MR57 Dual Uplink, PoE Redundancy and High Availability
Overview
MR57 has two Ethernet ports and can support 802.3af/802.3at/802.3bt/UPoE with link aggregation.
There are three PoE operation modes:
- Single PoE: Only one Ethernet port receives PoE.
- Dual PoE
- Power Sharing mode: Both Ethernet ports receive PoE. The power is split on both ports, not necessarily even.
- High Availability mode: Both Ethernet ports receive PoE. If PoE on one of the Ethernet ports fails, MR57 will seamlessly switch to the remaining Ethernet port without adversely affecting wireless clients' connectivity.
Note: Minimum firmware support for Dual Uplink High Availability is MR 30.1
Note: For more options on power sourcing refer to the MR57 installation Guide.
Power-Sharing
In Power Sharing mode, the power draw is not split equally among the two PoEs. MR57 tends to draw more power from the PoE with higher voltage. For example, if MR57 is connected to two 802.3af PSE ports and draws 23W in total, MR57 could draw more than 802.3af power from one PoE port (18W) while little from the other (5W). Some switch ports might shut down the port if the PD draws more power than the switch support, and MR57 will reboot. To solve this problem, MR57 needs to set the maximum power draw from the PSE depending on the classified PD type or LLDP/CDP negotiation results. In the event of a link failure, the MR57 will switch its primary uplink to the secondary port. For this to happen MR57 needs to be configured with Link Aggregation (regardless of upstraem LACP configuration being enabled/disabled) which is the default mode of operation.
High Availability
In High Availability mode, the MR57 can switch between the ethernet ports without rebooting or dropping any wireless clients. This high availability allows for seamless failover from the primary to the secondary uplink port. The MR57 has dual ethernet ports ETH0 and ETH1 with separate assigned MAC addresses. In High availability, the MR57 will check the link state of the redundant interface every 5 seconds. In the event of a link failure, the MR57 will switch its primary uplink to the secondary port. For this to happen MR57 needs to be configured with Link Aggregation (regardless of upstraem LACP configuration being enabled/disabled) which is the default mode of operation.
Note: Power sharing mode is the default mode of the MR57. When High Availability is configured, the power is not shared between links. If an MR57 uses High Availability and both ports receive 802.3at, the MR57 will register a single 802.3at power source. Reference the required power source combinations for operation in the table below.
|
PoE0 |
PoE1 |
2.4GHz |
5GHz |
6GHz |
Scan |
IoT |
USB |
|
AF |
AF |
Not Supported and AP does not power up |
|||||
|
AT |
AT |
4x4 |
4x4 |
4x4 |
ON |
ON |
OFF |
|
AT |
BT |
4x4 |
4x4 |
4x4 |
ON |
ON |
ON |
|
BT |
BT |
4x4 |
4x4 |
4x4 |
ON |
ON |
ON |
Link Aggregation
When using both ports of the access point for uplink/PoE link aggregation must be enabled on the access point. This allows the MR57 to monitor the link operational state of the secondary port.
Please refer to this link for additional information on configuring link aggregation on MRs.
Warning: Please note that port profiles and link aggregation on 2-port APs are mutually exclusive features. If you have a default port profile meant for your MR30H in the network you have to unassign this port profile from MR52/MR53/MR53E/MR84/MR57 (if applied by default) before link aggregation can be enabled on these models. For more information on port profiles please refer to AP port profiles documentation.
Warning: If both AP ports are connected to the same upstream infrastructure, link aggregation must always remain enabled on the AP configuration. Disabling link aggregation in this scenario can lead to network instability and degraded performance. This requirement applies regardless of whether LACP is enabled or disabled on the upstream infrastructure.
Configuration
Supported LACP Configurations
|
Setup |
AP Port setup |
AP port profile |
AP Link Aggregation |
Switch/ Switchstack LACP |
Uplink Failover (Physical link loss) |
|
1 |
EHT0 & ETH1 To same switch/ switch-stack |
No |
Enabled |
Enabled |
Yes |
|
2 * |
EHT0 & ETH1 To different or same switches/ switch-stacks |
No |
Enabled |
Disabled |
Yes
|
* Note: When utilizing Setup 2 with NAT mode SSIDs only that block local LAN access (Deny local LAN), if the access point cannot reach the cloud or its gateway through its primary port/uplink despite the physical link remaining active, the access point may periodically attempt to restore connectivity by reinitializing. During this process, the access point may send DHCP or ARP packets over the secondary link with the same source MAC address. This behavior could lead to temporary MAC flap events upstream, which should resolve once upstream connectivity is restored.
Power Mode Selection
- Mode selection can be made on the AP details page Wireless > Monitor > Access points.
- Select the MR57
- Within the Access point view page, change the Ethernet Power Mode to High Availability.
- Save the configuration
Note: Power sharing mode is the default mode of the MR57. When High Availability is configured, power is not shared between the links. For example, if two ports receive 802.3at, AP operates on a single 802.3at. Refer to the above power distribution.
Table summary of expected outcomes when LACP is enabled/ disabled on the AP operating either in Power sharing or High Availability mode.
|
AP port setup |
AP Link Aggregation | Ethernet Power Mode | Use case |
| Connected to same or different switch/switch-stack | Enabled | Power Sharing | Additional power is required. |
| Connected to same or different switch/switch-stack | Enabled | High Availability | Power and Data Redundancy. |
| Connected to same or different switch/switch-stack | Disabled | Power Sharing | No benefits, feature is disabled. |
| Connected to same or different switch/switch-stack | Disabled | High Availability | No benefits, feature is disabled. |