OSPF area's across a VPLS link

[michielj89]

dear cisco experts.

I'm currently in the process of creating an enterprise network (according to the Cisco Enterprise Campus Model) for a multinational company. (fictive).

I need to to solve my following situation:

--- HQ in Netherlands --                                                                                                                               --- Branch office in Germany ---

[ CORE ]                         < ---- >   router   <---> Orange International Ethernet Link (VPLS) <--->  router  <--->  [DISTRIBUTION]

   |                                                                                                                                                                                         |

[ DISTRIBUTION ]                                                                                                                                                           [ ACCESS ]

   |

[ ACCESS ]

The whole enterprise network will  operate in a 172.16.0.0/16 subnet, each with its own subnet within the main subnet (summary address).

Now I would like to create an OSPF design. I would like to have the backbone area 0 at the HQ in The Netherlands, while giving Germany an other area number.

Would it be a good practice to create an OSPF virtual link across the 2 routers at each side of the VPLS link? Or are there any other solutions?

Every other area should connect to the backbone Area 0 at the HQ in The Netherlands.

Suggestions would be appreciated

[Giuseppe Larosa]

Hello Michiel,

I would put the VPLS link in area 0 , so that you can extend area 0 to Germany  office. This gives you the capability to have multiple areas in Germany site if needed in the future.

There is no need to use virtual links in real world. Stay away from them and consider them a temporary fix when joining two separate networks not when designing a new network.

Hope to help

Giuseppe

[michielj89]

Dear Giuseppe,

Thank you for your input

So what you are meaning is that you would combine the Germany branch office AND the VPLS link together in one subnet and Area 0?

How about the HQ in The Netherlands? I thought Cisco best recommendation advises to always put your head office (HQ) Campus into Area 0 as a backbone area.

Maybe I'm a little bit confused hehe.

[Giuseppe Larosa]

Hello Michiel,

I have suggested  to put the VPLS link in area 0 to have more flexibility.

I would put the Germany office internal subnets in a separate area.

I would put the HQ office infrastructure in area 0 and HQ client subnets in a different area.

How much to extend area 0 in HQ is your choice. However, using multiple areas in OSPF provide some benefits like route control on internal routes.(you can perform route filtering at area border if needed and route summarization).

Using multiple areas is not only done for scalability, but  also for better control.

Avoid to use redistribute connected and use network ... area + passive interface instead to avoid unnecessary external routes (that cannot be filtered at area border).

Hope to help

Giuseppe

[michielj89]

Dear Giuseppe,

Thanks again for your advise

I think it's a good practice to put HQ in Area 0 + VPLS , and Germany in Area 1.

How would you assign the Area 1 as an kind of OSPF area? NSSA?

Thanks in advance

[Giuseppe Larosa]

Hello Michiel,

for area 1 in Germany office i would use a standard OSPF area.

Hope to help

Giuseppe

[michielj89]

Dear Giuseppe,

Thanks again Could you also explain why? And not create an stub area for Germany?

Greetings

Michiel