This community is currently under full moderation, meaning  all posts will be reviewed before appearing in the community. Please expect a brief delay—there is no need to post multiple times. If your post is rejected, you'll receive an email outlining the reason(s). We've implemented full moderation to control spam. Thank you for your patience and participation.

Expand all | Collapse all

Link Aggregation - EX4300 to Ubiquiti UniFi

  • 1.  Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-27-2021 14:17
    Hi All,

    Fairly new to Juniper - I am having some problems setting up Link Aggregation.

    I am connecting 2x EX4300-48T in a Virtual Chassis to a single Ubiquiti UniFi switch (after testing, there will be multiple).

    I've set the 2x 10GbE ports on the UniFi to Link Aggregation and set the port profile to "All" (which is all VLANs).

    On the EX4300 I've created a new link aggregation group, named ae0 in switching mode on xe-0/2/0 and xe-1/2/0 (so one 10GbE goes to the FPC0 and the second goes to FPC1). The purpose is so if one of the two VC's goes down the LACP should continue to pass traffic uninterrupted.

    The LACP is showing as Up;

    root# run show interfaces terse | match ae0
    xe-0/2/0.0 up up aenet --> ae0.0
    xe-1/2/0.0 up up aenet --> ae0.0
    ae0 up up
    ae0.0 up up inet

    It's also reporting the LACP as up on the UniFi switch.

    The problem I am having is two-fold.

    Problem 1
    If I set ae0 as a trunk and specify the VLAN members no traffic passes from the UniFi switch. If I change it to access mode then it will pass traffic. But that's no good as it will only pass traffic for one VLAN as that's all that can be selected for an access port of course.

    Problem 2
    Regardless of the VLAN mode mentioned in problem 1, if one of the two links is disconnected the LACP stops traffic flow and goes down. I thought the purpose by design was to continue passing traffic if one of the link members goes down.

    I've tried the device count as 1 and 2 to see if helped, but it didn't.

    I bet this is a simple one, but appreciate any help/advise on this. Thanks!


  • 2.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-27-2021 15:17
    Hi Richard:

    I am not familiar with Ubiquiti UniFi switches, but a simple thing, do you have minimum-links 1 configured under interfaces ae0 aggregated-ethernet-options?



  • 3.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-28-2021 05:18
    Thanks Stuart - I had mistakenly set the minimum-links to 2 (due to my inexperience I thought that just meant the actual number of links in the LACP). That's resolved the issue with it going down when one of the two links is disconnected - I just need to now get it to work in trunk mode rather than access mode.


  • 4.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-28-2021 00:39
    Can you post relevant configs from both devices, as well as 'show lacp interfaces ae0 extensive' from the Juniper device?

  • 5.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-28-2021 06:20
    Just tried that command but it wouldn't have it - However see below the output from "show interfaces ae0"

    root# show interfaces ae0
    native-vlan-id 1;
    aggregated-ether-options {
    minimum-links 1;
    lacp {
    unit 0 {
    family ethernet-switching {
    interface-mode trunk;
    vlan {
    members [ BackupVLAN BuildVLAN GuesWiFiVLAN ManagementVLAN PublicHostingVLAN SecurityVLAN StaffWiFiVLAN ];

    The UniFi switch I can't post any config as it's all done via a GUI - Really quite simple - You just select a port and tick it as aggregate, then enter the "from and to" port numbers, e.g. port 23 to 24 and that's it. I've looked online at tutorials and from what I can see that's all you need to do.

    The LACP is actually working though - It's just not passing the VLANs properly.

    The only thing to note, the above config shows the VLAN names (not the ID's) that I entered into the Juniper, but these are not named "exact" the same as on the UniFi system - however the VLAN ID's are the same.


  • 6.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-28-2021 09:51
    Hi Richard,
    Just to confirm the LACP LAG is up properly what do these commands show:
    show lacp interfaces ae0
    show interfaces ae0 statistics 
    show interfaces ae0 extensive

    Looking at the config on your ae the native vlan is 1 so all of your other vlan traffic will need to be tagged. I'm assuming the unfi does that, but sometimes the more simple switches do some strange things :p


  • 7.  RE: Link Aggregation - EX4300 to Ubiquiti UniFi

    Posted 05-28-2021 12:46
    Thanks Allyn.

    For some reason this started to work - passing VLAN traffic properly. I think all I did was include the default VLAN in the members list for the LACP as well as specifying it for the native VLAN. Before I was only specifying the native VLAN as the default VLAN, and not including it in the members list. Looks like it's all working though.

    I ran the commands suggested and all looks ok - no errors or dropped packets etc - I am going to continue doing some tests but looks like it should be ready to go into production soon.

    Thanks everyone for their help on this :)