[rbridge] Draft problem statement

[Erik Nordmark]

> This paragraph doesn't make sense to me as written.  We are going to 
> develop mechanism that could be deployed in routers, bridges or hosts 
> and that would therefore change them.
> 
> Perhaps what is intended is some kind of backwards compatibility statement?
> 
> Perhaps:
> "The BoF will explore combining benefits of bridges and routers in a way 
> that will co-exist with existing hosts, IP routers and bridges.  The 
> design should support both IPv4 and IPv6."

Yes, your text is better. The original text makes sense if you assume there
will be some new type of device which is neither a host, bridge, or router
but it is just as likely that existing bridges and/or routers would have
new functionality added to do whatever solution we come up with.

  Erik