[c-nsp] BFD w/ static routes

[Rodney Dunn]

You guys please open a TAC case and ask for it to
be attached to that bug I gave you and outline the
topology you want it for. That helps me help you.

 

On Thu, Aug 04, 2005 at 04:45:13PM +0200, Gert Doering wrote:
> Hi,
> 
> On Thu, Aug 04, 2005 at 05:08:00PM +0300, Pekka Savola wrote:
> > The ISPs PE routers run iBGP or an IGP between each other.  The 
> > customer is routed with static routing.  When the primary link goes 
> > down, due to media converters or whatever, the PE and customer router 
> > may still think the link is up.  The customer's prefix is still routed 
> > towards the failed link (and the same for customer's default route 
> > pointing to the ISP) and traffic is blackholed.
> 
> Full ACK.  Similar setup here - customers reachable via ethernet briding
> devices that do not properly set link-down when there's something broken
> in between.
> 
> > This problem is typically solved by running BGP or an IGP to detect 
> > link failures and reroute.  We don't want to run an IGP across an 
> > admin domain, and setting up and maintaining BGP is too complex for 
> > the customer.
> 
> ACK again.
> 
> [..]
> > Hope this clarifies.  If there are other ways to solve this problem 
> > (apart from using routing protocols or BFD), pointers are welcome..
> 
> object tracking via "ping" works, but is ugly.  BFD is much more elegant
> ("designed for that job").
> 
> I wonder whether BFD is already available in entry-level boxes (2600,
> 831, etc.)?

It's on the roadmap but I can't promise you what form it's going to
be in just yet because it's too new in development.

I agree with you that on the surface this appears to be a good
solution for these WAN link down detection issues and could
also help improve convergence times. Scalability concerns on the
PE would have to be kept in mind.

> gert
> -- 
> USENET is *not* the non-clickable part of WWW!
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> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de