The MPLS WG Archive

[Curtis Villamizar <curtis@fictitious.org>]

In message <4B6D09F3B826D411A67300D0B706EFDEB03B90@nt-exch-yow.pmc-sierra.bc.ca
>, Shahram Davari writes:
> Curtis,
> 
> I was more thinking in terms of how to make sure the backup/detour
> paths are working fine, while the traffic is still on the working path.
> 
> Yours,
> -Shahram


Currently you'd have to do that from each PLR.  We don't provide a
means to tell the ingress of the existance of a detour (except the
local-protect-available bit in the signaling itself which one major
implementation wasn't using last I checked).  We also don't provide a
means to tell a specific PLR to exercise its detour and report back.

Let's wait and hear from Kireeti or other authors whether they think
anything should be added or whether the intent is to require testing
initiated at each PLR.

There is no way to run a (non-intrusive) test that would determine
whether the traffic would be correctly diverted on failure.  That is
not a limitation of the protocol.  There is no way to test it other
than induce a failure.

Curtis


> > -----Original Message-----
> > From: Curtis Villamizar [mailto:curtis@fictitious.org]
> > Sent: Thursday, December 12, 2002 11:14 PM
> > To: Shahram Davari
> > Cc: mpls@UU.NET
> > Subject: Re: Last call on LSP Ping 
> > 
> > 
> > 
> > In message 
> > <4B6D09F3B826D411A67300D0B706EFDEB03B8C@nt-exch-yow.pmc-sierra.bc.ca
> > >, Shahram Davari writes:
> > > Hi,
> > > 
> > > Would the authors comment on how the MPLS-ping applies when
> > > Fast Reroute scheme exists? In other words how is the backup path
> > > and/or detour paths tested from the ingress?
> > > 
> > > Thanks,
> > > -Shahram
> > 
> > 
> > In ping mode you should not know that the backup is in use.
> > 
> > Perhaps an error return in traceroute mode would be helpful or an
> > indication that the next hop is part of a detour.
> > 
> > Keep in mind that once the detour is put into use it is usually a
> > matter of seconds before a new primary is created with its own set of
> > detours, none of which are in use.
> > 
> > Curtis
> > 
>