Re: Why can't I add a loopback interface to a bridge?

Kevin, hello.

On 14 Jul 2022, at 18:31, Kevin Oberman wrote:

> What may be missing is the concept of a bridge is that it is a layer 2
> connection between two or more 802-like devices. Such devices use MAC
> addresses and an IP address is a layer 3 entity. Trying to mix such on 
> a
> bridge would imply a routing capability (layer 3) which really does 
> not
> make sense with a layer 2 device.

Indeed -- the presence of both layer 2 and layer 3 elements in the 
if_bridge(4) description at least contributed to my confusion.  In my 
simple-minded picture of 'a switch', the only layer 3 element is a 
possible management interface.

However Kristof's remark that

>  An if_bridge is not just a switch, but also a NIC that’s plugged 
> into that switch.

is a valuable one, to the extent that I think it would be worthwhile 
somehow incorporating it into the manpage, in the paragraph starting 'A 
bridge works like a switch,...'

I do see that amongst the examples at the end of the manpage there there 
is a remark 'The bridge can be used as a regular host interface at the 
same time as bridging between its member ports', so there is an 
implication of 'a NIC that's plugged into the switch'.

Best wishes,

Norman


-- 
Norman Gray  :  https://nxg.me.uk