Date: Wed, 29 Nov 2000 17:52:45 +0100 From: Falco Krepel <krepel@fokus.gmd.de> To: Julian Elischer <julian@elischer.org> Cc: "freebsd-net@FreeBSD.ORG" <freebsd-net@FreeBSD.ORG> Subject: Re: New Protocol over Ethernet Message-ID: <3A25345D.FD3649CC@fokus.gmd.de> References: <3A142E0C.1B1D18DD@fokus.gmd.de> <3A14701F.4CF92AFB@elischer.org>
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Julian Elischer wrote: > > Hi, > > > > I want to implement my own protocol on top of ethernet. This protocol > > should should not influence other protocols running on the system. So I > > must distinguish my own frames from other frames. > > > > If I understood it right, three approaches exists: > > > > 1. I creat with netgraph a hook over ther ethernet interface. With this > > solution I am not shure how much overhead this adds because it could be > > possible that this runs into timing problems. > > > > There will be no more timing load that any other scheme you can think > of. > Netgraph is very efficient. > > it would help a bit if you gave more specific information as to the > characterisitics of the protocol you want. OK, I give you a short description about my project. The goal is to realize a wireless link simulation over ethernet. This is done by using 100MBit/s full duplex point to point links between the terminal and the simulation box (PC). The box contains a four port ethernet card, so it is possible to connect four terminals. Each packet receiving on one port must be forwarded to at least one other port. Between receive and send some bit level modifications are done depending on a channel error model. My idea was to encapsulate the wireless link frames in ethernet frames to reduce any further overhead. A timer give an indication for each frame. To synchronize the stations I will use the NTP protocol running over an extra ethernet card. So I receive my ethernet frames, do some modifications and send them out. I think netgraph is the best way to do this because it is possible to implement the protocol in user space and no kernel modifications are required. I create a hook on each ethernet port and get the ethernet frames and send them out through the hooks. Is it right that I get the raw ethernet frames through this hooks and is it possible to set a filter for special frames? > > Now my questions: > > > > - Does exist an implementation which could help me to find the solution? > > - Has anybody experience with such an implementation? > > > > many people have done this.. Great. It is possible that anybody share his implementation? This will be very helpful for me. Also links to implementations or implementation examples are useful for me. -- Falco Krepel Phone: +49-(0)30 - 34 63 - 7 276 GMD-FOKUS Fax: +49-(0)30 - 34 63 - 8 276 Kaiserin-Augusta-Allee 31 e-mail: krepel@fokus.gmd.de 10589 Berlin WWW: http://www.fokus.gmd.de/usr/krepel To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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