RE: Two Drafts for Resilience of Control Plane

["Ong, Lyndon" <Lyong@Ciena.com>]

Hi Igor,

Are you referring to controlling the LSP while one of the controllers is
still down?  That would mean that no restart has yet taken place.

The draft seems to be focused on providing standby control channels,
what
you're suggesting sounds more like a standby signaling controller.

Cheers,

Lyndon

-----Original Message-----
From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On
Behalf Of ibryskin@movaz.com
Sent: Friday, October 28, 2005 1:08 PM
To: dpapadimitriou@psg.com; dimitri.papadimitriou@alcatel.be
Cc: ibryskin@movaz.com; Drake@movaz.com; John E;
dimitri.papadimitriou@alcatel.be; Igor Bryskin; Zafar Ali; Kim Young
Hwa; ccamp@ops.ietf.org
Subject: Re: Two Drafts for Resilience of Control Plane

Dimitri,
See in-line.
> igor -
>
> you are already going beyond the specific discussion context
>
> 1. what is a control plane partitioned LSP ?

LSPs with one or more controllers down, so there is/are partitions in
hop-by-hop signaling
>
> 2. when you state "Suppose one or more signaling controllers managing
>     some LSP went out of service leaving the LSP's data plane intact."
>
>     what does it mean "one or more controllers" ? what if you support
>     RSVP GR ? why are you not able to recover the states ? etc.

See my response to John. There are no restarts in my example

>
> hence, i still miss the exact problem wrt to the control plane 
> protocol resilience
>
> but i think there is another issue (which is even more important) - 
> the resilience mechanisms of the control plane that we have today have

> been provided based on experience from the common use of the control 
> plane and for being resilient wrt common failures - but not for ALL 
> use of the control plane in ANY condition and for ALL possible 
> failures - indeed what you are asking here is like what shall i do 
> when the CP is completely down and the DP still up; it would surprise 
> me that the CP would be of any help in this specific condition

Believe me, CP could be still of a great help in such conditions. You
need some signaling extensions - which is why I think CP resilience is
an important topic within CCAMP - and then you can manage LSPs with
control plane gaps at least to the extend I described.

Igor

>
> thanks,
> - dimitri.
>
> ibryskin@movaz.com wrote:
>
>> Hi,
>>
>> Here is one of the problems that I've been thinking for a while - 
>> control plane partitioned LSPs. Suppose one or more signaling 
>> controllers managing some LSP went out of service leaving the LSP's 
>> data plane intact. As far as the user is concerned such LSP is 
>> perfectly healthy and operational.
>> Such situation could last for a considerable period of time. Do we 
>> need to manage such LSP via control plane? Sure, we must be capable 
>> to tear down such LSP, perform mb4b rerouting, distribute alarms 
>> between operational controllers, signal data plane faults and perform

>> recovery switchover, modify LSP status, etc. Can we do this today? 
>> No, but with some
>> (signaling) extensions the problem I believe is solvable. Is this 
>> some artificial, "fabricated" problem? No, I think it is real. Does 
>> it fall under the control plane resilience problem space? I believe
it does.
>>
>> Igor
>>
>>
>>>I agree with Zafar and Dimitri.  If someone wanted to document the 
>>>GMPLS control plane resiliency features, as was done for GMPLS 
>>>addressing, that might be a useful activity.
>>>
>>>
>>>>-----Original Message-----
>>>>From: dimitri papadimitriou [mailto:dpapadimitriou@psg.com]
>>>>Sent: Friday, October 28, 2005 9:56 AM
>>>>To: Igor Bryskin
>>>>Cc: Zafar Ali (zali); Kim Young Hwa; ccamp@ops.ietf.org
>>>>Subject: Re: Two Drafts for Resilience of Control Plane
>>>>
>>>>igor -
>>>>
>>>>over time CCAMP came with a set of mechanims to improve control 
>>>>plane resilience (RSVP and LMP GR upon channel/node failure) other 
>>>>WG
>>>
>>>protocol
>>>
>>>>work are also usable used here OSPF GR, etc. ... on the other side, 
>>>>mechanism such as link bundling have built-in resilience 
>>>>capabilities and most GMPLS control plane capabilities have been 
>>>>designed such as
>>>
>>>to
>>>
>>>>be independent of the control plane realisation (in-band, 
>>>>out-of-band,
>>>>etc.)
>>>>
>>>>so indeed i share the concern of Zafar what could we do more here 
>>>>than document these tools and provide our experience in using them;
>>>>
>>>>now, before stating there are (potential) problems(s) arising - 
>>>>would you please be more specific on what are these potential 
>>>>issue(s)
>>>
>>>and/or
>>>
>>>>problems ? (not related to policy/config. - note: all the issues you

>>>>have pointed here below are simply policy/config specific but none 
>>>>of them highlights a missing IP control plane resiliency feature)
>>>>
>>>>thanks,
>>>>- dimitri.
>>>>
>>>>
>>>>Igor Bryskin wrote:
>>>>
>>>>
>>>>>Zafar,
>>>>>
>>>>>The problem arises when the control plane is decoupled from the 
>>>>>data plane. The question is do we need such decoupling in IP 
>>>>>networks? Consider, for example, the situation when several 
>>>>>parallel PSC data links bundled together and controlled by a single

>>>>>control channel.
>>>>>Does it mean in this case that when the control channel fails all 
>>>>>associated data links also fail? Do we need to reroute in this case

>>>>>LSPs that use the data links? Can we rely in this case on control 
>>>>>plane indications to decide whether an associated data link is 
>>>>>healthy or not (in other words, can we rely on RSVP Hellos or 
>>>>>should we use, for example, BTD)? Should we be capable to recover 
>>>>>control channels without disturbing data plane? I think control 
>>>>>plane resilience is important for all layers. You are right, 
>>>>>Internet does work, however, we do need for some reason TE and 
>>>>>(fast) recovery in IP as much as in other layers,don't we?
>>>>>
>>>>>Cheers,
>>>>>Igor
>>>>>
>>>>>--- "Zafar Ali (zali)" <zali@cisco.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Hi All,
>>>>>>
>>>>>>I am unable to understand the problem we are trying to solve or 
>>>>>>fabricate. My control network is IP based and IP has proven 
>>>>>>resiliency (Internet *does* work), why would I like to take 
>>>>>>control plan resiliency problem at a layer *above-IP* and 
>>>>>>complicate my life. Did I miss something?
>>>>>>
>>>>>>Thanks
>>>>>>
>>>>>>Regards... Zafar
>>>>>>
>>>>>>
>>>>>>________________________________
>>>>>>
>>>>>>	From: owner-ccamp@ops.ietf.org
>>>>>>[mailto:owner-ccamp@ops.ietf.org]
>>>>>>On Behalf Of Kim Young Hwa
>>>>>>	Sent: Friday, October 28, 2005 6:04 AM
>>>>>>	To: ccamp@ops.ietf.org
>>>>>>	Subject: Two Drafts for Resilience of Control Plane
>>>>>>
>>>>>>
>>>>>>	Dear all,
>>>>>>
>>>>>>	I posted two drafts for the resilience of control plane.
>>>>>>	One is for requirements of the resilience of control plane, the 
>>>>>>other is for a protocol specification as a solution of that .
>>>>>>	These are now available at:
>>>>>>
>>>>>>
>>>>>
>>>>>http://www.ietf.org/internet-drafts/draft-kim-ccamp-cpr-reqts-01.tx
>>>>>t
>>>>>
>>>>>
>>>>>>
>>>>>
>>>http://www.ietf.org/internet-drafts/draft-kim-ccamp-accp-protocol-00.
>>>txt
>>>
>>>>>>	I want your comments.
>>>>>>
>>>>>>	Regards
>>>>>>
>>>>>>	Young.
>>>>>>
>>>>>>	===================================> >>	Young-Hwa Kim
>>>>>>	Principal Member / Ph.D
>>>>>>	BcN Research Division, ETRI
>>>>>>	Tel:     +82-42-860-5819
>>>>>>	Fax:    +82-42-860-5440
>>>>>>	e-mail: yhwkim@etri.re.kr
>>>>>>	===================================> >>
>>>>>>
>>>>>
>>><http://umail.etri.re.kr/External_ReadCheck.aspx?email=ccamp@ops.ietf
>>>.or
>>>
>>>>>
>>>g&name=ccamp%40ops.ietf.org&fromemail=yhwkim@etri.re.kr&messageid=%3C
>>>863
>>>
>>>>>>0a6db-0c31-49ab-a798-13b0dda04553@etri.re.kr%3E>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>__________________________________
>>>>>Yahoo! Mail - PC Magazine Editors' Choice 2005 
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>>
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