good software for drawing packet/protocol diagrams?

Question

I need to draw a bunch of packet diagrams (basically concatenated rectangles annotated by lengths/contents with maybe arrows or braces outside the rectangles, see wikipedia or MSDN for some examples).

Is there some decent software out there (NOT Visio please) that can help make it easy to draw these?

Answer 1

I'm a pretty big fan of Gliffy - not sure if it's too simple for your needs or not but it's pretty quick and easy to use.

Answer 2

If you're on OS X, OmniGraffle is great. We use it for a variety of drawing tasks. It's kind of like what Visio could have been if it didn't have sociopathic tendencies. ;)

Answer 3

Hmm, I don't need fancy features; after looking around a bit, I'm just going to use dot from Graphviz:

digraph g {
  node [shape = record,height=.1];
  node0[label = "header (a5 00)\n2 | data\n12 | checksum\n2 "];
}