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Re: Two Drafts for Resilience of Control Plane


    Just like with 'classic' MPLS, with GMPLS
I think you have a situation where the
data and control planes could be out of
sync., or at least out of contact with each other for
a period of time. This is certainly not a fabricated
problem, but a matter of 'how often' and 'how bad' when
it happens (i.e.: is the IP control plane sufficiently
resilient) As Zafar said earlier, there are already some
mechanisms in place to handle this. Some folks (vendors
only) have said they are sufficient. To me, this should
be a question that operator types should be answering.

    --Tom




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.txt
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
    ===================================> >>
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