So i was wondering, because VXlan requeres a high mtu to work properly (some set it even as high as the max configurable MTU (9000ish)), how would providing internet access for these nodes/servers residing in these vxlan networks be possible? I mean the default gateway would have to do heavy amounts of fragmentation which would obviously be very CPU intensive.
VXLAN is an L2 tunneling protocol over UDP/IP. Basically, the tunnel provides a virtual link, so you just route that traffic like you would route from/to any other link.
The inner frame is encapsulated by UDP and in turn by IP, so their headers plus the inner L2 header eat into the MTU of an inner L3 packet.
Using a larger outer MTU for VXLAN transport is highly recommended, so that a large, inner packet doesn't need to be fragmented before being sent over a reduced-MTU tunnel. Fragmentation wastes bandwidth and processing resources, but Internet access is certainly possible either way.
VTEPs MUST NOT fragment VXLAN packets. Intermediate routers may fragment encapsulated VXLAN packets due to the larger frame size. The destination VTEP MAY silently discard such VXLAN fragments. To ensure end-to-end traffic delivery without fragmentation, it is RECOMMENDED that the MTUs (Maximum Transmission Units) across the physical network infrastructure be set to a value that accommodates the larger frame size due to the encapsulation. Other techniques like Path MTU discovery (see [RFC1191] and [RFC1981]) MAY be used to address this requirement as well.
VXLAN is normally used within datacenters or across datacenter locations to provide consistent L2 connectivity (e.g. share a common IP subnet among hosts even if they grow in different racks or locations). In that scenario enlarging the outer frame and packet should be possible.
I don't really see a use case for Internet access though. You could very easily connect a router (either WAN or intermediate) to one of the VTEPs and then go on from there.