[Winpcap-users] determinist / speed up the transmission with winpcap ?

[Loris Degioanni]

It's definitely possible, but it's not easy stuff.
I suggest you to download the WinPcap source code, and give a look at 
the packetNTx folder. You will need the Microsoft DDK to compile the 
driver, especially the Write.c file.

If you need assistance, CACE Technologies provides kernel-level 
development support on a consultancy basis. Check http://www.cacetech.com/.

Loris


Soft Prodel wrote:
> Hi, 
> 
> Loris and Hadriel? thanks for your response.
> 
> i understood the principe in the UserMode, but is it possible directly in
> KernelMode (modifying the kernel driver) to send every x ms a packet.?
> If yes how to do that ??
> 
> Laurent.
> 
> 
> 
> 
> 
> 
> 
> 
> 
>> -----Message d'origine-----
>> De : Loris Degioanni [mailto:loris.degioanni at gmail.com] 
>> Envoyé : mardi 14 février 2006 18:01
>> À : soft at prodel-techno.fr; winpcap-users at winpcap.org
>> Objet : Re: [Winpcap-users] determinist / speed up the transmission with
>> winpcap ?
>>
>> WinPcap skips the protocol layer, but it still relies on the low part of 
>> the NDIS stack to transmit packets. In other words, it doesn't talk with 
>> the network card directly, but:
> 
>> 1. performs a transition from user mode (packet.dll) to kernel mode 
>> (npf.sys). This is normally quite slow.
>> 2. gives the packets to NDIS, which delivers it to the NIC driver for 
>> transmission. This is normally quite fast (microseconds), but the NIC 
>> driver may introduce arbitrary latencies that are not under the npf.sys 
>> control.
> 
>> If you don't need to be interactive, you can buffer the packets during 
>> the transaction from user mode to kernel mode (pcap_sendqueue* 
>> functions). This improves things a lot.
> 
>> Loris
> 
> 
> Soft Prodel wrote:
>> Hello All developers,
>>
>>  
>>
>> - excuse first for my bad English...-
>>
>>  
>>
>> I would like to know if with winpcap used with windows XP (pro) ,i can 
>> be determinist for the timing.
>>
>>  
>>
>> each milliseconde,(using the multimedia timer),i send a request to a 
>> server with UDP/IP protocol. at this moment i use traditional 
>> AsyncSocket windows API's.
>>
>> but all the layers, stacks of windows take time and is not determinist. 
>> when i decide to send a frame, the most of the time, the frame is 
>> emitted on the network 1, 5, 10, 50 ms after and sometimes, when i 
>> stress the PC, 250 ms later !!!.
>>
>> i know that XP is not a Real-Time operating system, but i try to speed 
>> up the transmission at least at 2 or 3 ms.
>>
>>  
>>
>> is winpcap able to skip all the system latency ?
>>
>> i think yes because it bypass all the layers but what with the HAL 
>> layer... ?
>>
>> or any person have information about to how to make ?
>>
>>  
>>
>> The application is for fast communicate with I/O system. without real 
>> time system like RTX or others. 
>>
>>  
>>
>> Thanks for attention.
>>
>>  
>>
>> Best Regards.
>>
>>  
>>
>> Laurent.
>>
>>
>> ------------------------------------------------------------------------
>>
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> 
> 
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