Sridhar Devarapalli, director of product management at Citrix Systems, talks to SDNCentral about how software-defined networking (SDN) and network functions virtualization (NFV) are changing virtualization, mobility management, networking, and cloud services.
What are the biggest ways SDN and NFV are affecting networking today?
Devarapalli: SDN brings to bear a fundamental change in networking that Citrix has always been a believer in: that networks exist solely to serve applications and therefore should have a simplified operating model that is easy for application owners to use. The heart of the problem is building and running large-scale infrastructure in an increasingly consolidated data center footprint.
NFV and SDN are two sides of the same coin, with both technology trends having coincidental, if not the same, goals. While SDN has largely focused on automating network operations in the data center, the NFV movement started with a goal to virtualize and disaggregate the various services offered by telco providers in both wired and wireless environments that traditionally ran on dedicated physical hardware.
The big advantage of disaggregation is a simplified operational model and increased agility. Running network functions in pure software makes it easier to install, license, move around, program, and scale them out without needing to rip and replace the underlying hardware. Virtualized services also simplify orchestration, a key aspect of an NFV environment.
How do SDN and NFV fit into Citrix’s product set? How do the technologies work with existing hardware appliances?
Citrix has always believed in software-based networking and offering our customers complete freedom of choice between platforms and features. Our NetScaler VPX product line is the leader in the virtual ADC space and has the exact same binary as our hardware appliances
Our virtualized products are the fastest growing products within the NetScaler product line, both in terms of revenue and net new customers. NetScaler SDX is an open and elastic platform that consolidates network services into a unified service delivery layer accessible as a whole by the application through open APIs.
We believe the network needs an application control layer. SDN enables a programmable networking model that allows us to disseminate our deep and broad application intelligence into the network, making the network a unified Layer 2–Layer 7 intelligent application fabric.
We aim to seamlessly integrate our technology into SDN environments as an always-on, elastic service that can be consumed on demand. That’s why we are focused on building NetScaler Control Center, a common multitenant platform that orchestrates NetScaler services across both physical and virtual appliances. It will allow customers to use all NetScaler appliances as an aggregate pool of capacity.
How does the NetScaler product team prioritize integration into other cloud management platforms (CMPs) and support for other hypervisors?
Devarapalli: We live in an era of coopetition in the technology space, where we listen to our customer’s needs and allow them to self-select between best-of-breed products and technologies. So while NetScaler has highly differentiated integrations with Citrix’s own products, we also treat other market leading products with priority. We provide integrations with OpenStack and VMware NSX through NetScaler Control Center in addition to deep integrations with Cisco ACI and Citrix Cloud Platform. In fact, Citrix led the first incarnation of LBaaS in OpenStack via the Atlas project. Our VPX virtual appliance is available on all leading hypervisors besides XenServer. It’s available on ESX, Hyper-V, and KVM, and it offers the exact same capabilities on all of them.
What’s happening with open source SDN today? What are your thoughts around open source and Open vSwitch?
Devarapalli: The open source arena is very interesting to watch for all infrastructure technologies, not just networking. Open source consortiums are like the new IETF, and it is where the industry think tanks are coming together to build open, vendor-neutral solutions for actual production deployment.
Vendors realize that a clearly defined open source strategy is vital to keep themselves credible and relevant to customers, who insist on openness and interoperability from the get-go. Open source projects like OpenStack have gained rapid momentum for valid reasons, but managing the size of the community and maintaining innovation and feature velocity can be a challenge, which we’ve begun to see in some of the OpenStack projects.
Another interesting consequence of the open source movement is that the consortiums have become new battlegrounds for success, with market leaders contending for leadership in the communities to demonstrate innovation and thought leadership. At the end, we believe these are all good trends and the customer ends up being the winner. Vendors are still innovating to claim differentiation – it’s just that the frontier of competitiveness has shifted and expanded.
You were an early participant in SDN. Before Citrix, you were also at Big Switch. What do you see around the turf battles between orchestration (CloudStack, OpenStack), automation, and controllers? What’s the relationship between those, and who do you think will win?
Devarapalli: I think it’s clear that a centralized control plane is definitely well suited for programmability and visibility. The question of whether the centralized control plane should be an SDN controller or an added function of the orchestration platform is debatable. I think the answer again lies in the use case.
Currently, multitenant cloud environments (both private and public) happen to be the most dominant use case for SDN solutions. Almost invariably, these environments need an overarching orchestration platform for overall infrastructure management. Most SDN controllers today integrate with the orchestration platforms to deliver networking functions such as network virtualization and service chaining. And the controllers provide increased scalability and advanced functions. However, there is no technical reason why the networking projects within the orchestration platforms – Neutron in OpenStack, for example – cannot evolve to include these capabilities.
It may be just a matter of time before the orchestration platforms evolve to include all the features and functions that are currently available in SDN controllers, possibly even more. This also assumes there’s enough interest in open source communities and commercial vendors to evolve orchestration platforms in that direction.
Turning from SDN to NFV, what do you think the implications are for physical Layer 4–Layer 7 services today?
Devarapalli: The most common way of virtualizing network functions is to make them available as virtual machines. Most vendors of L4/L7 services already have their solutions available as virtual appliances.
More advanced L4/L7 services can play a vital role in lending application intelligence to NFV environments through intelligent traffic steering between various virtualized services and enabling seamless availability, scalability, and performance of those services. They also can provide the ability to integrate into the application orchestration environment as well as open APIs to drive configuration programmatically.
Citrix’s view has always been that the core value of our products and technology should remain the same across both physical and virtual form factors. The choice of a physical appliance is primarily for performance and scalability reasons, which is generally addressed through a scale-out architecture in NFV environments. This is something NetScaler supports really well through our TriScale clustering technology.
What are the main SDN use cases you see in the data center? The campus? The WAN?
Devarapalli: Given NetScaler’s dominance in the data center, the main SDN use cases we see center around data center network virtualization as part of a larger automation and self-service IT initiative, where the IT operator is offering IaaS and PaaS services to individual LOBs (lines of business, or tenants). You can characterize this as a private cloud deployment, and the operational model is very similar to that of a public cloud-based IaaS offering.
There have been interesting use cases for SDN in the campus and the WAN environments, including automated network access control in the campus and centralized traffic engineering and bandwidth optimization in the WAN. However, at present, these use cases don’t constitute a strategic area of focus for NetScaler.
What do you see as Citrix’s roadmap in SDN and NFV – both from a commercial and proprietary standpoint, as well as from an open source standpoint?
Devarapalli: Strategically, Citrix NetScaler is very well positioned to play a critical role in the SDN value chain. Our strategy goes back to our core belief that I spoke about earlier, which is that networks exist to serve applications. Value for customers lies in networks understanding applications a lot better, and that’s where NetScaler’s application intelligence becomes an indispensable asset. We not only extract critical application information, we also disseminate that information through the network using the programmable interfaces that SDN offers.
By tightly integrating with SDN environments, we become a core part of the fabric, then interact with the switching layer to augment network intelligence with application visibility, application-based QoS, advanced security, application-aware routing, etc. – areas that are most relevant to the application and where we have spent decades innovating and building expertise in.
In NFV environments, NetScaler’s value add goes beyond large-scale load balancing of operator infrastructure. Its orchestration capabilities, open APIs, and TriScale technology form the key enablers for the agility and scalability needed in environments like the Evolved Packet Core. NetScaler’s native intelligence of various signaling protocols such as SIP and Diameter allows for optimization of virtualized voice and AAA services in both mobile and fixed line operator networks. Purpose built functions such as CG-NAT and NAT64 enable a seamless transition to IPV6, while NetScaler’s content and front-end optimization capabilities allow providers to offer a rich end-user experience for their mobile customers. Finally, NetScaler’s layer 7 intelligence and traffic steering capabilities enables intelligent chaining of virtualized services that can be customized per subscriber
On the open source front, we are active participants in the OpenDaylight community, shaping the direction of SDN by working closely with Cisco and many other industry leaders to forge innovation in the areas of Group Policy (an advanced policy abstraction model to describe all networking), OpFlex (a declarative policy protocol that enables highly scalable solutions), and Network service header (NSH) for intelligent traffic steering and service chaining.
Citrix has a DemoFriday coming up with us soon. Tell us a little about it.
Devarapalli: The demo will showcase how an enterprise IT operator or a cloud service provider can use NetScaler SDX in an OpenStack environment to offer self-service ADCaaS to individual LOBs, application owners, or tenants.
NetScaler Control Center forms the core engine of automation in the demo. It dynamically creates NetScaler instances that can be dedicated to a specific tenant or shared across multiple tenants.
We look forward to seeing it. Thanks for joining us today.
Devarapalli: Thank you for having me.