From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Just Keijser Date: Tue, 20 Apr 2010 14:49:57 +0000 Subject: Re: CRC-16 or CRC-32 Message-Id: <4BCDBF15.9020309@gmail.com> List-Id: References: <291B2C7721AC7B49AD11449A2883992E2C4A9BDC3C@SINTEFEXMBX01.sintef.no> In-Reply-To: <291B2C7721AC7B49AD11449A2883992E2C4A9BDC3C@SINTEFEXMBX01.sintef.no> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ppp@vger.kernel.org Hi, Arne Lie wrote: > Jan, > > 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. HH, JJK / Jan Just Keijser > > > >> -----Original Message----- >> From: Jan Just Keijser [mailto:jan.just.keijser@gmail.com] >> Sent: 20. april 2010 16:16 >> To: Arne Lie >> Cc: linux-ppp@vger.kernel.org >> Subject: Re: CRC-16 or CRC-32 >> >> Arne Lie wrote: >> >>> Hi, >>> >>> A very basic question: does PPP v2.4.5 support CRC-16 or CRC-32 (or >>> >> it may be configurable, in that case, how)? >> >> what exactly do you mean by CRC-16 or CRC-32? ( I know what CRC means ) >> BTW, the word 'crc' does not appear anywhere in the ppp source code. >>