Re: [mpls-tp] Demultiplexing to BFD sessions

[Curtis Villamizar <[e-mail]>]

In message <[e-mail]>
[e-mail] writes:
[.. trimmed for brevity ..]
> > Even if the OAM 
> > packet contains discriminator values, if the packet does not 
> > carry the label, determining the LSP and therefore the 
> > destination MEP would be difficult in order to do CV (since 
> > only the source MEP TLV will be carried in the packet). 
> > Therefore I think the OAM context will be lost in case of PHP.
>  
> NH=> Well yes, quite....but this misses the key point.  Once we have
> succumbed to using a short-cut label-swapping way of co-ps mode
> forwarding we can no longer trust the label even when we have the
> decency not to discard it as it's only a proxy for a DA, and the
> critical SA information that checks correct connectivity is missing
> altogether from the traffic units anyway!  So operators who seriously
> care about protecting their customers from misconnectivity need to
> introduce CV (BFD?) OAM flows on ALL connections (irrespective of how
> important they are) where the CV (BFD?) packets contain network
> significant SA information and not some locally generated ID.
>  
> regards, Neil


Wow.  I agree with Neil on something.  It happens occasionally.  :-)

If I'm not mistaken, the LSP_TUNNEL SESSION object is needed to
identify the tunnel.  The LSP_ID should be ignored.  An example of
this in use would be a soft-preempt of an LSP which should be
minimally disruptive and not trigger an OAM DOWN event.  With this
method, a make-before-break should not interfere with CC/CV OAM as
long as the delay difference of the two LSP are not greater than the
CC/CV time out (this is why the timer should be configurable and *not*
fixed at specific values).

BTW- I haven't seen any discussion of the interaction of
make-before-break on MPLS-TP OAM.  AFAIK we are not disabling
make-before-break along with PHP and multipath (by default).

For the "no control plane" case the tunnel ID to expect in OAM can be
configured along with the label mapping.

Curtis