Basic knowledge of Ethernet switch stack and cascade (1)

When the number of ports that a single switch can provide is insufficient to meet the requirements of the network computer, more than two switches must provide the corresponding number of ports, which also involves the connection between switches. Basically, there are two ways to connect vswitches: Stack and cascade.

1. GBIC and SFP

1) GBIC

Cisco GBICGigaStack Gigabit Interface Converter) is a common and low-cost Gigabit Ethernet stack module that provides high-speed connections between Cisco switches. It can build a high-density port stack, it can also be connected to servers or Gigabit trunk networks, providing a low-cost and high-performance solution for the transition from Fast Ethernet to Gigabit Ethernet. In addition, optical fiber can also be used to connect to the Remote High-Speed Backbone Network. GBIC modules are divided into two categories: GBIC modules for common cascade use and GBIC modules for stacking.

◆ Cascade GBIC Module

The GBIC modules used for Cascade are divided into four types, one is 1000Base-T GBIC Module 1), which is applicable to cat5e or cat6 twisted pair wires with a maximum transmission distance of 100 meters; the second is 1000Base-SX GBIC module 2), applicable to multimode multi-fiber MMF), the longest transmission distance is 500 meters; the third is 1000Base-LX/lh gbic module, applicable to single-mode optical fiber SMF ), the maximum transmission distance is 10 km; the fourth is 1000Base-ZX GBIC. It is applicable to long-wave single-mode optical fiber. The maximum transmission distance is 70 km ~ 100 km.

Figure 1 000Base-T GBIC Module

Figure 2 1000Base-SX GBIC Module

The GBIC module is installed in the GBIC slots of the Gigabit Ethernet module to provide gigabit connections to other switches and servers. 3 shows GBIC installed in the Cisco Catalyst 4006 Gigabit Ethernet module.

Figure 3 GBIC module installed in the GBIC Slot

◆ Stacked GBIC Module

The stacked GBIC module is used to implement cheap gigabit connections between switches. 4 shows the GigaStack GBIC stack module for Cisco Catalyst 2950/3550. It should be noted that GigaStack GBIC is specially used for the Gigabit stacking between switches, and the connection between GigaStack GBIC uses a dedicated stacked cable.

Figure 4 Cisco GigaStack GBIC stack module and Cable

2) SFPSFPSmall Form-factor Pluggables) can be simply understood as an upgraded version of GBIC. SFP Module 5) is half the size of the GBIC module. You can configure more than twice the number of ports on the same panel. The SFP module is basically the same as that of GBIC. Therefore, it is also called a miniaturized GBICMini-GBIC by some switch manufacturers ).

Figure 5 SFP Module

2. Switch Stack

Switches that provide stack interfaces can be connected through dedicated stack lines. Generally, the stacked bandwidth is dozens of times the speed of the switch port. For example, for a Mbps switch, the bandwidth between the two switches can reach hundreds of megabytes or even Gbit/s. The stacking of multiple switches is achieved by connecting a multi-port stacked parent module that provides backplane bus bandwidth with a single-port stacked sub-module, and inserting different switches to stack switches.

However, not all switches support stacking, depending on the brand of the switch, or even whether the model supports stacking.

Stacking requires not only dedicated stacking cables, but also dedicated stacking modules, such as Cisco GigaStack GBIC. In addition, switches in the same stack must be of the same brand. Otherwise, there is no way to stack switches. Therefore, if you are planning to expand the port through stacking, you must make a purchase plan in advance.

The stacking of switches is the quickest and most convenient way to expand ports. Stack has many advantages, including the following:

◆ High-density Port

Vswitches of different brands support different layers. Generally, at least two layers can be stacked, and at most eight layers can be stacked. Therefore, it can provide hundreds of ports for intensive computer networks in a small space.

◆ Ease of Management