avri's comments

[Rob Coltun <rcoltun@redback.com>]

Avri Doria wrote:

> Hi,
>
> Some comments in line.
> a.
>
> "Wijnen, Bert (Bert)" wrote:
> >
> > Any comments on this by other subIP Directorate members?
> >
> > Thanks,
> > Bert
> >
> > > ----------
> > > From:         Bala Rajagopalan[SMTP:BRaja@tellium.com]
> > > Sent:         Sunday, June 03, 2001 12:01 AM
> > > To:   'Wijnen, Bert (Bert)'
> > > Cc:   Scott Bradner; 'rcoltun@redback.com'; 'gregb@ciena.com'; Yangguang
> > > Xu (E-mail); 'ahuja@merit.edu'; 'lberger@movaz.com'
> > > Subject:      Restoration requirements questions
> > >
> > >
> > > Bert & Scott:
> > >
> > > Here's the first draft of questions to be investigated
> > > by the restoration requirements design team.
> > > This is based on input from myself, Yanguang,
> > > Greg Bernstein and Rob.
> > > Suggestions for further refining this are welcome.
> > >
> > > Regards,
> > >
> > > Bala
> > >
> > > ---------------------------------------------
> > >
> > > A. Definitions
> > >
> > > 1. In determining the specific requirements, the design team should
> > > precisely
> > >    define  the concepts "survivability", "restoration", "protection",
> > >    "protection switching",
> > >    "recovery", "re-routing" etc. and their relations. This would enable
> > > the
> > >    requirements doc to describe precisely which of these will be
> > > addressed.
> > >
>
> I would recommend adding recovery time to the things being defined,
> since this  is sometimes a two satge time interval, and several
> conversations I have been involved in talked about the intital
> stage (time to alternate path) but not the second stage
> (time to return to non-alternate path)
>
> ALso related to one of the other requirements below a defintion of
> local, global and maybe something in between. Though this may belong
> in that discussion.
>
> BTW do you really want to to use end-to-end as is used below.  After
> watching the discussion on e2e, I am not sure this isn't a rat hole in
> waiting.  If so, they better distinguish between some of the nuances
> and distinctions made in end to end (i.e what end are you talking
> about?)
>
> > >    In the following, the term "restoration" is used to indicate the broad
> > >    set of policies and mechanisms used to ensure survivability.
> > >
> > >
> > > B. Network types and protection modes
> > >
> > > 1. What is the scope of the requirements with regard to the types
> > >    of networks covered? Specifically,  are the following in scope:
> > >
> > >    -  Restoration of connections in mesh optical networks
> > >       (opaque or transparent)
> > >    -  Restoration of connections in hybrid mesh-ring networks
> > >    -  Restoration of LSPs in MPLS networks (composed of LSRs overlaid on a
> > >
> > >       transport network, e.g., optical)
> > >
> > >    (What other network types should be covered?)
> > >
> > > 2.  What are the requirements with regard to
> > >     the protection modes to be supported in each network type covered?
> > >     (Examples of protection modes
> > >     include 1+1, M:N, shared mesh, UPSR, BLSR, newly defined modes
> > >     such as P-cycles, etc.)
> > >
> > > 3.  What are the requirements on local span (i.e., link by link)
> > >     protection and end-to-end protection, and the interaction between
> > > them?
> > >     E.g.: what should be the granularity of connections for
> > >     each type (single connection, bundle of connections, etc).
> > >
> > > C. Hierarchy
> > >
> > > 1. Vertical (between two network layers):
> > >    What are the requirements for the interaction between restoration
> > >    procedures across two network layers,
> > >    when these features are offered in both layers?
> > >    (Example, MPLS network realized over pt-to-pt
> > >    optical connections.) Under such a case,
> > >    (i) Are there any criteria to choose which layer should provide
> > >        protection?
> > >    (ii) If both layers provide survivability features, what are the
> > >        requirements to coordinate these mechanisms?
> > >
> > >
> > > 2. Horizontal (between two areas or administrative subdivisions within
> > >    the same network layer):
> > >    What are the criteria that trigger the creation of protocol or
> > >    administrative boundaries pertaining to restoration? (e.g.,
> > > scalability?
> > >    multi-vendor interoperability? what are the practical issues?)
>
> not only multi vender but multi provider.
>
> > >    When such oundaries are defined,
> > >    (i) What are the requirements on how protection/restoration is
> > >        performed end-to-end across such boundaries?
> > >    (ii) If different restoration mechanisms are implemented on two sides
> > > of
> > >       a boundary, what are the requirements on their interaction?
> > >
> > > D. Policy
> > >
> > > 1. What are the requirements for policy support during
> > > protection/restoration,
> > >    e.g., restoration priority, preemption, etc.
> > >
>
> This also needs to deal with the multi-provider boundary.
>
> > > E. Signaling Mechanisms
> > >
> > > 1. What are the requirements on the signaling transport mechanism
> > >    (e.g., in-band over sonet/sdh overhead bytes, out-of-band over
> > >    an IP network, etc.) used to communicate restoration protocol
> > >    messages between network elements. What are the bandwidth and
> > >    other requirements on the signaling channels?
> > >
> > > 2. What are the requirements on fault detection/localization mechanisms
> > >     (which is the prelude to performing restoration procedures)
> > >     in the case of opaque and transparent optical networks?
> > >     What are the requirements in the case of MPLS restoration?
> > >
>
> This should include issues of fate sharing.
>
> > > 3. What are the requirements on signaling protocols to be used in
> > >    restoration procedures (e.g., high priority processing, security, etc).
> > >
> > > 4. Are there any requirements on the operation of restoration protocols?
> > >
> > > E. Quantitative
> > >
> > > 1. What are the quantitative requirements (e.g., latency) for completing
> > >    restoration under different protection modes (for both local and
> > > end-to-end
> > >    protection)?
> > >
> > > F. Management
> > >
> > > 1. What information should be measured/maintained by the control plane at
> > >    each network element pertaining to restoration events?
> > >
> > > 2. What are the requirements for the correlation between control plane
> > >    and data plane failures from the restoration point of view?
> > >
> > >
>
> I am not sure if this fell into one of the other categories, but there
> is the a distinction between pre-staged recovery paths and those that
> are calculated and set when the fault is realized.
>
> > > Bala Rajagopalan
> > > Tellium, Inc.
> > > 2 Crescent Place
> > > P.O. Box 901
> > > Oceanport, NJ 07757-0901
> > > Tel: (732) 923-4237
> > > Fax: (732) 923-9804
> > > Email: braja@tellium.com
> > >
> > > >
> > >
>
> --
>
> Avri Doria
> +1 401 663 5024
> ===============
> http://www.aidsride.org/new/northeast/index.htm
> Rider : 1063