My Netwok Dictionary

You might recall from our brief description of the protocols used in a setting IPX, it is an routable protocol and the routing information protocol (RIP) is used to propagate routing information.

The IPX version of RIP is quite similar to the IP version. Function essentially the same way, the routers periodically broadcast the contents of their routing tables and other routers are gathered listening and integrating the information they receive. Nodes only need to know your local network and make sure to send datagrams to other destinations through its local router. The router is responsible for collecting and redirects these datagrams to the next hop of the route.

In an IPX environment, we need to spread the net a second kind of information. Announcement Protocol (Service Advertisement Protocol, SAP) carries information about what services are available in which nodes in the network. For example, SAP is the protocol that allows users to obtain lists of file servers and network printing. Read the rest of this entry »

To configure Cisco routers, you must enter the user interface of the router using a terminal or remote access. When accessing a router, the user must log before executing any other command.

For security reasons, the router has two levels of access to commands:

• User EXEC mode: Typical tasks include checking the status of the router. Changes to the configuration of the router are not allowed in this mode.
• Privileged EXEC mode: Typical tasks include changes to the configuration of the router. The request for entry of user EXEC mode is displayed at login to the router. The commands available at the user level are a subset of available commands at the Privileged EXEC mode. For the most part, these commands allow the user to view information without changing the configuration of the router.

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A gateway is a device or element belonging to the network is configured to provide the PC that make up the network to go abroad, usually performing operations for this IP address translation (NAT: Network Address Translation).

This address translation capability allows you to apply a technique called IP masquerading, used very often to give Internet access to computers on a local area network sharing a single Internet connection, and therefore a single external IP address or arguably a public address. Read the rest of this entry »

Although you can use a router to segment the LAN, it is used primarily as a WAN device. Routers have LAN and WAN interfaces. In fact, routers communicate with each other through WAN connections. Routers are the backbone of the large internal networks and the Internet. It operates at Layer 3 of the OSI model, making decisions based on network addresses.

The two main functions of a router are the selection of the best route to and switching of frames to the corresponding interface. The router accomplishes this through the creation of routing tables and information sharing network of these tables with other routers. An administrator can maintain the routing tables by configuring static routes, but generally speaking, routing tables are maintained dynamically through the use of a routing protocol that exchanges information with other routers network topology (route). Read the rest of this entry »

Router LED:

Cisco routers use LED indicators to provide status information. LED indicators vary by model of Cisco router. Interface LED indicates the activity of the corresponding interface. If an LED is off when the interface is active and the interface is properly connected, can signal a problem. If the interface is very active, the LED is continuously lit. The green OK LED to the right of the AUX port is turned on after the system was initialized properly.

Review of initial startup of router:

The information and messages displayed during initial startup. This information varies, depending on the router interfaces and Cisco IOS software version. The screens shown in this chart are for reference only and may not reflect exactly what the screen displays on the console. Read the rest of this entry »

The routers are responsible for routing data packets from origin to destination on the LAN and provide connectivity to the WAN. Within a LAN, the router contains broadcasts, provides local services for address resolution, such as ARP, and can segment the network using a subnet structure. To provide these services, the router must be connected to the LAN and WAN.

In addition to determining the type of cable is necessary to determine whether DTE or DCE connectors required. The DTE is the endpoint of the user’s device in a WAN link. The DCE is usually the point where the responsibility for sending the data is transferred to the service provider. Read the rest of this entry »

Initial operation of Cisco routers:

A router is activated by the execution of three elements: the bootstrap, the operating system and file configuration. If the router can not find a configuration file, enter the initial setup mode (setup). Once the initial setup mode is completed, you can save a backup configuration file in nonvolatile RAM (NVRAM).

The purpose of the startup routines of the Cisco IOS software is to start operating the router. For this, the startup routines must:

• Ensure that the router hardware is in perfect condition and functional.
• Find and load the Cisco IOS software.
• Find and apply the startup configuration file or enter the initial setup mode (setup).

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It is not necessary to know the physical location of components within the router to know how to use it. However, in some situations, such as adding memory, it can be very useful. The exact components used and its location in the router vary from model to model. It identifies the internal components of a router.

External links:

The three basic types of connections on a router are LAN interfaces, WAN interfaces and port management. The LAN interfaces allow the router to connect to the means of local area network. Usually, this is a form of Ethernet. However, there may be some other LAN technologies, such as Token Ring or FDDI. Read the rest of this entry »

This article explains how DUAL maintains and updates the routing tables. DUAL tracks all routes published by the neighbors and compared based on the composite metric of each route. DUAL also guarantees that each path is loop-free. Then, insert the DUAL algorithm lower-cost routes in the routing table. These main routes are called successor routes. A copy of the successor routes is also placed in the topology table.

EIGRP keeps important information at the disposal route and topology in a neighbor table and topology table. These tables provide detailed information on the dual routes in case of problems on the network. DUAL uses the information in these tables to quickly select alternative routes. Read the rest of this entry »

This article discusses the three tables that EIGRP uses to store network information.

EIGRP routers keep route and topology information available in RAM, so they can react quickly to changes. Like OSPF, EIGRP keeps this information in various tables and databases.

Save EIGRP routes that are learned in specific ways. The routes are given a specific state can be labeled to provide additional useful information.

EIGRP maintains the following three tables:

• Table of neighbors
• Topology Table
• Routing Table

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