What exactly happens when connecting a second Nexus 5548?

[munson.t]

Hi all,

I am currently working on a project to implement a second nexus 5548UP for a backup/redundant configuration with a 5548P that is already in production.  I've been scouring the documents on VPC design and implementation and config-sync usage and I believe I have a decent strategy but there's still one thing that bothers me.  Can anyone tell me just what exactly happens once the VPC Peer link is established?  What I am afraid of is losing the configuration on the main 5548P already in production.  The 55XX Nexii don't automatically share configuration correct? I do have backups of the config but we all know the less downtime the better.  From what I've gathered it seems like nothing should happen when connecting the 2 Nexii until I make a config profile and commit it, but I am uncertain.

The current 5548P has 3 FEXs connected and configured as well as multiple port channels configured already.  My current implementation plan is roughly like the following (during a maintenance window so brief outages are OK):

- Enable vpc feature on production 5548P (already enabled it on the backup 5548UP)

- Create a switch profile  with the current config on the 5548P (this is still a little vague for me but I'd like to get config-sync working for the future)

- Apply current config to backup 5548UP so the configs are the same (minus the VPC priority, etc config)

- Establish VPC Peer Link between the two Nexii

- Configure Management ports as VPC Peer link (connected via a core 6509)

- Apply VPC config to the port-channels

- Re-wire/split the FEX and port-channel physical connections to the backup 5548UP to the proper VPC configured ports

- Test

Anyone out there who has experienced this type of implementation have any suggestions or pitfalls they see here?  I really appreciate it.

Thanks for your help!

EDIT:  The Nexii are working at L2 only, no routing.

Message was edited by: Travis Munson

[krun_shah]

I would suggest to set role priority on 5548up so that it does NOT become primary. Manually synch the configuration specialy mtu setting spanning tree configs etc

You have to establish peer keepalive first before peer link gets establish. Enable cfs over IP before configuring switch profile. Make sure both switches have same come

Sent from Cisco Technical Support iPhone App

[Oleksandr Nesterov · Accepted solution]

Hello Travis

1. you can import your running config into switch profile using keyword "import"

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/system_management/502_n1_1/Cisco_n5k_system_mgmt_cg_rel_502_n1_1_chapter3.html#task_FCC3ABE93B384672AA34804CAC92C5F8

But remember that the 2nd swith has to not have conflicting config (for example eth1/1 on both sides have different vlan assiged)- or commit will fail.

2. Configure Management ports as VPC Peer link (connected via a core 6509) - you can configure management ports as Keep-alive link - not vpc peerlink, and better will be if peer keep-alive will become online before peer-link. To let Nexuses see their peers.

3. As for fexes they can be preprovisioned on the second n5k:

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/operations/n5k_config_sync_ops.html

Please be aware that preprovision model has to be exactly same that you have otherwise fexes won't come online on the second n5k

HTH,

Alex