Subject: Re: netstat -i
To: Martin Konold <>
From: Jason Thorpe <>
List: tech-kern
Date: 06/26/1996 17:56:35
On Wed, 26 Jun 1996 23:34:23 +0200 
 Martin Konold <> wrote:

 > Name  Mtu   Network     Address              Ipkts Ierrs    Opkts Oerrs  Coll
 > le0   1500  <Link>       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
 > 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 - -- 
Jason R. Thorpe                             
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