This would be a bug which Juniper refers to as PR (Problem Reports). You can open an official ticket with JTAC to find out if it is known yet or new to report. Once identified you can find out from the database which version of Junos will have the fix.
Searching the current PR database shows a fair number with LACP in the description somewhere so it might not be easy to identify without a ticket.
https://prsearch.juniper.net/home?stype=affectingthis&ostype=junos&sid=EXSeries-junos&bv=23.4R2-S5&uv=&qt=lacp
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Steve Puluka BSEET - Juniper Ambassador
IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
http://puluka.com/home------------------------------
Original Message:
Sent: 10-06-2025 07:51
From: Boris Mekler
Subject: EX4650 LACP not coming up after upgrade to 23.4R2-S5.8
The settings didn't change, aggregated-devices ethernet device-count was set to the amount of aggregated links on the chassis, MTU is matching on both sides. The issue has been resolved by downgrading from 23.4R2-S5.8 to 23.4R2-S4.11.
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Boris Mekler
Original Message:
Sent: 10-06-2025 00:57
From: SURAJ SINGH
Subject: EX4650 LACP not coming up after upgrade to 23.4R2-S5.8
Hi,
Please check if below command is available in your configuration. If not please add and check. Also you configured the MTU size please match MTU @both end.
set chassis aggregated-devices ethernet device-count 10
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Suraj
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SURAJ SINGH
Original Message:
Sent: 10-04-2025 22:22
From: Boris Mekler
Subject: EX4650 LACP not coming up after upgrade to 23.4R2-S5.8
Pair of EX4650s in virtual chassis, three ports are configured in link aggregation and connected to ISP layer 2 point to point links. Other side is an Alcatel-Lucent OS6900-X48C6. Config excerpt:
interfaces { xe-0/0/8 { ether-options { 802.3ad ae2; } } xe-1/0/8 { ether-options { 802.3ad ae2; } } xe-1/0/9 { ether-options { 802.3ad ae2; } } ae2 { mtu 9216; aggregated-ether-options { lacp { active; } } unit 0 { family ethernet-switching { interface-mode trunk; vlan { members [ 10 20 30 ]; } } } }
Prior to upgrade (running 21.4R3-S3.4) it was working fine. After upgrading to the current recommended version (23.4R2-S5.8), the ae2 interface is down (other AEs are working, only this one is affected). The members are up, and I can see the other side's LLDP info on them, but they are not joining the aggregate. As a temporary workaround, I have removed one of them from the aggregate and configured it as a standalone VLAN trunk (on both sides), and traffic is flowing, so the link itself is fine. What steps can be taken to troubleshoot this?
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Boris Mekler
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