Pushpassis -

It is clear to me that what you propose is more complex to implement and more 
costly in its consumption of labels. What I do not yet appreciate is what 
capabilities protocol specific SRGBs provide which cannot be supported using a 
protocol independent SRGB. Could you please provide some specific examples? 
Please do not use an RSVP/LDP analogy - please use a proposed SR deployment 
case.

BTW, why do I say your proposal is more complex/costly?

On a node where redistribution of routes is occurring, the source of 
redistribution (the "best route") obviously allocates a local label based on 
its SRGB. But now the destination protocol for redistribution also has to 
allocate a local label based on its SRGB because it is expected that neighbors 
of the destination protocol will use a label from the destination protocol 
SRGB. So, you now have new requirements on the destination protocol and you 
have consumed twice as many local labels. Your forwarding plane now has to deal 
with the added complexity/cost - and your label manager has to manage more 
label ranges.

What I want to know is what do we gain for this added complexity? Thanx.

   Les


From: Pushpasis Sarkar [mailto:[email protected]]
Sent: Wednesday, July 29, 2015 11:16 PM
To: Les Ginsberg (ginsberg); [email protected]; Uma Chunduri; 
Aissaoui, Mustapha (Mustapha); [email protected]; Shraddha Hegde; Hannes Gredler
Subject: Re: [spring] Modeling SRGB configuration for draft-ietf-spring-sr-yang

Hi Les,

From: "Les Ginsberg (ginsberg)" <[email protected]<mailto:[email protected]>>
Date: Wednesday, July 29, 2015 at 11:01 PM
To: "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>, Uma 
Chunduri <[email protected]<mailto:[email protected]>>, 
"Aissaoui, Mustapha (Mustapha)" 
<[email protected]<mailto:[email protected]>>,
 "[email protected]<mailto:[email protected]>" 
<[email protected]<mailto:[email protected]>>, Shraddha Hegde 
<[email protected]<mailto:[email protected]>>, Pushpasis Sarkar 
<[email protected]<mailto:[email protected]>>, Hannes Gredler 
<[email protected]<mailto:[email protected]>>
Subject: RE: [spring] Modeling SRGB configuration for draft-ietf-spring-sr-yang

Stephane -

What is the requirement to have a per-protocol SRGB config?
This makes no sense to me operationally or architecturally.
[Pushpasis] In current MPLS architecture, the same label is not allocated by 
both RSVP and LDP in a given box. With SR mapped to MPLS data-plane, we would 
like to retain the same behavior. For the same destination the label allocated 
by ISIS should be different than the label allocated by OSPF. This can be 
achieved in two ways:

  1.  ISIS and OSPF using same SRGBs but different index ranges.
  2.  ISIS and OSPF using different SRGBs but can have the same index ranges.
I prefer option 2, as the operator does not need to maintain two different 
index ranges (one per-protocol).

(I am not talking about what may or may not have been implemented by vendors - 
the YANG model should be architecturally correct)

   Les


From: [email protected]<mailto:[email protected]> 
[mailto:[email protected]]
Sent: Wednesday, July 29, 2015 5:11 AM
To: Uma Chunduri; Les Ginsberg (ginsberg); Aissaoui, Mustapha (Mustapha); 
[email protected]<mailto:[email protected]>; Shraddha Hegde 
([email protected]<mailto:[email protected]>); Pushpasis Sarkar 
([email protected]<mailto:[email protected]>); Hannes Gredler 
([email protected]<mailto:[email protected]>)
Subject: RE: [spring] Modeling SRGB configuration for draft-ietf-spring-sr-yang

Hi all,

What if we keep the SRGB block config in "segment-routing" global module, and 
if we allow for YANG configuration of carving this block inside each protocol 
(maybe as a feature) ?

Stephane


From: Uma Chunduri [mailto:[email protected]]
Sent: Friday, July 24, 2015 16:59
To: Les Ginsberg (ginsberg); Aissaoui, Mustapha (Mustapha); LITKOWSKI Stephane 
SCE/IBNF; [email protected]<mailto:[email protected]>
Subject: RE: [spring] Modeling SRGB configuration for draft-ietf-spring-sr-yang

>Suggesting that the forwarding instruction (AKA label)  needs to be different 
>depending on what protocol provided
>the instruction is completely unnecessary - it simply wastes label space.

[Uma]: Les, No - I never suggested anything like that.
SRGB for a routing instance to be advertised should be part of the routing 
instance provisioning as far as the yang model is concerned.
Carving out the label space for SR is a local matter and agree, of course, this 
 can be done in so many ways through CLI, dynamically, statically etc...

--
Uma C.


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