OSPF Unnumbered interfaces

• Find 1 interface that will not be in OSPF and use it
• s1/1 is in another routing protocol

 interface Serial1/0
   ip unnumbered Serial1/1
 !
 router ospf 1
   passive-interface Serial1/1
   network 172.16.35.5 0.0.0.0 area 0
   network 172.16.50.0 0.0.0.255 area 10
   network 172.16.105.0 0.0.0.255 area 105