> -----Original Message----- > From: linux-ppp-owner@xxxxxxxxxxxxxxx [mailto:linux-ppp- > owner@xxxxxxxxxxxxxxx] On Behalf Of Milan P. Stanic > Sent: 20. april 2010 17:10 > To: linux-ppp@xxxxxxxxxxxxxxx > Subject: Re: CRC-16 or CRC-32 > > On Tue, 2010-04-20 at 16:49, Jan Just Keijser wrote: > > Arne Lie wrote: > > >Hm, my observations are that if there are bit errors introduced in > the PPP frame, the "ifconfig ppp0" will count such packets in the > "error" tab. From this I anticipated that the PPP stack included CRC > checking of its payload. By CRC-16 I mean 2 byte CRC, CRC-32 4 byte. > Our customer wants 4 byte CRC. From RFC2823 I see both are mentioned. > The question is, how does one select either? Perhaps it is not > configurable via pppd? > > > > > RFC2823 is about PPP SDL on SONET/SDH ; AFAIK the pppd code does not > > support this *at all* so I am not surprised that I did not find any > > references to CRCs in the headers... > > > > So the short answer to your question would be: no, PPP v2.4.5 does > > not support CRC-16 or CRC-32. > > In Linu CRC is done in kernel ppp driver not the ppp daemon. > ZLIB compression uses crc-32, AFAIR. [Arne::] Milan, thanks for your information. Yes, the CRC is done in the kernel part of PPP. My question was how, of possible, one could select CRC-16 or CRC-32 to be activated using options when starting pppd (in a similar manner as one is able to select compression algorithm). In http://fixunix.com/ppp/62264-hdlc-like-framing.html James Carson says that the Solaris implementation of pppd make it possible to negotiate to CRC-32. I read your answer this way: by choosing the deflate compression algorithm, which I believe is using ZLIB, then we *are* using the CRC-32 since it defaults to this. /Arne > > -- > Kind regards, Milan > -------------------------------------------------- > Arvanta, IT Security http://www.arvanta.net > Please do not send me e-mail containing HTML code. > -- > To unsubscribe from this list: send the line "unsubscribe linux-ppp" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ppp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
