In message <200412030941.53168.netbsdMLpostNO@SPAM.quake.ca>, Marc Tooley write
s:
>I've been running NetBSD for.. well pretty much forever it seems, and 
>recently (within the last year I guess) I've bumped into some troubles 
>when running most NIC (Intel etherexpress to 3com 3c905) under the 
>netbsd releases in that time period. Maybe it's just me but for some 
>reason putting the card into promiscuous mode sometimes freezes all 
>network operations for about a second or two. Similar UNIX-like systems 
>don't show any tcpdump output for a moment, but they all continue to 
>pass in/out network traffic from the rest of the system while the 
>interface is being put into promisc.

I see similar effects.  My assumption -- not validated by checking the 
driver source -- is that the process of setting the promiscuous mode 
bit involves a board reset.

		--Steve Bellovin, http://www.research.att.com/~smb