network command and ip ospf X area Y commands

Hi guys,

For some reason, when enabling ospf on interfaces, I tend to prefer the interface "ip ospf PID area AREAID" over the old school "network x.x.x.x y.y.y.y area AREAID" command under the routing process.

Couple of questions:

1) I notice the SG's tend to prefer the network command. Is there a reason for that? Would the ip ospf x area command be just as good? I would assume the protor's script would parse the output of "show ip ospf interface" so in theory I should be safe... Or should I?

2) When using the network command, I hardly see any uses of the bitmask (unless specified in the task requirement) in the SGs. When labbing, I tend to save myself a couple of modifications in my cut and paste routine by using the same network command on loopbacks (network 150.X.0.0 0.0.255.255) and interfaces on the same sub-network between 2 routers (network 136.1.1.0 0.0.0.255 matching both 136.1.1.4 and 136.1.1.5). Would the proctors care either way (when nothing is specied in the task requirements or do's and dont's of course)?

Cheers,

Eric

Comments

  • Eric,

    The Solution Guide was originally written before the IOS versions that added the interface-level commands to add an interface to an OSPF area. Some sections may have been edited to show the newer method.

    Unless there is a requirement in the task that requires or prohibits a particular method, any method that arrives at the desired outcome is valid.

    In some cases redistribution may be required by prohibiting both the network statement and the interface-level command. In some of the earlier versions of the workbook tasks were written to prohibit the use of the network statement, intending to force redistribution, but until those tasks were revised (if they have been) the option for the interface-level command was equally valid.

    In general: "Whatever is not Prohibited is Legal"

    Hi guys,

    For some reason, when enabling ospf on interfaces, I tend to prefer the interface "ip ospf PID area AREAID" over the old school "network x.x.x.x y.y.y.y area AREAID" command under the routing process.

    Couple of questions:

    1) I notice the SG's tend to prefer the network command. Is there a reason for that? Would the ip ospf x area command be just as good? I would assume the protor's script would parse the output of "show ip ospf interface" so in theory I should be safe... Or should I?

    2) When using the network command, I hardly see any uses of the bitmask (unless specified in the task requirement) in the SGs. When labbing, I tend to save myself a couple of modifications in my cut and paste routine by using the same network command on loopbacks (network 150.X.0.0 0.0.255.255) and interfaces on the same sub-network between 2 routers (network 136.1.1.0 0.0.0.255 matching both 136.1.1.4 and 136.1.1.5). Would the proctors care either way (when nothing is specied in the task requirements or do's and dont's of course)?

    Cheers,

    Eric

     

  • I like to use  "ip ospf x area y" instead of "network x.x.x.x ......."

    because I find the "network x.x.x.x" command not worked well when you enable multi ospf process

    on a router,for example:

     

    (1)

    router ospf 1 

    network 123.0.0.1 0.0.0.0 a 0

     

    (2) no router ospf 1

     

    (3)router ospf 2

    network 123.0.0.1 0.0.0.0 a 0

     

    for  some IOS version ,there are problems when you did this .

     

    multi ospf process can be used as a solution to problems caused by "PE-CE connect area is not area 0" .

     

     

  • Just to comment on the wildcard mask 0.0.0.0, the important thing is that you understand what it means, which you obviously do.  The reason INE and instructors use 0.0.0.0 is to be very intentional with their interface activation.  If you use a wildcard that covers multiple subnets, and you later add an interface address that must not be added to OSPF, you might accidentally do so without realizing it.  It's impossible to do that with the 0.0.0.0.

     

    As Darrell said, do it however you want, but make sure to do what they ask.  Realistically, the interface command is probably the best way to handle that, but if you're forbidden from using that then I'd definitely use 0.0.0.0 for your wildcard.

  • Thanks for sharing your opinions guys. This is exactly the kind of discussion I wanted to initiate :)

    Regards,

    Eric

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