My Netwok Dictionary

A switch is a network device that acts as a Layer 2 concentration point for connecting workstations, servers, routers, hubs and other switches.

A hub is an older type of aggregation device that also has multiple ports. However, the hubs are lower than those switches as all devices connected to a hub share the bandwidth and have the same collision domain.

Another disadvantage is that only hubs operating in half-duplex mode. In half-duplex mode, the hubs can only send or receive data at some point but can not do both simultaneously. The switches can operate in full duplex mode, which means they can send and receive data simultaneously. Read the rest of this entry »

The isdn switch-type command can be executed in global configuration mode or interface configuration mode to specify the provider ISDN switch.

The configuration command of isdn switch-type in the global configuration mode defines the same type of ISDN switch for all ISDN interfaces. After running the global configuration command, each interface can be configured individually to reflect a different type of switch.

Once installed the ISDN service, the service provider will send information on the switch type and SPID. SPID are used to define the services available to each individual subscriber ISDN service. Depending on the switch, you may have to add these SPID to the configuration. The National ISDN-1 switches and DMS-100 ISDN configuration requires SPID, but not the AT & T 5ESS switch. You must specify the SPID when using Adtran ISDN simulator. Read the rest of this entry »

This article explains how the switches and bridges filter frames. In the terms switch and bridge are synonymous. Most bridges can filter frames based on any field Layer 2 frame. For example, a bridge can be programmed to reject, without sending, all frames that originate from a particular network. As the data link layer often includes reference to a higher layer protocol, bridges usually can filter based on this parameter.

In addition, filters can be useful for managing unnecessary broadcast packets and multicast. Once the bridge has created a local address table is ready to operate. When receives the frame, it examines the destination address. If the address of the story is local, the bridge passes by. If the frame is the address of another LAN segment, the bridge copies the frame to the second segment.

• Skipping a frame is called filtering.
• Copy the frame is called send.

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The LAN design has evolved. Until recently, network designers used hubs and bridges to build networks. Switches and routers are key components of the LAN design and the capabilities and performance of these devices are getting better.

This module describes the roots of modern Ethernet LAN with emphasis on the evolution of Ethernet/802.3, the architecture of most widespread LAN implementation. A look at the historical context of the development of LANs and various network devices that can be used in the various layers of the OSI model will help students better understand the reasons why network devices have evolved. Read the rest of this entry »

This article presents the store and forward switching and cut-through switching. The following two switching modes are available for sending frames:

• Store and forward switching: The complete frame is received before performing any type of shipment. We read the source and destination addresses and filters are applied before sending the frame. Latency occurs while the frame is being received. Latency is greater with larger frames because the entire frame must be received before the start of the switching process. The switch can check all frames to see if there are errors, which can detect more errors.
• Cut-through switching: The plot is sent through the switch before it receives the complete frame. At a minimum, the destination address of the frame must be read before the plot can be sent. This mode reduces the latency of transmission, but also reduces the error detection.

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This article explains the default settings of a switch and how to verify it. At first light, a switch has default data in the active configuration file. The default hostname is Switch. Not set any password on the lines of console or virtual terminal (vty).

You may be granted to the switch IP address for management purposes. This is configured in the virtual interface, VLAN 1. By default, the switch has no IP address. The switch ports or interfaces are set to automatic mode and all switch ports are in VLAN 1. VLAN 1 is known as the management VLAN by default. Read the rest of this entry »

This article explains how the switches create and manage MAC address tables.
The switch examines the source address of frames that are received at the ports to learn the MAC address of workstations or PCs connected. These learned MAC addresses are recorded then a MAC address table. The frames that have a MAC address destination, which has been on the table, can be switched to the correct interface.

The command show mac-address-table can be entered in privileged EXEC mode to examine the addresses that a switch has learned. A switch dynamically learns and maintains thousands of MAC addresses. To preserve the memory and for optimal operation of the switch, the entries can be discarded learned the MAC address table. Read the rest of this entry »

Packet switched networks were developed to offset the expense of the public circuit switched networks and provide a more economical WAN technology.

When a subscriber makes a telephone call, the dialed number is used to set switches in the core along the route of the call so that there is a continuous circuit between the caller and the called party. Due to the switching operation used to establish the circuit, the telephone system is known as circuit switched network. If modems replace the phones, then switched circuit can carry computer data. Read the rest of this entry »

Circuit switching establishes a dedicated connection for voice and data between sender and receiver. Before you start switching, it is necessary to connect the switch setting. The telephone system performs this function by the number dialed. ISDN is used in both digital lines as in the voice-grade.

To avoid delays associated with setting up a connection, telephone service providers also offer permanent circuits. These dedicated leased lines or offer more bandwidth than is available in circuit switched. Examples of circuit-switched connections are:

• System of plain old telephone service (POTS)
• ISDN Basic Access Interface (BRI)
• ISDN Primary Rate Interface (PRI)

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A switch is simply a bridge with many ports. When only one node is connected to a switch port, the collision domain in the shared medium contains only two nodes. The two nodes in this small segment or collision domain, consisting of the switch port and the host connected to it. These small physical segments are called micro-segments. Another capability emerges when only two nodes are connected. In a network that uses twisted pair; one pair is used to carry the signal transmitted from one node to another.

A different pair is used for the return signal or received. It is possible that the signals pass through both pairs simultaneously. The ability to communicate in both directions at the same time is called full duplex. Most switches are capable of supporting full duplex, as are interface cards (Network Interface Card, NIC) in full duplex mode, there is no contention for the media. Thus, a collision domain no longer exists. In theory, the bandwidth is doubled when using full duplex. Read the rest of this entry »