I've got a Cisco 877 ADSL router from which I advertise a default route via OSPF to our central router. It also does a standard ADSL / PPP connection to one of our ISPs. What I want is to advertise the default route only when PPP is up. If it goes down stop advertising 0.0.0.0/0. We don't get a BGP or OSPF feed over that ADSL so I can't simply redistribute what I receive. Is that doable?
Here is the PPP config:
interface Dialer0 ip address negotiated ip access-group INTERNET-IN in no ip redirects no ip unreachables ip mtu 1492 ip nat outside ip inspect INTERNET out ip virtual-reassembly encapsulation ppp dialer pool 1 no cdp enable ppp authentication pap callin ppp pap sent-username ... ppp ipcp route default
And here is the OSPF config:
router ospf 1 log-adjacency-changes redistribute static subnets route-map ospf_tcl network 192.168.128.0 0.0.15.255 area 1 default-information originate metric 1 route-map ospf_tcl permit 10 match ip address prefix-list adsl_defroute ip prefix-list adsl_defroute seq 5 permit 0.0.0.0/0 ip prefix-list adsl_defroute seq 10 permit 192.168.128.0/20
UPDATE based on the comments below...
The main router has one other internet link (SHDSL) through a different ISP with BGP feed of national prefixes. The ADSL link (slow, cheap data) via Cisco 877 is primarily used for international traffic and the SHDSL link (fast, expensive data) for national traffic (welcome back to the 90's - that's what we get on a remote pacific island ;) However in the even of one link going down I want to automatically fail over all traffic to the other link. At the moment it requires a manual intervention on the main router manually replacing the default route.
The goal is to have under normal circumstances a higher metric default route over SHDSL, lower metric default route via ADSL and a bunch of more specific national routes via SHDSL. That part already works, just the default routes updating doesn't.
Here are the static routes from the Cisco box:
#show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route Gateway of last resort is 218.101.y.y to network 0.0.0.0 C 192.168.128.0/24 is directly connected, Vlan128 203.97.x.0/32 is subnetted, 1 subnets C 203.97.x.x is directly connected, Dialer0 218.101.y.0/32 is subnetted, 1 subnets C 218.101.y.y is directly connected, Dialer0 S* 0.0.0.0/0 [1/0] via 218.101.y.y S 192.168.128.0/20 [1/0] via 192.168.128.221
The main router is connected over