RuggedCom RX1100, RX1000 manual Ospf And Vrrp Example Network, Area And Subnets, Vrrp Operation

Chapter 13 – Configuring Dynamic Routing

OSPF And VRRP Example Network

This network consists of three routers connected in a ring with T1/E1 links. Router 1 and 2 and the switched network represent a remote site in which the routers supply a redundant gateway to the hosts via VRRP and the T1/E1 links supply a redundant network connection to the rest of the network.

Host 3

IP: 2.2.2.101

GW: 2.2.2.254

					2.2.2.254
		1.1.1.6					1.1.1.3
				Router 3
1.1.1.5		w2ppp					w1ppp	1.1.1.4
w1ppp									w2ppp
			w2ppp				w1ppp
Router 1								Router 2
			1.1.1.2		1.1.1.1
1.1.2.1								1.1.2.2
	VRIP = 1.1.2.254					VRIP = 1.1.2.254
	Priority = 100					Priority = 50

		Switch		Area 0
Host 1	IP: 1.1.2.101		IP: 1.1.2.102	Host 2
	GW: 1.1.2.254		GW: 1.1.2.254

Figure 115: OSPF And VRRP Example

Area And Subnets

As the OSPF design is simple, an area of 0 is used. The three point-to-point T1/E1 links are placed in the area by adding 1.1.1.0/24 to it. Router 1 and 2 will include their Ethernet links by adding subnet 1.1.2.0/24 to their area descriptions. Router 3 must also include 2.2.2.0/24 in its area description so that its existence is advertised.

The point-to-point T1/E1 interfaces and Ethernet interfaces on Router 1 and 2 must be made active. The Ethernet interface on Router 3 can be left passive since it does not participate in OSPF advertisements.

Router 1 and 2 must enable link-detect, to stop advertising 1.1.1.0/24 in the event of a link failure.

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.

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