Aside from the obvious cabling mess you avoid (which I know for us as network engineers is great, but hard to use as an excuse when reasoning with someone who sees no point in it), what do you gain versus copper straight through to a larger core?
Context: - Price is of no concern
Company had already decided on a dual Nexus core.
Option 1: Nexus 7004's, which would be nearly fully populated with 10G SFP+ and aggregate connections to several FEXs at the top of each rack in the DC, as well as aggregate SAN and various server connections
Option 2: Nexus 7009 cores that will be approx. 1/3 filled up with various modules to accommodate the aggregation of all fiber connections from all devices.
This is a colocated data center
Standard call center/enterprise domain related services hosted on the network
QoS is a very important bulletpoint to emphasize given that this company is a call center
- I am unable to justify going with Cisco's "top of rack" setup despite my wanting less of a cabling mess and a more modular design. I'm unable to do so because you are inserting a point of failure into the network. Doing this increases the latency (even if it's only by a small amount), etc. Not only that, but now that I think about it, since all FEXs rely on the Nexus to operate, you not only increase the chance of a hardware failure bringing down a block of devices, but now a software process that could wig out and cause the FEX to malfunction in some way.
So, before I put the top of rack design in the idea graveyard for this project, can anyone else see a reason not to go with a larger core and no FEXs given the lack of budget limitation?