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Sat, 25 Jun 2005
Strange breakage - 23:33
Anyway the new machine does not display the problem and is a fresh install of the new debian stable with the 2.6.8 kernel from that. This means I can finally do load balancing and priority for ssh and things like that on the gateway so bulk transfers will not make everything slow. (My flatmates all seem to be bittorrent or kazaa or whatever addicts)
When I first booted the box up and put in place I could ping machines the Big Bad Internet, however I was unable to make a tcp connection, tcpdump would see packets returning but they never seemed to get up to the application. This really had me stumped for a while, eventually I tried swapping the NIC hooked up to the ADSL modem with the NIC hooked up to the house LAN, to my surprise I found I was now unable to make tcp connections with machines in the house.
So it appears this NIC could process some packets such as ICMP, however did not fully process, or caused some other problem with TCP packets at least. I pulled the rather lovely DEC Tulip (one of two I purchased in 1999 because I wanted some real DEC Tulip cards before they ceased to exist) out of the old box and put it in in place of the card with the strange behaviour. Once the machine had booted with the Tulip everything worked perfectly.
The card with the strange behaviour is an older Tulip, a 21041 (10 MBit with a coax connector and cat5) rather than the 21141 now in there, both of them are using the de4x5 driver so it does not sound like a problem with the driver. Anyway, this is a really strange hardware problem.