From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guy Van Den Bergh guy.vandenbergh@pandora.be Date: Thu, 01 Feb 2001 20:40:23 +0000 Subject: [LARTC] subinterfaces Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org 
"subinterfaces" is no cisco speak for aliases.
The Cisco speak for aliases is "secondary"
In Cisco terms you can add an alias to an interface by typing:
ip address <address> <mask> secondary.
Even a third address can be added with this statement.

The subinterface concept is mainly used for running IP over frame relay 
networks.
You can have an interface to a frame relay network, with multiple 
subinterfaces for connecting to multiple hosts on the same frame relay 
network.
This has to do with the NBMA (non-broadcast multiple access) nature of 
frame relay. This basically means that basic ARP does not work on frame 
relay. And this is the reason why subinterfaces are really useful on 
these networks.

But I do not fully know this matter in Cisco, nor in Linux speak.

More information on the Cisco concept of subinterfaces can be found at:
http://www.cisco.com/warp/public/779/smbiz/service/knowledge/wan/subifs.htm

I guess John wants to know the capabilities of Linux concerning frame 
relay, but I don't know anyone with experience on this is on the list.

The linux equivalent for subinterfaces depends on what you want to do 
with it, I guess.


bert hubert wrote:

> On Wed, Jan 17, 2001 at 09:32:01PM -0500, John Russo wrote:
> 
>> Does Linux support the concept of subinterfaces?  If so can anyone point
>> me in the right direction for docs?
> 
> 
> I think 'subinterfaces' are Cisco speak for IP aliases - if so, yes, try
> this:
> 
> ip addr add your.ip.address.here dev eth0