Netgear XCM8806 Chassis User Manual - Page 680

NETGEAR 8800 User Manual Virtual links are also used to repair a discontiguous backbone area. For example, in Figure 73, if the connection between ABR1 and the backbone fails, the connection using ABR2 provides redundancy so that the discontiguous area can continue to communicate with the backbone using the virtual link. Virtual link Area 2 ABR 1 ABR 2 Area 1 Area 0 Figure 73. Virtual Link Providing Redundancy Area 3 EX_045 Point-to-Point Support You can manually configure the OSPF link type for a VLAN. Table 68 describes the link types. Table 68. OSPF Link Types Link Type Auto Broadcast Point-to-point Passive Number of Routers Description Varies XCM8800 automatically determines the OSPF link type based on the interface type. This is the default setting. Any Routers must elect a designated router (DR) and a backup designated router (BDR) during synchronization. Ethernet is an example of a broadcast link. Up to 2 This type synchronizes faster than a broadcast link because routers do not elect a DR or BDR. It does not operate with more than two routers on the same VLAN. The Point-to-Point Protocol (PPP) is an example of a point-to-point link. An OSPF point-to-point link supports only zero to two OSPF routers and does not elect a designated router (DR) or backup designated router (BDR). If you have three or more routers on the VLAN, OSPF fails to synchronize if the neighbor is not configured. A passive link does not send or receive OSPF packets. Note: The number of routers in an OSPF point-to-point link is determined per VLAN, not per link. 680 | Chapter 24. OSPF