encapOverhead

encapOverhead.go

package main

import (
	"fmt"
	"github.com/google/gopacket"
	"github.com/google/gopacket/layers"
	"github.com/google/gopacket/pcap"
	"os"
)

func layerOffset(packet gopacket.Packet, layer gopacket.LayerType) int {
	offset := 0
	for _, l := range packet.Layers() {
		offset += len(l.LayerContents())
		if l.LayerType() == layer {
			return offset
		}
	}
	return -1
}

func analyzePacket(packetFile string) {
	handle, _ := pcap.OpenOffline(packetFile)
	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
	for packet := range packetSource.Packets() {
		if packet.Layer(layers.LayerTypeGeneve) != nil {
			offset := layerOffset(packet, layers.LayerTypeGeneve)
			fmt.Println("GENEVE offset =", offset)
		}
	}
}

func main() {
	analyzePacket(os.Args[1])
}

OVN GENEVE Encap overhead