2017 Microchip Technology Inc. DS00002577A-page 1
INTRODUCTION
Microchip’s family of gigabit Ethernet switches have powerful capabilities that may be enabled using various methods
of configuration. Depending on the features needed in the network application, there are four primary methods to con-
figure these switches. This application note describes available switch configuration methods and options with their
associated trade-offs, allowing the developer to choose the best method for their application.
The following configuration options are available (applicable Microchip parts):
• Configuration Straps (KSZ9896C, KSZ9897R, KSZ9897S)
• Microcontroller Configuration (KSZ9897R, KSZ9897S)
•Ethernet In-Band Access (IBA) Configuration (KSZ9897R, KSZ9897S)
• Host Processor Configuration (KSZ8567R, KSZ9897R, KSZ9897S, KSZ9567R, KSZ9567S, KSZ9477S)
TABLE 1: AVAILABLE CONFIGURATION METHODS PER FEATURE - REFERENCE TABLE
Basic
Auto-Neg
EEE
VLAN
QoS
IEEE
1588 v2
802.1x
Security
ACL
PME
WoL
AVB
DLR/HSR
Config. Strap X X
8-bit MCU X X X X X X X X X X
IBA XXXXX X
Host Processor X X X X X X X X X X X X
Note: The user should take note of the difference between switch configuration mode and switch management
mode. Switch management mode provides the added ability to send and receive Ethernet frames during
normal operation. Switch configuration mode does not provide this ability.
CONFIGURATION STRAPS
The configuration strap option is a hardware method to configure the switch where pull-up or pull-down resistors are
used to set the logic level high or low on strapping pins of the switch. For example, the KSZ9896C has several strapping
pins with internal weak pull-up or pull-down resistors which allow the switch to operate in the unmanaged mode. A user
can add 1KΩ to 10KΩ external pull-up resistors on non-LED pins, or 750Ω to 1KΩ pull-down resistors on LED strapping
pins to override the effect of the weak internal resistors.
The strapping pins exhibit very high impedance when the device is in reset. They are internally sampled at the rising
edge of the reset pin, RESET_N. Once the RESET_N pin is high, all of these pins become driven outputs.
The user must be aware that the internal pull-up/pull-down resistors are weak. Therefore, if the application board uses
any external pull-up or pull-down resistors, care must be taken. If an external processor is connected with a switch, the
processor should also be checked for internal pull-ups or pull-downs, and it may be necessary to add an external resistor
to reinforce the default internal resistor of the Microchip switch. The KSZ9xxx family’s datasheet lists all the strapping
pins, their functionalities and default values.
AN2577
Getting Started with Gigabit Ethernet Switch
Configuration Options
