Access Control List (ACL):
An Access Control List is a way to control the network. Eg. can an IP address or list of IP addresses be denied access to a server
Auto MDI / MDI-X:
A feature in network devices that allows both crossed and even network cables. Eg. a connection between 2 PCs can be established using an equal network cable if one of the cards supports Auto MDI / MDI-X.
Broadcast is when a package is sent to all devices on a network. If these devices pass on these packages after receiving them, a loop will appear (see Spanning Tree Protocol), also called Broadcast Storm.
A buffer is a form of temporary data storage. For example, if a router Receiving 100 packages from a port to be sent out of another port, they will be stored in the buffer until they are sent.
Domain Name System (DNS):
DNS is a protocol that translates names to IPs. This is clearly visible on the Internet as all Internet addresses have an IP, but instead of remembering IPs, we can write an address that is easier to remember than the IP itself. Eg. can we write www.danbit.dk after which the DNS server translates this into an IP and sends us to Danbits server.
A gateway is the device that connects the network to another network. For example, Be a router that is connected to a cable modem that is connected to the Internet. Here is the router gateway for that network.
Jumbo frames differ from regular frames by size. A normal frame is 1500 bytes. Using Jumbo frames improves the efficiency of the switch as it requires more sending 6 frames at 1500 bytes than sending a frame of 9000 bytes. Jumbo frames are supported only by certain Gigabit switches and Gigabit networks.
DHCP is an abbreviation for Dynamic Host Configuration Protocol The DHCP protocol is part of the TCP / IP protocol suite and provides for managing and allocating IP addresses to different computers in a TCP / IP network. A DHCP server in a local area provides clients with all the information about network structure, subnet and gateways that are required for them to work. The information is displayed based on the client's unique hardware ethernet address (often called the Mac address). In a local area, it is often a router that acts as DHCP server.
A MAC address is a unique ID that all network devices have. In principle, it is not possible to change the MAC address as it must be unique to all other network devices in the world. The MAC address will include used in connection with DHCP, as the DHCP server uses the MAC address to send the network configuration.
Quality of Service (QoS):
QoS is a way to prioritize different packages. QoS can, for example, Configured to prioritize packages coming from IP telephony so they always come first in line. This ensures that there will be more delay in the packages that are less important and thus ensure the quality of data for highly prioritized services.
Service Set Identifier (SSID):
SSID is the name of a wireless network. SSID is unique within the area the access point covers. However, multiple access points may use the same SSID if they provide access to the same network. Certain access points have the option of having more SSIDs, this is used in conjunction with VLAN. Eg. VLAN 10 can use the first SSID and VLAN 20 the other SSID, etc. Thus, it is still possible to split the network even though all wireless devices are connected to the same access point.
Stress Tree Protocol (STP):
Spanning Tree Protocol is a protocol that switches users to avoid loops. A loop is when a packet is being sent around the network. STP ensures that there is only one way for the package, if that way goes down, use the other way. Rapid Spanning Tree Protocol (RSTP) is a sequel to STP, which is faster to choose which path is the preferred one. When a road goes down, it typically takes 1 second for RSTP to find a new one where it takes STP 30-50 seconds.
Trunking is a way to increase the speed between switches by connecting multiple ports. Two Gigabit switches can e.g. connect with 3 cables between each other and achieve a speed of 3 Gigabit / sec.
Also sometimes called a "Managed switch". The term may be used if the switches have more complex functions such as, for example, VLAN, "voltage tree", bandwidth distribution, etc. Setting these functions can be, for example, controlled by a console interface via a serial port on the switch, or a Telnet connection using TCP / IP, which can also use a web server built into the switch, which has gradually become the most widely used method.
Virtual Local Area Network (VLAN):
In a traditional local area, all switches and all ports are in the same "broadcast" domain so they can communicate with each other, but often there is a need to divide the network into smaller domains. It can, for example, be to limit traffic on the web or for greater security. This can be done, for example, by using separate cables and swtches, etc. for each domain, but usually it will be more convenient to use the network switch with VLAN function to achieve the same in a much more flexible way. For example, a VLAN switch can be configured internally so data can only be transferred between groups of selected ports. In this way, it will act as if there were more physically separate switches. Therefore, the method is called "port-oriented".
IEEE 802.1Q is a standard that describes a more flexible method called "VLAN tagging" based on the fact that the switch itself can add 32-bit data blocks to the Ethernet data packets, which indicates which VLAN group the package belongs to. This allows for more advanced VLAN networks, where the groups can be distributed over flare switches, as the individual VLAN switches exchange data packets through trunk links. See more about VLAN on Danbit's "Knowledge Base", located under "support".
All DANBIT's switches with VLAN support the IEEE 802.1Q standard, although not mentioned on the page.
WLAN / WiFi:
Wireless Local Area Network (WLAN) refers to a wireless network that acts as a wired network, using radio signals instead of cables between participants. See more about building wireless networks on the next page.
Basically, a WLAN is very vulnerable and unprotected. To secure a WLAN, it can be locked with a code encrypted by a security algorithm (WEP, WPA, or WPA2). It is also possible to hide the name of the wireless network - also called SSID (Service Set Identifier). This means that users must know the name before they can connect to the wireless network.
WLAN is defined by a set of standards called WiFi, which is based on the IEEE 802.11 standard, with new standards over time. The most used is 802.11g, which provides data rates of up to 54 MB / s and 802.11n up to 150 MB / s. To ensure safe connection, a lower fallback speed is automatically used for insufficient signal strengths.