ivan on ospf network statements…

ivan p. says:


In my network implementations, I use the network statements in three different ways:

  • If I have to assign a specific interface into an area, I would always use network x.y.z.w area n;
  • If the area address ranges are nicely assigned (which also helps immensely when you have to start summarizing), you can use a single network statement to cover the whole area. If, for example, area 3 has address range, use network area 3;
  • If the router has all interfaces in a single area, I would almost always use network area area-id (unless there is an extremely good reason that some interfaces should not be seen by the OSPF process).

now this is interesting… i was watching a kevin wallace video pbr in ospf here:


and at 8mins 25secs he uses this command…

network area 0

and it threw me… i often use network area 0 in labs because A) it’s now a  habit i picked up from doing arden packeer labs months ago and B) it’s fast and furious while i’m experimenting… i would never do this in production, of course… the more specific, the better…

so why would kevin wallace use area 0? WTF

to save himself some key strokes… see below:

dsw1(config)#router ospf 100
dsw1(config-router)#netw area 0
dsw1(config-router)#do sh run | b router ospf 100
router ospf 100
network area 0

ios to the rescue… however i will continue to use the all 1’s after the all 0’s because i’m insane and i don’t like shit like that…