Re: Other use cases for header insertion (was Re: Header Insertion and TI-FA)

[Uma Chunduri <[e-mail]>]

On Wed, May 13, 2020 at 3:50 AM Stewart Bryant <[e-mail]>
wrote:

> I am glad that we accept the NP is not SR!  Although it took a long time
> to get there, both in terms of the disintertwining and realisation that the
> concept was needed. It is a long time since I read it, but I am concerned
> about whether it has the full generality of the opaque instruction that
> MPLS has.
>
I guess, it has.


>
Assuming that it has the next issue and it is one we are discussing here is
> the overhead of adding a new instruction to a packet in flight.
>


That overhead per 8200 is 40 bytes aka encapsulation (with all good reasons
raised again and again why it has to be like that in L3), where in

L2.5 it is 4 bytes.  Though we may never get to 4 bytes we don't want it to
be 40 bytes, that's the holy grail of insert discussion (push).


The next thing is removal (pop) to me though this is being discussed and in
the document as PSP. The question is not at penultimate node

(regardless of benefit i.e., it is marginal or not) and segment end point
but at any node in the network.

I think at some level we are seeking to  have  these very basic
functionalities needed not only for TI-LFA but other inter-AS scenarios in
a single

domain.  We can all see the difficulties in the underlying  architecture to
get these while taking the goodies it offers (like the UNI and self-

description you mentioned). We need both and unfortunately I don't think
any other RH would get us  there.

--
Uma C.



>