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Community Member

Ospf Passive interface - design question

                   Hi Everyone,

I  have question here regarding OSPF passive interface.

We have remote office router running ospf.

Int gi0/0 is wan interface running ospf.

Then we have int gi0/1  and few vlans cretaed under it.

we have configured passive-int default under router ospf.

We have  config sub interfaces under gi0/1  which has vlans defined.

Some have backup wi fi connection and other has wi fi connection to other site.

My question is should i put vlan which has wi fi connection to other site under

router ospf

no passive interface gi0/1.1    ?????????????????????????????????????????????

gi0/1.1 is wi fi link to some other site

thanks

mahesh

Everyone's tags (5)
3 ACCEPTED SOLUTIONS

Accepted Solutions

Ospf Passive interface - design question

Hi,

The only interface where you shouldnt be using passive interface feature are the ones where u are talking ospf...

why would you want the wifi connection to be sending ospf´s hellos?

Use the passive interface feature to prevent innecesary traffic to be flooded and for security reasons... you dont want hellos reaching not trusted hosts...

Regards...

Wil

Hall of Fame Super Silver

Ospf Passive interface - design question

Hello Mahesh,

if there is another router in that other remote site and you want to have an OSPF adjacency with that remote site router you need to declare the interface as no passive as you have changed the default to passive.

If there is no need for OSPF neighborship on the link you can leave it passive.

Hope to help

Giuseppe

Hall of Fame Super Gold

Ospf Passive interface - design question

Mahesh

The command as you give it is correct. You need to specify the subinterface and not the physical interface for this situation.

HTH

Rick

6 REPLIES

Ospf Passive interface - design question

Hi,

The only interface where you shouldnt be using passive interface feature are the ones where u are talking ospf...

why would you want the wifi connection to be sending ospf´s hellos?

Use the passive interface feature to prevent innecesary traffic to be flooded and for security reasons... you dont want hellos reaching not trusted hosts...

Regards...

Wil

Hall of Fame Super Silver

Ospf Passive interface - design question

Hello Mahesh,

if there is another router in that other remote site and you want to have an OSPF adjacency with that remote site router you need to declare the interface as no passive as you have changed the default to passive.

If there is no need for OSPF neighborship on the link you can leave it passive.

Hope to help

Giuseppe

Hall of Fame Super Gold

Ospf Passive interface - design question

Mahesh

I think that Giuseppe is quite right. I would approach it slightly differently and offer this explanation. You need to use OSPF network statements to include interfaces whose subnets you want to advertise. Having included the interface in OSPF you need to decide whether there are any routers on that link with which you want to exchange OSPF updates. If there are routers on that link (typically on links connecting to other sites or to other routers within your site) then that interface needs to be not passive. If there are no routers on that link to exchange OSPF then make the interface passive.

HTH

Rick

Community Member

Ospf Passive interface - design question

Hi Rick,

Thanks for reply.

I fig out we need to establish ospf adj  on vlan .

On router we have created sub interfaces for each vlan.

So  under router ospf

no passive interface gi0/1.20 is  vlan which we need to establish nei adj.

So my question is  is above command  ok ?

or i need to do gi0/1 ??

Thanks

MAhesh

Hall of Fame Super Gold

Ospf Passive interface - design question

Mahesh

The command as you give it is correct. You need to specify the subinterface and not the physical interface for this situation.

HTH

Rick

Community Member

Ospf Passive interface - design question

Hi Rick,

Thanks for prompt reply.

Best Regards

MAhesh

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