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DCI with vPC L2+L3

This design issue has been bothering me for a while and I hope someone could answer this. Let's say I have this design:

DC1                                 DC2

N7K1 -------- 10G L2 Trunk -------- N7K3

  |                                  |

VPC peer link                       VPC peer link

  |                                  |

N7K2 -------- 10G L2 Trunk -------- N7K4

- Two data centers DC1 and DC2

- Each data center has a pair of N7Ks in VPC

- There are only two inter-dc links and they are set up as Layer 2 Trunks. Layer 2 trunking is necessary to extend some of the VLANs between data centers. The HSRP SVI default gateway for those VLANs lives in one of the data centers.

- Can't get any additional inter-DC links

- Requirement is not to use OTV

Issue: I also want to run Layer 3 routing between two data centers.

Option 1 - Is this possible?

- Put two inter-dc links into vPC

- Create VLAN 100 which is trunked only on N7K1-N7K3 trunk and nowhere else. Run EIGRP over it between SVI on N7K1 and SVI on N7K3

- Create VLAN 200 which is trunked only on N7K2-N7K4 trunk and nowhere else. Run EIGRP over it between SVI on N7K2 and SVI on N7K4

- Also add additional physical Layer 3 links between N7K1 and N7K2, and another one between N7K3 and N7K4.

- Is this even possible? If I add VLAN 100 on the top link and nowhere else, will this cause vpc inconsistency check failures? Can I fool it by adding VLAN 100 also on N7K2-N7K4 link, keeping that VLAN100 isolated/unused since VLAN 100 SVI is only configured on N7K1 and N7K3?

Option 2 - If Option 1 is not possible, is this my only option?

- Don't put inter-dc links into vPC. Rely on spanning-tree. The down side to this is suboptimal load-sharing of inter-dc links

- Create VLAN 100 which is trunked only on N7K1-N7K3 trunk and nowhere else. Run EIGRP over it between SVI on N7K1 and SVI on N7K3

- Create VLAN 200 which is trunked only on N7K2-N7K4 trunk and nowhere else. Run EIGRP over it between SVI on N7K2 and SVI on N7K4

- Also add additional physical Layer 3 links between N7K1 and N7K2, and another one between N7K3 and N7K4.

Thoughts?

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DCI with vPC L2+L3

Hi - we have a similar setup but where we use nx5k to service the DCI and VPC as solely L2 and then run the L3 on the NX7k. You need to have all the same vlans on the vpc as far as I know. You can't fool it - but you might be able to tricks something with some q-in-q trunks between the 2 sets of nx7k's

best regards /ti

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