LAG fails

Zakman Posts: 5  Freshman Member
edited April 2021 in Switch
I have 3 switches in the my company office. Old ProCurve 1800-24G and about one year old GS1900-24E and GS1900-8HP. Because of increasing traffic in the office I need more speed between switches.Therefore I tried to create 2 connections between switches to double the switch<->switch speed to 2Gbps.

First I created LAG1 in 8HP (p.7-8), Trunked ports in 24G (p. 23-24) and made LAG1 and LAG2 in 24E (p.21-22, p. 23-24). LACP off. Loop Guard off. No spanning tree. I saved the setups and turned off the switches. Then I connected the cables accordingly to ports and switched everything on.

What happens was that after boot process all traffic lights start to blink rapidly and network does not work. There was a loop? Power off from all and 2nd cable off. Everything works again BUT VERY strange effect on 24E. It was RESET to factory default !!  It took me some time to realize the reason why I could not connect to IP of the 24E. IP was changed back to default like all other settings in 24E.  I tried this again and same thing. How can 24E RESET to FACTORY DEFAULTS from this setup !?!

All firmwares are the newest available in Zyxel and HP sites.

My business is not related to IT networking and therefore knowledge of aggregated/trunked networking in switches is a bit new.

What am I doing wrong here?  Anyone help me out with this one? 


  • JasonTsai
    JasonTsai Posts: 104  Zyxel Employee
    edited September 2017
    Hi @Zakman,

    Welcome to Zyxel community!

    Is your topology like below:
    [GS1900-8HP]=========[GS1900-24E]=========[HP ProCurve 1800-24G]
    If not, please provide me your topology of your network.

    Please help me verify the following procedure to reproduce your issue:

    1. Follow user guide to create LAG1 on GS1900-8HP, LAG1 and 2 on GS1900-24E, trunked(LAG) ports on HP switch. (Those no cable on ports)
    2. Save configuration complete on three switches.
    3. Turn OFF three switches and connect cable accordingly to ports.
    4. Turn on three switches.
    Symptom: After three switches boot complete, the link have Broadcast Storm(Loop) in the network and GS1900-24E is reset to factory default.

    Here is the Link to download the User Guide for GS1900-8HP and GS1900-24E.
    You may find the information to configure Link Aggregation begin from P.129.

    The screenshot below is to create LAG in the Link Aggregation configuration page:

    This will help me to understand your issue and give more support for you.
  • Zakman
    Zakman Posts: 5  Freshman Member
    Thanks Jason for the fast reply.

    Yes, the topology is
    [GS1900-8HP]=========[GS1900-24E]=========[HP ProCurve 1800-24G]
    2 cables in 8HP and in 24G and 4 cables in 24E.

    Yes I did the procedure. Because of this reset effect I tried to do the both ways - 1) using Link Aggregation wizard in the front page and 2) "manually" from LAG configuration page. Both ways result to the same - after switch on all lights in all switches blink fast and after shutting the power down from switches 24E is reset to factory defaults.

    I tried to do the thing the easy way (wizard) but guess I need to do it the hard way = configuring the switch in specific screens. I thought that wizards are normally a shortcut to non-experts but in this case it does not work as expected. Anyway it really should not reset to factory default in any circumstances of normal using !! Only 24E was reset. There were no reset effect in 8HP and 24G.

    The manual says that "properly planned network use static link aggregation only". Do I have to put LACP on to do that?

    Here is the setup in pictures (no aggregation now because it does not work):

    In previous picture I tried to connect different ports and therefore the ports of LAG in the picture are incorrect.

    I will do more testing today/tomorrow if I have time. But my point is that 24E should never be resetted to factory defaults without intention (sw or hw reset button) and wizard should do ask all the necessary components to make a proper network. That was very confusing when network does not work and after undoing the changes cannot connect to one switch.

    There are too many options in the manual for the long learning curve. Is there a more simple approach like how to make a proper basic aggregation setup. I want a simple procedure and as recommended in your manual I want to set it to use static link aggregation.
  • JasonTsai
    JasonTsai Posts: 104  Zyxel Employee
    Hi @Zakman,

    Here is the procedure to simply create static LAG between GS1900-8HP and GS1900-24E in my local test:
    1. PC access to GS1900-8HP(  front page and click the LAG wizard.
    2. Move port 7 and port 8 to Group 1 and click "Next".
    3. Click "Finish" to exit the wizard.
    4. Click "Save" in the front page to save the configuration.
      Note: Please make sure you have saved the configuration before rebooting the switch, or the switch will turn the configuration back to the last save after rebooting.
    5. Do the procedure 1~4 to create LAG1 on port 21 and 22 of GS1900-24E(, and make sure you save the configuration after setting the LAG.
    6. Turn OFF the power of two switches and connect the cable then turn them on.
    7. After boot up,access the switches and go to "Monitor -> Link Aggregation", you may see the LAG status is on properly.
    We are suspecting that maybe you miss to save the configuration on GS1900-24E from last time you reset to default, so when you reboot the switch, it will reset to default configuration.

    You may do the procedure above without HP switch to see if GS1900-24E still reset to default after reboot.

    Hope it helps.
  • Zakman
    Zakman Posts: 5  Freshman Member
    edited September 2017
    Thank you again Jason.

    Yes I did remember to save every change in the system using that link in to top right corner, and yes that was the procedure I followed already in the first time.

    Just to test this out I did the procedure again, and again 24E was reset back to factory defaults.

    BUT I once more tried to boot up the switches one-by-one instead of powering up all switches at the same time. So I powered up 8HP and waited that it is up and running. Next 24E the same thing and last 24G. And voilà - everything works. Previously I powered all switches (the whole setup) up at the same time. Cables, ports and settings has been the same all the time.

    So there is something fishy in 24E when all power up at the same time. So for now everything seems to work. I have not yet tested if 2Gb link is really on. System is stable and LAGs are configured so it should. Is there a software to test the speed if 2Gb link is really on?

    But what really worries me that IF 24E keep on resetting at the whole-system-power-up and IF there happens a power failure in the office, when the power is back all system will power up at the same time and the result probably is that 24E get reset to defaults and it means that the whole network is down until someone fix the 24E. It cannot be so. And the default IP is the same than our system firewall IP which means that there is every time a big job to fix it and works are standing still.

    I still claim that any switch at any price class should not be reset to factory defaults without admin deliberately doing so. If there is an error in the system the way to say it 1) management UI telling so and/or 2) blinking certain code with LEDs. Not just reset the switch to factory defaults.

    What are you Zyxel going to do about this. Send me PM or email that we can figure out what to do.
  • JasonTsai
    JasonTsai Posts: 104  Zyxel Employee
    Hi @Zakman,

    I will PM you for this discussion.