Hello, Acee. indeed, I had misread the text. Thanks for pointing out!
greetings, sergio On Mon, Apr 19, 2010 at 12:47 PM, Acee Lindem <[email protected]> wrote: > Hi Sergio, > > On Apr 19, 2010, at 8:46 AM, Sergio Luis O. B. Correia wrote: > >> Hello all, >> >> I am trying to calculate the LS checksum regarding the following LSA >> header [1], but I am not able to get the 0x389d after applying >> Fletcher's checksum. >> >> RFC 2328, section 12.1.7 says the LS checksum field is the checksum of >> the complete LS header, excepting the LS Age field. For the LS Header >> shown in [1], what would I use as input for the checksum algorithm? > > RFC 2328 doesn't say that - it says "the complete contents of the LSA, > excepting the LS age field". So, if you're only using the LSA header, you're > certain to get the wrong result. > > Hope this helps, > Acee > > > > > > >> >> I am merely excluding the two first bytes (LS Age field) and using the >> LS checksum field as zero in this calculation, like this: >> >> 02 01 c0 a8 aa 03 c0 a8 aa 03 80 00 00 02 00 00 00 30 >> >> but it's giving me wrong results (not 0x389d). I believe I am doing >> something wrong, but I don't know what. Could someone point me the >> right way to perform this calculations? >> >> Thanks in advance, >> sergio. >> >> >> -- >> [1] LSA Header: >> >> LS Age: 1 seconds >> Options: 0x02 >> Link-State Advertisement Type: Router-LSA (0x01) >> Link-State ID: 192.168.170.3 (0xc0a8aa03) >> Advertising Router: 192.168.170.3 (0xc0a8aa03) >> LS Sequence Number: 0x80000002 >> LS Checksum: 0x389d >> Length: 48 (0x30) >> >> And follows the LSA header, as shown in wireshark: >> >> 00 01 02 01 c0 a8 aa 03 c0 a8 aa 03 80 00 00 02 38 9d 00 30 >> _______________________________________________ >> OSPF mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/ospf > > _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
