Dell EMC SmartFabric OS10 User Guide Release 10.5.0

Service Nodes

In an NSX-provisioned VXLAN environment, service nodes replicate L2 broadcast, unknown-unicast, and multicast (BUM) traffic that enter an OS10 VTEP to all other VTEPs. For the service node replication of BUM traffic to work, you need IP connectivity between the service nodes and the VTEP, so that the BUM traffic from a VTEP reaches the other remote VTEPs via a VXLAN overlay through the service nodes. The NSX controller manages a cluster of service nodes and sends the IP addresses of the nodes to the VTEP through OVSDB protocol. The service node cluster provides redundancy, and also facilitates load balancing of BUM traffic across service nodes.

The following shows BUM traffic replication in the controller-provisioned VXLAN environment:

Since VTEP relies on service nodes to replicate BUM traffic, we need a mechanism to monitor the connectivity between the VTEP and the service nodes. BFD can be used to monitor the connectivity between the VTEP and service nodes, and detects failures. The NSX controller provides parameters, such as the minimum TX and RX interval, and the multiplier, to initiate the BFD session between the VTEP and the service nodes. To establish a BFD session, enable the BFD on the controller and the VTEP. To enable BFD in the VTEP, use bfd enable command.

If BFD is not enabled in the VTEP, the VTEP uses IP reachability information to monitor connectivity to the service node.

OS10# show bfd neighbors
* - Active session role
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  LocalAddr      RemoteAddr    Interface        State RxInt TxInt Mult VRF     Clients
------------------------------------------------------------------------------------------
* 55.55.5.5      2.2.2.2       virtual-network0 up    1000  1000  3    default vxlan
* 55.55.5.5      2.2.2.3       virtual-network0 up    1000  1000  3    default vxlan