Question about Nexus 3548 vPC setup

Question

Hi.
We have just installed our two first Nexus 3548 switches in our Catalyst environment. We want to set up a vPC domain between the Nexuses, to use for connections to storage and other equipment.
I have read the guide at http://www.cisco.com/c/en/us/products/collateral/switches/nexus-3000-series-switches/white_paper_c11-685753.html and tried setting it up. I created a vPC domain on both switches like this:
nexus1:
vpc domain 1
  role priority 2000
  system-priority 4000
  peer-keepalive destination 192.168.105.40 source 192.168.105.39 vrf default
nexus2:
vpc domain 1
  system-priority 4000
  peer-keepalive destination 192.168.105.39 source 192.168.105.40 vrf default
The switches are connected with a port-channel consisting of 2x 10GE. The IP addresses above are the ones we use for managing the switches. When I configure the port-channel as "vpc peer-link", the vpc status looks OK:
vPC domain id                     : 1
Peer status                       : peer adjacency formed ok
vPC keep-alive status             : peer is alive
Configuration consistency status  : success
Per-vlan consistency status       : success
Type-2 consistency status         : success
vPC role                          : primary
Number of vPCs configured         : 0
Peer Gateway                      : Disabled
Dual-active excluded VLANs        : -
Graceful Consistency Check        : Enabled
Auto-recovery status              : Disabled
vPC Peer-link status
id   Port   Status Active vlans
1    Po2    up     1,6,100,102,106
The problem I have is that I lose connection to nexus2 when I bring up the vPC. I can no longer access it on its IP (192.168.105.40). I cannot ping it from nexus1 either. The Nexus switches are connected to our core switches, which are Catalyst 6509. nexus1 is connected to coreswitch1 using a portchannel of 2xGE and nexus2 is connected to coreswitch2 the same way. A spanning-tree cost has been set on the uplink from nexus2, to make spanning tree block that uplink, and allow traffic between the nexuses to go over the 2x 10GE portchannel instead of over the core switches. I have attached a drawing of this.
Maybe I shouldn't use the management IP:s for peer keepalive? Does the peer keepalive need to be on a different physical link than the peer-link?
Regards,
Johan

Answer 1

We are not using the management ports for management, but an ordinary Vlan Interface in the default vrf, as seen below. We can of course change that and instead use the mgmt0 port if that is the best approach.
vrf context management
vlan configuration 1,100
vlan 1
vlan 100
  name DMMgmtPriv
vpc domain 1
  role priority 2000
  system-priority 4000
  peer-keepalive destination 192.168.105.40 source 192.168.105.39 vrf default
interface Vlan1
interface Vlan100
  no shutdown
  no ip redirects
  ip address 192.168.105.39/23