OSPF Network Configuration

[FranciscoRC]

Hi everyone,

I´m doing a lab exercise, and I´m stuck at OSPF configuration...

The question I´m trying to answer is:

a) Configure OSPFv2 as per the topology diagram and prevent the inadvertent advertisement of OSPFv2 traffic into the VLANs. Summarise addresses where appropriate.Secure OSPFv2 from routing update spoofing.

My topology is attached, but in summary, Router R1 and both swtiches DLS1 and DLS2 are connected with each other with Layer3 interfaces. I´ve configure both switches as the gateway for all the vlans with HSRP and is working properly.

My question is that I feel that the DLS1 and DSL2 switches should not participate on the OSPF network, but if so how can I advertise the Vlans the the other routers on the network ?

Many thanks for you comments

Francisco

[Jon Marshall · Accepted solution]

The switches need to participate in OSPF to advertise the subnets to the router but you need to use the "passive-interface ...." configuration option under the OSPF configuration. 

So on those switches you add network statements for the vlan IP subnets but then you make the vlan interfaces (SVIs) passive under OSPF which stops OSPF traffic being sent in those vlans but the subnets are still advertised in OSPF. 

Jon

[FranciscoRC]

Jon, 

Thank you so much for your reply.

My doubt was in using it with point-to-point links on the routers. If R2 is the DR how would LSAs flow between R2 and the switches?

Final question, Can I use "ip ospf network point-to-point" interface configuration option?

I think I can use between Core and R2, but what about between R1 and the switches and between the switches?

Thanks for your time.

Francisco