DLR

[saishreevj]

Hello, 

I see DLR VM in vcenter while doing HOL labs, does DLR can be a VM also? I thought it's only a kernel module inside ESXI. 

[Sreejith Cheriangat]

 

 

 

At the data-plane level, we have DLR kernel modules (VIBs) that will get installed on the ESXi hosts when we do NSX preparation. If you need dynamic routing (DLR) or bridging functionality you need to use DLR with Control VM deployment. The DLR control plane is provided by the DLR virtual appliance (also called a control VM). This VM supports dynamic routing protocols (BGP and OSPF), exchanges routing updates with the next-hop route(ESG).

 

https://docs.vmware.com/en/VMware-NSX-Data-Center-for-vSphere/6.4/com.vmware.nsx.troubleshooting.doc/GUID-F9E5A0A4-898A-4268-B73E-BDB9E360CA2E.html

[saishreevj]

So DLR kernel modules is not enough for east west traffic?

I wonder why we need DLR VM as we have ESG for North South traffic. 

[Sreejith Cheriangat]

You are limited with Static routes without DLR-Control VM deployment and configuration.DLR  provides East-West distributed routing and ESG is for N-S routing. Technically you can connect workloads directly to ESG as well. Please go through the below links to know the traffic flow

https://docs.vmware.com/en/VMware-NSX-Data-Center-for-vSphere/6.4/com.vmware.nsx.cross-vcenter-install.doc/GUID-2482B032-F420-432F-A6D0-6CD91506BFCC.html?hWord=N4IghgNiBcICIBkBKIC+Q 

 

 

[Sarfraz Khan]

So DLR kernel modules is not enough for east west traffic?

---It's sufficient , you do not need control vm for east-west.

I wonder why we need DLR VM as we have ESG for North South traffic. 

--- DLR control VM is used for Dynamic routing between itself and ESG. It's also required in case of Cross-Vc with Local Egress feature.

 

[saishreevj]

 When I power off DLR VM I lost E-W connection and I cannot ping Vm's on diff Logical switches.

[Sarfraz Khan]

Hi there,

Could you tell me the placement of the 2 vms in different logical switches ? Are both vm Segments connected to the same DLR ? 

[saishreevj]

 Issue was with logical switch and it was in disconnected state in DLR edge. Post that VM to VM communication on diff switches is successful ( DLR VM is powered Off)

Thanks for the information on DLR

[saishreevj]

And also do we need to configure static/dynamic routing in between DLR and ESG for the traffic flow.

[Sarfraz Khan]

Yes, either Static/ Dynamic routing between DLR and EDGE is needed for N/S traffic.