https://community.extremenetworks.com/t5/data-center-mlx-cer-ces/ospf-over-gre-with-mtu-set-to-jumbo/m-p/92288#M220 <P>I have multiple links between the MLX routers connecting to other vendor devices (Ruckus ICX7750 and Cisco Catalyst 9500) via GRE which randomly get stuck in OSPF Exchange start.&nbsp; While the MTU at each end matches, I am able to restore the service by simply changing the MTU at each end of the tunnel to any value&nbsp;other that what is currently configured.&nbsp; I can go&nbsp;up with the MTU or I can go down with the MTU, if both sides match&nbsp;it works.&nbsp; I can then change the MTU setting back to its previous configuration (when I was stuck in EXST) and OSPF will remain up and stable.&nbsp; This condition randomly appears and I have NOT been able to identify any trigger for the event to take place.&nbsp; During troubleshooting I am able successfully send ICMP&nbsp;packets set with an MTU of the tunnel’s MTU size packets to the tunnel’s destination from its source without fragmentation or&nbsp;loss.&nbsp; Has anyone seen an issue like this in their environments?&nbsp; The MLX in question is running NetIron 0600c</P> Thu, 14 Jan 2021 04:19:38 GMT Joshua_Grant 2021-01-14T04:19:38Z https://community.extremenetworks.com/t5/data-center-mlx-cer-ces/ospf-over-gre-with-mtu-set-to-jumbo/m-p/92288#M220 <P>I have multiple links between the MLX routers connecting to other vendor devices (Ruckus ICX7750 and Cisco Catalyst 9500) via GRE which randomly get stuck in OSPF Exchange start.&nbsp; While the MTU at each end matches, I am able to restore the service by simply changing the MTU at each end of the tunnel to any value&nbsp;other that what is currently configured.&nbsp; I can go&nbsp;up with the MTU or I can go down with the MTU, if both sides match&nbsp;it works.&nbsp; I can then change the MTU setting back to its previous configuration (when I was stuck in EXST) and OSPF will remain up and stable.&nbsp; This condition randomly appears and I have NOT been able to identify any trigger for the event to take place.&nbsp; During troubleshooting I am able successfully send ICMP&nbsp;packets set with an MTU of the tunnel’s MTU size packets to the tunnel’s destination from its source without fragmentation or&nbsp;loss.&nbsp; Has anyone seen an issue like this in their environments?&nbsp; The MLX in question is running NetIron 0600c</P> Thu, 14 Jan 2021 04:19:38 GMT https://community.extremenetworks.com/t5/data-center-mlx-cer-ces/ospf-over-gre-with-mtu-set-to-jumbo/m-p/92288#M220 Joshua_Grant 2021-01-14T04:19:38Z