[Idr] Part 1 of CAR/CT Adoption call (7/6 to 7/20) - Informational Questions

[Susan Hares <[e-mail]>]

IDR WG: 

This message is part 1 of the adoption call for CAR/CT drafts in IDR.  

The IDR Chairs need input from the community on technology direction 
for these drafts.  The four questions ask your opinion on the
key facets of the technology direction.  Please help the IDR chairs by
answering some or all of these questions.   We'll use this input in our decision 
on the adoption call of the CAR and CT drafts. 

Part 2 of the CAR/CT adoption call is an adoption call for the drafts.  
  
Gyan Mishra states on: 
https://mailarchive.ietf.org/arch/msg/idr/Xt-xFxKep2lJzMrn8Rd5QetVmaU/

"The concept of coloring has existed for decades with MPLS, we just didn't
call it "colors" until now with the advent of Segment Routing SR-TE & Flex
Algo, as we called it different VPN SLO's with various QOS policies for
customer SLA Gold, Bronze, [or] Silver classes." 

Intent may be expressed in color, but it is more than color:   In 2015 in 
draft-hares-ibnemo-overview-01.html, I state: 
"As IP networks grow more complicated, these networks require a 
 new interaction mechanism between customers and their networks 
based on intent rather than detailed specifics. An intent-based 
language is need[ed] to enable customers to easily describe their 
diverse intent for network connectivity [requirements/needs] to 
the network management systems." 

IMHO, there is no clear and universal intent-based language in 2022.  
So, let us use color as a BGP defined value and transport class as a BGP defined value. 

1. What is the customer need driving the use of Color to express Customer Intent? 

a. Are applications requesting to be able to tag their routes 
with SLAs (color) at the service level? 
b. If so, is it due to QoS/SLA measurements on traffic between Data Center 
applications and user applications (such as applications on phone)? 

2. In the distant past QoS was hard to set-up seamlessly as a QoS pathway 
across multiple Autonomous systems (AS).  

a. Should Customer intent that expresses pathway "QoS" 
be passed in BGP routing updates sent between Autonomous Systems? 
b. Is it the purpose of color or transport class to allow automatic steering of 
traffic on into an "QoS" path (across different technologies)?  
c. How should this automatic steering interact with flow specification?  

3. For those who believe that BGP should set-up a seamless path across multiple 
Autonomous Systems for a single Intent/QoS, do the exact mechanisms matter 
or do you simply want an interoperable solution?  

If they matter, please describe what matters. 


4. RFC7606 focused on error handling in which the MP-NLRI focuses on destination keys 
(RD and Prefix) plus non-key material (Labels, SIDS).  Attributes (generally) apply to all NLRI.  
For example, MED applies to all NLRIs in the packet. 

a. Would error handling be better for color-aware routing if attributes 
relevant to a specific color/class be grouped in a MP-Color-Attribute? 
b.  Should IDR consider future work on a MP-Color Attribute?