Adding passive-interface default and no passive-interface [L3 ints]?

Answered Question
Oct 5th, 2009

Hi,

We have these floor switches connecting to out core/distribution switches but they don't have passive-interface default and no passive-interface po1, po2, etc.

I was wondering if I need to add the L3 vlans to the no passive-interface [iinterface] as well?

sh ip int bri shows:

po1

po2 and two other L3 vlans with IP addresses.

I am kind of confuse if we really need to add the L3 vlan interfaces too?

Please advise,

Masood

I have this problem too.
0 votes
Correct Answer by Jon Marshall about 7 years 2 months ago

Masood

"Currently I have only the two port-channels as no passive so participating in the eigrp routing exchange but i was wondering if I needed to add the L3 valns?

My thinking is not but i just wanted to make sure."

As long as you are exchanging and seeing all the routes you should be in the routing tables then the 2 existing neighborships you have with po1 and po2 should be enough.

Jon

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Jon Marshall Mon, 10/05/2009 - 12:12

Masood

It's not clear from your description exactly what is happening. However in general you would make an interface passive under the routing process if you don't want it to form a neigborship on that interface. The most common use of this is when you have a pair of distribution/core switches connected via a L2 trunk and you have multiple L3 vlan interfaces on each switch.

Each L3 vlan interface would form a neighborship across the L2 trunk which is not really necessary and creates extra routing update traffic. So you generally only need 2 peerings across the L2 trunk and you make all the others passive.

Does this make sense ?

Jon

masoodabooali Mon, 10/05/2009 - 12:16

Thanks man.

what I was trying to say is if i need to add L3 vlans to the following statemnets:

router eigrp 90

passive-interface default

no passive-interface po1

no passive-interface po2

when I type sh ip int bri, i see both port-channels and two other L3 vlans.

Currently I have onlt the two port-channels as no passive so participating in the eigrp routing exchange but i was wondering if I needed to add the L3 valns?

My thinking is not but i just wanted to make sure.

Regards,

Masood

Correct Answer
Jon Marshall Mon, 10/05/2009 - 12:22

Masood

"Currently I have only the two port-channels as no passive so participating in the eigrp routing exchange but i was wondering if I needed to add the L3 valns?

My thinking is not but i just wanted to make sure."

As long as you are exchanging and seeing all the routes you should be in the routing tables then the 2 existing neighborships you have with po1 and po2 should be enough.

Jon

Actions

This Discussion