RIP

The use of VRRP has a particularly strong influence on RIP, which is used to propagate information on the accessible routes and the corresponding routers.

• On the one hand, routes to remote sites which can be reached via a virtual router must be made known to the network.
• On the other hand, the routes that are propagated by the virtual routers themselves must be ignored.
• Ultimately, the propagated information is dependent upon the interface which it is to be passed on to.

The announcement of routing information via RIP is governed by the following rules:

• Routes are propagated on all virtual and physical interfaces and every virtual router counts as its own virtual interface.
• If routes are currently being propagated on a physical interface (LAN/DMZ) and a route that must be propagated is connected to a virtual router, then two cases must be differentiated:
  • When the virtual router is active on the interface, i.e. its address is in the address range of the respective interface, then the route will not be propagated.
  • If the virtual router on the interface is not active, then the route will be propagated normally, i.e. the physical interface address will be propagated as the best route.
• If routes are propagated on a virtual router, then only the routes that are connected to this virtual router may be propagated.
• If routes are propagated on a WAN interface, then all routes are propagated.
• Upon receiving a RIP packet, the sender address of the RIP packet must be taken into consideration. The routes contained in the packet must be ignored when they are propagated by a virtual router known by the R&S®NC router.
• If the R&S®NC router cannot establish a connection to the remote site because all channels are occupied, then RIP propagates the routes accessible through this remote site as "unavailable".
  • In addition, the VRRP module is notified in this case so that it can log off of the router connected to this remote site allowing a new master to be determined.
  • Similarly, VRRP receives notification when the connection is can be re-established in order to allow the virtual router to propagate with its main or backup priority again.