[c-nsp] Reliable static routes and 12.2S

[Gert Doering]

Hi,

On Mon, Jan 31, 2005 at 04:52:41PM -0500, Rodney Dunn wrote:
> On Mon, Jan 31, 2005 at 10:45:50PM +0100, Gert Doering wrote:
> > > For a DSL type environment you usually are not running
> > > a routing protocol over the links so what do you want
> > > to react?
> > 
> > Link status (or being able to tie static routes into BFD).
> That's the one part I was thinking about was static routes.
> 
> Link status is almost surely a no go.

Yes, understood.  This will make troubleshooting somewhat more difficult
(you can't tell ops to look at "show interface ..." first, and only 
if that's up/up go looking for more difficult problems - something which,
for example, ATM OAMs nicely provide, if you have end-to-end ATM), but
still, it would be *very* useful.

> > Just something to reliably notice that part of the "usual" something-
> > bridged-over-something-without-end-to-end-keepalives customer links
> > isn't working anymore, *without* having to run a full-featured routing
> > protocol with the CPE.
> 
> With statics I can see it.
> 
> 
> ie: default on the CPE with dial backup upon primary failure.

Yes, exactly this is the idea.  Right now we use ATM OAMs where possible,
and where that is not possible, SAA probes with static routes (on Cisco
gear) or even "if the line fails, pull out the ethernet cable so that
the dial backup kicks in".

> Issue would probably become scalability.

In that scenario, we wouldn't run BFD in "millisecond failover" mode - 
something like "10 seconds failure detection time" is perfectly fine...

gert

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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de