The MPLS WG Archive

["Thomas D. Nadeau" <tnadeau@cisco.com>]

At 10:07 AM 11/20/2002 -0500, Alia Atlas wrote:
>At 09:58 AM 11/20/2002 -0500, George Swallow wrote:
>> > The concept of avoiding the reserved labels in an MPLS hash as a "best 
>> way"
>> > makes some sense, though it would probably only be gradually available as
>> > hardware changes.
>>
>>One should observe that the technique is not useful unless you are
>>100% sure that very box in the path from source to destination is
>>behaving this way.
>
>Why is it not incrementally useful?  Every LSR along the path that does 
>this decreases the cases where an OAM packet may take a different route 
>from the data packet.   It does require every LSR to implement to 
>completely avoid OAM packets from taking different routes, but 
>incrementally does simplify determining what happened to the OAM packets 
>as compared to the data plane packets because there are fewer potential 
>branch points.

         There are cases where all LSRs need to understand
replies via the control plane in LSP Ping.  This may not
work unless everyone along the path understands what to
do.

         --Tom