Hi Robert,

Thanks for your email. Please see some replies inline with [Jie]:

From: spring [mailto:spring-boun...@ietf.org] On Behalf Of Robert Raszuk
Sent: Wednesday, January 27, 2021 8:03 PM
To: James Guichard <james.n.guich...@futurewei.com>
Cc: spring@ietf.org; spring-cha...@ietf.org
Subject: Re: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn

All,

Before I make a decision on expressing my support or indicate no support I 
would like to better understand what resource reservation is being discussed 
here.

[Jie] The resource reservation here refers to the data plane resources reserved 
for different virtual transport networks.

draft-ietf-spring-resource-aware-segments-01 also talks about "reservations" 
yet lacks clarity what those reservations will actually be. It provides analogy 
to MPLS-TE, but at least those who build MPLS-TE products are aware MPLS-TE or 
even MPLS GB-TE does not provide any data plane reservations. All both do is to 
provide control plane resource bookings.

[Jie] Agree that with MPLS-TE the reservation could just happen in the control 
plane and does not have to be in the data plane. 
draft-ietf-spring-resource-aware-segments-01 also mentions the inefficiency of 
the controller based resource management with existing SR in some scenarios, 
thus both the resource-aware-segments draft and this draft are talking about 
data plane resource reservation.

So fundamentally does draft-ietf-spring-resource-aware-segments-01 and this 
draft in question also are trying to now map SIDs to control plane resource 
bookings ? Note fundamentally in all above cases it only works when all traffic 
in yr network is actually using such reservations as otherwise unaccounted 
traffic will destroy the game completely for those who think we see green light 
we are good to go. That is also why for real TE it is/was critical in MPLS-TE 
to provide such engineering for all of your ingress-egress macro flows.

[Jie] As explained above, the idea is to associate different SIDs with 
different sets of data plane resources reserved in the network, so that traffic 
encapsulated with different SIDs will be steered into different set of data 
plane resources. This way the unaccounted traffic in your example will only be 
allowed to occupy the set of resources which are associated with the SIDs 
carried in the packet. Thus the mechanism could work without per-flow 
engineering.

Even then if you start to run other traffic on the same links ... say multicast 
or control plane storms of any sort - again all of your assumed reservations 
are immediately becoming unnecessary complexity with zero benefits.

[Jie] Similarly, based on the above mechanism, the impact of multicast or 
control plane storms can also be limited to a subset of data plane resources. 
This is the benefit of the data plane resource reservation.

So with that let's make sure we understand what is being proposed here.

Btw if someone has a pointer to discussion about  
spring-resource-aware-segments it would be great too. My few years of email 
history does not return much. Maybe the draft got renamed during publishing as 
SPRING WG item.

[Jie] The history is, draft-ietf-spring-resource-aware-segments was part of 
draft-dong-spring-sr-for-enhanced-vpn. After the first the adoption poll on 
this document last year, based on the received comments and the chairs’ 
suggestion, it was split out as a general enhancement to SR, and the rest part 
of draft-dong-spring-sr-for-enhanced-vpn continues as an application of the 
resource-aware segments.

Hope the above helps to provide some background information.

Best regards,
Jie

Thx,
R.


On Wed, Jan 27, 2021 at 12:46 PM James Guichard 
<james.n.guich...@futurewei.com<mailto:james.n.guich...@futurewei.com>> wrote:
Dear WG:

This message starts a 2 week WG adoption call for 
https://datatracker.ietf.org/doc/draft-dong-spring-sr-for-enhanced-vpn/ ending 
February 10th 2021.

After review of the document please indicate support (or not) for WG adoption 
to the mailing list and if you are willing to work on the document, please 
state this explicitly. This gives the chairs an indication of the energy level 
of people in the working group willing to work on this document. Please also 
provide comments/reasons for your support (or lack thereof) as this is a 
stronger way to indicate your (non) support as this is not a vote.

Thanks!

Jim, Bruno & Joel



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