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Tweaks for network speed arise from Empire

The classic HP 3000 adventure game Empire has been around since the 1980s. It's now running on a system at Tracy Johnson's datacenter, and he's used the services for the free game to explore network speed on a 3000 -- and how to improve it.

The Empire machine is on an admittedly slow network.  In other words it is on the cheapest Cox business line that was set up for 5Mb upload and 1Mb download. The circuit's real purpose is so visitors in our facility can surf the Internet over wireless without logging into our network.  So the Empire machine was put on it as the default endpoint for connections coming inbound.

My question is, given the outbound speed is only 1Mb, are there any arcane tweaks I could change in NMMGR? Would smaller packet sizes do? Do I really care about checksum?

Jeff Kell replied

Depending on the 3000 model, you're only running at 100Mbps, so there is really no "speed" tweak that is relevant. You want to insure basic connectivity issues. The 3000 isn't that great or reliable at autonegotiation, so you may need to hardcode the 3000 and the switch on the other side to 100Mbps/full duplex.  Nothing sucks worse than autonegotiation failure; a switch will typically "default" to 10/half if autonegotiation fails.

Kell added that "Checksums only matter if you care if the data is accurate :) If you turn them off, errors may go undetected."

If you have enough traffic on the link to really generate congestion, you may want to check your TCP timers. There have been numerous postings in the past on tweaking the default timers (which tend to recover slower than the typical network device on retransmits).

Donna Hofmeister from Allegro added a link to a relevant whitepaper.

"Take a gander at the Allegro paper on TCP timers: And yes, checksum matters."