To ensure a safe and stable configuration process, Meraki implements several specific mechanisms to ensure devices maintain a valid and functional configuration.
Config-Safe Mechanism
MS switches, like other Meraki devices, use a configuration fail-safe mechanism to ensure that the device is easily recoverable if a bad configuration is pushed that may impact device stability or connectivity. For MS devices, there are two important scenarios where this becomes relevant:
• 30-minute fail safe for new switch configuration: When configuring a new switch, any changes made to the configuration are marked as safe only after the switch operates stably for 30 minutes. If the switch loses extended connectivity to the Dashboard or experiences other major connectivity issues within this period, the changes will automatically revert to the previous known safe configuration.
• Two-hour safe marking after firmware upgrade: After a firmware upgrade, any configuration changes made on the switch are marked as safe after two hours of stable operation. If extended dashboard connectivity to the switch is lost during this time, the device will power cycle and force a rollback to the last known good configuration.
Auto-Rollback on Bad Uplink
In the case of a bad uplink configuration on a Meraki switch, a Dashboard alert is displayed, like that shown in Figure 7-33. If the switch encounters a bad uplink configuration, it will try to obtain an IP address from an alternate VLAN. This allows the switch to establish a stable network connection and maintain connectivity.
Figure 7-33 Dashboard Alert Resulting from a Bad Static Uplink Configuration
If the switch does not achieve stable operation within two hours after the loss of connectivity, it will automatically revert to the previous safe configuration. This rollback ensures the switch returns to a known good state and minimizes potential extended disruptions.
After reverting to the safe configuration, the previous configuration that led to the bad uplink will be marked as bad. This helps identify and track problematic configurations for future troubleshooting or analysis.
Pro Tip
These resiliency features are built into Meraki switches, as well as other Meraki platforms, to help maintain network stability and mitigate the impact of bad uplink configurations.
MS PoE Budget
When PoE devices are connected to the ports of Meraki-managed PoE-capable switches, the ports on the switches are typically labeled with a lightning bolt symbol (see Figure 7-34). This symbol serves as an indicator that power is being supplied from the switch (called power sourcing equipment [PSE] in PoE terminology) to the connected, powered devices (PDs).
Figure 7-34 Active PoE Ports as Shown on the Meraki Dashboard
In a Meraki switch, the PoE power budget is determined based on the classification of the PoE devices connected to it. For switches other than the MS390 and Catalyst 9300-M, the power budget can exceed the available power on the switch, as the budget serves as an estimation of the overall power consumption that might occur. However, it is important to note that devices will continue to be powered until the total power consumption exceeds the available power. For the MS390 and Catalyst 9300-M, power will be supplied until the budgeted power reaches the PoE capacity of the switch. In either case, the switch will begin to prioritize power allocation if the total power requested surpasses the available power. When this happens, the lowest port numbers will take precedence, meaning power will first be supplied to the devices connected to these ports. As the power budget is exhausted, the switch will continue to provide power to lower port numbers while denying power to devices connected to higher port numbers.
PoE consumption on the switch can be monitored live from the Dashboard, including consumption, budgeting values, and port-specific information, by selecting a specific port and scrolling to the Status section, shown in Figure 7-35.
Figure 7-35 Live PoE Consumption for a Switch Port
If your switches support power supply bonding or stacking, consider leveraging these features to increase PoE+ budgeting. Power supply bonding or stacking allows you to combine the power capacity of multiple power supplies or switches, providing additional power for PoE+ devices such as IP phones, wireless access points, and security cameras.
MS Power Overview
In Meraki switches, the Power Overview section provides comprehensive information about the power usage and distribution within a switch or a stack of switches. As Figure 7-36 shows, the Power Overview section displays detailed information about the power utilization of each switch. It includes data such as the power budget and the maximum power available for devices connected to the switch. The actual power consumption by connected devices is also shown, allowing you to monitor and manage power usage.
Figure 7-36 Power Overview and Stack Power Information in the Dashboard
The StackPower feature (currently available on Meraki MS390 and Catalyst 9300-M) aggregates all the available power from each switch and manages it as a single shared power pool for the entire stack of up to four switches. This means that the power budget for the stack is effectively shared among all the switches, optimizing power distribution and utilization within the stack.
The Power Overview section provides insights into the actual power consumption of devices connected to the switches compared to the budgeted power. This allows you to monitor whether the power usage is within the allocated budget or exceeds the available power.
