Huawei OLT + N3k , both in routing mode poor perfomance


I’ve got an Huawei OLT connected with a port channel to Nexus 3064X and Nexus is connected to another Nexus 9K and a Mikrotik Router. OLT is setup in routing mode and OSPF is setup on all devices with direct route redistribution. Nexus are running 9.3.7 NxOS

Currenlty direct path to Nexus with vlan 121 has OSPF cost 100

My issue is that I want to remove Mikrotik. Unfortunatly when I try to achieve it, upload from OLT give me speed < 1Mbps (instead of 600Mbps or including 1Gbps) and download speed is affected too (get 150Mbps instead of 600Mbps) and has very poor performance / user experience.

The behaviour looks bottleneck due to mtu or packet loss but I’ve double check and interfaces on OLT and Nexus has 1500 bytes MTU, no fragmentation, no errors, no packet loss on interfaces. Moreover as you can see on the diagram , I carry both VLANs from OLT over PortChannel , one finish on Mikrotik and the other one finish on N3k SVI interface.

Meanwhile upload is not routed by Nexus 3K it works. I mean if you route download through n3k and upload through mikrotik (playing with ospf cost) it works perfectly. If n3k achieve upload/download routing I’ve got the problem.

Any idea ?

Hello Sebastien

Thanks for sharing such a detailed diagram and explanation. So you want to remove the Mikrotik device. I assume you will terminate VLAN 122 on the N3k device, correct? And VLAN 127 will be eliminated.

I would suggest you check the following:

  1. what kind of load balancing is configured between the OLT and the Nexus 3k port channel?
  2. What is the nature of the link between the Nexus 3k and 9k devices?
  3. Check to make sure that routing on the Nexus 3k is modified appropriately when you remove the Mikrotik router.

With the information given, I can’t think of something else that would cause such behaviour. In any case, continue your troubleshooting, and let us know how you get along. If you have any more info, let us know so that we can attempt to help further…

I hope this has been helpful!