[ENet-discuss] Long Distance Packet Loss (maybe)?

[Jay Sprenkle]

>From my reading malformed packets are usually caused by flaws in hardware.
There are reports of poor network cables, cards, device drivers, and tcp
stacks on various machines. I'd try sending from a different machine and see
if the problem is resolved.

On Sun, Jan 17, 2010 at 3:55 AM, Alex Milstead <alex.milstead at gatech.edu>wrote:

> Thanks a bunch, Lee! That did it. Still doesn't quite explain the
> "malformed packet" information I was receiving from wireshark, although
> since I'm actually getting the packets this time, I suppose that doesn't
> really matter much.
>
> Cheers,
> Alex
>
>
> On 1/15/2010 12:25 PM, Lee Salzman wrote:
>
>> enet_host_flush just sends the packet only once. If the packet gets lost,
>> enet_host_service ensures it gets resent until it is delivered.
>>
>> Lee
>>
>> Alex Milstead wrote:
>>
>>> On 1/15/2010 11:28 AM, Lee Salzman wrote:
>>>
>>>> Are you regularly calling enet_host_service on the client?
>>>>
>>>> Lee
>>>>
>>>> Alex Milstead wrote:
>>>>
>>>>> Hey all,
>>>>>
>>>>> Just a heads up, (I don't know how reliable this is, exactly, but) I've
>>>>> been using a network packet monitoring tool call "wireshark" to monitor
>>>>> packets coming back and forth between client and server apps using an ENet
>>>>> wrapper I wrote.
>>>>>
>>>>> I'm using ENet to send a struct back and forth between machines. The
>>>>> struct itself isn't very big (only about 10 fields inside), and for the
>>>>> longest time sending it to and fro was no big problem. Recently, though,
>>>>> I've been testing out the server piece of the app(s) I'm writing, and
>>>>> according to wireshark, I'm receiving "Malformed Packets". I see this
>>>>> happening pretty frequently between machines when the client and server are
>>>>> in the same general (geographical) locale, however I've got a team member
>>>>> that is testing the client from Oregon (I'm in Georgia), and some seriously
>>>>> screwed up is happening. Every time he sends data, wireshark picks up that a
>>>>> packet is coming in, but ENet -never- hits the "ENET_EVENT_TYPE_RECEIVE"
>>>>> event on the server host that is servicing the connection.
>>>>>
>>>>> The basic break down of the apps ENet protocols are as follows (sans
>>>>> the client connecting to the server for the first time):
>>>>>
>>>>> Client code:
>>>>> ...
>>>>>
>>>>> SendData(void *data)
>>>>> {
>>>>>   if (connected) // flag set to true when enet_host_connect and
>>>>> subsequent (enet_host_service && event.type == ENET_EVENT_TYPE_CONNECT)
>>>>> events are true
>>>>>      ENetPacket *packet = enet_packet_create(struct_ref,
>>>>> sizeof(structReferenced), ENET_PACKET_FLAG_RELIABLE);
>>>>>      enet_peer_send(server, channel, packet);
>>>>>      enet_host_flush(connection);
>>>>> }
>>>>> ...
>>>>>
>>>>> Server Code:
>>>>> ...
>>>>> while (enet_host_service(connection, &event, connection_lifetime) >= 0
>>>>> && !quit) {
>>>>>       switch (event.type) {
>>>>>           case ENET_EVENT_TYPE_CONNECT:
>>>>>               cout << "A new client connected!";
>>>>>
>>>>>               break;
>>>>>           case ENET_EVENT_TYPE_RECEIVE:
>>>>>               ProcessPacket(event);
>>>>>               break;
>>>>>      }
>>>>> }
>>>>> ...
>>>>>
>>>>> The problem appears to be when packets are sent from the client machine
>>>>> in Oregon. Like I mentioned, wireshark is telling me that the packet
>>>>> actually made it, but the ENET_EVENT_TYPE_RECEIVE -never- occurs. Again, I'm
>>>>> not sure how reliable "wireshark" is, but it's telling me that the UDP
>>>>> packet being sent is "malformed". This doesn't seem to happen when I'm
>>>>> sending from a client machine that is geographically closer to the server
>>>>> (e.g. in my home, but sending requests to the frontal IP instead of a local
>>>>> IP), although wireshark still seems to report that the datagram sent from
>>>>> the closer machine is also sometimes "malformed".
>>>>>
>>>>>
>>>>> Any ideas on what's happening/going wrong?
>>>>>
>>>>> Thanks for any help in advance.
>>>>>
>>>>> Cheers,
>>>>> Alex
>>>>>
>>>>>  _______________________________________________
>>>> ENet-discuss mailing list
>>>> ENet-discuss at cubik.org
>>>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>>
>>> Yes. The method which calls "SendData", immediately calls
>>> enet_host_service afterward to listen for response packets from the server.
>>>
>>> Should I be using "enet_host_service(conn, &event, lifetime) &&
>>> event.type == ENET_EVENT_TYPE_CONNECT" before sending a packet? I thought
>>> the purpose of enet_flush_host was to send off packets without having to
>>> service the host.
>>> _______________________________________________
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>>> ENet-discuss at cubik.org
>>> http://lists.cubik.org/mailman/listinfo/enet-discuss
>>>
>>>
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>
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