[ENet-discuss] ordered packets

[Luis Cabellos]

Well, in the server I don't discriminate among the channel that the 
packet came from. So in the server I treat all packets the same way. 
Enet use the channels to mantain the order of packets. All the packets 
in the same channel are in-order, and if one of the packets arrive at 
server too later, it will be dropping and wait for acknowledgment.So if 
you know that the packets don't need the order, the use of a range of 
channels

Let me show one ASCII example :)

    When you use on channel
    Send:
     1 2 3 4 5 6 7 8 9 10 11 12  -> channel 1

    Receive:
     1 2 [>> 4 5 3 <<] 6 7 8 9 10 11 12  ->channel 1
     -> Enet drop 4 and wait for arrive of 3

    And when you use 3 channels, [ min = 1 , max = 3 ]
    Send:
     1     4     7     10        -> channel 1
       2     5     8      11     -> channel 2
         3     6     9       12  -> channel 3

    Receive
     1   4       7     10        -> channel 1
       2   5       8      11     -> channel 2
             3 6     9       12  -> channel 3
     -> And you get 1 2 4 5 3 6 7 8 9 10 11 12 without drop / wait

So the client is the only that change the lenght of the range of 
channels, with a long range less probability of out-of-order. And the 
change of the number of channels if you maintain that ( min <= max ) it 
will be always one channel at least. In the other hand, if you increase 
the range, I think that the server will not slow down too much with the 
use of more channels.

- Luis | Tragnarion

Paul Collier wrote:

>I'm curious about setting the range of channels. Is there any way to
>set it other than by the client at connection establishment? If
>someone tried to clone a program's protocol with enet but changed the
>number of channels, could this possibly affect the behaviour of the
>server you were running? (i.e. they set it to zero--could this break
>the server network code? Or perhaps they set it to a very high
>number--could this slow down the server?) Enet seems to be pretty good
>about security from what I've seen, in any case.
>
>- Paul
>
>On 3/30/06, Luis Cabellos <lists at tragnarion.com> wrote:
>  
>
>> You can send Unordered packets using a range of channels and send the
>>packets sequentially in those channels. e.g: If you reserve [min, max] for
>>unordered send, the next code snip will work like an unordered send.
>>
>>     packet = enet_packet_create( msg, size, ENET_PACKET_FLAG_RELIABLE );
>>     enet_peer_send( server, unorderedChannel, packet);
>>     ++this->unorderedChannel;
>>     if( unorderedChannel > MAX_UNORDERED ) {
>>         unorderedChannel = MIN_UNORDERED;
>>     }
>>
>> Luis | Tragnarion
>>