RuggedCom RuggedRouter RX1100 - Manual (Page 165)

17. Configuring Dynamic Routing
Revision 1.14.3 165 RX1000/RX1100™
Router 1 and 2 must enable link-detect, to stop advertising 1.1.1.0/24 in the event of a link failure.
17.1.6.2. VRRP Operation
Router 1 and 2 have VRRP setup on their Ethernet connection so that they can both function as the
gateway for the clients on their network segment. Normally Router 1 is the VRRP master, and only
in case of a link failure to the switch or the router failing, will Router 2 take over the virtual IP. The
virtual IP used as the gateway is 1.1.2.254. Each router also has its own IP on the network so that
each can be reached individually.
If Router 1 or its Ethernet link fail, VRRP will detect the link being down and remove the direct route
to the 1.1.2.0/24. VRRP on Router 2 will stop seeing messages from Router 1, elect itself master and
will take over the gateway for the network.
OSPF on router 1 will notice the link being down (and the route to 1.1.2.0/24 disappearing) and will
use information from router 2 install a route to 1.1.2.0/24 via Router 2.
Router 3 will notice than Router 2 is now a more direct path to 1.1.2.0/24 network and start sending
to Router 2 instead of Router 1.
After the failure all routers still know how to reach the entire network, and the clients on 1.1.2.0/24 can
still send on the network using the same gateway address. The clients will see only a MAC address
change of the gateway and experience a few seconds of network outage When the link returns, VRRP
will switch back to the master, and the routes will return to their normal state.
Note that if the Router 1 WAN link fails, Router will see routes to Router3 via the Router 1 – Router
2 WAN and Ethernet links. If the faster Router 1 – Router 2 Ethernet path fails, Router 1 will fall back
to the Router 1 – Router 2 WAN link.
Note that it would not be useful to leave the Ethernet 1.1.2.0/24 subnets out of the area and turn on
redistribute connected as OSPF would not use the subnets for routing.
17.2. Dynamic Routing Configuration
Figure 17.2. Dynamic Routing Main Menu
In order to begin dynamic route processing on RuggedRouter, one of the protocols, RIP, OSPF, or
BGP must be enabled in the Enable Protocols menu under Dynamic Routing.
The Core menu configures link related items such as link-detect and link cost.
The RIP, OSPF, and BGP menus configure the corresponding routing protocols.