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?
