Re: Static LSP Configuration

[Sudheer Dharanikota <sudheer@nayna.com>]

Shahram Davari wrote:

> Curtis,
>
> > -----Original Message-----
> > From: Curtis Villamizar [mailto:curtis@workhorse.fictitious.org]
> > Sent: Monday, May 06, 2002 4:31 PM
> > To: Sudheer Dharanikota
> > Cc: Gary Tam; Ajay Simha; curtis@fictitious.org; Ron Bonica; Brijesh
> > Kumar; 'Curtis Villamizar '; mpls@UU.NET; CCAMP WG
> > Subject: Re: Static LSP Configuration
> >
> >
> >
> > In message <3CD6C43C.94BACCEE@nayna.com>, Sudheer Dharanikota writes:
> > >
> > > Transport networks are *built* to provide 50 msec recovery
> > > times (e.g., rings, span, 1+1 etc). Hence a failures are
> > scoped to be
> > > within a domain (typically a ring or a span or in the worst case
> > > end-to-end[1+1 case]).  Excluding failure detection time in this
> > > 50 msec (taking from SONET knowledge), failure reporting
> > > and recovery should take 50 msec. Obviously this cannot
> > >  be done with OSS intervention. One can use SONET's
> > > inband signaling mechanisms for failure reporting or use
> > > *directed notification* mechanisms such as the ones proposed
> > > for signaling protocols. Note that if we assume a ring topology then
> > > the messages are only one hop away (with the assumption that
> > > only the DCS are the intelligent devices). So your worry of 5-10
> > > hop path is not valid in my opinion.
> > >
> > > Regards,
> > >
> > > sudheer
> >
> >
> > The discussion was about MPLS but an underlying assumption seemded to
> > enter into the thread with that last email that either APS was running
> > under MPLS or L2 was the application and APS was running over MPLS
> > provided over multiple end to end L2 tunnels.
> >
> > I don't know of anyone doing SONET APS over the L2 tunnels of an MPLS
> > backbone.
> >
> > I do know of providers who want to eliminate the APS on the sonet
> > links under their MPLS network cutting some costs significantly (but
> > with all things considered, not in half).
>
> What mechanism will they use to detect the failure then?

With most of the *recent* L2/L1 technologies, failure dection is not the
only problem.
Without APS-like mechanisms (sub-second) failure reporting is also a major
problem.
In my opinion, for the sake of the underlying technologies which does not
have
APS-like reporting mechanisms, we need to optimize our signaling protocols
and propose sensible control plane topologies.

Regards,

sudheer

>
>
> -Shahram
>
>   MPLS restoration needs to
> > work quite well to do this and still meet SLAs and carrying L2 service
> > is even more demanding.
> >
> > Curtis
> >