Uplinks to Nexus 7K as backup uplinks

[Khoa Pham]

I have my pair of Fabric Interconnect connected to 2 Nexus5000. There is a flaw in this design that if both Nexus 5000 are down, my UCS is cut off from the network. 

Is there a way that I can run another pair of connection to the Core Switches Nexus 7000, but set it up so the traffic only flows through the 5000 and if both 5000s down, then flow to the core Nexus 7000 ?

Thank you. 

[Walter Dey]

vPC between Fabric Interconnect and N5k, and then another pair of vPC between N5k and N7k

[Khoa Pham]

I assume you mean

1 VPC pair for the FIs and 5K

1 VPC pair for the FIs and 7K

If that the case , the FIs will try to load balance traffic to both 5K and 7K. Is there a way to run traffic through the 5K only and reroute traffic to 7K when 5K are down?

[Walter Dey]

The design I mention has no single point of failure, is bandwith and hop count optimized. Why are you so concerned about both N5k failing ? there are hundreds or thousands of such installations in the field working without a problem. In principle I could be paranoid, and raise the same issue for N7k, although they have 2 Sup's.

The UCS N5K vPC will only be used for intra VLAN traffic, e.g. server 1, vnic 1 connected to fabric A talking to server 2, vnic2, connected to fabric B, where vnic 1 and 2 are in the same vlan.

The traffic will be sent to N7K, for South-North traffic to WAN/Campus, resp. UCS inter Vlan traffic.

see eg.

http://www.cisco.com/cdc_content_elements/flash/dcap/6/#/enterprise/system-level-designs/virtualized-multi-tenant-data-center