You don't 'need' to use VXLAN in this case if you already have Layer 2 connectivity across the clusters, but there are a number of other benefits to VXLAN such as scalability (providing isolated networks without consuming VLANs which may be limited) and automation via APIs in addition to being able to provide Layer 2 connectivity across a Layer 3 transport network, eg if you didn't have the same VLANs defined across both clusters.
↧