Sometimes a Legend

And once again, an interesting item in the postel.org end-to-end group – “An interesting version of TCP was created a few years ago at a large data-storage-system company here — essentially, the TCP receive window was reduced to Go/No-Go, and startup was modified, so the sending Unix box would blast to its mirror at full wire rate from the get go. ACKs would have meaningless Window values, excepting 0, because sender and receiver had similar processing/buffering capability. Loss produced replacement, via repeated ACKs. Being LAN-based system overall made all these mods workable. But clearly, the engineers involved found normal TCP wanting in the ability to deliver data on high-speed links.”

Interesting how legends develop. This project was called the flamethrower┬ádemo done with a wirewrap version of SiliconTCP on a DEC PAM card with a NIC wired on (and that’s exciting with 100MHz logic).

We demo’d this to Microsoft, venture, and lots of other companies back in Summer 1998. One Microsoft exec (Peter Ford) noted that we were so overloading the standard NICs that an “etherlock” condition was likely to occur. Etherlock, for those who don’t know, occurs when all of the bandwidth is consumed and nothing else can communicate because there is no idle time effectively. And yes, we saw this occur.

One of the more interesting things we found is that many “standard” NICs were not standard compliant. I still have the wirewrap on my wall alongside a production board.

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