ospf lab 3...

start your engines...
make the dce's 64000

ospf process 1
links for r1 and r2 are in area 0
lo's also, and don't forget to make lo's point-to-point... why?

verify yer damn neighbors...

r1#sh ip ospf neigh

Neighbor ID     Pri   State           Dead Time   Address         Interface
10.1.2.1          0   FULL/  -        00:00:30    10.1.12.2       Serial1/1
r1#

r2#sh ip ospf neigh

Neighbor ID     Pri   State           Dead Time   Address         Interface
172.30.30.1       0   FULL/  -        00:00:38    10.1.12.1       Serial1/1
r2#

r1#sh ip route
omitted
Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
C        10.1.1.0/24 is directly connected, Loopback1
L        10.1.1.1/32 is directly connected, Loopback1
O        10.1.2.0/24 [110/65] via 10.1.12.2, 00:03:23, Serial1/1
C        10.1.12.0/24 is directly connected, Serial1/1
L        10.1.12.1/32 is directly connected, Serial1/1
      172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
C        172.30.30.0/24 is directly connected, Loopback30
L        172.30.30.1/32 is directly connected, Loopback30
r1#


here's a trick... i hate the L designation in the newer code...  very messy... hurts my eyes... if you try to exclude it you lose the loopback...

r2#sh ip route | excl L           
omitted    

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
O        10.1.1.0/24 [110/65] via 10.1.12.1, 00:08:36, Serial1/1
C        10.1.12.0/24 is directly connected, Serial1/1
C        10.1.23.0/24 is directly connected, Serial1/2

r2#

try this...

r2#sh ip route | excl L | incl Loop
omitted      
Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks
O        10.1.1.0/24 [110/65] via 10.1.12.1, 00:09:43, Serial1/1
C        10.1.2.0/24 is directly connected, Loopback2
C        10.1.12.0/24 is directly connected, Serial1/1
C        10.1.23.0/24 is directly connected, Serial1/2

r2#

yes virginia, you can use multiple filters...

add the links between r2 and r3 and the loopbacks in their respective areas with proper wildcard masks... lo's 100-103 go in area 100
don't forget to make the lo's point-to-point...

r3#sh run | beg router
router ospf 1
 network 10.1.3.0 0.0.0.255 area 23
 network 10.1.23.0 0.0.0.255 area 23
 network 192.168.100.0 0.0.3.255 area 100

r2#sh ip route | excl L | incl Loop

omitted

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks
O        10.1.1.0/24 [110/65] via 10.1.12.1, 00:10:59, Serial1/1
C        10.1.2.0/24 is directly connected, Loopback2
O        10.1.3.0/24 [110/65] via 10.1.23.3, 00:00:24, Serial1/2
C        10.1.12.0/24 is directly connected, Serial1/1
C        10.1.23.0/24 is directly connected, Serial1/2

r2#

the whole point of the exercise...   the networks in area 100 don't show up in r2's route table because they have no connection to the backbone area; the routes aren't advertised outside their area... the backbone area is kind of important, connecting to it even more...

chances are you will never get to do this in production... the need for this arises, ie, when one company merges with another, and they want to create temporary links between their routes during the transition without being overly disruptive... the emphasis here is on temporary...

read more here:
 http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9ee.shtml

All areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, you can use a virtual link to connect to the backbone through a non-backbone area. You can also use virtual links to connect two parts of a partitioned backbone through a non-backbone area. The area through which you configure the virtual link, known as a transit area, must have full routing information. The transit area cannot be a stub area. This document examines the OSPF database in a virtual link environment. You can read more about virtual links in the OSPF Design Guide.

find the router id's for the routers you want to form a virtual link...

r2#sh ip ospf | incl ID
 Routing Process "ospf 1" with ID 10.1.2.1

r3#sh ip ospf | incl ID
 Routing Process "ospf 1" with ID 192.168.103.1

create the transit area between them, in this case 23 (common) and each other's RID, as discovered above...

r3(config)#router ospf 1
r3(config-router)#area 23 virtual-link 10.1.2.1
r3(config-router)#

Aug 12 11:06:57: %OSPF-4-ERRRCV: Received invalid packet: mismatched area ID, from backbone area must be virtual-link but not found from 10.1.23.3, Serial1/2
r2(config-router)#area 23 virtual-link 192.168.103.1
r2(config-router)#
Aug 12 11:07:00: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.103.1 on OSPF_VL0 from LOADING to FULL, Loading Done
r2(config-router)#end
r2#
Aug 12 11:07:06: %SYS-5-CONFIG_I: Configured from console by console
r2#

r2# sh ip route | ex L | incl Loop
omitted     
Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks
O        10.1.1.0/24 [110/65] via 10.1.12.1, 00:46:06, Serial1/1
C        10.1.2.0/24 is directly connected, Loopback2
O        10.1.3.0/24 [110/65] via 10.1.23.3, 00:08:08, Serial1/2
C        10.1.12.0/24 is directly connected, Serial1/1
C        10.1.23.0/24 is directly connected, Serial1/2
O IA  192.168.100.0/24 [110/65] via 10.1.23.3, 00:11:57, Serial1/2
O IA  192.168.101.0/24 [110/65] via 10.1.23.3, 00:11:57, Serial1/2
O IA  192.168.102.0/24 [110/65] via 10.1.23.3, 00:11:57, Serial1/2
O IA  192.168.103.0/24 [110/65] via 10.1.23.3, 00:11:57, Serial1/2

r2#sh ip ospf inter
OSPF_VL0 is up, line protocol is up
  Internet Address 10.1.23.2/24, Area 0, Attached via Not Attached
  Process ID 1, Router ID 10.1.2.1, Network Type VIRTUAL_LINK, Cost: 64
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           64        no          no            Base


then you can get all slick rick on this shit by summarizing at the abr (r3)

r3#sh run | begin router  
router ospf 1
 area 23 virtual-link 10.1.2.1
 area 100 range 192.168.100.0 255.255.252.0
 network 10.1.3.0 0.0.0.255 area 23
 network 10.1.23.0 0.0.0.255 area 23
 network 192.168.100.0 0.0.3.255 area 100

a word about the DNA (donotage) from petr below

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CGIQFjAI&url=http%3A%2F%2Fblog.ine.com%2Fwp-content%2Fuploads%2F2011%2F01%2FLoop-Prevention-in-OSPF.pdf&ei=0ewnULTjE-6_0QHQyICwCg&usg=AFQjCNGkA0Un6Fwji-ma7px0qLVdg_sjgw&sig2=gLC2WXnjOZZfaMIbg44_ng




After the database exchange has been completed, further Hello packets are
suppressed on the virtual link. Effectively, the link is treated as a demand circuit.
Only intermittent OSPF database changes are flooded, i.e. those triggered by
topology changes. The reason for this is that virtual-link liveness is detected
based on the reachability of the remote ABR, so Hello probing is not required.
The LSAs exchanged over the virtual-link have DNA (do-not-age) bit set, which
prevents their expiration in LSDB and requires no periodic flooding over virtual-
links to refresh the LSAs



and finally there is this...


r3# sh ip route | incl Null
O     192.168.100.0/22 is a summary, 00:24:31, Null0
r3#



which means if the router advertising this summary receives a packet destined for the summary but not actually covered in the table, the packet is dropped...

we almost forgot about our pretend internet default route... let's propagate that sucker with default-information originate below...