From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Marcel Holtmann To: BlueZ users In-Reply-To: <1151334192.29221.7.camel@addu> References: <1151066205.6247.19.camel@addu> <1151324247.7694.10.camel@localhost> <1151334192.29221.7.camel@addu> Date: Mon, 26 Jun 2006 17:47:45 +0200 Message-Id: <1151336865.7694.37.camel@localhost> Mime-Version: 1.0 Subject: Re: [Bluez-users] L2CAP MTU and packet fragmentation? Reply-To: BlueZ users List-Id: BlueZ users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Sender: bluez-users-bounces@lists.sourceforge.net Errors-To: bluez-users-bounces@lists.sourceforge.net Hi Stephen, > > > I could live with the MTU being 64k with no fragmentation, but I seem to > > > get quite a lot of corrupt packets over around 2kB. > > > > I have no idea what you are talking about. The L2CAP layer is reliable > > and the underlaying ACL link, too. > > Sorry, correction, I get a lot of lost packets. I assume either because > they've become corrupted, or perhaps because they never arrive. > > I get between 20-40% packet loss with packet sizes around 3000 bytes, > and more loss as packet sizes increase. l2ping says 56% loss at 3500 > bytes. > > This loss is what prompted my question. This behaviour, actually, is why > I'm using L2CAP -- because it was likened to UDP in what I'd read > previously. Ironically, perhaps, it's just a little *too* lossy :-) with l2ping you use the L2CAP signal channel and it happens that some remote implementation don't handle this very well. Hence you might see a loss percentage. This actually means unanswered echo requests. If you actually use L2CAP data channel with SOCK_SEQPACKET then you won't see a loss at all. It is a reliable channel. > I'll either bolt on some packet segmentation to my app, or use RFCOMM > for now. Or help Martin Roehricht to extend L2CAP with retransmission and flow control. Once this has been implemented it will be possible to have a SOCK_STREAM on L2CAP like you have with RFCOMM. Regards Marcel Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Bluez-users mailing list Bluez-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bluez-users