Rethinking the Network

Marten Terpstra

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Top Stories by Marten Terpstra

Last week I walked through the packet formats for VXLAN and NVGRE specifically focused on ways by which the overlay packets provide information to the physical network that help the physical network. Some of the initial extreme thoughts that the overlay and physical network can and should be completely ignorant of each other have softened more recently and more pragmatic thoughts of collaborating layers are being articulated. At Plexxi we have often mentioned that we believe the physical network and the overlay need to be closely orchestrated to get the most benefit out of the total network solution. And orchestration != ECMP. In addition to VXLAN and NVGRE, Stateless Transport Tunneling (STT) is an encapsulation mechanism used by VMware, mostly for communication between server based vSwitches. It is a bit more involved and complicated than VXLAN and NVGRE, mostly ... (more)

Changing the Way We Configure and Provision Our Networks

Some people believe good or bad things always happen in threes. I believe you will always be able to find three (and probably more) things that are good or bad and somewhat related, but sometimes I get surprised by the apparent coincidental appearance of several closely related “things”. Last week the folks at posted a second installment of their “policy in the datacenter” discussion, Cisco announced the acquisition of tail-f and internal to Plexxi we had several intense architectural discussions around Configuration, Provisioning and Policy management. Maybe we... (more)

Open Compute, Open Switch API and Open Network Install Environment

Much has been published about the Open Compute Project. Initiated by Facebook, it has become an industry effort focused on standardization of many parts and components in the datacenter. Initially focused on racks, power and server design, it has also added storage and now networking to its fold. Its goal is fairly straightforward: “how can we design the most efficient compute infrastructure possible”, a direct quote from its web site. The focus of OCP has been mostly around hardware designs and specifications. If you look at the networking arm of OCP, you find several Top of Rack... (more)

Red Sox, Pumpkins and Packet Encapsulation

[This is not really about the Red Sox or pumpkins this Halloween, but how could I not use those in the title? Go Red Sox] I left an awful teaser at the end of my article last week. In Brent Salisbury's original article that triggered some of these additional virtualization thoughts, he articulated two very clear differences between native network based L2 virtualization mechanisms and the mechanisms that are being provided by overlay solutions based mostly in server vSwitch infrastructure. These two fundamental functions are MAC learning and tunnel encapsulation. In today's post... (more)

Managing Tables in Our New Virtual Reality

In traditional networks, MAC addresses are inserted into tables using standard learning techniques.  When packets arrive, if the source MAC address is not known, it is added to the MAC forwarding table for that VLAN with the ingress interface as its destination. If the destination is unknown, the packet is flooded through the VLAN, with the side effect that each switch along the way inserts the source MAC address in its own forwarding table for that VLAN. Assuming the destination actually exists, one of the flooded copies will reach its destination. The device at the destination ... (more)