Views and suggestions on selecting Layer Two switches

An engineer who has worked in the network industry for 10 years says 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 the user needs directly determine the purchase of equipment. After making the user needs, from a plane angle to make reasonable equipment purchase.

So how do we choose the two-tier switch we need?

1. Back Plate Bandwidth

Backplane bandwidth refers to the maximum amount of data that can be throughput between a switch interface processor or an interface card and an information bus. How do we choose the right backplane bandwidth? If a switch can achieve Full-duplex non-blocking Exchange, its backplane bandwidth value should be greater than the port total x maximum port bandwidth x2. If greater than, it is proved that the switch has the maximum data exchange conditions.

2. Throughput rate

Backplane bandwidth can not fully reflect the actual operation of the switch capacity, but also to see the switch throughput rate of this important indicator. When choosing the switch, the back plate bandwidth and swallow rate are considered synthetically.

3. Port Rate

In addition to backplane bandwidth, throughput, and so on, the port rate is a measure of the switch is an important indicator. Now the port speed is: 10M, 10/100m, 1000M, 10/100/1000m. The corresponding interface physical characteristics are also different.

When choosing a switch specifically, pay special attention to the higher port generation value of the high speed port. In the absence of immediate explicit requirements, the user access switch should select the 10/100m port, and for the trunk switch, the 1000M gbic port or 10/100/1000m RJ45 port can be selected based on the ease of wiring.

4. Port density

Port density is a measure of the number of ports that represents the maximum number of ports a single switch can contain. The larger the port density switch, the smaller the single port cost may be.

5. Exchange Mode

There are three modes of exchange: Cut-through, Store and forward, Fragment free. In fact, these three modes of exchange mainly represent the anti-interference ability of the switch, and strike a balance between speed and anti-jamming.

If the working environment is worse, electromagnetic interference is strong, this should choose the store and forward switch. If the working environment principle launch station and other strong radiation source, then can choose Cut-through switch completely. If you cannot accurately identify the working environment, and the speed requirements are not very harsh, you can choose fragment free. Some advanced switches can be set to convert each of these three modes of operation.

6. Stacking capacity

There are two ways to connect between switches, that is, cascading and stacking. Different types of switches can only be cascaded, and only similar switches can be stacked together. Pay special attention to this point. There are two ways to stack, one is a star stack and the other is a daisy-shaped stack. May be based on specific needs.

7.VLAN Support

VLAN has become the standard configuration of high-end switches now, but different manufacturers of the device to the VLAN support capabilities, the number of support VLAN is also different. When choosing a VLAN-enabled switch, it is not just to see how many VLANs it can support, but also to support several VLANs, and it is important to note that the protocol that supports trunk is ISL or 802.1Q.

8.MAC Address number

Like routers with routing tables, each switch has a table of MAC addresses. The number of MAC addresses refers to the number of MAC addresses that can be stored in the MAC Address table of the switch. The more the number of MAC addresses stored, the higher the speed and efficiency of data forwarding, and the stronger the ability to overflow the Mac.

9. Network Management Ability

For a medium and large network, the network management support ability is very important. However, now the various switch manufacturers provide different network management methods, and incompatible, so select the switch to pay special attention to what you are currently using the network management software, or the future of what network management software will be adopted.

10.QoS support capability

Now the LAN network is not like the previous only transmission data, but the voice, video applications are added to it, which also creates a hidden danger, the switch from the purchase date, the Exchange ability is determined, and video applications such as bandwidth demand is unlimited, not to mention the network also has to protect the business needs of transmission, At this point the QoS becomes particularly important. It preserves bandwidth for important businesses and is reasonably equipped with the bandwidth required for a wide range of applications within the capabilities allowed.