0 Replies Latest reply: Jun 17, 2019 1:32 PM by Anthony RSS

    Odd issue with SLAAC in VIRL


      I'm experiencing an odd issue with SLAAC in VIRL: an interface set to configure itself with a global unicast address via SLAAC is still able to do so despite the only router interface by which it could 'learn' an advertised prefix is in the shutdown state.


      • R3's Gi0/1 interface is set to configure itself with a global unicast address via SLAAC

      interface GigabitEthernet0/1

         description Link to SW2

         ip address

         no ip route-cache

         ipv6 address autoconfig default

         no cdp enable

      • R2's Gi0/2 interface is deliberately in the shutdown state to try to replicate the issue of stateless auto configuration not working as a result of a peer interface being in the shutdown state
      • Despite R2's Gi0/2 interface being in a shutdown state, R3's Gi0/1 is nevertheless configuring itself with a global unicast address and more bizarre is that this is based on the prefix of R1's Gi0/1 interface.


      I can't seem to work out why this is. If R1 is advertising its 2001:DB8:0:10::/64 prefix, how are these router advertisements able to get past R2's Gi0/2 interface (which is shutdown) and over to R3?

      SLAAC issue in VIRL.png

      The situation remains the same if, in addition to the shutdown command on R2s Gi0/2 interface, I also right-click the connector on that interface in VM Maestro's active canvas select Disable Interface (no difference after then disabling and re-enabling R3's Gi0/1 interface).

      SLAAC issue in VIRL - VM Maestro.png

      I've attached the VIRL file - would be interested in seeing if anyone else gets the same issue - or if I'm missing something!