My Netwok Dictionary

This article explains the comparison between the OSPF protocol and distance vector protocols such as RIP. The link-state routers maintain a common picture of the network and link exchange information at the time of initial detection or for changes in the network. The link-state routers do not send broadcasts routing tables in newspapers as do distance vector protocols. Therefore, the link-state routers use less bandwidth for routing table maintenance routing.

RIP is suitable for small networks and the best route is based on the least number of hops. OSPF is suitable for large and scalable inter-networks and the best route is determined based on the speed of the link. RIP and other distance vector protocols, use simple algorithms to calculate the best routes. The SPF algorithm is complex. Routers that implement the distance-vector protocols require less memory and less processing power than those that implement the protocol OSPF. Read the rest of this entry »

An important thing to know about IP is that, by itself, it is not reliable. Assume that ten people on your Ethernet started to download the latest version of the source code of the Netscape web browser, using GMU’s FTP server. The amount of traffic generated by this might be overkill for the catwalk for being too slow, or have short memories. If you then send a packet to quark, it could have run out of buffer space for a moment and therefore would not be able to forward it. IP solves this problem by simply discarding the packet which is lost irrevocably. This moves, therefore, responsibility to verify the integrity and accuracy of the data to the extreme nodes and its relay in case of error.

This process is responsible for other protocols: the Transmission Control Protocol (TCPl), which builds a reliable service over IP. The essential property of TCP is that it uses IP to give the user the impression of a simple connection between the processes on your computer and the remote machine, so you do not have to worry about how and on the path of the data via the route to travel. Read the rest of this entry »

It is often possible to find networks connected to each other through gateways or hosts link. These gateways may simply link two or more Ethernets, but may also liaise with the outside Internet. To use a gateway, it is necessary need to add additional information to the network layer. For example, Ethernets of the Virtual Brewery and Virtual Winery are the linked via a gateway, vlager.

Assuming that the machine has been configured vlager and we just have to add another record to the routing table of the machine to communicate and access all hosts on the Winery’s network through vlager. Route using the appropriate command and the gw keyword indicates that the following argument is a gateway: Read the rest of this entry »

SNMP is a protocol application layer designed to facilitate the exchange of management information between network devices. By using SNMP to access the management information data such as packets sent to an interface every second or the number of open TCP connections, network managers can more easily manage the performance to find and resolve problems in networks.

SNMP is currently the most popular protocol for managing corporate networks. The standardization activity continues even as vendors develop and market innovative management applications based on SNMP. SNMP is a simple protocol, but its feature set is powerful enough to handle the difficult problems associated with managing heterogeneous networks.

The organizational sub-model for managing SNMP-based network includes four elements:

• Network Management Station (NMS)
• Agent management
• Data Management Information
• Network Management Protocol

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The transport layer of TCP/IP are responsible for transporting data between applications in source and destination devices. It is essential to have a full understanding of the operation of the transport layer to understand the data management in modern networks. This module describes the functions and services of this critical layer model TCP / IP.

Several network applications that are in the application layer of TCP / IP are familiar even to casual web users. HTTP, FTP and SMTP, for example, is an acronym that users of Web browsers and email clients often use. This module also describes the role of these and other applications from the viewpoint of the model of TCP / IP. 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 »

IP has another complementary protocol of the one that have not talked still. This is the Internet Control Message Protocol (ICMP), used by the kernel networking code to communicate error messages to other posts. For example, we will assume that we find us in erdos again and we want to do telnet to the port 12345 in quark, but there is not processes listening in that port.

When the first TCP packet to port reaches ete quark, the network layer will recognize this arrival and immediately send an ICMP message to erdos starting with Port Unreachable.
The ICMP protocol provides several different messages, many of which deal with conditions error. However, there is a very interesting message called the message Redirect. Read the rest of this entry »

Internet was developed to provide a communication network that could continue to function in times of war. Although the Internet has evolved in ways very different from those envisioned by its architects, is still based on a set of TCP / IP. The design of TCP / IP is ideal for powerful, decentralized network that is Internet. Many of the protocols in use today were designed using the TCP / IP four-layer.

It is useful to know the OSI networking model and TCP / IP. Each model offers its own structures to explain how a network works, but the two share many features. The lack of understanding of any of the two models can make a system administrator does not have information sufficient to determine why a network is operating in a way. Read the rest of this entry »

This article will analyze VLSM, which represents the most common problem RIP networks. VLSM prevents the release of RIP routes. This is because RIP version 1 does not support VLSM. If RIP routes are not published, check the following:

• The existence of connectivity problems Layer 1 or Layer 2.
• Configuring VLSM subnetting. VLSM subnetting can not be used with RIP v1.
• A mismatch in the configuration of routing RIP v1 and RIP v2.
• Network Awards missing or incorrectly assigned to them.
• The outgoing interface is disabled.
• The advertised network interface is disabled.

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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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