Seeking Help: OSPF Adjacency Issue Between a Physical and a Virtual Layer 3 Switch

[mrafatpanah]

Hi everyone,

I'm encountering a puzzling issue with OSPF adjacencies in a mixed network environment and would greatly appreciate any insights or suggestions.

Network Setup:
Devices Involved:

• A Cisco 2900 router.
• A physical Layer 3 switch running SONiC 202211 NOS (which uses FRR).
• A PC running GNS3 with one virtual Layer 3 switch also operating on SONiC 202211 NOS (which uses FRR).

Topology:

• The virtual Layer 3 switch is connected to the physical network via a hub.
• Both the Cisco router and the physical Layer 3 switch are connected to the same hub.

The Issue:

• The Cisco 2900 router successfully establishes OSPF adjacencies with both the physical and the virtual Layer 3 switches using the default broadcast (multicast) hello packets.
• However, the physical and virtual Layer 3 switches do not form an OSPF adjacency with each other—even though they can ping each other successfully.
• Packet captures indicate that the physical switch is not receiving the multicast OSPF hello packets (sent to 224.0.0.5) from the virtual switch.
• When I reconfigure the virtual switch to use non-broadcast (unicast) hello packets, the OSPF adjacency is successfully formed. Nevertheless, I prefer to use the default broadcast configuration across all devices.

Additional Notes:

• Authentication: Not a factor.
• Router Priorities: Properly configured.
• MTU Settings: Consistent across devices.
  The fact that the Cisco router is forming adjacencies with both switches confirms that basic connectivity and multicast forwarding through the hub are functioning correctly.

My Question:
Has anyone experienced a similar issue or have any insights into why the physical and virtual Layer 3 switches fail to form an OSPF adjacency using multicast hello packets? I'm particularly interested in understanding if there are any subtleties in how FRR is implemented in SONiC 202211 NOS on different platforms or other configuration nuances that might cause this behavior.

Thank you in advance for your help!

[bingwang-ms]

OFPS is not support in SONiC currently.