Find the optimal network MTU

find_optimal_mtu.sh

#!/bin/bash

# Destination to ping
destination="1.1.1.1"
max_mtu=1500
min_mtu=1400
best_mtu=$min_mtu
best_time=999999

# Function to ping with a specific MTU and return the average ping time
ping_mtu() {
    local mtu=$1
    local ping_time=$(ping -D -s $(($mtu - 28)) -c 4 $destination | grep 'avg' | awk -F '/' '{print $5}')
    echo $ping_time
}

# Loop through MTU values and find the best one
for (( mtu=$max_mtu; mtu>=$min_mtu; mtu-- ))
do
    echo "Testing MTU: $mtu"
    avg_time=$(ping_mtu $mtu)

    if [ -z "$avg_time" ]; then
        echo "MTU $mtu: Packet fragmentation occurred or no response"
        continue
    fi

    echo "MTU $mtu: Average ping time = $avg_time ms"

    if (( $(echo "$avg_time < $best_time" | bc -l) )); then
        best_mtu=$mtu
        best_time=$avg_time
    fi
done

echo "Optimal MTU: $best_mtu with average ping time: $best_time ms"