[c-nsp] BFD for static routes

[Phil Bedard]

That's really the "killer app" for this so to speak, is in a L2 metro  
scenario where you can't propagate the customer link-state back to the  
terminating L3 router.   Even the lowest end Cisco router runs BGP  
these days, so I've used that in the past with private ASs for  
customers dual-homed, but that requires more configuration and  
monitoring, etc.  The other option is GRE tunnels but that isn't a  
very good solution imho.  BFD seems like a better option to me.  It's  
supported by Juniper, but Cisco seems to only have support in IOS XR.

I guess a question to pose to Cisco is what takes more CPU, BFD or IP  
SLA?  If they are the same, IP SLA (reliable static routes) is  
certainly an option.

Phil


On Jan 10, 2008, at 2:21 AM, Gert Doering wrote:

> Hi,
>
> On Wed, Jan 09, 2008 at 11:14:06PM +0100, Peter Rathlev wrote:
>> I'm a little puzzled here. BFD needs two BFD-speaking routers, right?
>> It's not enough that one of them can speak BFD, is it? And if a  
>> router
>> speaks BFD it probably also speaks some kind of routing protocol
>> semi-fluently. Why not use that option instead?
>
> Because you don't want to speak any routing protocol to customers.
>
> Consider things like customers being connected to your routers by a
> "LAN bridge" from some city carrier.  Ethernet on both ends, $funny  
> things
> in the middle of it.  Depending on the way these boxes work, both  
> sides
> might have a link at all times, no matter whether the link actually  
> works
> or not.
>
> Given that it's a customer connection, you do not want to do IGP  
> routing
> that way, and if it's a low-budget customer, you certainly do not  
> want to
> setup BGP routing.  So you need some other way to detect "line is  
> down,
> move to backup link".
>
> BFD-with-statics would very nicely fill that niche.
>
> (And yes - we used have a lot of those links...)
>
> gert
> -- 
> USENET is *not* the non-clickable part of WWW!
>                                                           //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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