> >is this still valid?
> 
> That was a quote from the Router Requirement RFC (RFC1812); it is a
> Proposed Standard.  RFC2400 lists it as "Elective", which is described
> as:
> 
>       A system may or may not implement an elective protocol. The
>       general notion is that if you are going to do something like this,
>       you must do exactly this.
> 
> implying that if you are going to do something like being a router, you
> must follow RFC1812.

I think it's relevant to ask the question about the IPv4 header checksum
verification since:

- IPv6 doesn't have a header checksum at all.
- The BBN MGR doesn't do header checksum verification at all, see
http://www.net-tech.bbn.com/craig/router.ps.

I wouldn't be surprised if there are also other high speed routers that
don't verify the header checksum.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no