On Thu, May 23, 2002 at 11:43:29AM -0400, Kent Yu wrote:
> Eric,
>
> > > I think it would be better if we could just signal the fast reroute
> without
> > > manually building the tunnels on every router. Kind of like making the
> > > routers create the tunnel interfaces automatically, is this why it is
> not
> > > easy in IOS?
> >
> > It's not easy because it's currently not possible. :) There's nothing
> > wrong with this idea, it's just not something we (currently) implement.
> >
>
> I think I realized how difficult it is to implement a feature that does not
> exist right now -;).
> What I was trying to ask was if there are some other reasons not
> implementing this? I would assume there should be some push from the
> customers about this, but as it is not implemented, I guess still not
> enough.
>
It's a good idea. ...mumble mumble...no comments on future
development...mumble mumble......it doesn't exist yet. :) The only
real argument I can think of to not implement it is that if you need
to steer tunnels explicitly (which you do if you use an offline tool
to generate your protection topology), then building tunnels
automatically isn't going to be good enough.
> > That works OK as long as all you need to do is avoid the link/node
> > you're protecting. If you explicitly need to steer a path in a
> > specific direction (so you don't protect an OC48 down an OC3, for
> > example)
>
> But this only happens because we cannot specify fast reroute for each LSP,
> this feature is called link/node protection, it is certainly OK if we only
> want manually build tunnels on every router on which we have links/nodes to
> protect.
If I read you right, you're saying that you explicitly need to steer a
path a backup LSP takes because you can't specify FRR for each LSP?
I'm not sure I understand what you're saying, and if I do understand,
I disagree. :)
Yes, it's OK to build protection tunnels anywhere you like. And there
are certainly ways to automate it. Without getting into the whole
backup tunnel placement thing, an easy way is to use exclude-address
to exclude the other end of the link (which you can deduce from a
config given the interface addr) or node (which you should already
know since it's your network) and have it build tunnels that way.
I agree 100% that it would be easier if you had a global knob like
'mpls traffic-eng fast-reroute automatic'. And I think we agree that
in the absence of such a knob, doing things manually is the best way
(mainly because it's the _only_ way, which I guess also makes it the
worst way?) to do things.
eric
>
> Kent
>
>
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