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How Cisco’s data center is built on openness

As customers embrace cloud strategy to build an agile data center, one of the key pillars is openness. Why openness? To move fast, accelerate time-to-market, drive higher level of innovation and avoid vendor lock-in are some of the benefits to openess. What does open mean? In this case, open source, open standards, open interfaces, open API’s, open tools set including automation, orchestration and DevOps.

Come and join Cisco at ONS June 15-18, 2015 to learn how we’ve been in the forefront developing and contributing to the open source community. Hear our speakers Tom Edsall Data Center SDN Solutions  June 18 @ 2:00 pm, Mike Cohen at the partner theater June 18 @ 12:40 pm and others

See demos in Cisco’s booth on OpenStack, Group Based Policy GBP that enables capturing application requirements directly rather than converting the requirements into a set of infrastructure configuration updates, Open Dayligt, and more. In the solutions showcase section, you’ll see a service chaining demo with Avi and One Convergence.

What else are we doing to drive openness in the data center? BGP-EVPN control plane to define how VxLAN tunnel endpoints map MAC addressed to IP addresses in a multi-vendor environment, Network Service Header NSH offering a method to identify network service path, OpFlex is an extensible policy protocol designed to exchange abstract policy between a network controller and a set of smart devices capable of rendering policy, open SDN with ACI  and many more.

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Cisco Enhances SDN Strategy and Offerings Across the Entire Nexus Portfolio with new VTS Automation Solution

Interest in Software Defined Networking (SDN) continues to grow through the ability to make networks more programmable, flexible and agile. This is accomplished by accelerating application deployment and management, simplifying automating network operations and creating a more responsive IT model.

Cisco is extending its leadership in SDN and Data Center Automation solutions with the announcement today of Cisco Virtual Topology System (VTS), which improves IT automation and optimizes cloud networks across the entire Nexus switching portfolio. Cisco VTS focuses on the management and automation of VXLAN-based overlay networks, a critical foundation for both enterprise private clouds and service providers. The announcement of the VTS overlay management system follows on Cisco’s announcement earlier this year supporting the EVPN VXLAN standard, which underlies the VTS solution.

Cisco VTS extends the Cisco SDN strategy and portfolio, which includes Cisco Application Centric Infrastructure (ACI), as well Cisco’s programmable NX-OS platforms, to a broader market and for additional use cases, which includes our massive installed base of Nexus 2000-7000 products, and to customers whose primary SDN challenge is in the automation, management and ongoing optimization of their virtual overlay infrastructure. With support for the EVPN VXLAN standard, VTS furthers Cisco’s commitment to open SDN standards, and increases interoperability in heterogeneous switching environments, with third-party controllers, and with cloud automation tools that sit on top of the open northbound API’s of the VTS controller.

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IT Business Leaders Open Up at ONUG

This week, May 13-14, ONUG, or the Open Networking User Group, will meet at Columbia University’s Alfred Lerner Hall in New York City, NY.

Columbia-Campus_SM-300x200

ONUG is the leading user-driven community of IT Business Leaders, CTOs, network architects, especially including those implementing SDN, who are focused on leveraging the power of their engineering and procurement to influence the pace and deployment of open networking solutions.

ONUG

If you are planning on attending, I’d like to provide you with a quick overview of the activities Cisco will be participating in at the Open Networking User Group.

On conference day 1, May 13, the SD-WAN and the Virtual Network Overlay Working Groups will present their top ten findings and present their work.

Check out the SD-WAN Working Group Update with Cisco speaker, Steve Wood, Principal Engineer, Enterprise Routing, from 10:00-10:45 am.

Then during the Technology Showcase Break, meet Sumanth Kakaraparthi, Product Manager, Enterprise Routing and Bill Reilly, Technical Marketing Engineer, Enterprise Routing who will deliver an IWAN/SD-WAN Demo at the Cisco demo station.

Next, attend the Virtual Networks/Overlays Working Group Update with Cisco speaker, Mike Cohen, Director of Product Management, Insieme Networks, on May 13 from 12:00-12:45 pm.

Following these updates will be a luncheon presentation: “Faster WAN Delivery: Software Defined WAN-as-a-Service” on May 13 from 1:30-2:30 pm delivered by Cisco speaker, Jeff Reed, VP, Enterprise Infrastructure and Solutions Group.  Jeff will be joined by partner speakers: Jeff Gray, Glue Networks CEO and Matt Cook, Forsythe Sr. Director – Network & Workspace Solutions.

From 4:05-5:00pm, there will be a lively debate on “Closed vs. Open Source Software” moderated by Ernest Lefner, Bank of America, between Charles Giancarlo, Silver Lake, taking the Pro Closed position and Lew Tucker, Cisco VP/CTO for Openstack, taking the Pro Open position.  You can carry on the debates yourselves afterwards at the Cocktail Reception from 5:00-7:00.

The next day on May 14 from 2:45-3:45 pm there will be a Town Hall Meeting with leaders from Facebook, Ansible, Nuage, vArmour and our own, Mike Dvorkin, Cisco Distinguished Engineer, Insieme Networks, who will all speak on “Will the DevOps Model Deliver in the Enterprise?”.

Finally, that evening join us at a Cisco Sponsored After Party from 5:00 – 9:00 pm.

For Further Information

Cisco Intelligent WAN

ONUG Blog – VXLAN Comes of Age with BGP-EVPN

MP-BGP eVPN control plane for VXLAN – SDN is growing up

Cisco Border Gateway Protocol Control Plane for Virtual Extensible LAN

VXLAN Network with MP-BGP EVPN Control Plane

Follow ONUG

LinkedIn Groups Open-Networking-User-Group

Twitter ONUG

OpenNetworkingUserGroup.com

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A Summary of Cisco VXLAN Control Planes: Multicast, Unicast, MP-BGP EVPN

With the adoption of overlay networks as the standard deployment for multi-tenant network, Layer2 over Layer3 protocols have been the favorite among network engineers. One of the Layer2 over Layer3 (or Layer2 over UDP) protocols adopted by the industry is VXLAN. Now, as with any other overlay network protocol, its scalability is tied into how well it can handle the Broadcast, Unknown unicast and Multicast (BUM). That is where the evolution of VXLAN control plane comes into play.

The standard does not define a “standard” control plane for VXLAN. There are several drafts describing the use of different control planes. The most commonly use VXLAN control plane is multicast. It is implemented and supported by multiple vendors and it is even natively supported in server OS like the Linux Kernel.

This post tries to summarize the three (3) control planes currently supported by some of the Cisco NX-OS/IOS-XR. My focus is more towards the Nexus 7k, Nexus 9k, Nexus 1k and CSR1000v.

Each control plane may have a series of caveats in their own, but those are not covered by this blog entry. Let’s start with some VXLAN definitions:

(1) VXLAN Tunnel Endpoint (VTEP): Map tenants’ end devices to VXLAN segments. Used to perform VXLAN encapsulation/de-encapsulation.
(2) Virtual Network Identifier (VNI): identify a VXLAN segment. It hast up to 224 IDs theoretically giving us 16,777,216 segments. (Valid VNI values are from 4096 to 16777215). Each segment can transport 802.1q-encapsulated packets, theoretically giving us 212 or 4096 VLANs over a single VNI.
(3) Network Virtualization Endpoint or Network Virtualization Edge (NVE): overlay interface configured in Cisco devices to define a VTEP

VXLAN with Multicast Control Plane
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VXLAN/EVPN: Standards based Overlay with Control-Plane

Given the tremendous interest in VXLAN with MP-BGP based EVPN Control-Plane (short EVPN) at Cisco Live in Milan, I decided to write a “short” technology brief blog post on this topic.

VXLAN (IETF RFC7348) has been designed to solve specific problems faced with Classical Ethernet for a few decades now. By introducing an abstraction through encapsulation, VXLAN has become the de-facto standard overlay of choice in the industry. Chief among the advantages provided by VXLAN; extension of the todays limited VLAN space and the increase in the scalability provided for Layer-2 Domains.

Extended Namespace – The available VLAN space from the IEEE 802.1Q encapsulation perspective is limited to a 12-bit field, which provides 4096 VLANs or segments. By encapsulating the original Ethernet frame with a VXLAN header, the newly introduced addressing field offers 24-bits, thereby providing a much larger namespace with up to 16 Million Virtual Network Identifiers (VNIs) or segments.

 

 

 

While the VXLAN VNI allows unique identification of a large number of tenant segments which is especially useful in high-scale multi-tenant deployments, the problems and requirements of large Layer-2 Domains are not sufficiently addressed. However, significant improvements in the following areas have been achieved:

  • No dependency on Spanning-Tree protocol by leveraging Layer-3 routing protocols
  • Layer-3 routing with Equal Cost Multi-Path (ECMP) allows all available links to be used
  • Scalability, convergence, and resiliency of a Layer-3 network
  • Isolation of Broadcast and Failure Domains

IETF RFC7348 – VXLAN: A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks

Scalable Layer-2 Domains

The abstraction by using a VXLAN-like overlay does not inherently change the Flood & Learn behavior introduced by Ethernet. In typical deployments of VXLAN, BUM (Broadcast, Unicast, Multicast) traffic is forwarded via layer-3 multicast in the underlay that in turn aids in the learning process so that subsequent traffic need not be subjected to this “flood” semantic. A control-plane is required to minimize the flood behavior and proactively distribute End-Host information to participating entities (typically called Virtual Tunnel End Points aka VTEPs) in the same segment – learning.

Control-plane protocols are mostly employed in the layer-3 routing space where predominantly IP prefix information is exchanged. Over the past years, some of the well-known routing protocols have been extended to also learn and exchange Layer-2 MAC addresses. An early technology adoption with MAC addresses in a routing-protocol was Cisco’s OTV (Overlay Transport Virtualization), which employed IS-IS to significantly reduce flooding across Data Center Interconnects (DCI).

Multi-Protocol BGP (MP-BGP) introduced a new Network Layer Reachability Information (NLRI) to carry both, Layer-2 MAC and Layer-3 IP information at the same time. By having the combined set of MAC and IP information available for forwarding decisions, optimized routing and switching within a network becomes feasible and the need for flood to do learning get minimized or even eliminated. This extension that allows BGP to transport Layer-2 MAC and Layer-3 IP information is called EVPN – Ethernet Virtual Private Network.

EVPN is documented in the following IETF drafts

Integrated Route and Bridge (IRB) – VXLAN-EVPN offers significant advantages in Overlay networking by optimizing forwarding decision within the network based on Layer-2 MAC as well as Layer-3 IP information. The decision on forwarding via routing or switching can be done as close as possible to the End-Host, on any given Leaf/ToR (Top-of-Rack) Switch. The Leaf Switch provides the Distributed Anycast Gateway for routing, which acts completely stateless and does not require the exchange of protocol signalization for election or failover decision. All the reachability information available within the BGP control-plane is sufficient to provide the gateway service. The Distributed Anycast Gateway also provides integrated routing and bridging (IRB) decision at the Leaf Switch, which can be extended across a significant number of nodes. All the Leaf Switches host active default gateways for their respective configured subnets; the well known semantic of First Hop Routing Protocols (FHRP) with active/standby does not apply anymore.

Summary – The advantages provided by a VXLAN-EVPN solution are briefly summarized as follows:

  • Standards based Overlay (VXLAN) with Standards based Control-Plane (BGP)
  • Layer-2 MAC and Layer-3 IP information distribution by Control-Plane (BGP)
  • Forwarding decision based on Control-Plane (minimizes flooding)
  • Integrated Routing/Bridging (IRB) for Optimized Forwarding in the Overlay
  • Leverages Layer-3 ECMP – all links forwarding – in the Underlay
  • Significantly larger Name-Space in the Overlay (16M segments)
  • Integration of Physical and Virtual Networks with Hybrid Overlays
  • It facilitates Software-Defined-Networking (SDN)

Simply formulated, VXLAN-EVPN provides a standards-based Overlay that supports Segmentation, Host Mobility, and High Scale.

VXLAN-EVPN is available on Nexus 9300 (NX-OS 7.0) with  Nexus 7000/7700 (F3 linecards) to follow in the upcoming major release. Additional Data Center Switching platforms, like the Nexus 5600, will follow shortly after.

A detailed whitepaper on this topic is available on Cisco.com. In addition, VXLAN-EVPN was featured during the following Cisco Live! Sessions.

Do you have appetite for more? Post a comment, tweet about it and have the conversation going … Thanks for reading and Happy Networking!

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