Dell PowerConnect series LAG & LACP configuration

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Dell PowerConnect series LAG & LACP configuration

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I am having trouble understanding how Dell's LACP works with LAG. I mean, I do understand, but let me explain my situation. I have started at a company which has several Dell PowerConnect switches. Each floor has a core Dell switch and they all have LAG enabled on the switch. We have two newer models (Dell PowerConnect 5448 & 5324), and then some older models (PowerConnect 2748 & 2824).

The 5448 & 5324 support LACP to aggregate the ports to a LAG. However, the company is using LAG configurations between all of these switches. So between the newer models and the older models, LAG is enabled, but it is impossible to enable LACP.

What is the advantage of having all the switches have LACP enabled on the LAG configurations? Is there a problem enabling LAG between the two with LACP? Of course the 5448 & 5324 have both LACP & LAG enabled. I guess I am asking, what is the difference between having LACP enabled and not having it enabled? Especially since this network is mixed with some supporting both (which are enabled), and then the newer and older switches setup on with LAG (since LACP is not supported on the older models).

Verified Answer
  • LACP provides protection against mis-cabling.

    It also provides logical link indication.  For example, if two switches are connected via a LAG with LACP enabled and one of the switches crashed but physical link did not drop, then at the end of the LACP timeout the switch that is still up would declare the link disconnected.   If the two switches were connected via a static LAG and one crashed without bringing down physical link, there would be no indication to the running switch that the LAG was now connected to an non-functional switch.

All Replies
  • LACP provides protection against mis-cabling.

    It also provides logical link indication.  For example, if two switches are connected via a LAG with LACP enabled and one of the switches crashed but physical link did not drop, then at the end of the LACP timeout the switch that is still up would declare the link disconnected.   If the two switches were connected via a static LAG and one crashed without bringing down physical link, there would be no indication to the running switch that the LAG was now connected to an non-functional switch.

  • Thank you so much! I appreciate it. That explains my whole confusion. In the help section on the OpenManage interface of the switch, it mentioned a little bit of that, but I appreciate a clear answer.  Thank you.

  • Why does the Manual for the 28xx series show LACP support? Doesn't that include Dynamic Link Aggregation?

    I am trying to determine the best mode for link bonding for a PowerEdge 2950 running PROXMOX to a PowerConnect 2824.

    Proxmox is Debian-Based and here are the modes:

    http://www.debianhelp.co.uk/bonding.htm

    Thanks.