The MPLS WG Archive

[Ben Black <ben@layer8.net>]

are you saying that LDP need not include an MTU communication
mechanism because, on rare occassions, it is expedient to
violate accepted specifications?


ben

On Tue, Dec 12, 2000 at 09:15:03AM -0500, Steve Elias wrote:
> 
> hello,
> 
> indeed it is nice and is preferred that fragmentation occur outside
> the mpls domain.  but that's not always possible or reasonable in 
> real networks.
> 
> so within the mpls domain, and especially at the step where an ip
> packet is converted to mpls, it is quite possible and sometimes quite
> crucial to exceed the MTU.  for example, this is reasonable on
> ethernets on which there are only two (or a few) nodes present and for
> which the wire is not too close to the maximum length as determined by
> the medium's propagation speed and the collision-detect portion of the
> ethernet timing specification.
> 
> yes, this sort of thing violates a variety of standards.  
> but it solves customer problems.  
> 
> as long as the router does not default to being able to violate the
> MTU or an MPLS fragmentation specification, i say that it is a Good
> Thing for customers to be able to configure the router it to do so.
> 
> for example, in the simplest case, to send a 1504
> byte "baby giant" packet over a ethernet...
> 
> regards,
> 
> steve elias
> ios network protocols
> cisco systems
>