Some opinions and suggestions on L2 Switch Selection

One engineer who has worked in the network industry for ten years said that the first important thing in network construction is the demand, the second is the demand, and the third is the demand. It can be said that user requirements directly determine the procurement of equipment. After making user requirements, make reasonable device purchases from a plane perspective. So how should we select the required L2 Switch?

1. Board bandwidth

The backboard bandwidth refers to the maximum amount of data that a vswitch interface processor, interface card, and data bus can process. How can we choose the right backboard bandwidth? If a vswitch may realize full-duplex non-blocking switching, the bandwidth value of the backboard should be greater than the total number of ports × maximum port bandwidth × 2. If the value is greater than, it indicates that the vswitch has the maximum data exchange condition.

2. Throughput

The bandwidth of the backboard does not fully reflect the working capacity of the switch, but also depends on the throughput of the switch. When selecting a vswitch, we generally need to comprehensively consider the bandwidth and swallowing rate of the backboard.

3. Port Rate

In addition to the backboard bandwidth and throughput, the port rate is also an important indicator of the vswitch. The current port speed is 10 M, 10/100 M, 1000 M, 10/100/1000 M. The physical features of the corresponding interfaces are also different.

When selecting a vswitch, pay special attention to the higher value of the port generation of the high-speed port. If you do not have specific requirements in the near future, you should select port 10/100 M for the access switch. For the trunk switch, you can select port 10/100 mgbic or port/1000MRJ45 Based on the wiring ease.

4. Port Density

Port density is a measure of the number of ports. It indicates the maximum number of ports that a vswitch can contain. For a vswitch with a higher port density, the cost of a single port may be lower.

5. exchange mode

There are three switching Methods: Cut-through, Storeandforward, and Fragmentfree. In fact, these three switching modes mainly represent the anti-interference capability of the switch, which is to strike a balance between speed and anti-interference.

If the operating environment is harsh and the electromagnetic interference is strong, the Storeandforward switch should be selected. If the operating environment is similar to the launch station, you can select the Cut-through switch. Fragmentfree can be selected if the work environment cannot be accurately confirmed and the speed requirement is not very demanding. Some advanced switches can switch between the three working modes through settings.

6. Stack capability

There are two ways to connect a vswitch: cascade and stack. Different types of switches can only be connected at a level, and only similar switches can be stacked together. Pay special attention to this. There are two stack modes: Star stack and Chrysanthemum stack. Depends on the specific needs.

7. VLAN support

VLAN has become a standard configuration for medium-and high-end switches. However, devices of different vendors have different VLAN support capabilities and the number of VLANs varies. When selecting a vswitch that supports a VLAN, you should not only check the maximum number of VLANs that it supports, but also note that the Protocol that the switch supports TRUNK is ISL or 802.1Q.

8. Number of MAC addresses

Like a router with a route table, each vswitch has a MAC address table. The number of MAC addresses refers to the maximum number of MAC addresses that can be stored in the MAC address table of the vswitch. The more MAC addresses are stored, the higher the speed and efficiency of data forwarding and the stronger the ability to defend against MAC overflow.

9. network management capability

For a medium/large network, the network management support capability is crucial. However, the network management methods provided by various switch manufacturers are different and incompatible. Therefore, when selecting a switch, pay special attention to the network management software you are using, or what network management software will be used in the future.

10. QoS support

The current LAN network is no longer used to transmit data, but to add voice and video applications, which also creates a hidden risk that switches start from the date of purchase, the switching capability is fixed, and video and other applications have unlimited bandwidth requirements. What's more, QoS is especially important when there are services that must be protected in the network that need to be transmitted. It can reserve bandwidth for important services and reasonably allocate the bandwidth required by various applications to the extent permitted by the capability.

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