Subject: Re: does gif(4) do RFC 2003 IPv4-in-IPv4 encapsulation?
To: NetBSD Networking Technical Discussion List <tech-net@NetBSD.ORG>
From: William Waites <>
List: tech-net
Date: 03/04/2002 15:03:30
On Mon, Mar 04, 2002 at 02:32:09PM -0500, Greg A. Woods wrote:
> Does 'gif' really do encapsulation is according to RFC 2003?

Based on the example Cisco configs in the man pages gif(4), 
gre(4) and ipip(4), and experience configuring gif tunnels to
talk to a Cisco, I infer the following:

- since the default tunnel type on a Cisco is GRE and the configuration
  examples are identical in both gre(4) and  ipip(4), the standard
  "IP unnumbered" config can be accomplished with either gre(4) or

- confusingly, when making a gif(4) tunnel speak to a Cisco, you
  need to tell it "tunnel mode ipip".


Cisco "ipip" != BSD "ipip"
Cisco "ipip" == BSD "gif"
Cisco "gre" == BSD "gre" == BSD "ipip"

Is this correct?