RE: Two Drafts for Resilience of Control Plane

[ibryskin@movaz.com]

Zafar,
>> c)	leave LSP as it is and wait for the dead controller to
>> be replaced or
>> repaired. This would mean the need to perform normal
>> operations like, for example, monitoring of data plane
>> alarms, changing LSP admin status (for example, disabling
>> alarms on all nodes), perform power monitoring and
>> equalization, perform recovery operation in case of a fatal
>> data plane failure. All what depends on hop-by-hop signaling
>> won't work today.
>> Don't tell me that these problems are fabricated; they are
>> real because they are raised by the customers. Dimitri seems
>> to understand the problem but he is saying that the CP in
>> this case is hardly of any use. This IMO is a dangerous
>> statement for the future of CP in non-packet environments.
>> The Management plane aficionados will jump on it and say that
>> management plane does not have such a problem - NMS has a
>> direct access to any NE on the network, so it can do all
>> necessary cleanup no matter what happened.
>> Customers will say: "Well, if there are situations when CP
>> suddenly becomes useless and we have to use management plane
>> anyway, why would we use the CP in the first place?'
>>
>> Fortunately, I believe that the problems could be solved
>> entirely via CP by making it more resilient. Hence, CP
>> resilience is a good direction to work on within CCAMP WG
>
> Igor,
>
> W.r.t. option C, please note that traffic CANNOT be forwarded in a
> "head-less mode" for a very long time . If you control network melts or
> a peering controller goes down, either RSVP GR or refreshes will take
> care of the clean-up of the affected RSVP states. Similarly LMP CC SM
> will go down (after states are cleared, i.e., degraded-to-down),
> eventually removing the TE links from topology.
>

Sticking to the example I described:
a) absence of RSVP refreshes does not affect data plane in any way;
b) use of LMP is not mandatory and, becides, I don't see now it helps.
True, the TE link could be withdrawn, however, the LSP will still be
operational

Igor


> Thanks
>
> Regards... Zafar
>
>>
>> Igor
>>
>> > If "Considerable period of time" is not equal to infinity,
>> then there
>> > will be an RSVP graceful restart.  If a controller is
>> really and truly
>> > dead, then presumably the operator will either replace it
>> or re-assign
>> > its data-plane resources to another signaling controller.
>> In either
>> > case, there will then be an RSVP graceful restart.
>> >
>> > Thanks,
>> >
>> > John
>> >
>> >
>> >
>> >> -----Original Message-----
>> >> From: ibryskin@movaz.com [mailto:ibryskin@movaz.com]
>> >> Sent: Friday, October 28, 2005 1:00 PM
>> >> To: Drake, John E
>> >> Cc: ibryskin@movaz.com; dpapadimitriou@psg.com;
>> >> dimitri.papadimitriou@alcatel.be; Igor Bryskin; Zafar Ali;
>> Kim Young
>> > Hwa;
>> >> ccamp@ops.ietf.org
>> >> Subject: RE: Two Drafts for Resilience of Control Plane
>> >>
>> >> John,
>> >>
>> >> I think you missed my point here. "Dead" controllers in my example
>> >> *do
>> >> not* come back for a considerable period of time. So there are no
>> > restarts
>> >> here (graceful or not graceful) :=)
>> >>
>> >> Igor
>> >>
>> >> > What part of your problem, as stated below, is not
>> handled by RSVP
>> >> > graceful restart?
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: ibryskin@movaz.com [mailto:ibryskin@movaz.com]
>> >> >> Sent: Friday, October 28, 2005 11:41 AM
>> >> >> To: Drake, John E
>> >> >> Cc: dpapadimitriou@psg.com;
>> dimitri.papadimitriou@alcatel.be; Igor
>> >> >> Bryskin; Zafar Ali; Kim Young Hwa; ccamp@ops.ietf.org
>> >> >> Subject: RE: Two Drafts for Resilience of Control Plane
>> >> >>
>> >> >> 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.t
>> > xt
>> >> >> >> >
>> >> >> >> >>
>> >> >> >> >>	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=%3C8
>> > 63
>> >> >> >> >
>> >> >> >> >>0a6db-0c31-49ab-a798-13b0dda04553@etri.re.kr%3E>
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >
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>> >> >> >> >
>> >> >> >> >
>> >> >> >> > __________________________________
>> >> >> >> > Yahoo! Mail - PC Magazine Editors' Choice 2005
>> >> >> >> > http://mail.yahoo.com
>> >> >> >> >
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