Migrating N5K from N7K to N77 Strategy

Thameem Maranveetil Parambath · ‎02-18-2015

Hi there,

We are planning for replacing our N7K pair with a N77 pair. Please advise on the migration strategy.

Current infra.

1. (N2K pair) dual homed to (N5K pair) which intern dual homed to (N7K pair).

2. SVIs on N7K with HSRP configured.

3. Rootbridge for vlans on N7K pair.

4. Layer3 OSPF on N7K pair (adjacency between 7K pair and adjacency with other core routers from each 7K).

5. Active FW (juniper SRX) on N7K-1 and Standby FW on N7K-2.

6. Many SVIs in FW as well.

7. UCS-FI on N5Ks.

My plan is as follows.

1. Configure the new N77 pair with VPC best practices.

2. Connect (N77 pair) with the existing (N7K pair) through VPC port-channel.

3. Form OSPF adjacency between N77 pair and from each N77 to corresponding N7K.

4. Connect (N5K pair) with (N77 pair) on a new VPC port-channel. So now, (N5K pair) will have connectivity to both (N7K pair) and (N77 pair).

5. Shutdown standby SVI interface on N7K and configure it in N77. After forming HSRP adjacency, shutdown active SVI interface on N7K and configure it in N77. This way the SVIs will be migrated to N77.

6. Migrate all connections from N7K to N77 and complete the migration.

My concern with the above plan is the spanning tree which will form when I connect (N5K pair) with (N7K pair) and (N77 pair). Is this design OK. Will there be any SPT loop? Do you have a better idea for above migration?

This datacenter is critical and hosts all enterprise applications.

richbarb · ‎02-24-2015

Hi Thameem,

I would consider follow this action plan:

1. Configure the new N77 pair with VPC best practices.

2. Connect (N77 pair) with the existing N5K through VPC port-channel.

3. Connect (N77 pair) with the N7K through L3 (routed ports).

4. Form OSPF adjacency between N77 pair and from each N7K.

5. Configure all SVIs interface on N77 and be prepared to bring that up. Shutdown all SVI interface on N7K and bring it up on N77. (There is a short period of downtime).

6. Migrate all connections from N7K to N77 and complete the migration.

This is just a suggestion since the L3 connection between the N7K and N77 will protect you against possible L2 loops.
Another thing is the hsrp behavior with vpc, that always work as active-active and this way the migration would occur in pair, since a short downtime is certain anyway.

Regards,
Richard