Description

Question raised on whether MX304 with LMIC16 supports 1G copper SFP optics, specifically PN 740-013111.

Confusion arose because MX301 (half of MX304, same chipset family as LMIC16) appears to support 1G Cooper SFP, suggesting LMIC16 might have equivalent support or scheduled qualification.

Symptoms

1G copper SFP (PN 740-013111 or equivalent) inserted into LMIC16 port on MX304 fails to come up / no link.

Sometimes chassis alarms reports Multiple PIC errors alarms

Interface stays down, no auto-negotiation, or PHY not detected

PHY could be detected but TX does not works.

Optic may be recognized at inventory level but link does not establish.

Behavior persists regardless of cable, peer device, or port selected on LMIC16

Same 1G Cu SFP works as expected on MX301 (or other platforms with Cooper-capable HW), reinforcing that the issue is LMIC16-specific and not optic/cable related

After installing 25.4R1 interface can work but we haven't qualified 1G Cooper SFP, so if it fails of have issues, Juniper/TAC may not support.

Supported plaftorms are listed here:


https://apps.juniper.net/hct/model/SRX-SFP-1GE-T/supported-platforms



Solution

LMIC16 on MX304 does not support 1G copper SFP optics, including PN 740-013111


  • 1G Cu SFP was not a day-1 requirement for LMIC16 >>> HW not designed to accommodate copper PHY
  • EMC qualification for copper optics has not been performed on LMIC16
  • No qualification testing currently scheduled for LMIC16 + 1G Cu


Modification History

2026-05-15 : Article Created