Explore Common Types of Stacking Cables and When to Use Each

Stephane

February 3, 2021

Switch stacking is not unusual in today’s network switch world. It becomes a quick way to increase capacity and flexibility by “stacking” stackable switches and operating them as a single unit. Some stackable switches can be stacked via DAC cables while some must be connected via stacking cables as vendors claim. What exactly are stacking cables here? Are they the same as DAC cables? Find answers in the article below.

What Are Stacking Cables?

Stacking cables, some also called stack cables, are the cables used for multiple stackable switches to be physically connected together as the name suggests. Which cables to choose depends on the stacking types of the switches, how far your switches are, your budget and other elements. Following list the common stacking cables and the alternatives for switch stacking.

DAC/AOC Cables

AOC and Direct Attach Copper cable (DAC cable) are the commonly used connectivity solutions for data transmission by connecting network switches to switches, routers, or servers via the data ports. For some certain stackable switches, DACs and AOCs are not only applicable for transferring data but also used as the stacking cables. DAC and AOC are one of the most cost effective and simple solution to stacking. And DAC cables are more widely used by significantly reducing more costs over the AOCs of the same length.

When to Use DAC/AOC Cables for Stacking?

When the stackable switch supports front-panel stacking (FPS), which represents stacking via the Ethernet ports on the front panel of the switch, cables for data transmission can be used as stack cables. This makes DAC cables or AOC cables applicable.

The stack cable is connected to the Ethernet port on the front panel of one switch, and the opposite end of the cable is plugged to the stacking ports of the row on the opposite directions of another switch. Taking FS S5860-20SQ stackable switches as an example, the switch model allows for up to 2 units stacking through 10G/25G/40G data ports. The following image shows stacking two FS S5860-20SSQ switches by connecting 40G DAC cables through the 40G QSFP ports.

Optical Modules and Cables/Copper Cables

Optical modules and cables or individual copper cables, according to the data port types, are conventional types for data connectivity between switches and switches. They also offer solutions for connecting stackable switches.

When to Use Optical Modules and Cables or Copper Cables for Stacking?

Whether optical modules and cables combination or copper cabling are alternative solutions to stacking cables lies in front-panel stacking (FPS) technology. Though investing in DACs and AOCs reduces costs and time, they probably encounter the problems of limited distance or compatibility issues. Individual optical transceiver modules and cables are more flexible to offer longer distance based on your needs.

Dedicated Stacking Cables

Dedicated stacking cable refers to a category of stacking cables connected to the dedicated port of the stackable switch, instead of the Ethernet ports. They are not like DAC cables with unified industrial standards and specifications. Different switch vendors utilize their proprietary special cables for stacking their stackable switches. They are not available to reuse in other brand switches or even other series switches from the same vendor. It makes the dedicated stacking cable irreplaceable. Thus the cost for dedicated stacking cables are commonly seen higher than the other two stacking cables noted before.

When to Use Dedicated Stacking Cables for Stacking?

Dedicated stacking cables must be used when the stackable switches support backplane stacking (BPS) — switch stacking through the special stack modules on the backplane of switch. For example, Cisco Catalyst 9300 switch has two special back-panel StackWise ports on the back panel. To configure a stack in Catalyst 9300 switches, you should use the dedicated Cisco stack cables — so-called StackWise cables to plug into the stack ports located on the back panel. Apparently, these stacking cables have different ends from the regular DAC cables.

Note: Numericys  currently does not supply dedicated stacking cables for third-party stackable switches.

Can DAC Cables Be Used Stacking Cables?

After the introduction above, you‘ve probably hold a clear impression of the answer in your mind. DAC cables used for stacking should satisfy the following conditions: The switch stack units support stack via Ethernet ports, the DAC cables are compatible with the stackable switch, and the cable length meets the requirement. Numericys offers stackable switches supporting FPS technology and massive DAC cables compatible with 200+ brands in different lengths, which enhances network performance and reduces equipment resources.