Juniper’s PTX MPLS-optical supercore switch — completing a cloud play

By  Tom Nolle

Juniper made its second major announcement in two weeks, this time its PTX MPLS-optical supercore switch. The product’s roots probably lie in early interest (“early” meaning the middle of the last decade) by Verizon in a new core architecture for IP networks that would eliminate the transit routing that was common in hierarchical IP cores. Since then, everyone from startups (remember Corvus?) to modern players like Alcatel-Lucent, Ciena, and Cisco have been announcing some form of optical-enabled core. What makes Juniper’s PTX different?

Good question, and it’s not easy to answer it from the Juniper’s announcement, but I’d say that the differentiator is the chipset. Junos Express appears to be the same basic chip used in the recently announced QFabric data center switch. Thus, you could say that the PTX is a based on a low-latency MPLS switching architecture that’s more distributed than QFabric. Given what we perceive as a chipset link between the products, I’m creating a term to describe this: Express Domain. An “Express Domain” is a network domain that’s built using devices based on the Express chipset. A PTX network is an Express Domain in the WAN and QFabric is an Express Domain within a data center.

If you look at the PTX that way, then what Juniper is doing is creating an Express Domain linked by DWDM and running likely (at least initially) in parallel with other lambdas that still carry legacy TDM traffic. It becomes less about having an optical strategy than it is about creating a WAN-scale fabric with many of the deterministic features of QFabric. Over time, operators would find their TDM evolving away and would gradually migrate the residual to TDM-over-packet form, which would then make the core entirely an Express Domain. The migration would be facilitated by the fact that the latency within an Express Domain is lower (because packet handling can be deterministic, as it is with QFabric) and because the lower level of jitter would mean it’s easier to make TDM-over-packet technology work. Overall performance of the core would also improve. In short, we’d have something really good for none of the reasons that have been covered so far in the media.

This (if my interpretation is right) is a smart play for Juniper. It creates an MPLS-based virtual domain that can be mapped to anything from a global core to a data center. Recall that I noted in the QFabric announcement that Juniper had indicated that QFabrics could be interconnected via IP/MPLS. Clearly they could be connected with PTXs, and that would create a supercloud and not just a supercore.

What would make it truly revolutionary, of course, would be detailed articulation of cloud-hosting capability. I think that capability exists, but it’s not showing up at the right level of detail in the positioning so far. In any event, if you add PTX to QFabric in just the right way, you have a cloud—probably the best cloud you can build in today’s market.

If Juniper exploits the Express Domain concept, then the PTX and QFabric combine to create something that’s top-line valuable to the service providers. Yes, there are benefits to convergence on packet optical core networks, but those benefits are based on cost alone, and cost management isn’t the major focus of operators right now—monetization is. You can’t drive down transport cost per bit enough for it to be a compelling benefit in overall service pricing, or enough to make low-level services like broadband Internet profitable enough.

Furthermore, achieving significant capex savings for the operator means achieving fewer total sales for the vendor. That’s the old “cost-management-vanishes-to-a-point” story. But you can do stuff at the service layer that was never possible before, drive up the top line, and sell more gear overall rather than less. Or so I think. We’ll be asking for clarification on these points, and in our March Netwatcher we’ll report on what we find.