WALKTHROUGH: Virtual Links

Back to the Virtual Links Lab

So you're stuck or don't trust your work. Here is the cheat/check page. Note that this is all done from the perspective of J2300-1. Adapt to other routers as needed.

1. See if your router has a route to R14's loopback address at 14.14.14.14

admin@J2300-1> show route 14.14.14.14 

admin@J2300-1> 
[edit]

2. See if your router has a route to 13.13.13.13

admin@J2300-1> show route 13.13.13.13 

admin@J2300-1> 

3. Check and see if your LSDB has a Router LSA for 13.13.13.13

admin@J2300-1> show ospf database lsa-id 13.13.13.13

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router   13.13.13.13      13.13.13.13      0x80000004  1441  0x22 0x5e3b  36

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router   13.13.13.13      13.13.13.13      0x80000008   208  0x22 0xf36b  48

admin@J2300-1> 

4. Configure your router with a virtual link to bring the 13.14.13.14 area into the network so it is reachable across the entire OSPF domain

admin@J2300-1> edit 
Entering configuration mode

[edit]
admin@J2300-1# edit protocols ospf area 0 

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# ...or-id 13.13.13.13 transit-area 101.101.101.101              

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# 

5. See if you have a virtual link showing up as an OSPF interface

admin@J2300-1> show ospf interface 
Interface           State   Area            DR ID           BDR ID          Nbrs
fe-0/0/1.12         PtToPt  0.0.0.0         0.0.0.0         0.0.0.0            1
fe-0/0/1.13         PtToPt  0.0.0.0         0.0.0.0         0.0.0.0            1
lo0.0               DRother 0.0.0.0         0.0.0.0         0.0.0.0            0
vl-13.13.13.13      PtToPt  0.0.0.0         0.0.0.0         0.0.0.0            1
fe-0/0/1.1001       DRother 0.0.0.1         10.1.0.1        0.0.0.0            1
fe-0/0/1.13         PtToPt  0.0.0.1         0.0.0.0         0.0.0.0            1
fe-0/0/1.100        DRother 30.30.30.30     99.99.99.99     10.0.0.4           7
fe-0/0/1.101        DRother 101.101.101.101 10.10.10.10     10.0.0.4           6
fe-0/0/1.102        DRother 102.102.102.102 10.10.10.10     10.0.0.4           6

admin@J2300-1> 

6. Inspect your neighbor session across the virtual link

admin@J2300-1> show ospf neighbor area 0           
Address          Interface              State     ID               Pri  Dead
10.0.12.2        fe-0/0/1.12            Full      10.0.0.2         128    35
  Area 0.0.0.0
10.0.13.3        fe-0/0/1.13            Full      10.0.0.3         128    37
  Area 0.0.0.0
13.0.0.0         vl-13.13.13.13         Full      13.13.13.13        0    32
  Area 0.0.0.0

admin@J2300-1> 
[edit]

7. Inspect your own Router LSAs and see which areas your router is advertising a vitual links

admin@J2300-1> show ospf database lsa-id 10.0.0.1 router detail 

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router  *10.0.0.1         10.0.0.1         0x8000002a   239  0x22 0xd7ba  96
  bits 0x3, link count 6
  id 10.0.0.2, data 10.0.12.1, Type PointToPoint (1)
    Topology count: 0, Default metric: 5
  id 10.0.12.0, data 255.255.255.0, Type Stub (3)
    Topology count: 0, Default metric: 5
  id 10.0.0.3, data 10.0.13.1, Type PointToPoint (1)
    Topology count: 0, Default metric: 5
  id 10.0.13.0, data 255.255.255.0, Type Stub (3)
    Topology count: 0, Default metric: 5
  id 10.0.0.1, data 255.255.255.255, Type Stub (3)
    Topology count: 0, Default metric: 0
  id 13.13.13.13, data 10.101.0.1, Type Virtual (4)
    Topology count: 0, Default metric: 2510
  Topology default (ID 0)
    Type: Virtual, Node ID: 13.13.13.13
      Metric: 2510, Bidirectional
    Type: PointToPoint, Node ID: 10.0.0.3
      Metric: 5, Bidirectional
    Type: PointToPoint, Node ID: 10.0.0.2
      Metric: 5, Bidirectional          

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router  *10.0.0.1         10.0.0.1         0x80000049   239  0x20 0xabd1  48
  bits 0x3, link count 2
  id 10.1.111.101, data 10.1.111.1, Type Transit (2)
    Topology count: 0, Default metric: 2500
  id 10.0.0.3, data 0.0.0.69, Type PointToPoint (1)
    Topology count: 0, Default metric: 2500
  Topology default (ID 0)
    Type: PointToPoint, Node ID: 10.0.0.3
      Metric: 2500, Bidirectional
    Type: Transit, Node ID: 10.1.111.101
      Metric: 2500, Bidirectional

    OSPF database, Area 30.30.30.30
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router  *10.0.0.1         10.0.0.1         0x8000004c   239  0x22 0xafa6  36
  bits 0x3, link count 1
  id 10.30.30.30, data 10.30.30.1, Type Transit (2)
    Topology count: 0, Default metric: 2500
  Topology default (ID 0)
    Type: Transit, Node ID: 10.30.30.30 
      Metric: 2500, Bidirectional

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router  *10.0.0.1         10.0.0.1         0x8000004c   239  0x22 0xed26  36
  bits 0x7, link count 1
  id 10.101.0.10, data 10.101.0.1, Type Transit (2)
    Topology count: 0, Default metric: 2500
  Topology default (ID 0)
    Type: Transit, Node ID: 10.101.0.10
      Metric: 2500, Bidirectional

    OSPF database, Area 102.102.102.102
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Router  *10.0.0.1         10.0.0.1         0x8000004a   239  0x22 0xf91e  36
  bits 0x3, link count 1
  id 10.102.0.10, data 10.102.0.1, Type Transit (2)
    Topology count: 0, Default metric: 2500
  Topology default (ID 0)
    Type: Transit, Node ID: 10.102.0.10
      Metric: 2500, Bidirectional

admin@J2300-1> 

Only in area 0.0.0.0

8. See if R14's loopback is reachable

admin@J2300-1> show route 14.14.14.14 

inet.0: 72 destinations, 72 routes (72 active, 0 holddown, 0 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

14.14.14.14/32     *[OSPF/10] 00:05:03, metric 2520
                    > to 10.101.0.10 via fe-0/0/1.101

admin@J2300-1> ping count 3 14.14.14.14 
PING 14.14.14.14 (14.14.14.14): 56 data bytes
64 bytes from 14.14.14.14: icmp_seq=0 ttl=62 time=2.381 ms
64 bytes from 14.14.14.14: icmp_seq=1 ttl=62 time=3.765 ms
64 bytes from 14.14.14.14: icmp_seq=2 ttl=62 time=3.850 ms

--- 14.14.14.14 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 2.381/3.332/3.850/0.673 ms

admin@J2300-1> 

Back to the Virtual Links Lab

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Last page update 5 December 2012

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