My Netwok Dictionary

As the IP subnets have grown, administrators have sought ways to use its space of addressing with more efficiently. In this article a technique is presented that is called VLSM. With VLSM, a network administrator can use a mask in networks with only some hosts, with a mask cut on the subnets with a lot of hosts.

To implement VLSM, a network administrator must use a routing protocol that provides support for it. Cisco routers support VLSM with routing protocols OSPF, Integrated IS-IS, EIGRP, RIP v2, and static routing. Read the rest of this entry »

The NOS are designed to provide network processes to customers. Network services include web servers, file sharing, mail exchange electronic mail, directory services, remote management and printing services. Remote administration is a powerful service that allows network administrators to configure systems in remote locations.

It is important to understand that these network processes called “services” in Windows 2000 and “daemons” on UNIX and Linux. Network processes all provide the same functions, but how these are charged and interact with the NOS is different in each operating system. Read the rest of this entry »

Ethernet has evolved from the first technologies, the fast technologies to the Gigabit already the Multi-Gigabit. Although other LAN technologies are still installed (old plants), Ethernet dominates the new LAN installations. The extent that some Ethernet call the “dial tone” of the LAN, Ethernet has become the standard connection for horizontal, vertical and between buildings.

An Ethernet version currently under development is blurring the difference between LAN, MAN and WAN. While 1-Gigabit Ethernet is very easy to find in the market, and it is becoming easier to get products from 10 Gigabits, the IEEE and the Alliance of 10 Gigabit Ethernet are working on standards for 40, 100 and even 160 Gbps. Read the rest of this entry »

The design of a WAN is basically the following:

• Select a connection pattern or design of linkages between different locations.
• Select technologies for these links meet the needs of the company at a reasonable cost.

Many WAN using a star-shaped topology. As the company grows and adds new branches, these are connected to the central office and produce a star-shaped topology. Sometimes a connection is crossed with the end points of the star creating a mesh topology or partial mesh. This allows many combinations of interconnection. When designing, re-evaluate or modify a WAN, you must select a topology that meets the design requirements. Read the rest of this entry »

Some of the fields that are permitted or required in 802.3 Ethernet frame are:

• Preamble
• Start frame delimiter
• Destination address
• Source address
• Length / Type
• Data and filling
• FCS
• Length

The preamble is an alternating pattern of ones and zeros that is used to synchronize the time deployments and less than 10 Mbps Ethernet. The faster versions of Ethernet are synchronous timing information and this is redundant but it is retained for compatibility. Read the rest of this entry »

The knowledge of the typical errors is invaluable to understand so much the operation as the detection of failures of the Ethernet networks.

The following are the sources of error in Ethernet.

• Collision or runt: Simultaneous transmission occurring before the lapse of the time slot.
• Late collision: Simultaneous broadcast that occurs after having passed of the time slot.
• Errors interval long story, jabber: Excessive or illegally long transmission.
• Short frame, collision fragment or runt: Illegally short transmission.
• FCS error:Transmission damaged.
• Alignment error: Insufficient or unnecessary number of bits transmitted.

Read the rest of this entry »

A WAN is a network of communication that operates beyond the geographical reach of a LAN. One of the primary differences between a WAN and a LAN is that a company or organization must subscribe to a service provider external WAN network services using a service operator WAN.

A WAN data links using the services provided by an operator to access the Internet and connect sites together an organization with sites of other organizations, outsourcing and remote users. WANs generally carry several types of traffic such as voice, data and video. The telephone and data services are the most widely used WAN. Read the rest of this entry »

This article explains how the physical and logical interfaces are added to a network design. In a traditional situation, a network with four VLANs requires four physical connections between the switch and external router.

A measure that technologies such as for example the link inter-switch (ISL) become more common, network designers are beginning to use trunk links to connect routers to switches. Although you can use any trunking technology such as ISL, 802.1Q, 802.10 or LAN emulation (LANE), Ethernet-based approaches such as ISL and 802.1q are more common. Read the rest of this entry »

Many WAN will be connected to Internet companies. This poses problems in security, but is also an alternative for traffic between branch offices.

Part of the traffic that must be considered during the design goes or comes for Internet. Since the Internet is probably in all places where the company LAN, there are two main ways in which this traffic can be transported. Each LAN may have a connection to your local ISP or it may have a single connection from one of the core routers to an ISP. The advantage of the first method is that traffic is transported over the Internet instead of through the network of the company, which will probably lead to smaller WAN links.

The downside to allow multiple links is that the whole enterprise WANs is open to Internet-based attacks. It is also difficult to control and secure the many points of connection. It is easier to control and secure a single point of connection, although the enterprise WAN have to carry some traffic that otherwise would have carried on the Internet. Read the rest of this entry »

Types of lines:

When there is a need to permanently connect two or three points each, we can use three different ways. Consider a company with one central and two branches, and we want to interconnect two branches permanently to the central or the case of three hospitals in a city that wants to be permanently connected to each other. To this end there is the possibility of contracting with the telephone company is called a point to point line.

X.25 line:

The first option is called X.25 lines were born in the mid 70’s and the maximum transmission speed of 64 Kbps. Naturally we had to contract with as many circuits as the company wanted to connect dots, logically were virtual circuits joined by those central points, was never a direct line from one point to another. Read the rest of this entry »