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Saturday, July 21, 2012

OSPF network types - Part 2


the physical topology remains the same:
But in this example all 3 routers are connected in full mesh topology, through the frame-relay cloud, which the default OSPF network type is NON-BROADCAST.

R1#sh ip ospf interface
Serial0/0 is up, line protocol is up
  Internet Address 10.1.123.1/24, Area 0
  Process ID 1, Router ID 192.168.11.1, Network Type NON_BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 192.168.11.1, Interface address 10.1.123.1
  No backup designated router on this network
  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5
    oob-resync timeout 120
    Hello due in 00:00:23
  Supports Link-local Signaling (LLS)
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 0, maximum is 0
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 0, Adjacent neighbor count is 0
  Suppress hello for 0 neighbor(s)
Loopback1 is up, line protocol is up
  Internet Address 192.168.11.1/24, Area 0
  Process ID 1, Router ID 192.168.11.1, Network Type LOOPBACK, Cost: 1
  Loopback interface is treated as a stub Host

The attributes for this type of network are as follow:
LAS flooding – Unicast
Neighbor statement – Yes
DR/BDR Election – Yes
Timers – 30/120
Modify next-hop – No

Note that this type of network is the default for frame-relay physical and Point-to-Multipoint.

In order to accomplish adjacency between all three we will have to configure neighbor statements on each one of them.

R1:
R1#sh running-config | s ospf
router ospf 1
 log-adjacency-changes
 network 10.1.123.1 0.0.0.0 area 0
 network 192.168.11.1 0.0.0.0 area 0
 neighbor 10.1.123.2
 neighbor 10.1.123.3

The result:
R1#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.22.1      1   FULL/BDR        00:01:36    10.1.123.2      Serial0/0
192.168.33.1      1   FULL/DR         00:01:50    10.1.123.3      Serial0/0



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