Hello,
Q1) When the Broadband link is down, is the ethernet Port Line Protocol also down ? Can the ISDN link detect that the primary link is down in this ?
--> Yes, in case your primary connection goes down, the line protocol goes down as well. The line protocol being down is enough for the backp BRI interface to come up. Configure your primary interface with the line:
interface ethernet0
backup interface bri0
Q2) If I have gateway x.x.x.x for the Primary link and gateway y.y.y.y for the ISDN link, so can I have the following static routes ?
ip route 0.0.0.0 0.0.0.0 x.x.x.x
ip route 0.0.0.0 0.0.0.0 y.y.y.y
Please clarify the routing for the Primary Link and the backup link.
--> give the static route that points to the ISDN connection a higher administrative distance, that way you make sure that traffic is only routed through that route when the primary route is down (this is generally called a floating static route)
ip route 0.0.0.0 0.0.0.0 y.y.y.y 200
Q3) How to configure a static route is higher precidence than the other ?
--> same as in the previous question:
ip route 0.0.0.0 0.0.0.0 y.y.y.y 200
HTH,
Georg