Learning CCNA

Some commands that may help you start your use of Cisco devices ...

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you can enter to switches Cisco for free :

STEPS:
1. INSTALL ANY TELNET-CLIENT SOFTWARE :
PuTTYtel: http://the.earth.li/~sgtatham/putty/...6/puttytel.exe

OR USE WINDOWS CMD -NOT RECOMMENDED-.

2. USE ONE OF THE FOLLOWING IP ADDRESSES WITH THE CERTAIN PORT:
EACH PORT GOES TO ONE OF THE 8-SWITCHES IN THE DIAGRAM:
: telnet 98.169.34.136 49001
: telnet 98.169.34.136 49002
: telnet 98.169.34.136 49003
: telnet 98.169.34.136 49004
: telnet 98.169.34.136 49005
: telnet 98.169.34.136 49006
: telnet 98.169.34.136 49007
: telnet 98.169.34.136 49008
PRIVILEGE MODE PASSWORD: cisco
All switches are Layer 3 switches, and support IP routing, routed ports, SVI's and routing protocols like RIP, EIGRP, OSPF and BGP. All Cisco IOS commands are availab
3. NOW YOU ARE IN THE THIS TOPOLOGY! CONFIGURE, CONNECT, TRY, TEST AND PASS

Please follow these simple rules:

1. Do not change the line console settings.
2. Do not erase the IOS image or format the flash filesystem.
3. If you need to set a password, use "cisco"
4. Do "wr erase" and "reload" when you're done (type "no" when it asks to save the config).

more information about CCNA R&S at :
http://www.cisco.com/web/learning/certifications/associate/ccna/index.html

hello Everyone How you doing ? I hop you Enjoy learning on this page and I will Add New posts as soon as I can sorry I wasn't available because of my job *_^

The Cisco Three-Layered Hierarchical Model :
Cisco has defined a hierarchical model known as the hierarchical internetworking model. This model simplifies the task of building a reliable, scalable, and less expensive hierarchical internetwork because rather than focusing on packet construction, it focuses on the three functional areas, or layers, of your network:

Core layer: This layer is considered the backbone of the network and includes the high-end switches and high-speed cables such as fiber cables. This layer of the network does not route traffic at the LAN. In addition, no packet manipulation is done by devices in this layer. Rather, this layer is concerned with speed and ensures reliable delivery of packets.

Distribution layer: This layer includes LAN-based routers and layer 3 switches. This layer ensures that packets are properly routed between subnets and VLANs in your enterprise. This layer is also called the Workgroup layer.

Access layer: This layer includes hubs and switches. This layer is also called the desktop layer because it focuses on connecting client nodes, such as workstations to the network. This layer ensures that packets are delivered to end user computers.

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By default, EIGRP calculates metrics based on:

The cumulative interface delay…
The minimum interface bandwidth…
Of all outgoing links in the end-to-end route.

IPv6 :
Every device on the Internet must be assigned an IP address in order to communicate with other devices. With the ever-increasing number of new devices being connected to the Internet, the need arose for more addresses than IPv4 is able to accommodate. IPv6 uses a 128-bit address, allowing 2128, or approximately 3.4×1038 addresses, or more than 7.9×1028 times as many as IPv4, which uses 32-bit addresses. IPv4 allows only approximately 4.3 billion addresses. The two protocols are not designed to be interoperable, complicating the transition to IPv6.
IPv6 addresses are represented as eight groups of four hexadecimal digits separated by colons, for example 2001:0db8:85a3:0042:1000:8a2e:0370:7334, but methods of abbreviation of this full notation exist.
you can check your IPv6 by :
http://test-ipv6.com

IPv4 :
what's about IPv4 ?
An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there.
In IPv4 an address consists of 32 bits which limits the address space to 4294967296 (232) possible unique addresses. IPv4 reserves some addresses for special purposes such as private networks (~18 million addresses) or multicast addresses (~270 million addresses).
IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 172.16.254.1. Each part represents a group of 8 bits (octet) of the address. In some cases of technical writing, IPv4 addresses may be presented in various hexadecimal, octal, or binary representations.

More information about the OSI layers :

Application(Layer 7) : This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services.

Presentation(Layer 6) : This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.

Session(Layer 5) : This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination.

Transport(Layer 4) : This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.

Network(Layer 3) : This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.

Data Link(Layer 2) : At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sublayers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sublayer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.

Physical(Layer 1) : This layer conveys the bit stream - electrical impulse, light or radio signal -- through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects.

OSI Layer Model for concentrators

Hubs/Repeaters are found in the Physical Layer

Switches /Bridges/Wireless Access Point are found in the Data Link Layer

Routers are found in the Network Layer

Gateway are found in All 7 of the OSI Layers

Brouter are found in both the Data Link and Network Layer

OSI OSI 7 Layer Model

7. Application Layer - DHCP, DNS, FTP, HTTP, IMAP4, NNTP, POP3, SMTP, SNMP, SSH, TELNET and NTPmore)

6. Presentation layer – SSL, WEP, WPA, Kerberos,

5. Session layer – Logical Ports 21, 22, 23, 80 etc…

4. Transport - TCP, SPX and UDPmore)

3. Network - IPv4, IPV6, IPX, OSPF, ICMP, IGMP and ARPMP

2. Data Link- 802.11 (WLAN), Wi-Fi, WiMAX, ATM, Ethernet, Token Ring, Frame Relay, PPTP, L2TP and ISDN-ore)

1. Physical-Hubs, Repeaters, Cables, Optical Fiber, SONET/SDN,Coaxial Cable, Twisted Pair Cable and Connectors (more)