Well,

Now, there are multiple treads being discussed here under one topic:

- how big should the the field be?
- should there be common registry for all technologies?
- where should it be defined and which WG should standardize it?

To me the first question is totally dependent on the answer to the last two, 
since the use case pointed out suggests a common registry.

Now there may be different opinions (I believe there are from this exchange) 
whether we should or should not have a common registry, how complicated would 
it be and whether it would tax all groups trying to use that. But even before 
we go there, the basic question has to be answered:
- which WG would own that registry. It is not in a charter of BIER to own it 
nor it is in a charter of SR nor it is in a charter of ISIS. Do none of them 
should own and mandate use. We are chartering LSR now - should we add registry 
for all IGP algorithms, we have routing WG, others?  Would like to hear AD’s 
opinion. Note that although LSR appears obvious, the algorithms to compute BIER 
may be controller-based that do bot require LSR (same applies to SR).

- if we do agree to have a common registry, I would assume we all then tax 
everyone to signal that the same way. That would mean changes to SR and changes 
to BIER.

This seems a lot. We have implementations of both technologies, so are changes 
to those warranted or is it too late and we should pursue independent  alg 
definition and registry as it has been set-up in the existing drafts. And we 
are talking only of those two but more WG will come and want to define things 
for them as well.


Andrew

Sent from my iPhone

On Feb 16, 2018, at 2:51 AM, IJsbrand Wijnands 
<[email protected]<mailto:[email protected]>> wrote:

I think its clear from the discussion there are different opinions on the 
matter on how to make BIER use the BAR field. The reason for me to support 16 
bits is that everybody seemed ok go move forward with an 8bits BAR without a 
registry, a 16bits BAR does not change anything, its just a bigger field. But 
at least with 16bits, we can split in Type, Value, and support different 
use-cases. IMO, pointing to whatever the Unicast underlay is providing is the 
main use-case, but it allows other ways to do things.

One thing is clear, with just 8bits, it will be very hard to reach an agreement 
what the registry would look like. If we make it 16bits, we know we can solve 
multiple use-cases. The main question (I think) is whether we document how a 
16bit BAR is carved up now, or we defer that to later. And as I said, since 
everybody seemed ok with 8bit BAR without a registry, I don’t see why its now 
different for 16bits. It gives us time to workout exactly how to use it and get 
input from the WGs.

And, of course, the goal is to create a registry for the 16 bits through a new 
draft!

Thx,

Ice.


On 15 Feb 2018, at 18:28, Tony Przygienda 
<[email protected]<mailto:[email protected]>> wrote:



On Thu, Feb 15, 2018 at 9:20 AM, Greg Shepherd 
<[email protected]<mailto:[email protected]>> wrote:
On Thu, Feb 15, 2018 at 8:53 AM, Tony Przygienda 
<[email protected]<mailto:[email protected]>> wrote:


On Thu, Feb 15, 2018 at 8:38 AM, Greg Shepherd 
<[email protected]<mailto:[email protected]>> wrote:
For the record, there is no SR Registry. There is only an IGP Algo Type 
Registry as defined in draft-ietf-ospr-segment-routing-extensions-24 section 8.5

So is that a good idea, having multiple drafts in flight with fields expecting 
to have magic couplings to each other while leaving e'thing "unspecified" to 
"publish RFCs" while we "decide things later"?

That was a pivot, but still; there is no reference, there is no coupling.

Tangental: draft-ietf-ospr-segment-routing-extensions-24 has been around for a 
while, and the IGP Algo registry will be tied to this draft and it's fate. If 
anyone is expecting to use this registry outside of the scope of this draft, it 
would be in their best interest to pull the registry description out into a 
separate draft.


OK, and I agree that if such a registry is pulled and under a clear charter of 
mandating multiple technologies within an independent body then a discussion 
starts to make sense and what the size of that should be given that mandates 
algorithms over multiple technologies (SR, unicast, mcast, whatever) and 
implies a "God's eye view" of all the elements of all the technologies (and if 
a computation touches elements from two technologies they become [optionally] 
coupled).  We are not talking IGP registry or multicast computation registry or 
SR registry then but a "wider scope registry". Yes, that is an intriguing 
thought with its own validity but outside the scope of charter we're under as 
BIER.  Personally, I consider multiple, if needed loosely coupled registries 
for each technology a less centralized and hence "more Internet like" solution 
but I see how opinions on such a thing can diverge ...

thanks

--- tony



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