Containers Expo Blog Authors: Liz McMillan, Yeshim Deniz, Elizabeth White, Zakia Bouachraoui, Pat Romanski

Related Topics: Containers Expo Blog, Microservices Expo, @CloudExpo, Cloud Security, @DXWorldExpo, SDN Journal

Containers Expo Blog: Blog Post

Red Sox, Pumpkins and Packet Encapsulation

Network virtualization allows the amount of attached VLANs & networks to scale beyond what a single physical switch can handle

[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 I will spend a little more time looking at encapsulation differences.

redsox pumpkinOutside of logical separation of multiple virtual networks or tenants, network virtualization allows the amount of attached VLANs, networks and devices to scale well beyond what a single physical switch can handle. In a traditional network, an edge switch will only maintain tables for its local VLANs, ports and learned MAC addresses, but core switches that connect these edge switches together will have to maintain the union of all these edge tables, limiting the size of the network, or forcing extremely large (read expensive) core switches that can cope.  In a virtualized network, a VLAN is no longer a unique identifier. The same VLAN can appear many times on different ports in the network, all mapped to different virtual networks or tenants.

To achieve this scaling and re-use of VLAN space, original user traffic has a new header added to it, effectively hiding the original VLAN, source and destination MAC address. Traffic is exchanged between edge switches that serve the specific members of this virtual network, passing through the core of the network based on the new header alone. Using this re-encapsulation creates a tunnel and intermediate switches are oblivious to the original packet, allowing them to scale by having to know only how to locate the edge switches.

Traditional L2 virtualization mechanisms use an extra L2 header for the tunnel, most commonly a MAC-in-MAC encapsulation. This encapsulation adds a new ethernet header onto the original packet, with the source edge switch as the source MAC, the destination edge switch as the destination MAC, and some other fields including an identifier for the virtual network. Switches in the core must only provide end to end ethernet service to the edge switches, since all they see are these newly ethernet encapsulated packets. Their tables stay sparsely populated, since the edge switch MAC addresses and the VLANs used for transport are the only bits needed for packet forwarding.

And this is where overlay solutions have taken a step forward. Whether its VXLAN, NVGRE or STT, all proposed/used overlay encapsulation mechanisms wrap the original packet into an IP packet. The tunnel between the edge switches is an IP/UDP connection (except for STT which "uses" TCP, but really doesn't), and transport requires regular IP connectivity between them. Now, this certainly increases the size of an original packet by quite a bit, the edge switch adds a UDP header, an IP header and then (assuming its still transported across an ethernet network) an ethernet header, but it creates an abstraction and a degree of freedom between the edge devices, and the transport network that connects them.

There is nothing wrong with ethernet based encapsulations for a virtualized network. I have seen them work, I have seen them work well. But when the virtualization edge becomes the vSwitch in a server, the sheer amount of edge switches (vSwitch in this case) that need to be connected together using a single or small number of transport VLANs in an ethernet core may start to run into the scaling concerns for a single broadcast domain discussed last week. When it is hundreds of edge devices some of the SPB or TRILL based solutions may become challenged, I bet you almost all of them will when you start talking thousands of edge devices.

Besides the obvious ability to create tunnels between remote but IP connected virtual network islands, having tunnels based on IP is actually an added convenience, even if the network based virtualization solution can be created on top of a single VLAN ethernet network. An extra set of headers provide additional tables, additional lookup opportunities in hardware to send traffic where you want it to be sent. Not the ECMP way, but in a controlled and carefully calculated way in order to satisfy the needs of the virtual network. And that makes VXLAN equally suited as a pure physical network based virtualization transport mechanism even if there is no overlay.

Rather than leaving a poor hint of what to expect, next week I will discuss the second major difference from Bren't original article: MAC learning in a virtualized network and the role of a controller in determining virtual network membership and location.

Happy Halloween!

[Today's fun fact: Lego produces more rubber tires than any other tire company in the world (381 million in 2011)]

The post Red Sox, Pumpkins and Packet Encapsulation appeared first on Plexxi.

Read the original blog entry...

More Stories By Marten Terpstra

Marten Terpstra is a Product Management Director at Plexxi Inc. Marten has extensive knowledge of the architecture, design, deployment and management of enterprise and carrier networks.

IoT & Smart Cities Stories
Moroccanoil®, the global leader in oil-infused beauty, is thrilled to announce the NEW Moroccanoil Color Depositing Masks, a collection of dual-benefit hair masks that deposit pure pigments while providing the treatment benefits of a deep conditioning mask. The collection consists of seven curated shades for commitment-free, beautifully-colored hair that looks and feels healthy.
The textured-hair category is inarguably the hottest in the haircare space today. This has been driven by the proliferation of founder brands started by curly and coily consumers and savvy consumers who increasingly want products specifically for their texture type. This trend is underscored by the latest insights from NaturallyCurly's 2018 TextureTrends report, released today. According to the 2018 TextureTrends Report, more than 80 percent of women with curly and coily hair say they purcha...
The textured-hair category is inarguably the hottest in the haircare space today. This has been driven by the proliferation of founder brands started by curly and coily consumers and savvy consumers who increasingly want products specifically for their texture type. This trend is underscored by the latest insights from NaturallyCurly's 2018 TextureTrends report, released today. According to the 2018 TextureTrends Report, more than 80 percent of women with curly and coily hair say they purcha...
We all love the many benefits of natural plant oils, used as a deap treatment before shampooing, at home or at the beach, but is there an all-in-one solution for everyday intensive nutrition and modern styling?I am passionate about the benefits of natural extracts with tried-and-tested results, which I have used to develop my own brand (lemon for its acid ph, wheat germ for its fortifying action…). I wanted a product which combined caring and styling effects, and which could be used after shampo...
The platform combines the strengths of Singtel's extensive, intelligent network capabilities with Microsoft's cloud expertise to create a unique solution that sets new standards for IoT applications," said Mr Diomedes Kastanis, Head of IoT at Singtel. "Our solution provides speed, transparency and flexibility, paving the way for a more pervasive use of IoT to accelerate enterprises' digitalisation efforts. AI-powered intelligent connectivity over Microsoft Azure will be the fastest connected pat...
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Druva is the global leader in Cloud Data Protection and Management, delivering the industry's first data management-as-a-service solution that aggregates data from endpoints, servers and cloud applications and leverages the public cloud to offer a single pane of glass to enable data protection, governance and intelligence-dramatically increasing the availability and visibility of business critical information, while reducing the risk, cost and complexity of managing and protecting it. Druva's...
BMC has unmatched experience in IT management, supporting 92 of the Forbes Global 100, and earning recognition as an ITSM Gartner Magic Quadrant Leader for five years running. Our solutions offer speed, agility, and efficiency to tackle business challenges in the areas of service management, automation, operations, and the mainframe.