My Netwok Dictionary

In the case of remote access VPN or VPDN, the possibility of encapsulating PPP frames, which are the ones that transmit normally a VPN client of this type on IP datagram. There are various options to encapsulate PPP (which in turn can encapsulate other protocols of network, such as IPX, etc or possibly IP) over IP.

• The PPTP protocol (Point-to-Point Tunneling Protocol) specifies a technique for encapsulating PPP frames but does not add authentication services. These services can be performed using the same protocols using PPP, as PAP (Password Authentication Protocol) or CHAP (Challenge Handshake Authentication Protocol).

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This article explains the differences and similarities between EIGRP and IGRP. Distance information and distance vector technology used in IGRP is also used in EIGRP.

EIGRP improves the convergence properties and operates with greater efficiency than IGRP. This allows a network has an improved architecture and can maintain the current investment in IGRP.

Comparisons between EIGRP and IGRP can be divided into the following categories:

• Compatibility Mode
• Calculation of metrics
• Number of hops

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EIGRP automatically summarizes the routes on the border with class. This is the boundary where the network address ends in accordance with the definition of class-based addressing. This means that even though RTC is connected to the subnet 2.1.1.0 only, post that is connected to the entire Class A network, 2.0.0.0.

In most cases, automatic summarization is beneficial because it maintains the routing tables as compact as possible. However, automatic summarization may not be the best option in certain cases. For example, if there are non-contiguous subnets automatic summarization must be disabled for routing to work properly.

To turn off automatic summarization, use the following command:

router (config-router) # no auto-summary Read the rest of this entry »

PPP configurable aspects include methods of authentication, compression, error detection, and if it supports multilink or not. The following section describes the various PPP configuration options.

Configuring PPP:

The following example enables PPP encapsulation on serial interface 0 / 0:

Router # configure terminal
Router (config) # interface serial 0 / 0
Router (config-if) # encapsulation ppp

Compression software point to point can be configured interfaces serials that use encapsulation PPP. Compression runs on the software and can affect system performance significantly. Compression is not recommended if most of the traffic consists of compressed files. Read the rest of this entry »

The two main classes of IGP are distance vector and link state. Both types of routing protocols seek routes through autonomous systems. Distance vector and link state routing protocols use different methods to perform the same tasks.

Algorithms link state routing, also known as algorithms Open Shortest Path First (OSPF), maintains a complex database of topology information. The routing algorithm maintains link-state full details of distant routers and interconnection.

On the other hand, the distance vector algorithms provide information not specified on distant networks and no information about remote routers. It is important to understand how routing protocols operate link state to configure, verify and troubleshoot. This module explains routing protocols, link state, describes their functions, describes the algorithm used and highlights the advantages and disadvantages of link-state routing. Read the rest of this entry »

The services actually provided to users via the Internet is not defined by the routing mechanisms of transmission control protocol/Internet protocol (TCP IP) but on the contrary, application protocols high level, for example hypertext transport protocol (HTTP), the file transfer protocol (FTP), network news transfer protocol (NNTP) and simple mail transfer protocol (SMTP).

Since these protocols are not incorporated into the Internet itself, it is possible to use a new protocol to the application layer consists only of a server to transmit the protocol data in the appropriate format and a client to receive and interpret such data. However, the usefulness of a service to users increases with the number of servers that service. Read the rest of this entry »

This article presents the OSPF protocol. OSPF is a link-state routing protocol based on open standards. It described in various standards of the Internet Engineering Task Force (IETF). The term “free” in “First Open Shortest Path” means that it is open to the public and is not owned by any company.

Compared with RIP v1 and v2, OSPF is preferred because it is scalable IGP. RIP is limited to 15 hops, it converges slowly and sometimes slow routes chosen because it ignores critical factors such as bandwidth to determining the route. OSPF has overcome these limitations and has become a robust and scalable routing protocol and suitable for modern networks. Read the rest of this entry »

There are many ways to classify the networks, namely in terms of its logical topology (point to point or broadcast), physical topology (radial, bus, and ring), according to the transmission medium (wired, wireless, fixed, mobile); speed transmission protocol, etc.

Internet is often classified as a packet switched network. According to this classification there are three basic types of networks: circuit switched (e.g., telephone networks) connection-oriented packet-switching (such as examples include the X.25 and X.75) and packet switching.

On the other hand, Internet can also be classified as a separate logical architecture of the particular characteristics of the network that connects different types of networks so that computers and people to communicate without doing so may need to know what network are using or how to route the information. Read the rest of this entry »

A protocol is a set of rules for communication between devices (e.g. computers, phones, routers, switches, etc). The protocols governing the format, timing, sequencing and error control. Without these rules, the devices could not detect the arrival of bits.

But the protocols go beyond just basic communication. Suppose you want to send a file from one computer to another. You could send the whole file at once. Unfortunately, it could stop the other users who are using the LAN during the time it takes to send the file. Additionally, if an error occurs during transmission, the entire file would be sent again. To resolve these problems, the file is broken into small pieces called “packets” grouped a certain way.

This means that certain information must be added to the package to tell the receiver where each group belongs in relation to others, but this is a minor issue. To improve the reliability of the information, synchronization and correction must be added the famous package. A useful information (i.e. the message), along with additional information is called a protocol. Read the rest of this entry »

The PAP, which is used by many Internet Service Providers (ISP), basically works the same way as the normal login procedure. The client authenticates itself by sending a username and password (optionally encrypted) to the server, which is compared by the server with its database of keys / secrets. This technique is vulnerable to intruders who may try to get the password listening on a serial line and others who make repeated attempts to attack by trial and error.

The CHAP does not have these defects. With CHAP, the authenticator (i.e. the server) sends a string of “challenge” to the client randomly generated, along with its computer name. The client uses the computer name to find the appropriate key, combines it with the challenge, and encrypts the string using an encryption function of a single sense. The result is returned to the server along with the name of the client computer. The server now performs the same computation, and warns the customer if you get the same result. Read the rest of this entry »