This article will explain a possible scenario where a few OSPF neighbors are stuck in ExStart in collapsed core EVPN setup.
Topology:
192.168.1.20 192.168.1.30 192.168.1.40 +---------+ +---------+ +---------+ | SW2 | | SW3 | | SW4 | +---------+ +----|----+ +-/-------+ \-- | /--- \-- | /-- 192.168.1.10 \-- | /--- 192.168.1.50 +---------+ +--\---|------+ +---------+ | SW1 |---------| L2 switch ----------- SW5 | +---------+ +-------------+ +---------+ | | +---------+ | | +---------+ |EX9253-1 |----+ +----|EX9253-2 | | |--------------| | +---------+ EVPN +---------+ 192.168.1.1 192.168.1.2
A few OSPF neighbors are stuck in ExStart
{MASTER} root@EX9253-1> show ospf neighbor instance all Instance: VRF_JTAC Address Interface State ID Pri Dead 192.168.1.10 irb.100 ExStart 192.168.1.10 128 38 <--- Peer SW1 192.168.1.2 irb.100 Full 192.168.1.2 128 11 192.168.1.20 irb.100 Full 192.168.1.20 128 36 192.168.1.50 irb.100 Full 192.168.1.50 128 11 192.168.1.40 irb.100 Full 192.168.1.40 128 36 192.168.1.30 irb.100 Full 192.168.1.30 255 35
On the peer side, the OSPF is stuck in Exchange state
{master:0} root@SW1> show ospf neighbor instance all Instance: master Instance: JTAC Address Interface State ID Pri Dead 192.168.1.1 irb.100 Exchange 192.168.1.1 252 36 <--- Peer EX9253-1 192.168.1.20 irb.100 2Way 192.168.1.20 128 39 192.168.1.40 irb.100 2Way 192.168.1.40 128 36 192.168.1.30 irb.100 2Way 192.168.1.30 128 32 192.168.1.50 irb.100 Full 192.168.1.50 255 33 192.168.1.2 irb.100 2Way 192.168.1.232 252 39
Clearing, deleting or adding OSPF did not clear this state. Also MTU is discarded
Only when rebooting the second spine (EX9253-2), the OSPF will recover.
Check the configuration for EVPN and if "no-gateway-community" is not configured, add it and check OSPF state.
root@EX9253-1> show configuration routing-instances EVPN1 protocols evpn | display set set routing-instances EVPN1 protocols evpn encapsulation vxlan set routing-instances EVPN1 protocols evpn extended-vni-list all set routing-instances EVPN1 protocols evpn multicast-mode ingress-replication
{MASTER}[edit] root@EX9253-A# set routing-instances VPN1 protocols evpn default-gateway no-gateway-community {MASTER}[edit] root@EX9253-1# run show ospf neighbor instance all Instance: VRF_JTAC Address Interface State ID Pri Dead 192.168.1.10 irb.100 ExStart 192.168.1.10 128 38 192.168.1.2 irb.100 Full 192.168.1.2 128 11 192.168.1.20 irb.100 Full 192.168.1.20 128 36 192.168.1.50 irb.100 Full 192.168.1.50 128 11 192.168.1.40 irb.100 Full 192.168.1.40 128 36 192.168.1.30 irb.100 Full 192.168.1.30 255 35 {MASTER}[edit] root@EX9253-A# commit and-quit re0: configuration check succeeds re1: commit complete re0: commit complete Exiting configuration mode {MASTER} root@EX9253-1> show ospf neighbor instance all Instance: VRF_JTAC Address Interface State ID Pri Dead 111.112.0.10 irb.100 Full 111.112.0.10 128 39 111.112.0.2 irb.100 Full 111.112.0.2 128 36 111.112.0.40 irb.100 Full 111.112.0.40 128 29 111.112.0.30 irb.100 Full 111.112.0.30 128 34 111.112.0.50 irb.100 Full 111.112.0.50 128 37 111.112.0.20 irb.100 Full 111.112.0.00 255 32
Refer to KB32854 - EVPN VXLAN configuration knobs and caveats [juniper.net] , specifically the section on " no-gateway-community ".
08/09/2026-Article Review, title correction