Mallik Mahalingam, Principal Engineer, vSphere Networking R&D, says …
What are the challenges?
Cloud computing holds the promise of using shared resources in a secure, scalable and self service manner. These basic virtues of cloud computing are placing huge demands on the physical network infrastructure in today’s data centers. While compute and storage are virtualized, network is the last remaining barrier to workload agility. Networks continue to operate in the old way, tying workloads to underlying physical network and to non-scalable, hard-to-automate constructs. In addition, cloud infrastructure dictates new networking constructs for multi-tenancy, application isolation, scale and increased programmability.
VMware has been working with customers to understand the key challenges as it relates to networking and the cloud. The primary feedback was the need for a network that can support hosting large number of “tenant” applications while enabling the paradigm of elastic compute, any application to any host. Ideally customers would like this scale, elasticity and operational efficiency on top of their existing physical infrastructure.
Eureka! – VXLAN
Armed with the requirements from our customer, VMware along with the support of our partner ecosystem has developed an innovative technology called VXLAN [Virtual eXtensible LAN]. VXLAN enables multi-tenant networks at scale alongside the ability to flexibly tap into any available compute/storage resources in the data center. It is the first step in the path towards logical, software-based networks that can be created on-demand, enabling enterprises to leverage capacity wherever it’s available.
VXLAN provides a Layer 2 abstraction to virtual machines (VMs), independent of where they are located. It completely untethers the VMs from physical networks by allowing VMs to communicate with each other using a transparent overlay scheme over physical networks that could span Layer 3 boundaries. Since VMs are completely unaware of the physical networks constraints and only see the virtual Layer 2-adjacency, the fundamental properties of virtualization such as mobility and portability are extended to an unprecedented level.
VXLAN enables better programmability by providing a single interface to authoritatively program the logical network. Operationally, it will provide the needed control and visibility to the network admin while allowing the flexibility of elastic compute for the cloud admin.
Key technical points about VXLAN:
- Uses MAC-in-UDP encapsulation to build the overlay network that can span across L3 networks.
- Use of MAC-in-UDP allows efficient load-sharing with the existing data center networks due to the use of Equal Cost Multipathing (ECMP) in the core networks, unlike other encapsulation technologies such as GRE
- Allows overlapping of VM’s MAC and IP addresses using VXLAN Network identifier
- Takes advantage of efficient multicast protocols such as IGMP and PIM for VM’s broadcast and multicast communication needs
Collaboration with leading Partners on VXLAN
VMware has collaborated closely with our industry partners such as Arista, Broadcom, Brocade, Cisco, Emulex, Intel and others in making this as industry wide effort to ensure a seamless experience across virtual and physical infrastructure. As part of this effort, we have published an informational IETF draft (see http://www.ietf.org/id/draft-mahalingam-dutt-dcops-vxlan-00.txt) to detail the use case and the technology.
VXLAN is the first and the flagship of a set of capabilities that we are building to deliver this new model of cloud centric networking. At VMware, we see a need to evolve the datacenter network of today from a Non scalable, hard-to-automate to a Dynamic, Workload-aware network.
Stay tuned for the update on the next blog post where we will discuss the broader story articulating the dynamic, elastic, workload-aware network built on the foundation of VXLAN.