Getting the two to tango
In my previous post, I concluded:
…there are things that you just can’t get if you’re “flying high”, and I think that there are some very good synergies that can be had if SDNs could leverage the capabilities present in IP/MPLS transport networks. However, it takes two to tango, and I’ll be curious to see if enough interest materialises from both sides of the fence to make something like this to happen.
After a bit of a think, I come to conclusion that such integration is already quite possible to a certain extent, and likely with only minimal changes on the NVP side.
It is probably best described in an example: let’s say we’re a Service Provider who operates cloud infrastructure located in several Data Centres and our own IP/MPLS transport network that interconnects them. We would then like to provide our cloud customers with three types of virtual networking services across our multiple Data Centres:
- A “devil may care” best effort, which runs over unprotected label switched paths. It could at times get contended while network operates normally or can completely die if we lose a major transmission link or a network node that was serving it.
- A “business class” protected service, with guaranteed uncontended performance when all transport paths are in operation, but which can get a bit squished if a major transmission link or a network node goes belly up.
- A “first class” service, which is guaranteed its bandwidth at all times.
Now, we associate these three types of network services with a VPRN which connects our Data Centres, and allocate DSCP code points so that we can associate incoming GRE PDUs with the corresponding underlying label switched paths that make the magic happen (unprotected / protected / guaranteed).
The only thing that needs to happen for this to work is for NVP to be aware that it has these three differentiated network services available, and mark GRE PDUs with the corresponding DSCP values accordingly.
Virtualisation customers would then have a choice when creating their virtual network segments, which will be assured by the underlying transport network. Win-win.
Or is it? Given that the scenario above relies on a fairly sophisticated IP/MPLS transport network, it may fly somewhat against one of Nicira’s stated goals of turning transport network into a set of simple IP pipes, running on cheap commodity hardware.
I guess the time will tell what wins out – the desire to be the king of the hill for a day, or the long-term interests of the customers for who’s sake the whole cloudy shabang has been created in the first place.
Traditional clarification: this post assumes that the cloudy end-customers here are the “traditional” Enterprises, who care about VM mobility, flexible multi-VM configurations and service guarantees.