Purchase of low-end Switches

Low-end switches are quite common, So I studied how to correctly select low-end switches. Here I will share with you, hoping to be useful to you. Currently, low-end switches in the Chinese market cover many brands from foreign network giants such as Cisco to domestic manufacturers such as Huawei and TCL, the price also ranges from about 50 RMB per port to several hundreds or thousands of RMB on average. There is great room for choice.

Therefore, choosing a suitable switch product has become a major challenge for many users. In particular, the low-end switch products are mainly intended for small businesses and home users. These users usually do not have professional network technicians, so the selection is more difficult. In fact, when purchasing a low-end switch, you can choose a suitable product by carefully balancing your own needs, suppliers, and products.

① View yourself

This is the most basic and important step for purchasing vswitch products. On the basis of understanding the number of network nodes and other basic network environments, there is a clear goal for the required vswitch products, such as the number of ports, the switching rate, and the price range that you can afford. Only in this way can you select products that meet your needs in a wide range of products.

② Brand View

When selecting a low-end switch product, you should be aware of the brand appeal, user reputation, product quality certification, R & D capabilities and core technical strength of product suppliers. At the same time, carefully study the differences between the solutions provided by the supplier and the actual application environment. In some cases, understanding the maturity of products in the market through the specific success stories of suppliers is also a simple and effective way. In addition, we need to carefully understand the after-sales services of suppliers to reduce worries. In many cases, the value of excellent customer services is far better than the money saved in procurement.

③ Viewing rate

The switch switching rate is an important factor that determines the network transmission performance. Although in today's low-end switch product market, the M switch still occupies the mainstream position, but the Gigabit Switch market is rapidly emerging, especially the proposal of the new network application concept of "Gigabit to desktop, it also promotes the demand for gigabit switch products. Therefore, when purchasing vswitch products, users must also follow the new network development trend and try to select products with Gigabit ports or upgrades to meet the needs of future network upgrades.

④ Number of viewing ports

The number of ports of a low-end switch is generally 8, 12, 16, 24, and 48. According to the current sales situation, in the low-end switch product market, port 24 is the most popular. This is because a 24-port switch can be used as either a working group switch or a backbone switch for a small enterprise or campus network environment with less than one hundred people. In terms of practical application, compared with port 8 and port 16, the 24-port switch provides more expansion space to better meet users' needs for network expansion in the future. Therefore, when selecting a low-end switch, if there is no clear port requirement, you should select a 24-port switch.

⑤ View Management Performance

In the past, many low-end vswitches were non-managed. These products are easy to configure and can only use ASIC solutions. Because these vswitches are not equipped with processors, their prices are relatively low. However, these vswitches are not highly flexible and cannot meet specific requirements. In recent years, with the increasing competition in the market of low-end switches, management switches with processors have also emerged in the market. This type of switch product provides multiple control and management functions, including remote management and security management. Therefore, the configuration is flexible and suitable for different network environments. Therefore, these vswitches have occupied a large market share in the low-end vswitch product market in recent years. Users can choose manageable or non-managed products based on their actual needs during the purchase.

6. scalability

The scalability of A vswitch directly determines the ability to upgrade the transmission rate of each information point in the network. Therefore, scalability is also an important aspect for users to consider when selecting vswitch products. This includes the internal scalability of the switch, external scalability, and the maximum rate of the switch.

7. view the price

In terms of price, there is a "one cent free trade ". Therefore, when the economic strength permits, we should try our best to select mainstream products from well-known suppliers, and do not blindly pursue low-price products. Of course, you cannot blindly Choose high-performance, high-price products, resulting in idle product functions and waste.

Others

In addition, the status of vswitch products also includes VLAN support, Mac address list quantity, QoS service quality and other related technical indicators, in these aspects, users can make measurements and trade-offs based on their actual needs, and will not go into detail here.

Important Technical Parameters of vswitches

Next, I will introduce the important technical parameters of vswitches, so that users can compare different products of different manufacturers when purchasing vswitches. Each parameter affects the performance, functions, and different integration features of the vswitch.

1. forwarding technology: Does a vswitch adopt direct forwarding or storage forwarding technology?

2. latency: How long is the switch's data exchange latency?

3. Management function: How many manageable functions does a vswitch provide?

4. Single/Multi-MAC address type: Is each port a single MAC address or multiple MAC addresses?

5. External monitoring support: Does the vswitch allow external monitoring tools to manage all traffic of ports, circuits, or vswitches?

6. Extended tree: Does a switch provide an extended tree algorithm or other algorithms to detect and limit the Topological Ring?

7. Full Duplex: Does the switch allow simultaneous receiving/sending of ports and full duplex communication?

8. High-speed port integration: Does the switch provide a high-speed port to connect to a key service server or upstream trunk?

The following describes parameters one by one:

1) Forwarding technology: Forwarding Technologies)

The forwarding technology refers to the forwarding mechanism used by the switch to decide how to forward data packets. Each forwarding technology has its own advantages and disadvantages.

Forward through technology: Cut-through)

Once the switch interprets the destination address of the data packet, it starts to send the data packet to the destination port. Generally, when the switch receives the first six bytes of the data packet, it knows the destination address and can decide which port to forward the data packet. The advantage of direct-through Forwarding is that the forwarding rate is fast, the delay is reduced, and the overall throughput is improved. The disadvantage is that the switch has started data forwarding before completely receiving and checking the correctness of the data packets. In this way, in an environment with low communication quality, the switch will forward all the complete data packets and error data packets, which actually brings a lot of junk communication packets to the entire switching network, the switch is misunderstood as a broadcast storm. In short, direct forwarding applies to network environments with good network link quality and fewer error packets.

Storage and forwarding technology: Store-and-Forward)

The storage and forwarding technology requires the switch to decide how to forward after receiving all data packets. In this way, the switch can check the integrity and correctness of data packets before forwarding. The advantage is that there is no incomplete data packet forwarding, which reduces the potential unnecessary data forwarding. Its disadvantage is that the forwarding rate is slower than that of direct forwarding. Therefore, the storage and forwarding technology is more suitable for the network environment with common link quality.

Collision avoidance forwarding technology: Collision-avoidance)

Some vendors 3Com) Switch also provides this vendor-specific forwarding technology. The collision avoidance forwarding technology reduces network error propagation and selects a compromise solution between high forwarding rate and high accuracy rate.

2) Latency: Latency)

Switch latency refers to the interval between the time when the switch receives the data packet and the time when it begins to copy the data packet to the destination port. There are many factors that affect the latency, such as forwarding technology. Vswitches using the forward-through technology have fixed latency. Because a pass-through switch determines the forwarding direction based on the destination address regardless of the overall data packet size. Therefore, the latency is fixed, depending on the rate at which the switch interprets the destination address in the first six bytes of the data packet. Because a vswitch using the storage and forwarding technology must receive complete data packets before it starts to forward data packets, its delay is related to the packet size. If the data package is large, the latency is large; if the data packet is small, the latency is small.

3) Management function: Management)

The management function of a vswitch refers to how the vswitch controls the user's access to the vswitch and how visible the user is to the vswitch. Generally, vswitch vendors provide management software or remote management switches that meet the requirements of third-party management software. A general switch supports the snmp mib I/MIB II statistical management function. In addition, complicated vswitches support the active monitoring function of RMON by using the built-in RMON group mini-RMON. Some switches also allow external RMON probes to monitor the network conditions of the available ports.

4) Single/Multi-MAC address type: Single-versus Multi-MAC)

Each port of a single MAC switch has only one MAC hardware address. Each port of a Multi-MAC switch is bound with multiple MAC hardware addresses. A single MAC switch is designed to connect an end user, share resources on the network, or use a non-bridging router. They cannot be used to connect a hub or a network segment containing multiple network devices. Multiple MAC switches have enough storage bodies to remember multiple hardware addresses on each port. Each port of a Multi-MAC switch can be considered as a hub, while a multi-MAC switch can be considered as a hub of a hub. The Buffer capacity of each vendor's switch varies. The Buffer capacity limits the swap address capacity that the switch can provide. Once the address capacity is exceeded, some switches discard other address data packets, and some switches copy data packets to each port for no exchange.

5) external Monitoring support: Extendal Monitoring)
 
Some switch manufacturers provide "monitoring port" monitoring port), allowing external network analyzers to directly connect to the switch to monitor network conditions. However, the implementation methods vary from vendor to vendor.

6) Extension Tree: Spanning Tree)

Because the switch is actually a multi-port transparent bridge device, the switch also has the inherent problem of the bridge device-Topology Loops ). When a data packet in a network segment is transmitted to another network segment through a bridge device, the returned data packet returns the source address through another bridge device. This phenomenon is called a "Topological Ring ". Generally, a switch uses the extended Tree Protocol algorithm to let every bridging device in the network know each other and automatically prevents topological loops. A vswitch disconnects a port in the detected "Topological Ring" to eliminate the "Topological Ring" and maintain the integrity of the topology tree in the network. In network design, the "Topological Ring" is often recommended for selecting redundant backup links for key data links. Therefore, vswitches with support for the extended Tree Protocol can be used to connect to the swap redundancy of key resources in the network.

7) Full Duplex: Full Duplex)

The full-duplex port can send and receive data at the same time, but the switch and connected devices must support full-duplex operation. Vswitches with full duplex function have the following advantages:

1. High Throughput): two times the communication Throughput in the ticket mode.

2. Avoid Collision Avoidance): no sending/receiving Collision.

3. Breakthrough length restriction Improved Distance Limitation): Because there is no collision, the length of the CSMA/CD link is not limited. The length limit of the communication link is only related to the physical media.

Full-duplex communication protocols are supported: Fast Ethernet, Gigabit Ethernet, and ATM.

8) High-Speed port integration: High-Speed Intergration)

A vswitch can provide high-bandwidth "pipe" fixed ports, optional modules, or multi-link tunnels) to meet the switch traffic switching requirements with the upper-level trunk. Prevents trunk communication bottlenecks. Common High-Speed ports are: FDDI: The application is earlier and has a wide range. However, there is a cost for protocol conversion. Fast Ethernet/Gigabit Ethernet: easy to connect, low protocol conversion costs, but limited by the network size. ATM: provides high-speed switching ports, but the protocol conversion costs are high.