Subject: Re: MS-SPring [Was: Moving forward with the CCAMP charter]

From: "Diego Caviglia" <[email-masked]>
Date: Wed, 17 Aug 2005 14:55:09 +0200

Hi Dimitri,
            given the high number of MS-SPRing protected transport network
already deployed seems reasonable to me, from a Network Operator point of
view, to use at the same time MS-SPRing protection with GMPLS restoration.

Let's say the first failure is recovered via MS-SPRing in less than 50 ms
while subsequent failures can be recovered via GMPLS restoration with lower
performance.

Basically that is the rationale behind my initial question.

What is your view on that?

Regards

Diego

dimitri papadimitriou <[email-masked]> on 17/08/2005 14.43.17

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Subject:    Re: MS-SPring [Was: Moving forward with the CCAMP charter]

richard,

> Dimitri,
>
> "why (and where) ring topologies are suitable" ?
>
> Transport networks (e.g. SONET/SDH, WDM, RPR) have been, and will
> continue to be, widely deployed based on (dual) ring topologies in
> the access/metro because they provide fast protection and reliability
> whilst making efficient use of fibre.
>
> I do not think this can be disputed so I don't understand where you
> are coming from with this question?

while i do not see why this can't be discussed (e.g. there are dozens of
studies available on this topic) and i can just point out that one can
deliver fast (time efficient), resource efficient and reliable
protection without using rings

therefore, it would worth having some operational feedback and state
what are the real drivers and rationales if such topic is getting
started i.e. what is the real appealing rationale behind this mechanism

note: these are just questions that i think where missing from most
documents produced on this topic since so far and that are important to
be addressed

last point you are mentioning RPR so what would be the interaction with
the IPORPR WG ?

> Regards, Richard
> .

---

From: dimitri papadimitriou <[email-masked]>
Date: Wed, 17 Aug 2005 17:01:23 +0200

diego

> view, to use at the same time MS-SPRing protection with GMPLS restoration.

there are already two questions here 1. is there an operational need to 
control such rings using GMPLS (? for instance is it effective knowing 
that ring based protection is mainly data plane driven ?) and 2. how to 
position the ring protection wrt to the LSP recovery segment/end-to-end 
recovery

> while subsequent failures can be recovered via GMPLS restoration with lower

is it because it is a "local" protection (i.e. wouldn't a segment 
recovery provide the same time efficiency) or because it is ring based

> What is your view on that?

my view is that a problem statement should cover such base questions - i 
am in agreement with adrian stand here -

---

From: Huub van Helvoort <[email-masked]>
Date: Fri, 19 Aug 2005 10:40:16 +0200

Hallo Dimitri,

> position the ring protection wrt to the LSP recovery segment/end-to-end 

The first step in MS-Spring is indeed dataplane driven (using APS)
but that involves only nodes adjacent to the fault.

The reconfiguration of the ring after this first switch is controlplane
driven and concerns all nodes in the ring.

Cheers, Huub.

-- 
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---

From: dimitri papadimitriou <[email-masked]>
Date: Fri, 19 Aug 2005 12:06:47 +0200

hi huub,

Huub van Helvoort wrote:

>> there are already two questions here 1. is there an operational need 
>> to control such rings using GMPLS (? for instance is it effective 
>> knowing that ring based protection is mainly data plane driven ?) and 
>> 2. how to position the ring protection wrt to the LSP recovery 
>> segment/end-to-end recovery
> 

ok, btw, is there a reason to restrict to MS/line protection ring ?

> driven and concerns all nodes in the ring.

ok with this - like for other linear protection schemes the control 
plane would be involved in the provisioning

also, what about the (informational) notification to maintain the 
control plane aware about the data plane status after failure detection 
and/or after the APS operation

thanks,
- dimitri.

---

From: Huub van Helvoort <[email-masked]>
Date: Sat, 20 Aug 2005 16:39:21 +0200

Hello Dimitri,

> ok, btw, is there a reason to restrict to MS/line protection ring ?

If you refer to the APS protocol, this can be used in ring
protection and linear protection, because it operates between
source and sink of a trail or LSP.
In its most simple form it provides 1:1 protection, and more
general N:M protection

> and/or after the APS operation

Maybe it is a good idea to include a description in the document
Diego is preparing (in the book on functional modeling I need
six pages to describe this protection mechanism).

Have a nice weekend, Huub.

---

From: dimitri papadimitriou <[email-masked]>
Date: Sun, 21 Aug 2005 11:30:48 +0200

Huub,

[snip]

> In its most simple form it provides 1:1 protection, and more

i was referring to the scope of the document - should it be restricted 
to MS/line shared protection ring or include other types (e.g. path 
protection ring) - note: in my view not

>> control plane aware about the data plane status after failure 
>> detection and/or after the APS operation
> 

imho, an overview should be enough to skim the ring protection scheme 
and the APS operation (no need to include full details that can be found 
elsewhere)

---

From: Huub van Helvoort <[email-masked]>
Date: Sun, 21 Aug 2005 11:59:01 +0200

Hi Dimitri,

I agree with you on both points.

- no restriction of the scope: linear + ring protection
- the fundamentals in Diego's document with references to
   relevant (standard) documents and articles.

Cheers, Huub.

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