Description

Customer has configured a gre tunnel between two endpoints with a static route configured to include the same destination IP as what is defined in the gre tunnel destination. Upon doing this, the links are seen flapping.

Symptoms

Customer has the following configuration used for a gre tunnel:

 

set interfaces gr-0/0/0 unit 0 description DC-FRA-to-DC-AMS
set interfaces gr-0/0/0 unit 0 point-to-point
set interfaces gr-0/0/0 unit 0 tunnel source 192.168.1.100
set interfaces gr-0/0/0 unit 0 tunnel destination 192.168.1.101
set interfaces gr-0/0/0 unit 0 family inet mtu 1476
set interfaces gr-0/0/0 unit 0 family inet address 172.16.248.1

 

Customer also has the following static route configured with the destination IP the same as what's configured under the gre tunnel destination.

 

set routing-options static route 192.168.1.101/32 next-hop gr-0/0/0.0

 

Following adding the aforementioned configuration, we see a plethora of link flaps for gr-0/0/0.0:

 

Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_UP: ifIndex 535, ifAdminStatus up(1), ifOperStatus up(1), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_DOWN: ifIndex 535, ifAdminStatus up(1), ifOperStatus down(2), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_UP: ifIndex 535, ifAdminStatus up(1), ifOperStatus up(1), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_DOWN: ifIndex 535, ifAdminStatus up(1), ifOperStatus down(2), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_UP: ifIndex 535, ifAdminStatus up(1), ifOperStatus up(1), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_DOWN: ifIndex 535, ifAdminStatus up(1), ifOperStatus down(2), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_UP: ifIndex 535, ifAdminStatus up(1), ifOperStatus up(1), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_DOWN: ifIndex 535, ifAdminStatus up(1), ifOperStatus down(2), ifName gr-0/0/0.0
Jul 8 10:25:15 firewall mib2d[24750]: SNMP_TRAP_LINK_UP: ifIndex 535, ifAdminStatus up(1), ifOperStatus up(1), ifName gr-0/0/0.0

Solution

Following removal of the offending static route, the link flaps ceased.


This is expected behavior. Please ensure that you have the correct route configured.

Modification History

2026-07-09 : Article Created