Vyatta Network OS Documentation

Learn how to install, configure and operate the Vyatta NOS, which helps drive our virtual networking & physical platforms portfolio.

Configuring BFD for OSPFv2 on a virtual link by using IPv4 addressing

To configure BFD for OSPFv2 neighbors on a virtual link, you must first configure the virtual link between the disconnected backbone area routers and then enable BFD on the virtual link.

Consider a scenario in which you have two systems, R1 and R2. R1 and R2 share an OSPFv2 session, sharing a virtual link, as illustrated in the reference network diagram. The following list provides the addresses of R1 and R2.
  • R1 router-id—1.1.1.1
  • R2 router-id—2.2.2.2
  • R1 interface address facing R2—10.1.1.1
  • R2 interface address facing R1—10.1.1.2
Figure 1. Configuring BFD for OSPFv2 on a virtual link by using IPv4 addressing

Virtual link is configured in a transit area. A virtual link chooses any address to reach other virtual link end points in the same transit area. Therefore, the source and destination addresses in a three-router configuration or a more-complex configuration are selected dynamically. You must ensure that you select the correct source and destination addresses for your BFD commands for OSPFv2 and OSPFv3 virtual links. To configure a BFD session between R1 and R2, perform the following steps in configuration mode.

Table 1. Configuring BFD for OSPFv2 on a Virtual Link by Using IPv4 Addressing
Router Step Command
R1 Create a BFD template called test. See section Configuring the BFD template.
R1 Associate the BFD test template with the destination address of R2 and the source address of R1.
vyatta@R1# set protocols bfd destination 10.1.1.2 source 10.1.1.1 template test
R1 Register R2 as a BFD neighbor.
vyatta@R1# set protocols ospf area 1 virtual-link 2.2.2.2 fall-over bfd
R1 Commit the configuration.
vyatta@R1# commit
R1 Save the configuration.
vyatta@R1# save
R1 Display the configuration.
vyatta@R1# show protocols ospf
 ospf {
        area 1 {
                network 10.1.1.0/24
                virtual-link 2.2.2.2 {
                        fall-over {
                                bfd
                        }
                }
        }
        parameters {
                router-id 1.1.1.1
        }
 }


vyatta@R1# show protocols bfd 
 bfd {
        destination 10.1.1.2 {
                source 10.1.1.1 {
                   template test
                }
        }
        template test {
                auth {
                        simple {
                                key "********"
                        }
                }
                minimum-rx 300
                minimum-tx 300
                multiplier 3
        }
 }
R2 Create a BFD template called test. See section Configuring the BFD template.
R2 Associate the BFD test template with the destination address of R1 and the source address of R2.
vyatta@R2:~$ set protocols bfd destination 10.1.1.1 source 10.1.1.2 template test
R2 Register R1 as a BFD neighbor.
vyatta@R2# set protocols ospf area 1 virtual-link 1.1.1.1 fall-over bfd
R2 Commit the configuration.
vyatta@R2# commit
R2 Save the configuration.
vyatta@R2# save
R2 Display the configuration.
vyatta@R2# show protocols ospf
 ospf {
        area 1 {
                network 10.1.1.0/24
                virtual-link 1.1.1.1 {
                        fall-over {
                                bfd
                        }
                }
        }
        parameters {
                router-id 2.2.2.2
        }
 }


vyatta@R2# show protocols bfd 
  bfd {
        destination 10.1.1.1 {
                source 10.1.1.2{
                   template test
                }
        }
        template test {
                auth {
                        simple {
                                key "********"
                        }
                }
                minimum-rx 300
                minimum-tx 300
                multiplier 3
        }
 }