Subject: Re: netstat -i
To: Martin Konold <zxmmz01@fiwi02.wiwi.uni-tuebingen.de>
From: Jason Thorpe <thorpej@nas.nasa.gov>
List: tech-kern
Date: 06/26/1996 17:56:35
On Wed, 26 Jun 1996 23:34:23 +0200 
 Martin Konold <zxmmz01@fiwi02.wiwi.uni-tuebingen.de> wrote:

 > Name  Mtu   Network     Address              Ipkts Ierrs    Opkts Oerrs  Coll
 > le0   1500  <Link>      8.0.9.15.65.54       78186     0    97958     0  1210

...this is the "link level" address.  The address is the ethernet (MAC)
address of the interface.

 > le0   1500  134.2.170   centauri.tat.phys    78186     0    97958     0  1210

This is the IP subnet and address of the interface.

 > What I would like to know (any pointers to documentaion) is:
 > 
 > What is special about 8.0.9.15.65.54?
 > 
 > Why are there two entries for the single ethernet device?

See above :-)

 > Is there done any copying inside the kernel?

There is some copying done ... firstly, the data is copied from the card 
into an mbuf chain.  If there is a bpf listener, a copy of the packet is 
made for it.  There are other cases where the data might be copied, but 
there is an attempt to keep this to a minimum.

 > Where may I optain technical information about the *BSD kernels and 
 > networking?

The Design and Implementation of the 4.4BSD Operating System is a good 
book, and has a good sized chunk on the networking subsystem.

 -- save the ancient forests - http://www.bayarea.net/~thorpej/forest/ -- 
Jason R. Thorpe                                       thorpej@nas.nasa.gov
NASA Ames Research Center                               Home: 408.866.1912
NAS: M/S 258-6                                          Work: 415.604.0935
Moffett Field, CA 94035                                Pager: 415.428.6939