 
 func run(identifier: String) {
     let serverChannel = try! DatagramBootstrap(group: group)
+        .channelOption(ChannelOptions.explicitCongestionNotification, value: true)
         // Set the handlers that are applied to the bound channel
         .channelInitializer { channel in
             return channel.pipeline.addHandler(ServerEchoHandler())

    private func sendBytes(clientChannel: Channel) {
        var buffer = clientChannel.allocator.buffer(capacity: 1)
        buffer.writeInteger(3, as: UInt8.self)
        // Send the data.
        let envelope = AddressedEnvelope<ByteBuffer>(remoteAddress: remoteAddress, data: buffer)
        clientChannel.writeAndFlush(self.wrapOutboundOut(envelope), promise: nil)
    }
    

    let clientHandler = ClientHandler(remoteAddress: remoteAddress)

    let clientChannel = try! DatagramBootstrap(group: group)
        .channelOption(ChannelOptions.explicitCongestionNotification, value: true)
        .channelInitializer { channel in
            channel.pipeline.addHandler(clientHandler)
        }
