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From: | Patrick Klos |
Subject: | Re: [lwip-users] PPP: IPCP bad fcs issue |
Date: | Wed, 15 Aug 2018 17:46:21 -0400 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 8/15/2018 4:19 PM, Sylvain Rochet wrote:
But what is very strange is that checksum including checksum itself for comparison purpose for "0x01 0x01 0x16 0x03 0x6 0x81 0x6 0x83 0x06 0x6e 0xdb" is 0xeb 0xbe, which is not 0x4114 (nor 0x1441 with byte swap) as displayed in your "Dropping bad fcs" debug print, how is that even possible ?
For what it's worth, 0x4114 is the complement of the byte swap 0xebbe (and that's how the FCS is added to a PPP packet). I didn't look at the actual code to see at what stage and which value the message prints, but it's close enough to say it's probably right.
Patrick
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