James, You could use dummynet(4) to introduce delays, limit throughput, etc. You could also play with the various sysctl(8) variables.
net.inet.ip.rtexpire net.inet.ip.rtminexpire net.inet.ip.rtmaxcache net.inet.tcp.delacktime net.inet.tcp.delayed_ack Just to name a few. Trying doing: sysctl -A | grep "net.inet" You can even mess around with some of the ipc related variables: sysctl -A | grep "kern.ipc" You should be able to manipulate the stack enough with that but there is always the source. :-) -- Adam Migus ([EMAIL PROTECTED]) ([EMAIL PROTECTED]) FreeBSD (http://www.freebsd.org) | The Power to Serve -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of James B. Wilkinson Sent: Thursday, May 16, 2002 8:25 PM To: [EMAIL PROTECTED] Subject: I've got to teach a new graduate course in networking this fall. I'm looking at using vol 1 and maybe vol 2 of "TCP/IP Illustrated" by Richard Stevens. The basic premise of the book seems to be to do experiments on a working network in order to learn about the protocols. One thing that I thought about doing is to have them do that sort of thing here as well as to read about what he did to do the book. It seemed useful to me to have some of the machines set up with a version of FreeBSD that let you fool around with what the IP and TCP layers were doing. E.g. introduce delays in the transmission of ack's so that packets get retransmitted or so that you can watch the RTT estimate catch up. Maybe pick out particular TCP segments and lose them. When I started looking at how one might do this, it seemed like it might be hard. So I got to wondering if somebody had already done it so that I don't have to. I have no idea how to do a Google search for something like that. Do any of you guys know about any software like that. I spose it would have to be a hacked version of a kernel. Thanks -- ------------------------------------------------------------- Jimmy Wilkinson | Perfesser of Computer Science [EMAIL PROTECTED] | The College of Charleston (843) 953-8160 | Charleston SC 29424 If there is one word to describe me, that word would have to be "profectionist". Any form of incompitence is an athema to me. Metathesis??? Don't ax me. To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-net" in the body of the message To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
