Important technical parameters of the switch

I will introduce the key technical parameters of the switch to make it easier for users to compare the different products of different manufacturers when choosing the switch. Each parameter affects the performance, functionality, and different integration characteristics of the switch.

1, Forwarding technology: Switch using pass-through forwarding technology or storage and forwarding technology?

2, Delay: Switch data exchange delay how much?

3, the management function: The switch provides to support how many manageable functions?

4, single/Multiple MAC address type: Each port is a single MAC address, or multiple MAC address?

5. External monitoring support: Does the switch allow external monitoring tools to manage all traffic for ports, circuits, or switches?

6. Extended tree: Does the switch provide extended tree algorithms or other algorithms to detect and restrict topology loops?

7. Full Duplex: Does the switch allow the port to receive/send at the same time, Full-duplex communication?

8. High-speed Port integration: Does the switch provide high-speed port connectivity to key business servers or upstream trunk?

The parameters are discussed below:

1) Forwarding Technology: (Forwarding Technologies)

Forwarding technology refers to the forwarding mechanism used by the switch to determine how to forward packets. Various forwarding techniques have their advantages and disadvantages.

Pass-through forwarding technology: (Cut-through)

Once the switch interprets the destination address of the packet, it begins sending packets to the destination port. Typically, the switch is aware of the destination address when it receives the first 6 bytes of the packet, allowing it to decide which port to forward the packet to. The advantage of pass-through forwarding is that the forwarding rate is fast, the delay is reduced and the overall throughput rate is increased. The disadvantage is that the switch begins data forwarding before it is fully received and the packet is checked for correctness. In this way, in an environment with low communication quality, the switch forwards all the full packets and bad packets, which in effect brings a lot of spam packets to the entire switching network, and the switch is misinterpreted as a broadcast storm. In a word, pass-through forwarding technology is suitable for network environment with better network link quality and less error packets.

Storage and Forwarding technology: (Store-and-forward)

Store-and-forward technology requires the switch to decide how to forward after receiving all packets. This allows the switch to check packet integrity and correctness before forwarding. The advantages are: No incomplete packet forwarding, reducing the potential for unnecessary data forwarding. The disadvantage is that the forwarding rate is slower than the direct forwarding technique. Therefore, the storage and forwarding technology is more suitable for the network environment with common link quality.

Collision Avoidance Forwarding Technology: (collision-avoidance)

Some manufacturers (3COM) of switches also provide this vendor-specific forwarding technology. Collision avoidance forwarding Technology chooses a compromise solution between high forwarding rate and high accuracy rate by reducing network error propagation.

2) Delay: (latency)

Switch latency is the time interval between the receipt of packets from the switch and the start of replicating packets to the destination port. There are a number of factors that affect the latency size, such as forwarding technology and so on. There is a fixed delay for the switch using pass-through forwarding technology. Because the pass-through switch determines the forwarding direction only based on the destination address, regardless of the overall size of the packet. Therefore, its delay is fixed, depending on the rate at which the switch interprets the destination address in the first 6 bytes of the packet. The switch with store-and-forward technology is related to packet size because it has to receive the full packet before it can start forwarding packets. The data packet is big, then the delay is big, the data packet is small, the delay is small.

3) management function: (Management)

The management function of the switch refers to how the switch controls the user's access to the switch and how well the user is visible to the switch. Typically, switch vendors provide management software or meet remote management switches for Third-party management software. The general switch satisfies the SNMP MIB I/MIB II statistical management function. The more complex switches increase the ability to support RMON active monitoring via the built-in RMON group (Mini-rmon). Some switches also allow external Rmon to monitor the network condition of the optional port.