WB1 RIP 4.17~4.18 Conditional Default Routing

4.17 RIPv2 Conditional Default Routing

R4:
router rip
  default-information originate route-map TRACK_LINK_TO_BB3
!
ip prefix-list LINK_TO_BB3 seq 5 permit 204.12.1.0/24
!
route-map TRACK_LINK_TO_BB3 permit 10
  match ip address prefix-list LINK_TO_BB3

以上的設定是假設R4的路由表中會存在204.12.1.0/24這筆路由時，才會將default-route放出
這不一定好，應該用下面的範例


4.18 RIPv2 Reliable Conditional Default Routing

R4:
ip sla 1
  icmp-echo 204.12.1.254 source-interface FastEthernet0/0
    timeout 2000
    frequency 5
ip sla schedule 1 start-time now
!
track 123 rtr 1
!
router rip
  default-information originate route-map RELIABLY_TRACK_LINK_TO_BB3
!
ip route 169.254.0.1 255.255.255.255 Null0 track 123
!
ip prefix-list DUMMY_ROUTE_TRACKED_VIA_SLA seq 5 permit 169.254.0.1/32
!
route-map RELIABLY_TRACK_LINK_TO_BB3 permit 10
  match ip address prefix-list DUMMY_ROUTE_TRACKED_VIA_SLA


Ping不到BB3時，track down，169.254.0.1路由表消失，
跟著prefix-list的條件也不會成立，最後是轉發default的理由也消失了。。。

當我第一次看到這樣的時候，我的媽呀，這樣也可以喔～～～真強