[rbridge] TTL only - was RE: New fields in shim header?

[Caitlin Bestler]

Joe Touch wrote:

> 
> I don't think we're precluding ingress/egress filtering on
> the LAN, just that it isn't needed inside the rbridge campus.
> Traffic either originates inside the LAN (on an rbridge node
> or host) or enters via a transit (a router). Both can be
> constrained with the outer ethernet header addresses; there's
> nothing magic about the ingress or egress rbridge node as far as
> filtering is concerned. 
> 

Agreed.

More precisely, there WILL be environments with sufficient
perimeter ingress control that internal checking would not
be required. But if we put the extra fields in the header
they will ALWAYS be there.

Most of the extra fields CAN be derived from other information.
For example the enclosed source MAC address implies the 
source RBridge. Therefore it is hard to make a case that
they will provide a permanent benefit.