NVE1
        +------------+                       DGW1
IP1+----+(BD-1)      | +---------------+ +------------+
        |  \         | |               | |            |
        |(IP-VRF)-(SBD)|               (SBD)-(IP-VRF) |-----+
        |  /    IRB(M1)|               | IRB(M3)      |     |
    +---+(BD-2)      | |               | +------------+    _+_
    |   +------------+ |               |                  (   )
 SN1|                  |     VXLAN/    |                 ( WAN )--H1
    |            NVE2  |     GENEVE/   |                  (___)
    |   +------------+ |     MPLS      |     DGW2           +
    +---+(BD-2)      | |               | +------------+     |
        |  \         | |               | |            |     |
        |(IP-VRF)-(SBD)|               (SBD)-(IP-VRF) |-----+
        |  /    IRB(M2)|               | IRB(M4)      |
SN2+----+(BD-3)      | +---------------+ +------------+
        +------------+