Bad Intel PRO100/S Network Adapter
For the last two weeks I’ve been having problems with my Point to Point over Ethernet connection to the Internet. I haven’t said anything about it, or given it much attention, since I was and I still am very busy with exams.
Now that the first week of exams is over, I’ve reserved some time to troubleshoot the problem.
First, what were the symptoms? Packet loss, lots of TCP Fast Retransmissions, Checksum errors, Packet Fragmentation Needed but not done (ICMP messages wouldn’t reach the remote server)… My network card is an Intel PRO100/S Desktop Adapter. So what did I do to fix it? I’m glad to say the problem wasn’t with MTU or MSS, I’ve tinkered with the ppp daemon settings a lot but nothing fixed the problem. I’ve searched for a tool to configure my network card to stop doing TCP Checksum Offloading, but I found out the card is very old and Intel is not supporting or producing it any more, and the tools to configure the card (Intel ProTools) are also old and unsupported. Eventually I gave up, so I plugged the network cable in another one of my network cards, used iptables to spoof the MAC address, reconfigured pppd and restarted it. I was surprised to see my speed back up. I have up to 4 MB/s on the WAN and up to 500KB/s on the Internet, but while I was having problems, my WAN speed was as low as 20KB/s and my Internet hanged a lot and wouldn’t go faster than 10KB/s.
Now I’m back into busyness 😉
I hope it stays that way.