My Netwok Dictionary

ISDN (Integrated Services Digital Network) is a standard digital telephone designed to replace analog connections using standard copper wire used in standard telephone lines.

ISDN was developed to provide digital transmission of both voice and data, with better quality and faster than that of classical systems Public Switched Telephone Network (PSTN).

Familiar with the digital protocol
There are two types of ISDN channels:

• Channel B - is known as the Bearer (”B”) and a 64 kbps channel used to transfer voice, video, data or multimedia content. These aggregates may be having a wider use of bandwidth.
• Channel D - known as Delta channel (D) may be either 16 Kbps or 64 Kbps and is used mainly for switching signals between equipment. Some say that the separation of data channels and control adds security ISDN.

Note: The Digital Signal 0 (DS0) is a digital signal based on 64K that can be used to describe a single channel Bearer. Read the rest of this entry »

1. Can the user “see” the WLAN?
If the utility does not show the user’s client service set indentifier (SSID) of your WLAN, you can use a WLAN WIDS or manager to identify and verify the operation of remote access point closest to the user. If all access points are operational, Use case testing portable tool to “hear” the SSID in the location of the user.

If the meter you see the SSID but no, check that there has been no hardware or software problems of the client (for example, disable the driver old / damaged). Verify that the client uses a standard and a domain compatible (ie, exclude the channel and modulation coupled correctly). Consider the signal strength: if the signal-to-noise meter is low, the access point may be too far because a client can see it very powerful. Note that the client may have difficulty seeing your SSID if your access point does not carry the broadcast SSID or multiple SSIDs do not send in the same signal. Read the rest of this entry »

CAT5 and CAT6 are the two most common types of cable networks today.

The main difference between the two categories lies in the technical specifications of the cable: CAT6 provides higher performance level and is preferable in high speed networks. The largest number of windings per unit length and higher quality of shielding allow the CAT6 cable to be more tolerant in places where electrical interference is a problem. Read the rest of this entry »

There are five types of EIGRP packets:

- Hello: used for the dynamic creation of adjacencies. They are sent to multicast address 224.0.0.10 and do not require ACK. The time interval between sending a hello packet and the immediately following is called the hello interval. For connections with high bandwidth that time is 5 seconds (default), but for slower links (with bandwidth <= T1) amounts to 60 seconds. Furthermore, adiancenza is removed at the end of the so-called hold time (default is 3 times the hello interval), the number of seconds to wait without receiving a hello before the router declares the neighbor unreachable. Read the rest of this entry »

The Virtual Router Redundancy Protocol (VRRP) is a simple but robust method that can provide additional availability in your network. VRRP can be implemented in using Red Heat Enterprise Linux and / or open source implementations VRRP

VRRP provides redundancy at the gateway allowing each router to share a virtual Ethernet MAC address and a virtual IP address. When virtual addresses are active on a particular router, the router is said master. Routers without control virtual address are for the backup.

VRRP works over the Internet as its own protocol (that does not use either TCP or UDP) and transmits the signal through a multicast address so that they can be “heard” by external VRRP router. If a backup does not receive anything from the master, the backup will be initiated through an election process that involves the router with the highest priority of VRRP routers.

Generally, VRRP is a protocol used in enterprise environments where routing redundancy is necessary for hosts, especially in end-user workstations. In this article, we propose an overview of the uses of VRRP and some suggestions for effective use of this methodology. Read the rest of this entry »

When adopted TCP/IP in the 80, the IP version 4 (IPv4) offered an addressing strategy that, although it was scalable for some time, produced an inefficient allocation of addresses.

In the mid-90s began to detect the following difficulties over IPv4:

• Exhaustion of the remaining IPv4 network addresses not assigned. At that time, Class B space was running low.

• There was a large and rapid increase in the size of Internet routing tables as Class C networks are connected online. The resulting flood of new information on the network threatened the capacity of Internet routers to exercise effective management. Read the rest of this entry »

To set the console password MADRID should access the console interface with the command line console 0:

Router # configure terminal
Router (config) # line console 0
Router (config-line) # login
Router (config-line) # password MADRID Read the rest of this entry »

The current settings of the router are stored in RAM, this type of memory loss when switched off the content router. To prevent this from happening it is necessary to make a copy to the NVRAM. The copy command is used for this purpose, identifying a data source to store and a destination where such data are stored. You can save settings to NVRAM RAM, the RAM to a TFTP server, etc…

MADRID # copy running-config startup-config
Copy RAM to NVRAM

MADRID # copy running-config startup-config
A copy of the NVRAM to RAM Read the rest of this entry »

The Cisco Discovery Protocol (CDP) is used to obtain information from routers and switches that are connected locally. The CDP is a Cisco proprietary protocol, for neighbor discovery and is independent of the media and the routing protocol. Although the CDP will only display information about directly connected neighbors, this is a very useful tool.

The CDP Protocol is a Layer 2 protocol that connects lower physical media with the network protocols of the upper layers. Read the rest of this entry »

The process of creating an ACL is done creating the list and then linking them to an incoming or outgoing interface.

Standard ACL Configuration

Router (config) # access-list [1-99] [permit | deny] [source address] [wildcard mask]

Where:

Identifies the range 1-99 and the list.

Permit | deny indicates whether this entry will allow or block traffic from the specified address.

Source address identifies the source IP address.

Joker or wildcard mask identifies the bits of the address field will be checked.

The default mask is 0.0.0.0 (coincidence of all the bits). Read the rest of this entry »