sun#format

follow the below screen shots.

next create a filesystem on partition.
#newfs /dev/rdsk/c0t0d0s(enter the slice no you have selected)


1.create a user account with home directory and assign password to the user.
sun#useradd -d /export/home/<home dir> -m sun<username>
sun#passwd <username>
password:
confirm password :

2.mount the partition on user home directory.
sun#mount /dev/dsk/c0t0d0s<no> /export/home/<user home dir>

quota permissions:
sun#cd /export/home
sun#touch quotas
sun#quotaon -v /export/home
sun#edquota <username>
new window will appear
fs /export/home   blocks(soft=4,hard=8)
                inodes (soft=4,hard=8)
then save the file.

To copy the quota permissions from one user to another user.
sun#edquota -p <old user> <new user>

To verify-
sun#repquota -v /export/home

To turnoff quota
sun#quotaoff -v /export/home.

                                                Thank you for Reading.

  

CISCO MDS 9509 vs Brocade DCX - Fibre Channel Showdown

In the past few years Brocade and Cisco have dominated the fibre channel director market. Both companies produce top-notch equipment; the Brocade DCX is a powerful, enterprise-class director rivaled only by the CISCO MDS 9509.
With very similar technology and offerings, which director is the best for your existing SAN switching infrastructure?
Here are 5 things to consider when deciding which director, the Brocade DCX or the Cisco MDS 9509, is a better fit for your enterprise needs.
Brocade DCX vs Cisco MDS 9509

1. Reliability: Both Brocade and Cisco MDS produce high-quality, reliable switching infrastructure. As the directors have no single point of failure, the Brocade DCX and Cisco MDS 9509 are both dependable SAN directors that prevent downtime.
Brocade and Cisco MDS directors are built to support mission-critical networks and prevent downtime. Since SAN directors contain individual blades, failed blades can be replaced without causing inconvenient downtime for the director. Since any difference in reliability would be slight, the Brocade DCX and Cisco MDS 9509 seem to be tied in this category.

2. Scalability: The Brocade DCX backbone and Cisco 9509 provide the scalability to conquer even the fastest growing SAN networks. The Brocade DCX scales up to 384 ports and is well-suited for large enterprises. The Brocade DCX will hold up to eight blades and supports Fibre Channel technology as well as Fibre Channel over IP.
The Cisco MDS 9509 provides nine blade slots and scales up to 336 Fibre Channel ports. This large, powerful director is equipped to support demanding growth. With similar growth options and scalable models to accommodate future needs, the Brocade DCX and Cisco MDS 9509 appear to be even in terms of scalability.

3. Latency: In an effort to reduce latency, the Brocade DCX Backbone offers a local switching option that the Cisco MDS 9509 does not possess. Local switching reduces latency for devices that are connected to the same blade and lowers the total amount of traffic that travels through the core switching blades.
Although Cisco says that local switching does not actually result in a reduction in latency, a lack of local switching is a weak point of the Cisco MDS 9509. In terms of latency, the Brocade DCX director has the advantage.*

4. Raw Throughput and Performance: Both the Brocade DCX and Cisco MDS directors provide powerful switching infrastructure built to handle demanding storage environments.
Offering 256 Gbps raw throughput per port, the Brocade DCX backbone provides one of the fastest Fibre Channel switching infrastructures on the market. When comparing the two directors, the Cisco MDS director appears to be slightly slower as it provides only 96 Gbps raw throughput per port.

5. Strategy: In the long run, one other important consideration when choosing a director is how that director will fit with the rest of your switching infrastructure and your future switching strategy. What brand of switches do you currently have implemented in your SAN environment? Does the enterprise plan to stay with fibre channel technology and invest in Brocade’s highly developed 16 Gbps fibre channel product line, or is the enterprise interested in changing protocols?
Noting strategy differences and matching current products with your future plan should help you choose whether a Cisco MDS 9509, a Brocade DCX backbone, or another SAN director is the right fit for your enterprise environment.

Disable Ping on Linux Server

How do you disable ping to Linux server? Here is the quick steps:

 To disable ping:

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all

To enable ping:

echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

That's all..!

brocade zoning

hi ,

 Now i am going to  show you zoning in brocade fabric switches.

Access logix 

          access logix provides LUN masking that allows sharing of storage system.
any host that connects to the storage system will then have access to all of the
 LUNs on that storage system.in environment when multiple hosts are connected
 will cause problems.any one can access any Lun so the access logix solves the
 problems by LUN masking  - it masks certain LUNS from hosts that are not 
authorized to see them.

sample brocade zoning

 

Step by Step Procedure of Zoning via Cli.

1.Create a Zone Alias using "AliCreate"

SW0:admin> alicreate "SUNX4_HBA0"
2.Add member to Alias using "Aliadd"

SW0:admin> aliadd "SUNX4_HBA0","21:00:00:1b:32:13:a8:9f"

3.Create a Zone using "ZoneCreate"

SW0:admin> zonecreate "CX_4_SPB4_SUNX4_HBA0"
4. Add membet to Zone using "ZoneAdd"

SW0:admin> zoneadd "CX_4_SPB4_SUNX4_HBA0","CX_4_SPB4"

5.Add a Zone to Zone configuration "CfgAdd".

SW0:admin> cfgadd "SAN_U2_SW0_Config","CX_4_SPB4_SUNX4_HBA0"

6.Save the Configuration using "CfgSave".

SW0:admin> cfgsave

7.Enable the Configuration using "CfgEnable".

SW0:admin> cfgenable "SAN_U2_SW0_Config"

Note : Always use single initiator Zone which typically include one storage
 and one host wwpn.

implementing zoning  via scripting

!!NOTE: This is fabric A
!! Make all the aliases for systems
alicreate "Storage_HBA1_A", "50:01:43:81:02:45:DE:45"
alicreate "Storgae_HBA2_A", "50:01:43:81:02:45:DE:47"
alicreate "Server_HBA1_A", "50:01:23:45:FE:34:52:12"
alicreate "Server2_HBA1_A", "50:01:23:45:FE:35:52:15"
alicreate "Server2_HBA1_A", "50:01:23:45:FE:35:52:17"

!! Make the zones

zonecreate "Z_server_to_Storage_HBA1_A", "Server_HBA1_A;

 Storage_HBA1_A"

zonecreate "Z_server_to_Storage_HBA2_A", "Server_HBA1_A;

 Storage_HBA2_A"

zonecreate "Z_server2_to_Storage_HBA1_A", "Server2_HBA1_A;

 Storage_HBA1_A"

zonecreate "Z_server2_to_Storage_HBA2_A", "Server2_HBA1_A;

 Storage_HBA2_A"

!!NOTE: effective config and zone members on SWITCHA_config Fabric
cfgcreate "SWITCHA_config", "Z_server_to_Storage_HBA1_A;

 Z_server_to_Storage_HBA2_A;

 Z_server2_to_Storage_HBA1_A; Z_server2_to_Storage_HBA2_A"

cfgsave
cfgenable "SWIT

NOTE:

 All Brocade switches have a telnet and ssh access.These commands

can just be cut and pasted into the session to execute them. 

unbreakable quantum encryption

Perfect secrecy has come a step closer with the launch of the world’s first computer network protected by unbreakable quantum encryption at a scientific conference in Vienna.

The network connects six locations across Vienna and in the nearby town of St Poelten, using 200 km of standard commercial fibre optic cables.

Quantum Cryptography is inherently unbreakable !

Quantum cryptography is completely different from the kinds of security schemes used on computer networks today.

These are typically based on complex mathematical procedures which are extremely hard for outsiders to crack but not impossible given sufficient computing resources or time.

But quantum systems use the laws of quantum theory, which have been shown to be inherently unbreakable.

“All quantum security schemes are based on the Heisenberg Uncertainty Principle, on the fact that you cannot measure quantum information without disturbing it,” he explained.

Real breakthroughs are not found because you want to develop some new technology, but because you are curious and want to find out how the world is

- Anton Zeilinger, Vienna University

“Because of that, one can have a communications channel between two users on which it’s impossible to eavesdrop without creating a disturbance. An eavesdropper would create a mark on it. That was the key idea.”

In practice this means using the ultimate quantum objects: photons, the “atoms of light”. Incredibly faint beams of light equating to single photons fired a million times a second raced between the nodes in the Vienna network.

Each node, housed in a different Siemens office (Siemens has provided the fibre links), contains a small rack of electronics – boxes about the size of a PC – and a handful of sensitive light detectors.

Numerical key

From the detected photons, a totally secret numerical key can be distilled, which encodes the users’ data much like the keys used in normal computer networks do.

The advantage is that no-one else can know the key without revealing themselves.

As we saw in the demonstration, when an intruder did try to listen in on the quantum exchange, photons became scrambled, and a rise in the error rate at the node detectors signalled the attack. The system automatically shut down without being compromised.

More importantly, the demonstration also showed that the network is robust.

If one quantum link breaks down, the connections can be re-routed via other nodes, much as phone calls get re-routed automatically through a telecoms network, so that any two users on the network can remain in continuous secure contact.

Dr Hannes Huebel of Vienna University, operating one of the nodes, explained how robustness was now as important as security in the development of quantum encryption systems.

“We are constantly in touch with insurance companies and banks, and they say it’s nearly better that they lose 10m euros than if the system is down for two hours, because that might be more damaging for the bank,” said Dr Huebel.

“So that’s what we have to prove, that we have a reliable system that delivers quantum keys for several weeks without interruption, and then they might be more interested.”

Polarised light

The final element of the EU-sponsored project (called SECO-QC) was the interconnection of different realisations of quantum cryptography.

There are many ways photons of light can encode a numerical key: through the direction they’re polarised (like Polaroid glasses) for example, or the precise timing of their arrival.

Different schemes have different strengths and weaknesses, and a viable network would have to handle whatever individual users choose to use, explained the project’s director, Christian Monyk – just as a mobile phone network has to handle handsets from many manufacturers.

Quantum cryptography is a surprising outgrowth of recondite arguments that bounced around for decades about the meaning of quantum mechanics.

Albert Einstein, who discovered the quantum properties of photons of light – indeed, discovered the very concept of the photon – always resisted quantum theory’s spooky behaviour, “God does not play dice”, being among his oft-quoted objections.

But experiments eventually proved that he apparently does, and also laid the technical foundations for today’s quantum information revolution – cryptography, teleportation, and computation.

One of the grandees of quantum science, Vienna University’s Anton Zeilinger, used the occasion to argue for continued funding of fundamental science in these increasingly application-focused days.

“Real breakthroughs are not found because you want to develop some new technology, but because you are curious and want to find out how the world is,” Dr Zeilinger said.

“It may not have surprised the founding fathers of quantum science that technology has advanced so that you can play with individual quantum systems, in great detail.

“Maybe this would not surprise, but what could surprise them is that people are thinking and doing practical applications.”

source : google.

how to hide hard disk partition in windows

Hi,

Want to hide your hard disk partition fully in windows operating system ? There is a command available to do this task. It is “diskpart” command which needs to be used in command prompt to get the job done. This technique works only in windows operating systems.

Using this command you can hide the hard disk volumes such as C:\ ,D:\, E:\. Here is the step by step method to carry over it.

1.Type “diskpart” in run command box without quotes. (A command window will get opened)

2.Then type “list volume“. (Your hard disk partitioned volumes will be listed)

3.Now type “select volume <volume number>” – (Volume number is the numeric variable which is shown in the volume listing)

4.Type “remove letter <volume letter> – (Volume letter is the alphabetic character of the drive such as C,D,E,F…)

Thus your hard disk partition is hidden. If you need to resume it then follow the first three steps as usual and

in the fourth step replace “remove” with “assign“. I hope this technique helps.

FBI’s Action on March 8 May Block Millions off the Internet

According to 'RT,' innumerable people globally may get impacted starting March 8, 2012, incase the U.S. FBI proceeds to execute its plans towards taking PC-servers offline which were deployed for countering malware. Deccan Chronicle published this on February 15, 2012. It's asserted that the FBI substituted PC-servers, which had been infected with DNSChanger a malicious Trojan virus, with fresh ones of its own, as also is presently considering taking those substituted servers, offline.
Last year (2011), officials in Estonia feared that 6 men understandably created one malevolent PC-script known as the DNSChanger. After allowed to permeate the Web, the Trojan infected PCs in over 100 countries, with a total of 500,000 computers in USA alone. The FBI after sometime entered the scene as it substituted the corrupted PCs with its own computer-servers while attempting at rectifying the destruction; however, it was only briefly that the solution lasted. Now FBI may terminate its substitute servers in early March 2012 when Internet for innumerable users might actually snap.
Reportedly, the DNSChanger struck PCs, diverting end-users from some specific websites onto certain malevolent ones. If contaminated with the Trojan, websites visited inside online browsers were compromised and linked up with malevolent servers that then diverted the Web-surfers onto a different, fake site.
Moreover 'RT' further asserts that FBI took 6 persons in custody over their alleged making of the Trojan. Quoting Internet Identity (IID), a security firm, RT stated that the tentative closure, when substitute servers would get ushered in, was well prepared towards impacting 50% of the entire Fortune 500 enterprises along with over 24 prominent government organizations within USA.
At this pace, according to President and CTO (chief technology officer) Rod Rasmussen at IID, many people, on 8th March 2012, will witness their Internet crash indefinitely. RT reported this on February 15, 2012.
Rasmussen continues that he can imagine far many people at that juncture becoming careful. As contaminated end-users are being alerted towards rectifying the problem right away, uncountable people globally are actually infected. Rasmussen adds that it surely will work as one intriguing social experiment incase the said servers simply got disconnected.

source » SPAMfighter News

User Creation and Remove commands in solaris 10

Hi,

Creating User Accounts

To create a user account:
# useradd -u 100 -g other -d /export/home/newuser1 -m -s /bin/ksh -c
"Regular User Account" newuser1

# passwd newuser1

# /usr/sadm/bin/smuser add -- -n newuser2 -u 500 -g other -d
/export/home/newuser2 -c "Regular User Account 2" -s /bin/ksh -x
autohome=N

# passwd newuser2

Modifying User Accounts

To change the login name and home directory for newuser1 to usera.

# usermod -m -d /export/home/usera -l usera newuser1

To change the login name and home directory for newuser2 to userb.

# /usr/sadm/bin/smuser modify -- -n newuser2 -N userb -d /export/home/userb

Deleting User Accounts
# userdel usera        ==> to remove the user account

# userdel -r usera    ==> to remove both the users account & home directory


# /usr/sadm/bin/smuser delete -- -n userb    ==> the users home directory                             should be deleted manually

Creating a Group Entry
# groupadd -g 301 class1

# /usr/sadm/bin/smgroup add -- -n workgroup -g 123 -m usera


Modifying a Group Entry
# groupmod -g 400 class1    ==> to change group ID

To change group name
# /usr/sadm/bin/smgroup modify -- -n workgroup -N schoolgroup


Deleting a Group Entry
# groupdel class1

# /usr/sadm/bin/smgroup delete -- -n schoolgroup


# vi /etc/default/passwd    ==> to control the properties for all users’
                    passwords on the system:


# ls -l /usr/sadm/defadduser    ==> to display default values for useradd
                    command

# useradd -D

# cat /usr/sadm/defadduser 

                                        Thanks for Reading. 

CABLEING

Hi ,
 first we are going to know basics of networking concepts .

what is network ?
a network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks.
The most common topology or general configurations of networks include the bus, star, token ring, and mesh topologies. Networks can also be characterized in terms of spatial distance as local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs).

topologies : 

mesh 

token ring

bus

star

what is networking ?

 communication between the devices or nodes using protocols is called as networking simply by using protocols send/receive data from one node to another node is calles as networking.

Networks may be classified according to a wide variety of characteristics such as the medium used to transport the data, communications protocol used, scale, topology, and organizational scope.
Communications protocols define the rules and data formats for exchanging information in a computer network, and provide the basis for network programming. Well-known communications protocols are Ethernet, a hardware and Link Layer standard that is ubiquitous in local area networks, and the Internet Protocol Suite, which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, as well as host-to-host data transfer, and application-specific data transmission formats.

present we are using 2 types of cables as a media
1.twisted pair cables.
2.unshieled twisted pair.UTP

cross over cable:
for similar devices we are using cross over cable.for example pc-pc,switch-switch etc.

A cross-over cable is a segment of cable that crosses over pins 1&2 and 3&6. This cable is normally used to connect two PCs without the use of a hub, or can be used to cascade two hubs without using an uplink port. Some DSL modems require a crossover calbe to the PC or hub they are connected to. 

 straight through cable :

 For dissimilar  devices straight over cable are using . pc-switch etc

The above tool is called as crimping tool.

UTP :

Cat 5: Out of the three types of cable we’ll be discussing, Category 5 is the most basic. Cat 5 cable is available in two varieties: Unshielded Twisted Pair (UTP), the type widely used in the United States, and Screened Twisted Pair (SCTP), which has shielding to provide a measure of extra protection against interference, but is rarely used outside of Europe. Cables belonging to Category 5 are either solid or stranded: Solid Cat 5 is more rigid, and the better choice if data needs to be transmitted over a long distance, while Stranded Cat 5 is very flexible and most likely to be used as patch cable. Cat 5 cable can support 10, 100, or 1000 Mbit/s Ethernet. The 1000BASE-T standard for Gigabit Ethernet over UTP was designed to work over up to 100 meters of plain old Cat 5.
Cat 5e: Cat 5e (which stands for Category 5, enhanced) cable goes along the same lines as basic Cat 5, except that it fulfills higher standards of data transmission. While Cat 5 is common in existing cabling systems, Category 5e has almost entirely replaced it in new installations. Just like Cat 5, Cat 5e can handle data transfer at 1000 Mbit/s, and is suitable for Gigabit Ethernet. Cat 5e experiences much lower levels of near-end crosstalk (NEXT) than Cat 5.
Cat 6: Of the three cable categories we’re discussing, Category 6 is the most advanced and provides the best performance. Just like Cat 5 and Cat 5e, Category 6 cable is typically made up of four twisted pairs of copper wire, but its capabilities far exceed those of other cable types because of one particular structural difference: a longitudinal separator. This separator isolates each of the four pairs of twisted wire from the others, which reduces crosstalk, allows for faster data transfer, and gives Category 6 cable twice the bandwidth of Cat 5! Cat 6 cable is ideal for supporting 10 Gigabit Ethernet. Since technology and standards are constantly evolving, Cat 6 is the wisest choice of cable when taking any possible future updates to your network into consideration. Not only is Category 6 cable future-safe, it is also backward-compatible with any previously-existing Cat 5 and Cat 5e cabling found in older installations.

What are the maximum lengths for cables?

For Solid UTP:
Fast Ethernet 100baseT 100 Meters (328 feet)
Twisted Pair Ethernet 10baseT 100 Meters (328 feet)

Recommended maximum lengths for Patch Cables made from stranded cable:
Fast Ethernet 100baseT 10 Meters (33 feet)
Twisted Pair Ethernet 10baseT 10 Meters (33 feet)

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