The backup interface stuff is fairly lame, the various flavors of
dial-on-demand provide more flexibility. Basically you need to
use some kind of active protocol over the ethernet/wireless like
to the other side, such that packets will always flow over the
ethernet if you have working end-to-end connectivity, but if they
iGP withdraws the route, a backup/default route tries to send
packets over the isdn, it takes a deep breath and dials...
Depending on the failure characteristics of the RF link, you may
want to use BGP or something that lets you control how it behaves
in the fact of the RF link "flapping".
George
> From: <nick@arc.net.my>
> To: cisco-nsp@puck.nether.net
> Date: Mon, Jun 18 2001 6:29:21 GMT+0000
> Subject: [nsp] Wireless LL and ISDN backup
>
> We have deployed a scenario for wireless local loop ISP access using Cisco Aironet and Breezecom utilizing 2.4Ghz ISM. Since this is an open band, at some locations we are facing problems with interference and are planning to use ISDN backup when the wireless link 'fails' due to interference.
>
> >From the subscriber unit it is an ethernet link to the router and this link is always 'up' despite the wireless link 'failing'. So utilizing the following configuration:
>
> int eth0
> backup interface bri0
>
> will not work as to the router the ethernet port is 'up' and hence the whole wireless link. Well unless we manually unplug the ethernet link.
>
> Any ideas on how to solve this to fool the router into bringing up the ISDN backup link?
>
> Thanks in advance.
>
> -nick
>
> mailto:nick@arc.net.my
>
>
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