Security Basics mailing list archives
Re: TCP/IP CRC question
From: Alex V.Lukyanenko <y_avenger_y () ua fm>
Date: Thu, 7 Oct 2004 02:11:22 +0300
Hello Jorge, Wednesday, October 6, 2004, 9:15:19 AM, you wrote: JMB> I've been reading about the TCP/IP protocol stack (TCP/Ilustrated Vol1 JMB> by Richard Stevens) lately and since Ethernet is quite common nowadays JMB> almost all link layer examples refer to it (I also checked Douglas Comer JMB> Internetworking with TCP/IP vol1). JMB> I tried searching RFC but found it very time consuming without good JMB> results (maybe I'm not used to it...yet) JMB> The Ethernet Frame contains a field known as FCS which contains a CRC. JMB> Now, my question is: JMB> If the CRC is generated from DATA field among others, What's the point JMB> of using checksums on the upper protocolos (IP checksums etc..)? JMB> Thanks for your time. Because the protocols are independant of the underlying/overlying protocols, i.e.: 1. Ethernet can be used for the transmission of higher-level protocols that do not perform CRC checking 2. IP can go over a protocol that does not perform CRC checking. It's better to be safe than sorry. -- Best regards, mailto:y_avenger_y () ua fm
Current thread:
- TCP/IP CRC question Jorge Mendez Bonini (Oct 06)
- RE: TCP/IP CRC question David Gillett (Oct 07)
- Re: TCP/IP CRC question Jonathan Loh (Oct 07)
- RE: TCP/IP CRC question Shaineel Singh (Oct 07)
- Re: TCP/IP CRC question Alex V . Lukyanenko (Oct 07)
- Re: TCP/IP CRC question Fernando Gont (Oct 07)
- RE: TCP/IP CRC question Shaineel Singh (Oct 07)
- Re: TCP/IP CRC question Ansgar -59cobalt- Wiechers (Oct 07)
- Re: TCP/IP CRC question Fernando Gont (Oct 07)
- Re: TCP/IP CRC question Miles Stevenson (Oct 07)
- Re: TCP/IP CRC question Miles Stevenson (Oct 08)
- RE: TCP/IP CRC question Clement Dupuis (Oct 12)
- Re: TCP/IP CRC question Miles Stevenson (Oct 08)
- <Possible follow-ups>
- Re: TCP/IP CRC question Don Parker (Oct 07)
- RE: TCP/IP CRC question Ted A (Oct 07)
- RE: TCP/IP CRC question Simon Zuckerbraun (Oct 13)