Re: Re: draft-suping-bfd-mpls-fecmismatch-00 questions

[David Ward <[e-mail]>]

David -

In these cases, it would be best if the violating node sent the 
proper diag code and said that their forwarding plane was insane. We don't
want this protocol resonsbile for checking up to 4B FIB entries to see if they 
are installed correctly. To take this to a logical end, we would have to
check all addrs in all AF/SAF and all potential mismatches. The node itself
has to take some responsiblity when possible. When it is not possible, e.g.
GR, BFD can help detect some failures.   

If this problem is as we seem to agree a control plane programming issue,
an OAM protocol seems more applicable at config time.

-DWard

On Sun, Feb 27, 2005 at 04:21:39PM -0500, David Allan wrote:
> It is not detecting a control plane failure, it is detecting inconsistencies
> in forwarding such that synch between control and data plane has been lost..
> connectivity to somewhere exists but is not necessarily correct...IMO that
> is still a data plane problem...
> 
> Dave
> 
> > -----Original Message-----
> > From: [e-mail] 
> > [mailto:[e-mail]] On Behalf Of David Ward
> > Sent: Sunday, February 27, 2005 10:48 AM
> > To: zhaisuping
> > Cc: [e-mail]
> > Subject: Re: Re: draft-suping-bfd-mpls-fecmismatch-00 questions
> > 
> > 
> > Unfort., what you write is 180 degrees opposite from the 
> > charter of the BFD WG and the philosophy of how the protocol 
> > is to function. BFD is not to check the consistency of the 
> > forwarding and control plane. We do not want to 
> > take this protocol into the realm of control plane failure 
> > detection system (as there are many better protocols or 
> > protocol machinery for that) but,  focus on forwarding 
> > failure detection that can send alarms, event notification, 
> > diags, etc up the stack.
> > 
> > 
> > -DWard
> > 
> > 
> > 
> > On Sat, Feb 26, 2005 at 09:41:49AM +0800, zhaisuping wrote:
> > > Hi, all
> > > The purpose of FEC filter in BFD is to detect the consistence of
> > > the control plane and data plane. So that in the MPLS network, just
> > > running the BFD session(LSP-Ping is not needed) is enough for the
> > > defect detection. Or else such tools as LSP-Ping is needed because
> > > the BFD session can't detect the inconsistence of the control plane
> > > and data plane. 
> > > In the section 2 of the draft, there is description of the 
> > > problem the draft want to solve.
> > > >> Wouldn't LSP-Ping (or VCCV) be a more appropriate place 
> > to do this 
> > > >> filter verification?
> > > 
> > > 
> > > >
> > > >LSP-Ping does a verification on the FEC itself, so a 
> > filter would add 
> > > >nothing.
> > > >
> > > >VCCV is not a protocol.  Just a little sideband for sending IP 
> > > >packets down a pseudowire so that you can run LSP-Ping, BFD, etc. 
> > > >between the two ends.
> > > >
> > > >....George
> > > >
> > > 
> > >=============================================================
> > ===========
> > > >George Swallow             Cisco Systems                  
> > [phone]
> > > >                           1414 Massachusetts Avenue
> > > >                           Boxborough, MA 01719
> > 
> > 
> >