Some Terminology for Switches

switch

A switch is a device used to implement a switched network. In ISO's OSI model, it is a device located at the second layer, the data link layer, which can operate on frames and is an intelligent device.

2. IEEE 802.3 Ethernet Standard

3. IEEE 802.3u Fast Ethernet Standard

4. IEEE 802.3ab Gigabit Ethernet (unshielded twisted pair) standard

5. IEEE 802.3z Gigabit Ethernet (fiber, copper) standard

6. IEEE 802.3x flow control standard

7. IEEE 802.1X port-based access control standard

8. IEEE 802.1q VLAN Standard

9. IEEE 802.1p Traffic Priority Control Standard

10. IEEE 802.1d Spanning Tree Protocol

11. Data link layer

It is located in the second layer of the ISO / OSI reference model. It is responsible for transmitting a frame of data without error through a series of means such as detection, flow control, and retransmission on the line between nodes, so that it can be transmitted from its upper layer (network layer ) Looks like an error-free link.

12. Full and half duplex

In the network, full duplex refers to the use of two independent channels for reception and transmission, which can be performed simultaneously without interference. However, half-duplex is the same channel for receiving and transmitting, and can only send or receive at the same time, so half-duplex may cause conflicts. What we call a switch is a full-duplex device, and a hub is a half-duplex device.

13. MAC address

The MAC address is the address used in the media access layer. In popular terms, it is the physical address of the network card (LAN node). In the physical transmission process at the bottom of the network, the host (LAN node) is identified by the physical address. The current MAC address generally uses 6 bytes and 48 bits.

14. IP address

An IP address is a 32-bit address assigned to each host connected to the Internet. You can access each host through the IP address.

15. Auto-Negotiation

The Auto-Negotiation standard enables the switch to adapt to the working rate and working mode in the following order: 100M full duplex, 100M half duplex, 10M full duplex, 10M half duplex.

16. Full-duplex flow control

Following the IEEE 802.3x standard, when the network is congested, the network device uses a predefined Pause frame for flow control.

17. Half-duplex flow control (Backpressure)

Based on the IEEE802.3x standard, when the processor finds that the buffer is about to fill, it sends a false collision signal to the source station, delays it for a random time, and then continues to send. Can alleviate and eliminate congestion.

18. wire speed

The theoretical maximum value of data forwarded by the switch.

19. Broadcast Storm Control

The abnormal increase in the number of broadcast frames (because it is forwarded) on the network affects normal network communication. A broadcast storm will occupy a considerable amount of network bandwidth, causing the entire network to malfunction. Broadcast storm control allows ports to filter broadcast storms that appear on the network. After broadcast storm control is enabled, when the number of broadcast frames received by a port reaches a predetermined threshold, the port will automatically discard the received broadcast frames. When this function is not enabled or the broadcast frames have not accumulated to the threshold, the broadcast frames will be broadcast to other ports of the switch normally.

20.TRUNK (port aggregation)

It is usually used to aggregate multiple ports together to form a high-bandwidth data transmission channel. The switch treats all ports aggregated as one logical port.

21. VLAN (Virtual Local Area Network, virtual local area network)

It is a broadcast domain composed of a group of terminal workstations. Hosts (switch ports) in the same VLAN can communicate with each other. It does not need to consider the specific wiring structure to establish a logical work group. Flexible configuration to increase system security.

22. Port VLAN

Port-based VLANs can communicate with each other only if they are in the same VLAN port.

23. Tag VLAN

Based on IEEE 802.1Q, VID is used to divide different VLANs.

24. VID (VLAN ID)

VLAN identifier, used to indicate a tag VLAN.

25. MTU VLAN

In the VLAN setting of the switch, the port occupied by each user and the uplink port are divided into a separate VLAN.

26. MAC Address Aging Time

Each port in the switch has the function of learning addresses automatically. The source address (source MAC address, switch port number) of frames sent and received through the port will be stored in the address table. The aging time is a parameter that affects the learning process of the switch. Timing starts after an address record is added to the address table. If each port does not receive a frame with the source address as the MAC address within the aging time, these addresses will be forwarded from the dynamic address table (by They correspond to the port number of the switch). The static MAC address table is not affected by the address aging time.

27. Static Address Table

The static MAC address is different from the dynamic MAC address learned in general. Once a static address is added, the address will remain valid until it is deleted, without being limited by the maximum aging time. The static address table records the static addresses of the ports. A MAC address in the static address table corresponds to a port. If set, all data sent to this address will only be forwarded to that port. Also becomes MAC address binding.

28. SNMP

Simple Network Management Protocol (SNMP for short) is an OSI layer 7 (application layer) protocol, which is used to remotely monitor and configure network devices. SNMP enables network management workstations to read and modify the settings of gateways, routers, switches, and other network devices.

29. IGMP (Internet Group Management Protocol)

IP manages multicast communications by using switches, multicast routers, and hosts that support IGMP. A group of hosts, routers (or switches) exchange multicast data streams with members belonging to the same multicast group. And all the devices in this group use the same multicast group address. IGMP Snooping technology is aimed at applications such as video on demand, which greatly improves network utilization. In the network, when performing IP multicast communication for a variety of multimedia applications, you can reduce unnecessary bandwidth usage by setting IGMP on each port of the switch.

30. IEEE 802.1D / STP

When IEEE 802.1D Spanning Tree Protocol detects a loop on the network, it automatically disconnects the loop. When there are multiple connections between switches, only the most important connection will be started, and all other connections will be blocked, and these connections will become standby connections. When there is a problem with the primary connection, the spanning tree protocol will automatically start the backup connection to take over the work of the primary connection without any manual intervention.

31. IEEE 802.1X authentication protocol

Port-Based Access Control Protocol. The protocol architecture is divided into three parts: client, authentication system, and authentication server.