My Netwok Dictionary

It must produce multiple exchanges for a router to connect to another using ISDN. To make a call ISDN D channel is used between the router and the ISDN switch. Signaling System 7 (SS7) is used between the switches within the network service provider.

The D channel between the router and the ISDN switch is always enabled. The standard ISDN Q.921 describes the processes LAPD data link protocol operated as a Layer 2 in the OSI reference model. The D channel is used for call control functions such as setting, marking and cutting of the call. These functions are implemented according to the Q.931 protocol. The Q.931 specifies the functions of Layer 3 of OSI reference model. Read the rest of this entry »

More nodes are added to the physical Ethernet segment, it increases the containment of the media. Ethernet is a shared medium, which means that only one node can transmit data at the same time.

By adding more nodes, increases the demand on the available bandwidth and imposes an additional burden on the media. When it increases the number of nodes in a single segment, it increases the likelihood of collisions, and this causes more retransmissions. One solution is to divide a large segment into parts and separate it into isolated collision domains.

To accomplish this, a bridge keeps a table of MAC addresses and their associated ports. The bridge then forwards or discards frames based on the entries in your table. The following steps illustrate the operation of a bridge mode:

• The bridge has just been turned, so the bridging table is empty. The bridge only expected traffic on that segment. When it detects traffic, the bridge is processed.

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From the point of view, telephone, the protocol takes care of the voice signal for the establishment, management and culling call is SIP (Session Initiation Protocol). It is a protocol developed by IETF as a standard (RFC 3261) and supported in the client’s on-board mobile phone from Nokia.

The same SIP, then handles the message from the server side, ie the IP PBX, Cisco. The router in fact, the CME configuration, you can use two main VoIP protocols: a Cisco proprietary protocol called Skinny Protocol (SCCP), which is precisely the SIP. For an introduction to the protocol from the point of view, Cisco, see the documents listed on the site. Read the rest of this entry »

The network analysis:

A “network analyzer” is a device that allows you to “hear” the traffic of a network, i.e. to capture the information on them.

In fact, in a switched network, data is sent to all network terminals. However, with a normal exploitation of the terminals ignore packets that are not intended for them. Then, using the network interface in a particular mode (usually called promiscuous mode) you can hear the traffic passing through a network adapter (Ethernet card, a wireless network card, etc.).

Using the sniffer:

A sniffer is a powerful tool that allows studying the network traffic. Generally serves administrators to diagnose problems on their networks and to know that traffic circulates. So the intrusion detection systems (IDS) are based on a sniffer to capture textures, and use a database of rules to find the suspected plots. Read the rest of this entry »

The bandwidth is a measure of the amount of information that can traverse the network in a given period of time. Therefore, the amount of available bandwidth is critical for the specification of the network.

A typical LAN could be built to provide 100 Mbps to each individual workstation, but this does not mean that each user can actually move one hundred megabits of data over the network per second of use. This could only happen under the most ideal circumstances. The concept of transfer rates will help us to understand the motive.

The transfer rate refers to the actual measured bandwidth, at a given time of day, using specific Internet routes, and to transmit a specific set of data. Unfortunately, for various reasons, the transfer rate is often much smaller than the bandwidth of possible digital medium. Read the rest of this entry »

Once you have configured NAT, you can use clear and show commands to verify it is operating properly. By default, dynamic address translations are deleted from the NAT translation table after spending a certain time limit of inactivity. If port translation is configured, translation entries are deleted after 24 hours, unless the timers are reset using the ip nat translation timeouttimeout_seconds command in global configuration mode.

The translation information can be displayed by carrying out one of the operations described in EXEC mode. Another alternative is to use the show run command and search for NAT commands, access list, interface, or in conjunction with the required values.

Troubleshooting the configuration of NAT and PAT:

When IP connectivity problems exist in a NAT environment, it is often difficult to determine the cause of the problem. It is often wrongly blamed NAT, when in fact there is an underlying problem. 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 »

For a LAN is effective and meets the needs of users, it must be designed and implemented in accordance with a planned series of systematic steps. This article describes the following steps:

• Gather requirements and expectations
• Analyze requirements and data
• Design the structure or topology of Layers 1, 2 and 3 of the LAN
• Document the physical and logical implementation of the network

The information is gathering process to help clarify and identify any actual network problem. This information includes the history of the organization and its current status, projected growth, operational policies and procedures of administration, office systems and procedures and points of view of people who actually use the LAN. Read the rest of this entry »

It should be assigned a static local DLCI to network layer address of a remote router when the remote router does not support Inverse ARP protocol. This is also true when the need to control broadcast traffic and multicast through a PVC. This method of assigning DLCI in frame relay is called static mappings.

Use the command frame-relay map protocol protocol-address dlci [broadcast] to assign a static address to the remote network layer local DLCI.

Problems range of routing updates in NBMA:

By default, a frame relay network provides connectivity non-broadcast multiple accesses (NBMA) between two remote sites. NBMA environment is considered equal to other environments multiple access media, such as Ethernet, in which all routers are in the same subnet. However, to reduce costs, NBMA clouds are usually built following a star topology. In the star topology, physical topology does not provide an access function does provide multiple Ethernet. The physical topology consists of multiple PVC.

The NBMA topology of frame relay may cause two problems:

• Problems relating to scope routing updates.
• The need to replicate broadcast packets in each of the PVC when a physical interface contains more than one PVC.

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NAT has several advantages, namely:

• Conserves legally registered addressing scheme by allowing the privatization of internal networks.
• It increases flexibility of connections to the public. You can deploy multiple sets, sets of backup and load balancing to ensure that public network connections are reliable.
• Uniform addressing scheme in the internal network and a network without private IP addresses and NAT, Public IP address change requires the renumbering of all hosts in the existing network. The cost of renumbering hosts can be high. NAT allows the existing scheme remain, while admitting a new public address system.

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