If you’re building a Greenfield private cloud, you SHOULD consider using virtual network services appliances (firewalls, load balancers, IPS/IDS systems), removing the need for additional hard-to-scale hardware devices. But can we go a step further? Can we replace all networking hardware with x86 servers and virtual appliances?
Of course we can’t. Server-based L2/L3 switching is still way too expensive; pizza-box-sized ToR switches are the way to go in small and medium private clouds (I don’t think you’ll find many private clouds that need more than 2 Tbps of bandwidth that two 10GE ToR switches from almost any vendor give you) … but what about WAN edge routers?
If your data center uses 1Gbps uplinks, and you’re a Cisco shop, I can’t see a good reason not to consider Cloud Services Router (CSR 1000V). You can buy a 1Gbps license with the latest software version and I’m positive you’ll get 1Gbps out of it unless you have heavy encryption needs.
Connecting to the outside world
Most servers have a spare 1Gb port or two. Plug Internet uplinks into those ports and connect the uplink NIC straight to the router VM using hypervisor bypass.
I know it’s a psychologically scary idea, but is there a technical reason why this approach wouldn’t be as secure as a dedicated hardware router?
Why Would You Do It?
There are a few reasons to go down the all-virtual path:
- Reduced sparing/maintenance requirements – you need hardware maintenance for ToR switches and servers, not for dedicated hardware appliances or routers;
- Increased flexibility – you can deploy the virtual network appliances or routers on any server. It’s also easier to replace a failed server (you probably have a spare server already running, don’t you?) than it is to replace a failed router … and there’s almost no racking-and-stacking if a blade server fails;
- If you believe in distributed storage solutions (Nutanix or VMware VSAN), you need only two hardware components in your data center: servers with local storage and ToR switches. How cool is that?
I’m positive you’ll find a few other reasons. Share them in the comments.