The stack is a technology that expands ports and simplifies management on data center network switches. It is a non-standardized technology. The stack is only implemented between the devices of the manufacturer. It is a private internal implementation. The device must be configured with a stacking function. The stack requires a dedicated stacking module and stacking cables. The number of stacking devices supported by different models is different. The equipment is 2~4, and the box equipment is 2~10.
Nowadays, stacking has become a must for data center network equipment. Some people regard this technology as a kind of virtualization technology, which realizes the “multiple virtual ones” of the equipment. This stacking technology has become a new generation data center network. One of the essential technologies for construction. However, many people ignore the limitations of stacking technology.
After using the stacking technology, the network operation and maintenance process often encounter practical problems. For example, stacking is a non-standardized technology. Therefore, stacking between devices of different vendors cannot be formed. Some devices also require the same model and software version to be stacked. These stringent requirements are inconsistent with the trend of the data center network becoming open; stacking equipment Although the management efficiency is improved and multiple devices are managed at the same time, there are a large number of private message interactions between different devices, which consumes the internal bandwidth of the device. If congestion or discard occurs, the solution will be un-stacked. It may cause network business interruption, but it will increase the risk of network operation.
When the stacking technology increases the port density and bandwidth, it also increases the risk of network service failure. If there are multiple devices, the scope of one device failure is limited, but if it is a stack system, one of the devices is easy to fault. Affects the operation of other devices. If the stacking software is not handled properly, it may cause large-area network service interruption. When the stacking device requires a software upgrade, it often needs to interrupt the traffic upgrade, which brings great inconvenience to the software update. Therefore, many people are also beginning to question the applicability of stacking technology, whether it is suitable for the needs of a highly reliable network such as the data center. Smart humans have even designed alternative stacking technologies, which are derived from stacking, but better than stacking.
802.1BR
IEEE 802.1BR is an international standard. As early as 2009, Cisco proposed the prototype VN-tag of 802.1BR and submitted it to the standardization organization. The IEEE established the 802.1Qbh working group called “Bridge Port Extension”. In the summer of 2011, the submission was extracted from 802.1Q, and 802.1BR was created separately, which has since become an open standard.
802.1BR is a standard set by the IEEE for local and large data center networks. It can provide multiple port expansion capabilities for multiple physical server connections, blade servers, or separate interfaces for virtual machines to achieve logical connections. The goal is to break the physical limitations. Extend and manage objects through 802LAN technology and interactive interfaces. 802.1BR has completely designed the virtualization of network devices, extending the ports of network devices to the end of the network, enabling cascading of all network devices, and finally virtualizing all network devices in the entire data center.
From the perspective of the network, 802.1BR extends the functions and logic of the network, enters the server and connects with the virtualization technology, and uses port extension technology to solve the visibility problem of network management in the virtualized environment. Compared with the stack, 802.1BR technology is an open standard protocol. All network vendors must abide by the implementation. It is very simple to implement the management of different vendors’ devices at the same time. As long as the 802.1BR protocol is opened, all the 802.1BR technologies will be used.
The network device forms a protocol tree, which can be added to the tree from the root node to the end node of the network. Therefore, the network device that 802.1BR can manage can reach hundreds of devices, and only the port interconnection cable is connected or Disconnecting can implement node leaving and joining. This process has no impact on the entire network. It is easy to upgrade the software in the network. As long as the network environment is redundant, the traffic can be cut off. After the software upgrade is completed. Switching the traffic back will not cause interruption of traffic.
Cross-device aggregation E-Trunk
An E-Trunk (Enhanced Trunk) is also called enhanced aggregation. It is a technology for implementing cross-device link aggregation. It is based on LACP (Standard for Link Aggregation of Single Device) and can implement link aggregation between multiple devices to improve link reliability from the board level to the device level.
The traditional LACP aggregation is to bind multiple ports on one device together, while the E-Trunk can bind different ports of multiple devices together so that traffic load sharing can be implemented on different devices. The effect of the stacking environment is achieved, and there is no relationship between the actual multiple devices. This not only eliminates stacking cables and stacking ports, but also saves costs and enables redundant backup of the stacking environment.
Especially when upgrading the device, you only need to do the next link switch, you can isolate the device and upgrade it. The network traffic will not receive any impact, and it is convenient to do network routine software update and maintenance. Of course, E-Trunk is not a virtualization technology. It is impossible to virtualize different devices into one device. This is the limitation of E-Trunk. E-Trunk and stacking technologies have some mutually exclusive places, so they can only be Choose one of the two. From the perspective of the future development of data center network technology, E-Trunk has a broader development space and will be more popular.
Although stacking technology has probably grown in less than a decade, popularity is very fast. From the beginning of the box network equipment to the full range of network equipment can now support almost. Once upon a time, the stacking technology was once popular, and the network equipment supporting the stacking technology became fragrant, grabbed a lot of orders.
However, as data centers become more demanding on the reliability and flexibility of networks, the limitations of stacking are beginning to emerge. This technology has become less and less suitable for the development of data centers, so many data center It has begun to consider the possibility of abandoning the stacking technology. The original stacked device is taken apart and used to restore the scene used by the original network. Perhaps the simplest is the best.
It seems that stacking technology is really outdated and certainly cannot adapt to the future development of the data center. Perhaps, this technology will slowly die out in a few years, at least not in the new data center, which is the inevitable trend of technological development, the survival of the fittest. Looking back at history, there have been a lot of network technologies disappearing in the long history of technological history, and stacking technology may be the next one?