< Virtual Link Case 1 > ////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////// Two purposes of Virtual Link. 1. Linking an area that does not have a physical connection to the backbone. 2. Partitioning the backbone (for linking discontinuous parts of the backbone using a virtual link) Reference Diagram : diag_virtual1.ps ////////////////////////////////////////////////////////////////////////// How to make a virtual link The virtual link has to be established between two ABRs with one ABR connected to the backbone. 1. Make 3 Areas Dexter, Radia and Mrhorse (Area 0) Radia, Tony, and Yakov (Area 1) Yakov and Big-baby (Area 2) Radia and Yakov are ABRs 2. Make a area which is not physically connected to area 0 Shutdown one of Mrhorse interfaces 3. Make a Virtual Link between Radia and Yakov. 2. Compare with non-virtual link setup using traceroute. Reference Diagram: virtual_link_diagram1.ps ////////////////////////////////////////////////////////////////////////// Before making a virtual link. Trace route from big-baby to dexter. big-baby#trace 131.252.215.4 (dexter) Tracing the route to dexter.cs.pdx.edu (131.252.215.4) 1 * * * 2 * * * 3 * * * ////////////////////////////////////////////////////////////////////////// Make a Virtual Link between Radia and Yakov on the Radia, area 1 virtual-link 131.252.215.81 (yakov) on the Yakov area 1 virtual-link 131.252.215.49 (yakov) Show the virtual link information show ip ospf virtual-link RADIA ----- radia#config t radia(config)#router ospf 100 radia(config-router)#area 1 virtual-link 131.252.215.81 radia#sh ip ospf virtual-linkVirtual Link OSPF_VL1 to router 131.252.215.81 is up Run as demand circuit DoNotAge LSA not allowed (Number of DCbitless LSA is 1). Transit area 1, via interface FastEthernet0/1, Cost of using 2 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:07 radia#exit Yakov ----- yakov(config)#router ospf 100 yakov(config-router)#area 1 virtual-link 131.252.215.49 yakov#sh ip ospf virtual-link Virtual Link OSPF_VL1 to router 131.252.215.49 is up Run as demand circuit DoNotAge LSA not allowed (Number of DCbitless LSA is 1). Transit area 1, via interface FastEthernet0/0, Cost of using 2 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:04 Adjacency State FULL (Hello suppressed) Index 1/3, retransmission queue length 0, number of retransmission 0 First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0) Last retransmission scan length is 0, maximum is 0 Last retransmission scan time is 0 msec, maximum is 0 msec //////////////////////////////////////////////////////////////////////////////////// After making a virtual link The route from big-baby to dexter goes through yakov, tony and radia. big-baby#trace 131.252.215.4 (dexter) Type escape sequence to abort.Tracing the route to dexter.cs.pdx.edu (131.252.215.4) 1 131.252.215.81 4 msec 0 msec 4 msec 2 131.252.215.65 4 msec 0 msec 4 msec 3 131.252.215.49 4 msec 0 msec 0 msec 4 131.252.215.33 4 msec * 0 msec big-baby#exit ////////////////////////////////////////////////////////////////////////////////////