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OSPF is stuck in ExStart in an EX9253 collapsed EVPN setup

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Article ID: KB37231 KB Last Updated: 07 Sep 2021Version: 1.0
Summary:
A few OSPF neighbors are stuck in ExStart in an EX9253 collapsed EVPN setup.
Symptoms:
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 in an EX9253 collapsed EVPN setup      

{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. Only when rebooting the second spine (EX9253-2), the OSPF will recover. 

Solution:

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, specifically the section on "no-gateway-community".  
 

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