Symptom
Static routes pointing to tunnel dissapear from the RIB after physical Cellular interface, associated to the Dialer used in the ip unnumbered command, flaps.
Tunnel goes down and up as expected but the static routes are delete from RIB and not added again.
Conditions
Using static routes that point to interface tunnel (no IP for next-hop) and such tunnel is using ip unnumbered Dialer command.
Falpping if the Cellular interface associated to the Dialer that is source for the tunnel interface
Workaround
Configure a track and associate the track to the static route.
track 1 interface Tunnel1 line-protocol
delay up 10
ip route x.x.x.x y.y.y.y Tunnel1 track 1
Further Problem Description
The issue only happens with the tunnel configured with ip unnumbered Dialer command.
Trigger: The problem is that, if we have a break on the internet access on the Dialer, Tunnel interfaces flap (as expected) and the static routes pointing to the Tunnel will not be installed to the routing table anymore(not showing in show ip route output).
Recover by doing:
- shutdown/no shutdown on the Tunnel
- or delete and re-add the static route to the configuration
We tried to use 3 different IOS, but the problem was visible with all of them.
IOS versions that were used:
c1100-universalk9_ias.16.09.02.SPA.bin
c1100-universalk9_ias.16.09.04.SPA.bin
c1100-universalk9_ias.16.06.05.SPA.bin
Found bug CSCuo10678 which describes the exact same behavior customer is experiencing. The bug occurs under the same conditions and the workarounds are the same applied. However, the bug was created on 2014 and it is fixed in version 15.4.3S so we need to confirm if it is affecting this release 16.9.2
