When you have a large, fast network to support, you need more than just high-end switches. You need the ability to link switches together, and stacking technology is the primary way to accomplish this goal.
Within the Cisco ecosystem, Stackwise is the longstanding, thoroughly proven technology that allows you to stack a wide range of switches. Whether you’re looking to minimize costs, maximize performance, or optimize in any other way, you’ll be working with some version of Stackwise.
To date, there are six developed versions of StackWise technology (including the cousin technology known as FlexStack), each designed for a different range of hardware and accompanying applications.
When you know these six, you can more easily find the right hardware for your network, and you will clearly understand optimization and performance caps for the switches you end up choosing.
So, let’s take a minute to go through each of the six so that you can make easy comparisons.
When Cisco first released Catalyst switches, the intent was to make stackable switches. Multiple switches can link together to make a centralized network, and Stackwise was the uplink technology designed for this purpose.
The core concept behind StackWise is simplicity. A single switch can control the rest of the stack, and Stackwise makes that management as easy as possible without compromising on control.
The original StackWise technology was designed for ring architecture, which enabled spatial reuse protocol (SRP). SRP allows the stacking technology to squeeze a little more total speed out of each ring, enabling greater total bandwidth in a network stack.
The original Stackwise supported up to 4 units per ring and up to 9 units in each stack. Optimized, the stacks could provide 32Gbps (32G) of total bandwidth.
Later improvements on StackWise led to StackWise Plus and brought bandwidth up to 64G per stack, depending on the specific switches utilized.
After the success of Stackwise, FlexStack was developed and released. While it offers less overall performance compared to Stackwise, FlexStack proved a great technology for linking up more affordable switches in simpler networks and configurations.
FlexStack does not support ring architecture, and as a result, it also cannot utilize SRP. As a result, FlexStack caps at 4 units per stack and up to 20G of total bandwidth in each stack.
FlexStack Plus / Extended
As Cisco continued to develop more powerful hardware, FlexStack needed an upgrade to keep pace with those improvements. That led to FlexStack Plus and FlexStack Extended. While these are separate technologies, they utilize the same concepts and provide the same levels of performance.
Hardware that utilizes either Plus or Extended can support up to 8 units per stack, and the maximum bandwidth jumps up to 40G as a result.
Stackwise 480 represents a big step up in performance and design, and it’s the first in a new line of names. With 480, Cisco started adding stack metrics to the name of the stacking technology.
In other words, switches supported by StackWise 480 can provide maximum stack bandwidths up to 480G.
To provide such high speeds, a few things are necessary.
First, StackWise 480 also uses ring architecture. You can create up to 6 rings per stack, and 480 supports a total of 9 units in each stack. Since each ring can hit a maximum bandwidth of 40G, maxing everything out will get you to 480G performance.
It’s important to note that you can only hit this maximum speed by utilizing SRP. You can use Stackwise 480 without SRP, but the maximum speeds will drop as a result.
Stackwise 480 was designed for use with the 3850 and 9300 switch series, and these switches have powered high-end networks for some years now. Stackwise 480 has been a staple in enterprise and data center networking, and you’ll still find it in plenty of those systems to date.
That said, there are two newer technologies for stack management, each offering competitive advantages over 480.
This series follows the same convention as the 480, yet the 320 version was released after the 480. So, why did the 320G stacking technology come later?
It’s all about budget.
The Cisco 9300 series proved to be an excellent choice for top-end networking, but there were plenty of operations that required something very fast that cost a little less. The switches that catered to this idea are the 9300L and the 9300LM, and Stackwise 320 was developed to support these switches and their intended purposes.
In most ways, StackWise 320 behaves the same as 480 — it just offers less total bandwidth per stack. The stacks support up to 9 devices per stack and up to 40G per ring. The big difference is that 320 only supports 4 rings per stack, limiting the maximum bandwidth.
The idea is that these switches and this technology can still support the same speeds for endpoint devices, but they can save money on high-speed networks that need fewer direct connections as compared to 480 systems.
The last item in the series is Stackwise-1T. Whereas StackWise 320 represented a small downgrade and lower operating cost than its predecessor, 1T is all about performance.
It’s easy to miss at a glance, but this version follows the same naming pattern as those before. In other words, Stawise-1T supports total bandwidths up to 1Tbps (1T).
This is still accomplished via ring architecture, and 1T supports up to 6 rings per stack, with a total of 9 switches per stack. This upgraded design can handle 90G throughput in each ring, making it the new top option in Cisco switch stacking.
1T also supports SRP (like the previous technologies), and it is with SRP that your stack can hit the full 1Tbps of bandwidth.
Currently, 1T is only available with select 9300X switches. It’s the best you can get from Cisco right now, and when speed matters more than anything else, 1T devices are the way to go.
And, that concludes Stackwise technology. You can find quality switches that use each variation; it’s all a matter of matching the right hardware to your networking needs.
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