Hi All,


This document seems to talk of "resource group" SIDs that is something 
interesting - specifically for SR-MPLS (I don't see the same relevance for 
SRv6).



I support the adoption of (what is coming across to me as) this concept of a 
new "resource group" scope for SR SIDs as a work item for the Spring WG. Rest 
should be moved into a separate informational document since all of that seem 
unrelated, nothing new and not suitable for a standards track document.



Therefore, the draft needs more work before it is ready for adoption.



Following are my more specific comments on this draft:



  1.  SR SIDs that are scoped to a MT or Algo or MT+Algo combination can 
already be associated with some "resources" on routers today. There is nothing 
new here to be standardized. If there is interest in the WG for documenting how 
resources are carved out and assigned to say a Flex-Algo and/or MT scoped SIDs, 
it should be in an independent informational document. There seems to be a lot 
of overlap of this with work in the TEAS WG. Much of Section 2 seems to be of 
this nature.



  1.  IGP SR SIDs are today scoped to an MT and Algo. This draft seems to be 
introducing another "resource group" type of scoping within an MT+Algo context 
for Prefix and Adjacency SIDs. When packets using SID labels belonging to a 
"resource group" arrive at a router, it helps the router associate those 
service flows to the QoS profile provisioned for that "resource group" on that 
specific link/router. This is what it seems is the whole essence of the 
proposal - but this is not clear in the document.  The routing of these SIDs is 
going to follow whatever MT and/or FlexAlgo computation provides - therefore, I 
am not sure I understand how these "resource group" SIDs are creating some new 
"Virtual Network Topology". Isn't this just a "network slice" of resources?



  1.  I am not sure how the discussion in Section 3 is bringing in anything new 
and again it is purely informational in nature. Perhaps I am not able to follow 
the point.



  1.  Much of Section 4 is also similarly informational in nature and about how 
some vendor/operator may want to use "resource group" SIDs. However, it does 
not formally and normatively define this new concept of "resource group" SIDs.  
Other implementations and operators may choose to do this differently - so why 
standardize this one way? Discussion like assigning/allocation of SIDs, 
distribution of their information and setting up paths through the network 
using these SIDs are basic concepts of SR - not sure if they need description 
and repetition in a standards track document.



  1.  Section 5, Scalability is not giving the right picture. The proposal ends 
replicating each SID label forwarding entry (e.g. for prefix SID) multiplied by 
each "resource group" on each router simply for the sake of identifying QoS 
resources for it. That is not really scalable and will end up consuming a large 
set of label forwarding entries on the routers depending on the network scale 
and now many of these "slices" are instantiated.



  1.  Finally, I have an objection to the use of terms like "enhanced VPN" and 
"VPN+" in the document that sound more like marketing terms than technical 
terminologies. There was a similar comment made by one of the Spring chairs for 
a previous version, but I don't see it being addressed. VPNs might be but one 
of the services that can leverage the resource aware SIDs in their underlay.



I look forward to responses from the authors and updates to the document to 
address these comments.



Thanks,

Ketan


From: spring <spring-boun...@ietf.org> On Behalf Of James Guichard
Sent: 15 July 2020 16:47
To: spring@ietf.org
Cc: spring-cha...@ietf.org
Subject: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn

Dear WG:

This email begins a 2 week WG adoption call for 
https://datatracker.ietf.org/doc/draft-dong-spring-sr-for-enhanced-vpn/ ending 
Wednesday 29th July 2020.

Please speak up if you support or oppose adopting this document into the WG.. 
Please also provide comments/reasons for that support (or lack thereof). 
Silence will not be considered consent.

Thanks!

Jim, Joel & Bruno



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