Two Questions for Readers

I have two questions for readers:

1. What is the cheapest switch you've found that offers a SPAN port?

2. Is anyone interested in writing a chapter providing an overview of peer-to-peer protocols? I have been unable to contact the subject matter expert I hoped to contribute this section to my new book. I am looking for someone with experience detecting, interpreting, and controlling peer-to-peer protocols on internal networks. I am interested in providing the reader the following:

- Overview of general p2p principles and networks
- Discussion of popular p2p implementations
-- Networks and clients
-- General analysis of packet traces via Ethereal or Tethereal or Tcpdump captures (save captures for inclusion in book, if possible)
- Ways to detect p2p activity
- Ways to control (but not eliminate) p2p on internal networks; in other words, allow BitTorrent for downloading .iso's, but don't let it consume too much bandwidth
- Other topics you find relevant and interesting

I recommend responding via comment for the first question, and emailing taosecurity at gmail dot com for the second. I've just sent an email to the guys at Slyck.com to see if they'd like to help.

Update: I found this listing of switches reportedly offering mirror ports at Colasoft.