Network-Engineering | 2 min read

Mitigating EX2300 Ethernet Switch constraints

ngworx Team
January 2020
written by Pietro Stäheli
Network & Security Engineer

After helping multiple customers with constraints on the EX2300 and EX3400 line of Juniper switches, we’ve decided to document the most common problems and applicable solutions related to these devices.

Lack of storage space for a JunOS SW upgrade

On EX2300/3400 products, the limited size of flash storage and the growing storage requirements for JunOS require special care when doing SW updates from JunOS release 18.1 and later.

Several Juniper knowledgebase articles offer solutions:

  • Article 1: [EX] Insufficient space and how to successfully upgrade Junos on EX2300/EX3400 in a Virtual Chassis environment
  • Article 2: Not enough storage while upgrading Junos EX2300 and EX3400

If you are looking for a workaround, you might also find our blog on that subject interesting. Click here to check it out!

With EX2300-MP products, this is no longer a concern, as these devices have a substantially larger internal flash memory.

The switch might stop forwarding traffic or responding to console

At some point, after over a week of uptime, the following symptoms might appear:

  • The switch does not respond to ping, SNMP requests, or SSH
  • No output on the console port
  • DHCP requests are not answered
  • Devices that are connected after the switch goes into the problematic state do not work, while devices that were previously connected may continue to work
  • LACP aggregated ethernet interfaces go down, but devices with a single link continue to work

This issue can only be recovered by power cycling the switch.


Upgrade to 18.2R3-S2 or newer. The issue is resolved in the following versions:

  • 18.3R3-S1
  • 18.2R2-S6
  • 18.4R3
  • 19.2R1-S2
  • 18.2R3-S2
  • 18.4R2-S3
  • 18.4R1-S5
  • 17.4R3
  • 18.3R2-S3
  • 19.1R3
  • 19.2R2
  • 19.3R2
  • 19.4R1

The related PR can be found here.

  • Article 3: EX2300-48T Stop working after random time after upgrade to 19.1R1.6
  • Article 4: EX2300 losing port aggregation, losing console, and not accessible; hard reboot is only fix

LACP flaps

According to the most recent Juniper documentation, LACP on EX2300/3400 must be configured with periodic SLOW timer to keep the CPU from being overloaded, causing flaps on AE interfaces.

  • Article 5: Configuring Aggregated Ethernet Interfaces and LACP

High CPU usage

If your network design requires large broadcast domains, e.g. for wireless roaming between APs in a campus network, check if the CPU is handling large amounts of multicast traffic. High CPU load may cause instability to LACP interfaces, or the switch itself.

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ngworx Team
January 2020
written by Pietro Stäheli
Network & Security Engineer

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