RE: Two Drafts for Resilience of Control Plane

["Drake, John E" <John.E.Drake2@boeing.com>]

> -----Original Message-----
> From: Zafar Ali (zali) [mailto:zali@cisco.com]
> Sent: Friday, October 28, 2005 5:08 PM
> To: Drake, John E; Ong, Lyndon; ibryskin@movaz.com;
> dpapadimitriou@psg.com; dimitri.papadimitriou@alcatel.be
> Cc: Drake@movaz.com; dimitri.papadimitriou@alcatel.be; Igor Bryskin;
Kim
> Young Hwa; ccamp@ops.ietf.org
> Subject: RE: Two Drafts for Resilience of Control Plane
> 
> > -----Original Message-----
> > From: Drake, John E [mailto:John.E.Drake2@boeing.com]
> > Sent: Friday, October 28, 2005 4:52 PM
> > To: Ong, Lyndon; ibryskin@movaz.com; dpapadimitriou@psg.com;
> > dimitri.papadimitriou@alcatel.be
> > Cc: Drake@movaz.com; dimitri.papadimitriou@alcatel.be; Igor
> > Bryskin; Zafar Ali (zali); Kim Young Hwa; ccamp@ops.ietf.org
> > Subject: RE: Two Drafts for Resilience of Control Plane
> >
> >
> >
> > > -----Original Message-----
> > > From: Ong, Lyndon [mailto:Lyong@Ciena.com]
> > > Sent: Friday, October 28, 2005 1:28 PM
> > > To: ibryskin@movaz.com; dpapadimitriou@psg.com;
> > > dimitri.papadimitriou@alcatel.be
> > > Cc: Drake@movaz.com; Drake, 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
> > >
> > > 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,
> > [JD]
> >
> > What is the utility of having standby control channels, as
> > opposed to just having multiple *active* control channels?
> >
> 
> There is no advantage, but there are numerous disadvantages. Having
> multiple *active* control channels is what I was referring to as let
IP
> layer provide the  resilience for Control Plane. In fact there are
> disadvantages of having active and standby control channel and some
> other entity have to manage them. Now you have to worry about
signaling
> and control channels to be in-sync, fast switchover, etc.
> 
> My motivation is to keep is simple, but yet superior.
[JD] 

Years ago, when we first started on LMP, we had the notion of active and
standby control channels and it was George Swallow that pointed out that
this was a really *BadIdea*tm.

Thanks,

John
> 
> Thanks
> 
> Regards... Zafar
> 
> 
> > > what
> > > you're suggesting sounds more like a standby signaling controller.
> > [JD]
> >
> > A standby signaling controller is an implementation option
> > that shouldn't affect the existing GMPLS protocols
> >
> > >
> > > 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-r
> > eqts-01.tx
> > > >>>>>t
> > > >>>>>
> > > >>>>>
> > > >>>>>>
> > > >>>>>
> > >
> > >>>http://www.ietf.org/internet-drafts/draft-kim-ccamp-accp-pr
> > otocol-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=ccam
> > p@ops.ietf
> > > >>>.or
> > > >>>
> > > >>>>>
> > >
> > >>>g&name=ccamp%40ops.ietf.org&fromemail=yhwkim@etri.re.kr&mes
> > sageid=%3C
> > > >>>863
> > > >>>
> > > >>>>>>0a6db-0c31-49ab-a798-13b0dda04553@etri.re.kr%3E>
> > > >>>>>>
> > > >>>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>>__________________________________
> > > >>>>>Yahoo! Mail - PC Magazine Editors' Choice 2005
> > > >>>>>http://mail.yahoo.com
> > > >>>>>
> > > >>>>>
> > > >>>>>.
> > > >>>>>
> > > >>>
> > > >>>
> > > >>>
> > > >>
> > > >>
> > > >>
> > > >> .
> > > >>
> > > >
> > >
> >