google ad

Wednesday, April 30, 2008

IP Subnet Table

Class A

Number of bits borrowed

Number of usable subnets

Number of usable IPs

Subnet Mask

2

4

4mt

255.192.0.0

3

8

2mt

255.224.0.0

4

16

1mt

255.240.0.0

5

32

524t

255.248.0.0

6

64

262t

255.252.0.0

7

128

131t

255.254.0.0

8

256

65,536

255.255.0.0



Class B


Number of bits borrowed

Number of usable subnets

Number of usable IPs

Subnet Mask

2

4

16,380

255.255.192.0

3

8

8,190

255.255.224.0

4

16

4,094

255.255.240.0

5

32

2,046

255.255.248.0

6

64

1,022

255.255.252.0

7

128

510

255.255.254.0

8

256

254

255.255.255.0



Class C


Number of bits borrowed

Number of usable subnets

Number of usable IPs

Subnet Mask

2

4

60

255.255.255.192

3

8

30

255.255.255.224

4

16

14

255.255.255.240

5

32

6

255.255.255.248

6

64

2

255.255.255.252





Friday, April 25, 2008

TCP/IP Subnet Table

PrefixSubnet MaskNumber of HostsNetworks (Class B) * Networks (Class C) * Inverse Mask +Notes
/16255.255.0.0655341
0.0.255.255Class B
/17255.255.128.0327660+1
0.0.127.255In Class A networks, CIDR, or subnet-zero enabled networks only
/18255.255.192.0163822+1
0.0.63.255
/19255.255.224.081906+1
0.0.31.255
/20255.255.240.0409014+1
0.0.15.255
/21255.255.248.0204630+1
0.0.7.255
/22255.255.252.0102262+1
0.0.3.255
/23255.255.254.0510126+1
0.0.1.255
/24255.255.255.0254254+110.0.0.255Class C
/25255.255.255.128126510+10+10.0.0.127in class B or larger networks, CIDR, or subnet-zero enabled networks only
/26255.255.255.192621022+12+10.0.0.63
/27255.255.255.224302046+16+10.0.0.31
/28255.255.255.240144090+114+10.0.0.15
/29255.255.255.24868190+130+10.0.0.7
/30255.255.255.252216382+162+10.0.0.3
/31255.255.255.2540


Invalid mask since it leaves no host bits
/32255.255.255.2551

0.0.0.0Special single host mask
www.mindflip.com

OSI Diagram


OSI Network Architecture

Open Systems Interconnection (OSI) model is a reference model developed by ISO (International Organization for Standardization) in 1984, as a conceptual framework of standards for communication in the network across different equipment and applications by different vendors. It is now considered the primary architectural model for inter-computing and inter-networking communications. Most of the network communication protocols used today have a structure based on the OSI model. The OSI model defines the communications process into 7 layers, dividing the tasks involved with moving information between networked computers into seven smaller, more manageable task groups. A task or group of tasks is then assigned to each of the seven OSI layers. Each layer is reasonably self-contained, so that the tasks assigned to each layer can be implemented independently. This enables the solutions offered by one layer to be updated without adversely affecting the other layers.




















The specific description for each layer is as follows:

Layer 7: Application Layer

  • Defines interface-to-user processes for communication and data transfer in network
  • Provides standardized services such as virtual terminal, file and job transfer and operations

Layer 6: Presentation Layer

  • Masks the differences of data formats between dissimilar systems
  • Specifies architecture-independent data transfer format
  • Encodes and decodes data; encrypts and decrypts data; compresses and decompresses data

Layer 5: Session Layer

  • Manages user sessions and dialogues
  • Controls establishment and termination of logic links between users
  • Reports upper layer errors

Layer 4: Transport Layer

  • Manages end-to-end message delivery in network
  • Provides reliable and sequential packet delivery through error recovery and flow control mechanisms
  • Provides connectionless oriented packet delivery
  • Device used - PC

Layer 3: Network Layer

  • Determines how data are transferred between network devices
  • Routes packets according to unique network device addresses
  • Provides flow and congestion control to prevent network resource depletion
  • Device used - Router

Layer 2: Data Link Layer

  • Defines procedures for operating the communication links
  • Frames packets
  • Detects and corrects packets transmit errors
  • Device used - Bridge/Switch

Layer 1: Physical Layer

  • Defines physical means of sending data over network devices
  • Interfaces between network medium and devices
  • Defines optical, electrical and mechanical characteristics
  • Device used - Repeater/NIC, Hub/Tranceiver
www.networkdictionary.com

Rollover Cable

Rollover cable (also known as Cisco console cable) is a type of null-modem cable that is most commonly used to connect a computer terminal to a router's console port. This cable is typically flat (and has a light blue color) to help distinguish it from other types of network cabling. It gets the name rollover because the pinouts on one end are literally rolled over when RJ45 plugs are used at both ends.
www.wikipedia.org


Devices can be connected by Roll-over:

Console port to Switch

Console port to Router

Wednesday, April 23, 2008

Cross Over Cable

The image “http://discountcablesusa.com/568A-568B.gif” cannot be displayed, because it contains errors.

Crossover Cable

The image “http://discountcablesusa.com/568A-568B.gif” cannot be displayed, because it contains errors.


Crossover cable that maps all output signals on one electrical connector to the input signals on the other connector, allowing two electronic devices to perform full-duplex communication. Most commonly, the term refers to the Ethernet crossover cable, but other cables follow the same principle. It also allows devices to communicate without a switch, hub, or router. Cross-Over cables are used to connect two computers directly through NICs without the use of a Hub or Switch or to uplink two or more hubs, switches or routers. The Pins of the RJ-45 Connectors at both ends of a cross-over cable are connected as follows:

Pin 1 ----------- Pin 3
Pin 2 ----------- Pin 6

www.wikipedia.org



Crossover used to connect same devices.


Devices can be connected by Crossover:

PC to PC

Router to Router

Switch to Switch

Hub to Hub

PC to Router




Straight-throught Cable- RJ-45 Plug

The image “http://www.patraswireless.net/tutorial/basic%20tutorial/tut-equipemt/cable_utp_clip_image001.gif” cannot be displayed, because it contains errors.

Straight-throught Cable

The image “http://lusitani.com/IMAGES/ROLL/568a.jpg” cannot be displayed, because it contains errors.s

Straight-through Cable

The image “http://lusitani.com/IMAGES/ROLL/568a.jpg” cannot be displayed, because it contains errors.



Straight-through cable is a type of twisted pair copper wire cable for local area network (LAN) use for which the RJ-45 connectors at each end have the same pinout (i.e., arrangement of conductors).

It is identical to crossover cable, except that in the latter the wires on the cable are crossed over so that the receive signal pins on the connector on one end are connected to the transmit signal pins on the connector on the other end.

Straight-through cable is also commonly referred to as patch cable. However, this might be confusing in some situations because patch cable also has a broader definition that emphasizes the fact that there is a connector on each end rather than the equality (or lack thereof) of the pinouts.

Straight-through cable is used to connect computers and other end-user devices (e.g., printers) to networking devices such as hubs and switches. It can also be used to directly connect like devices (e.g., two hubs or two switches) if the cable is plugged into an uplink port on one (but not both) of the devices. Crossover cable is used to connect two like devices without the use of an uplink port.


www.linfo.org


The image “http://www.patraswireless.net/tutorial/basic%20tutorial/tut-equipemt/cable_utp_clip_image001.gif” cannot be displayed, because it contains errors.



Straight-through used to connect different devices.


Devices can be connected by Straight-through:

PC to Switch

PC to Hub

Switch to Router

Hub to Router

Friday, April 18, 2008

Transmission Control Protocol (TCP)

The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. TCP provides reliable, in-order delivery of a stream of bytes, making it suitable for applications like file transfer and e-mail. It is so important in the Internet protocol suite that sometimes the entire suite is referred to as "the TCP/IP protocol suite." TCP is the transport protocol that manages the individual conversations between web servers and web clients. TCP divides the HTTP messages into smaller pieces, called segments, to be sent to the destination client. It is also responsible for controlling the size and rate at which messages are exchanged between the server and the client.



www.wikipedia.org

Monday, April 14, 2008

Cisco Router Configuration Commands

Requirement Cisco Command
Set a console password to cisco Router(config)#line con 0
Router(config-line)#login
Router(config-line)#password cisco
Set a telnet password Router(config)#line vty 0 4
Router(config-line)#login
Router(config-line)#password cisco
Stop console timing out Router(config)#line con 0
Router(config-line)#exec-timeout 0 0
Set the enable password to cisco Router(config)#enable password cisco
Set the enable secret password to peter.

This password overrides the enable password and is encypted within the config file

Router(config)#enable secret peter
Enable an interface Router(config-if)#no shutdown
To disable an interface Router(config-if)#shutdown
Set the clock rate for a router with a DCE cable to 64K Router(config-if)clock rate 64000
Set a logical bandwidth assignment of 64K to the serial interface Router(config-if)bandwidth 64
Note that the zeroes are not missing
To add an IP address to a interface Router(config-if)#ip addr
10.1.1.1 255.255.255.0
To enable RIP on all 172.16.x.y interfaces Router(config)#router rip
Router(config-router)#network 172.16.0.0
Disable RIP Router(config)#no router rip
To enable IRGP with a AS of 200, to all interfaces Router(config)#router igrp 200
Router(config-router)#network 172.16.0.0
Disable IGRP Router(config)#no router igrp 200
Static route the remote network is 172.16.1.0, with a mask of 255.255.255.0, the next hop is 172.16.2.1, at a cost of 5 hops Router(config)#ip route
172.16.1.0 255.255.255.0 172.16.2.1 5
Disable CDP for the whole router Router(config)#no cdp run
Enable CDP for he whole router Router(config)#cdp run
Disable CDP on an interface Router(config-if)#no cdp enable


Cisco Router Show Commands

Requirement Cisco Command
View version information show version
View current configuration (DRAM) show running-config
View startup configuration (NVRAM) show startup-config
Show IOS file and flash space show flash
Shows all logs that the router has in its memory show log
View the interface status of interface e0 show interface e0
Overview all interfaces on the router show ip interfaces brief
View type of serial cable on s0 show controllers 0
(note the space between the 's' and the '0')
Display a summary of connected cdp devices show cdp neighbor
Display detailed information on all devices show cdp entry *
Display current routing protocols show ip protocols
Display IP routing table show ip route
Display access lists, this includes the number of displayed matches show access-lists
Check the router can see the ISDN switch show isdn status
Check a Frame Relay PVC connections show frame-relay pvc
show lmi traffic stats show frame-relay lmi
Display the frame inverse ARP table show frame-relay map


Cisco Router Basic Operations

Requirement Cisco Command
Enable Enter privileged mode
Return to user mode from privileged disable
Exit Router Logout or exit or quit
Recall last command up arrow or
Recall next command down arrow or
Suspend or abort and and 6 then x
Refresh screen output
Compleat Command TAB


Cisco Router Copy Commands

Requirement Cisco Command
Save the current configuration from DRAM to NVRAM copy running-config startup-config
Merge NVRAM configuration to DRAM copy startup-config running-config
Copy DRAM configuration to a TFTP server copy runing-config tftp
Merge TFTP configuration with current router configuration held in DRAM copy tftp runing-config
Backup the IOS onto a TFTP server copy flash tftp
Upgrade the router IOS from a TFTP server copy tftp flash


Cisco Router Debug Commands

Requirement Cisco Command
Enable debug for RIP debug ip rip
Enable summary IGRP debug information debug ip igrp events
Enable detailed IGRP debug information debug ip igrp transactions
Debug IPX RIP debug ipx routing activity
Debug IPX SAP debug IPX SAP
Enable debug for CHAP or PAP debug ppp authentication
Switch all debugging off no debug all
undebug all





Packet

A packet is piece of a message transmitted over a packet-switching network. See under packet switching. One of the key features of a packet is that it contains the destination address in addition to the data. In IP networks, packets are often called datagrams.

A unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network. When any file (e-mail message, HTML file, GIF file Uniform Resource Locator request, and so forth) is sent from one place to another on the Internet, the Transmission Control Protocol (TCP) layer of TCP/IP divides the file into "chunks" of an efficient size for routing. Each of these packets is separately numbered and includes the Internet address of the destination. The individual packets for a given file may travel different routes through the Internet. When they have all arrived, they are reassembled into the original file (by the TCP layer at the receiving end).

IP Address

Internet protocol (IP) is the set of techniques used by many hosts for transmitting data over the Internet. The current version of the Internet protocol is IPv4, which provides a 32-bit address system.

Internet protocol is a "best effort" system, meaning that no packet of information sent over it is assured to reach its destination in the same condition it was sent. Often other protocols are used in tandem with the Internet protocol for data that for one reason or another must have extremely high fidelity.

Every device connected to a network, be it a local area network (LAN) or the Internet, is given an Internet protocol number. This address is used to identify the device uniquely among all other devices connected to the extended network.

The current version of the Internet protocol (IPv4) allows for in excess of four billion unique addresses. This number is reduced drastically, however, by the practice of webmasters taking addresses in large blocks, the bulk of which remain unused. There is a rather substantial movement to adopt a new version of the Internet protocol (IPv6), which would have two to the one-hundred twenty-eighth power of unique addresses. This number can be represented roughly by a three with thirty-nine zeroes after it.

Subneting

Subnetting is the process of breaking down an IP network into smaller sub-networks called "subnets." Each subnet is a non-physical description (or ID) for a physical sub-network (usually a switched network of host containing a single router in a multi-router network).

Cisco CCNA subnetting tutorial


Download links:

link 1
semsim.com
link 2