Re: [Idr] draft-bashandy-idr-bgp-repair-label-01: when does PE revert back to standard label?

[Jakob Heitz <[e-mail]>]

> -----Original Message-----
> From: Robert Raszuk [mailto:[e-mail]] 
> Sent: Saturday, April 02, 2011 3:24 PM
> To: Jakob Heitz
> Cc: idr
> Subject: Re: [Idr] draft-bashandy-idr-bgp-repair-label-01: 
> when does PE revert back to standard label?
> 
> Hi Jakob,
> 
> > If PE3 sends an MPLS packet to PE1, PE1 uses the repair 
> label to send
> > to PE2. If CE2 sends an IP packet to PE1, PE1 should use the primary
> > label to send it to PE2. It should NEVER use the repair 
> label to send
> > that packet.
> >
> > The reason? If the link PE2 - CE were to fail, PE2 would not use the
> > backup to PE3.
> 
> Nope - sorry.
> 
> 1st point: We are working here to protect against single failure not
> double failure like in your example.

It's not a double failure.

> 
> Now direct answer with sequence of events including time scale for 
> better description:
> 
> - -10ms CE2 communicates via PE1 with CE without any protection
> -  0ms CE is getting re-homed from PE1 to PE3
> -  20ms PE1 on data plane is starting to use a backup label and nh=PE2

It uses repair label for packets received from PE3. (MPLS)
It uses primary label for packets received from CE2. (native IP)

> - 300ms PE1 converges control plane and starts to use primary label as
>    advertised by PE2 (in the same time all network is recalculating as
>    well removing CE via PE1 path)

still:
It uses repair label for packets received from PE3. (MPLS)
It uses primary label for packets received from CE2. (native IP)

> - @ next failure - PE2-CE fails PE2 will already have a backup via PE3
>    in it's data plane using backup label as advertised by PE3.
> 
> Rgs,
> R.
> 
>