PTP820C/S and LACP

Hi all,

I wanted to share a recent lesson learned involving PTP820C/S and LACP. Basically, PTP820C/S supports LACP for HSB, but for data aggregation we must configure the switches that the PTP820 radios connect to for static LAG and not LACP. 

LACP is only supported on PTP820C/S for the purpose of line protection 1+1/2+2 HSB.

If the customer would like to aggregate two ports from the same unit, only Static LAG can be used. This requires:

- no LACP config on the unit ---> only LAG group with the two physical ports;

- setup static LAG on the switch --> LACP should be disabled;

- disable stp/mstp on the switch ports connected to the unit;

PTP820C/S LACP will work with Cisco LACP for HSB if configured properly.

In order to do this:

  1. Configure the GE ports on the external switch in LACP mode. The external switch (Cisco) must support LACP.
  2. Connect one port on the external switch to an Ethernet port on the active PTP820, and the other port on the external switch to an Ethernet port on the standby PTP820.
  3. Enable LACP on the Ethernet interface connected to the external switch on the active PTP820:
  4. Select Ethernet > Interfaces > Logical Interfaces. The Logical Interfaces page opens.
  5. Select the interface and click Edit. The Logical Interfaces – Edit page opens.
  6. In the Interface Mode field, select LACP
  7. Click Apply, then Close.

Otherwise, the PTP820C/S will not respond to Cisco LACP negotiations. LACP works by sending frames (LACPDUs) down all links that have the protocol enabled. If it finds a device on the other end of the link that also has LACP enabled, it will also independently send frames along the same links enabling the two units to detect multiple links between themselves and then combine them into a single logical link.

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Very helpful!