Re: [mpls] Update to the bullets on the first page of my review of draft-song-mpls-extension-header-09

[Tony Li <[e-mail]>]

Hi Haoyu,

> How is the desired order communicated?
> 
> [HS] The desired order is an implementation issue for device vendor. It doesn't need to be communicated or dicated by standard. 


So that means that an operator and buy box X, use it, replace it with box Y and suddenly get a completely different result?

Suppose that a packet has two actions encoded.  One is to increment a counter, the other has an error and causes the packet to be dropped. Is it ok if box X drops before counting and box Y counts before dropping?

The ideal of orthogonal semantics would be wonderful, but the reality is that we can’t guarantee that, especially in the face of user-defined actions.

So, how would a head-end encode options to achieve a given intent if each box has its own unique interpretation of the semantics?   

What if the semantics drift over software releases?  Does the head end have to know the definitive behavior of every box and every release?

Tony