Stackable vs. Chassis Switch: How to Choose?
Currently, there are three types of Ethernet switch solutions: standalone, stacked, and chassis switch. The discussions about stackable switches and modular switches have been around for a long time. Prima facie, stackable switches are understood to be for medium and low-end customers while chassis switches are considered for high-end market customers and service providers. In this article, we will mainly make a comparison between stacked and chassis network switches and guide you to reach appropriate decisions.
What Is Stackable Switch?
A stackable switch, as the name suggests, is a network switch that not only operates standalone but also operates with other network switches together. Stacking cables, transceivers & patch cables, and DAC cables play important roles in connecting stackable switches. Generally speaking, the maximum number of switches in a stack depends on the brand and the type of stackable switches. For example, the FS 48-port Ethernet L3 data center stackable switch N5860-48SC supports up to 2 units stacking. These switches can be configured as a single unit, sharing the same IP address. By setting up a group of stackable switches, you can not only add extra available ports on your switches but also simplify network configuration and structure, eliminate loops, and improve reliability.
What Is Chassis Switch?
In contrast to a stackable switch, a chassis switch is configurable with various types of line cards to provide the type and quantity of required network ports. A chassis switch has a certain number of fixed slots which are used to insert different types of line cards. By inserting extra line cards into a chassis switch, you can have more available ports. For example, you can insert line cards NC8200-8C, NC8200-16Q, and NC8200-24BC in the chassis switch NC8200-4TD. Then the chassis switch has the function of a 25/40/100GbE switch. Besides, both the line cards with copper ports and fiber optical ports can be inserted into one chassis switch. Chassis switches are widely used for consolidation and unified management.
The Differences Between Stackable Switches and Chassis Switches
A chassis switch normally tends to be more expensive than a stackable switch since it contains line cards, power supplies, fan modules, and blades that go into it. However, the chassis switch often supports more queues and thresholds per port. When new features come out, upgrading those modules like line cards is cheaper than upgrading a stackable switch.
A stacked switch solution has a smaller compact 1U form factor and won’t waste any space in the rack, whereas a chassis system that isn’t being used to its full capacity will take up more space. It would require over double the rack space to achieve the same port density as stackable switches.
The failure rate of a stackable switch increases with the number of power supplies. The more power supply it has, the more likely it is to have a failure. Unlike a stackable switch, a chassis switch has fewer power supplies, which considerably reduces the chance of power supply failure. So the Mean time between Failure(MTBF) of chassis switches is higher than stackable switches.
Since chassis-based network switch generally features a high-speed backplane module, it is possible to attain line-rate L2 and L3 switching on all ports of the entire chassis, making a lossless Ethernet of zero packet loss, low latency, and non-blocking. Nevertheless, it is difficult to realize such non-blocking configurations in stackable switches.
When adding or removing switches in a large stack, the management of stackable switches is a challenge. But things are different in a chassis switch, since all the ports supported by the individual line cards are a part of the chassis switch, you can use only one application to manage all the line cards. Besides, if you want to update the program of a chassis switch, you just need to update only one application of the chassis. The unified management of chassis switches makes management more convenient and time-saving.
The table below gives a detailed list of the differences between a stacking switch and a chassis switch.
|Parameter||Stackable Switches||Chassis Switches|
|Cost||Less expensive||More expensive|
|Easy of Redeployment||Easier to resize or redeploy||Difficult to resize or redeploy|
|Placement||Preferably at the access layer||Preferably at the core and distribution layer|
|MTBF (Mean Time Between Failure||Usually lesser than chassis switches||Usually higher than stack switches|
|Failure Rate||Greater failure as many power supplies at stack members||Lesser power supplies mean less chance of power supply failure|
|Physical Space||Less space consuming||Twice the space of stacks|
|Management and Upgrade||Adding or removing switches in a large stack can be problematic||Ease of management and upgrade|
|Performance||Low on performance||High on performance|
|Interface Selection||Lesser choice of interface selection||More choice of interface selection|
|Dedicated Modules for Data, Control, and Management Plane||Yes||No|
Stackable Switch vs. Chassis Switch: How to Choose for Your Data Center?
When it comes to choosing the right switch for your data center between stackable switches and chassis switches, there are three factors that need to be considered. Let's have a detailed introduction of them one by one.
Reliability is a significant characteristic of a switch. When a stackable switch in one stack group experiences a failure, you need to unhook the connection of stacking cables and transceivers and take the switch out of the rack. Then you should replace a new one on the rack and connect it with other stackable switches. What needs more attention is that switches from different manufacturers and brands cannot be stacked. So it is more time-consuming and difficult than using a chassis switch. However, when it comes to the breakdown of a line card in the chassis, you can easily remove and replace a new one without shutting down the system as the line cards are hot-swappable. Besides, a chassis switch has a better cooling system and a bigger power supply than stackable switches. So chassis switches are less prone to break down than stackable switches.
Flexibility is essential for data center networks, as they need to accommodate diverse requirements. Both stackable switches and chassis switches can offer the combination of different port speeds and transmission types, chassis switches are limited to specific vendors' equipment. Stackable switches, on the other hand, provide more flexibility in terms of brand compatibility, they can work with other brand switches. Besides, unlike a stackable switch, there is no self-sufficient operation for individual line cards in a chassis switch. It's worth noting that chassis switches may occupy more rack space when the number of used ports is not that much.
Considering the long-term costs, the lifespan of switches is a crucial factor. Chassis switches generally have a longer lifespan compared to stackable switches. When you want to improve the speed of one port from 10 Gigabit to 100 Gigabit on a stackable switch, you have no choice but to buy a new switch. But if you use a chassis switch, you just need to remove a 10 Gigabit port line card and insert a 100 Gigabit port line card. Then you go with the same old chassis switch. Although chassis switches have a higher initial investment than stackable switches, chassis switches may have a longer lifespan.
This article focuses on the introduction of stackable switches and chassis switches, and some considerations about choosing between stackable switches and chassis switches for your data center, including reliability, flexibility, and longevity. You can make a decision on choosing the best ethernet switch solution for setting up or upgrading your network based on your real needs.