RFC 1219 takes 12 pages to say, basically, “start counting from the left, not the right, when you need to assign new subnets.” But how weird that there’s an RFC on how to number your subnets. (For non-techies: a subnet is a group of numbers assigned to a group of hosts.)
I just started reading TCP/IP Illustrated.
If you run netstat -in, you can find the MTU sizes for all your connections. In trying to find the actual path MTU, I read this in traceroute(1) for Mac OS 10.3:
Note that the gateways 12, 14, 15, 16, & 17 hops away either don’t send ICMP “time exceeded” messages or send them with a TTL too small to reach us. 14 - 17 are running the MIT C Gateway code that doesn’t send “time exceeded”s. God only knows what’s going on with 12.
HISTORY
This command is currently in beta test.
Here’s a fun site about MTUs: Raising the Internet MTU.
I’ve tried to find a program that will give me a traceroute-style calculation of path MTU, but haven’t found one yet.
AS AN ASIDE, I just spent probably an hour figuring out that Movable Type will not let me put the word “traceroute” in my entries (unless there are surrounding characters). I’m Not Kidding.