A pair of SNMP link up and down traps is seen on an unused ge- interface that is down and has no SFP/cable connection.
This is rare, but it can happen with ge- ports on NEO MIC[3D 20x 1GE(LAN) SFP] in MX5/10/40/80/104 platforms or MPCE/MPC2E in other MX platforms.
SNMP link up/down trap is reported on an unused ge- interface that is down and has no SFP/cable connection.
User@MX> show chassis hardware
Hardware inventory:
Item Version Part number Serial number Description
FPC 1 BUILTIN BUILTIN MPC BUILTIN
MIC 0 REV 24 750-028392 xxxxxxx 3D 20x 1GE(LAN) SFP
PIC 0 BUILTIN BUILTIN 10x 1GE(LAN) SFP
PIC 1 BUILTIN BUILTIN 10x 1GE(LAN) SFP
Fan Tray Fan Tray
*** messages ***
Sep 19 08:50:51 MX rpd[1731]: EVENT <UpDown> ge-1/1/2 index 152 <Up Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:51 MX rpd[1733]: EVENT <UpDown> ge-1/1/2 index 152 <Up Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:51 MX rpd[1732]: EVENT <UpDown> ge-1/1/2 index 152 <Up Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:51 MX rpd[1730]: EVENT <UpDown> ge-1/1/2 index 152 <Up Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:51 MX rpd[1702]: EVENT <UpDown> ge-1/1/2 index 152 <Up Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:51 MX mib2d[1698]: SNMP_TRAP_LINK_UP: ifIndex 532, ifAdminStatus up(1), ifOperStatus up(1), ifName ge-1/1/2
Sep 19 08:50:52 MX rpd[1731]: EVENT <UpDown> ge-1/1/2 index 152 <Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:52 MX rpd[1733]: EVENT <UpDown> ge-1/1/2 index 152 <Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:52 MX rpd[1732]: EVENT <UpDown> ge-1/1/2 index 152 <Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:52 MX rpd[1730]: EVENT <UpDown> ge-1/1/2 index 152 <Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:52 MX rpd[1702]: EVENT <UpDown> ge-1/1/2 index 152 <Broadcast Multicast> address #0 40.71.83.f0.a6.8a
Sep 19 08:50:52 MX mib2d[1698]: SNMP_TRAP_LINK_DOWN: ifIndex 532, ifAdminStatus up(1), ifOperStatus down(2), ifName ge-1/1/2
User@MX > show interfaces ge-1/1/2 media
Physical interface: ge-1/1/2, Enabled, Physical link is Down
Interface index: 152, SNMP ifIndex: 532, Generation: 155
Description: to kopt secoundary_spare
Link-level type: Ethernet, MTU: 1514, MRU: 1522, LAN-PHY mode, Speed: 100mbps, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled, Remote fault: Online
Pad to minimum frame size: Disabled
Device flags : Present Running Down
Interface flags: Hardware-Down SNMP-Traps Internal: 0x0
Link flags : None
CoS queues : 8 supported, 8 maximum usable queues
Hold-times : Up 0 ms, Down 0 ms
Damping : half-life: 0 sec, max-suppress: 0 sec, reuse: 0, suppress: 0, state: unsuppressed
Current address: 40:71:83:f0:a6:8a, Hardware address: 40:71:83:f0:a6:8a
Last flapped : 2018-09-19 08:50:52 JST (8w6d 12:47 ago)
Input rate : 0 bps (0 pps)
Output rate : 0 bps (0 pps)
Active alarms : LINK
Active defects : LINK
The issue is that only this port (ex. ge-1/1/2) has link flapping occasionally, while other ports are okay. Electrical noise can trigger this. A possibility can be noisy hardware somewhere (around ge-1/1/2) on the board.
Without the SFP plugged in, there could be noise on the input that could change the "partner ability" register for auto negotiation. If a certain short sequence of bits is received, then the "partner ability" register can be updated (/C/ character), hence the fake link up/down event.
This link up/down snmp trap is only cosmetic, and can safely be ignored. Disabling the interface can be a workaround.
RMA is not necessary for rare occurrences, but MIC RMA is recommended for frequent occurrences.
2018-12-18: Minor, non-technical edit.
2020-08-03: Fixed typo in the cause section.