Update README with VXLAN setup instructions

Added VXLAN setup instructions for multiple hosts in the README.

Author: vickiegpt

README.md

@@ -73,3 +73,44 @@ exit
 ../qemu_integration/launch_qemu_cxl1.sh &
 ```
 
+for multiple hosts, you'll need vxlan
+
+```bash
+#!/bin/bash
+set -eux
+
+DEV=enp23s0f0np0
+BR=br0
+VNI=100
+MCAST=239.1.1.1
+BR_IP_SUFFIX=$(hostname | grep -oE '[0-9]+$' || echo 1)   # optional auto-index
+# Or set manually:
+# BR_IP_SUFFIX=<1..4>
+
+# Clean up
+ip link del $BR 2>/dev/null || true
+ip link del vxlan$VNI 2>/dev/null || true
+
+# Create bridge
+ip link add $BR type bridge
+ip link set $BR up
+
+# Create multicast VXLAN (no remote attribute!)
+ip link add vxlan$VNI type vxlan id $VNI group $MCAST dev $DEV dstport 4789 ttl 10
+ip link set vxlan$VNI up
+ip link set vxlan$VNI master $BR
+
+# Assign overlay IP
+ip addr add 192.168.100.$BR_IP_SUFFIX/24 dev $BR
+
+# Optional: add local TAPs for QEMU
+for i in 0 1; do
+    ip tuntap add tap$i mode tap
+    ip link set tap$i up
+    ip link set tap$i master $BR
+done
+
+echo "Bridge $BR ready on host $(hostname)"
+```
+for every host and edit the qemu's ip with `/usr/local/bin/setup*` and `/etc/hostname`.
+