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Blogs

Short articles that discuss data center networking solutions

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SmartFabric

Time Synchronization in Network Devices—the Why and How

AnuPaul Parayil

Thu, 06 Aug 2020 19:04:17 -0000

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In this post, we will talk about Precision Time Protocol (PTP) and how it goes beyond Network Time Protocol (NTP) to offer better accuracy and time synchronization. 

Why?

Let us take the modern wireless network for example - precision timing and synchronization are crucial for basic communication as well as providing the ability to detect location and movement. Although time synchronization plays a prominent role in packet-based networks, it is often implemented as an afterthought. 

Every aspect of securing and debugging a network typically involves determining when events happen and accurately correlating log files between network devices. Here are several reasons why time synchronization is important for your network:

  • When something goes wrong, you need to look through the log messages to identify the root cause and which device caused it. If your clocks are not synchronized, this becomes a difficult task.
  • Manually setting up your clock against a common time source can be time consuming.
  • Tracking network usage, latency issues, and security breaches can be impossible if timestamps in logs are inaccurate. 
  • By synchronizing clocks on network devices, they can act as a time source to other devices in the same network.

How?

There are several time synchronization mechanisms that can be used in a network. The most common ones are Network Time Protocol (NTP) and Precision Time Protocol (PTP). The older and well-known NTP (currently in its fourth version) was primarily developed to achieve accuracy in the submillisecond range and is widely adopted for network timekeeping. Since NTP is based on software timestamping, it can be less accurate for certain industrial applications where greater levels of synchronization are required.

Precision Time Protocol (IEEE 1588 Version 2) is a network-based time synchronization standard designed for distributing precise time and frequency from a clock source over packet-based networks. PTP uses hardware timestamping to achieve submicrosecond accuracy. PTP also enables switches and routers to deliver synchronization with a higher level of accuracy than NTP that is suitable for today’s cloud networks and data center infrastructures. It can be especially useful in industrial and financial applications where microseconds matter. The applications of PTP can be applied to almost any industry, all the way from enterprise data centers to financial sectors, and many more.

To ensure clock synchronization, PTP sends messages between the time source and the receiver to determine the accurate measurement of the path delay. With PTP, time is carried in “event” messages transmitted from a Grand Master (GM), or primary clock, to a secondary clock, and vice versa. The network nodes synchronize to the primary clock, and thus all the clocks are synchronized within a PTP network. 

Let us take a brief look at the different network node models that define the hierarchy in the PTP protocol. The Best Master Clock Algorithm (BMCA) runs on all clocks available in the network to determine the best clock.

  • Grand Master (GM) is the primary clock source within a PTP domain. It usually has a precise time source, such as a GPS or atomic clock, and functions as the reference clock. 
  • Boundary Clock (BC) acts as a secondary clock at the port that connects to the primary  and distributes time to all other downstream devices. The secondary port synchronizes the time from the upstream PTP device. 
  • Transparent Clock (TC) forwards the PTP message after updating the residence time of a PTP event message. Ports do not have any state in this clock. A TC on a network only provides support for processing IEEE 1588 Version 2 messages and does not recover time or frequency. 

 

 

 IEEE 1588 Version 2

Did you know that Dell EMC SmartFabric OS10 supports PTP to achieve deeper levels of accuracy? You can configure global and interface-level settings to set up the OS10 switch to function as a PTP device. See the Dell EMC SmartFabric OS10 User Guide to learn more about configuring the boundary clock and transparent clock using different PTP transport methods.


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Ansible SmartFabric

A Network Automation Journey with Ansible—Part 1

AnuPaul Parayil

Wed, 15 Jul 2020 18:59:46 -0000

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Why Network Automation

Data center networks are being designed and built at a massive scale to support a wide range of applications and services ranging from real-time video, to social media, to augmented reality, and more. Although today’s robust networks are fully capable of running these complex configurations, performing monitoring, and implementing security checks, it is often a tedious task to write manual, CLI-based scripts that are repetitive and subject to human error.

With all the given interdependencies and challenges of today’s networks, the expectations for high performance, availability, and reliability of these networks are higher than ever. By automating everyday network tasks like configuration management and device provisioning, network efficiency and agility of a data center infrastructure can be significantly improved.

Network automation enables the software to automatically provision, configure, manage, and monitor network devices with a minimum number of steps and fewer errors. Automation reduces the complexities of network infrastructure, allowing network administrators to focus more on the innovations of their business needs. The entire network can now be remotely managed without much human intervention. This software-driven architecture is essential for businesses to lower operational costs and improve time-to-market.

The Ansible Story...

Ansible is a simple automation language that can perfectly describe an IT application infrastructure. The same benefits that Ansible brings to compute nodes can now be extended to the network nodes. With Ansible, network teams:

  • Use a simple, powerful, and agentless automation framework
  • Use a data model (a playbook or role) that easily spans network devices
  • Benefit from a wide variety of community and vendor-generated playbook and role content to help accelerate network automation projects

This is why Ansible is a powerful tool that can be utilized to effectively change your day-to-day network operations using automation. Ansible can help teams automate routine tasks and focus on the bigger stuff!

Ansible includes hundreds of network modules, roles, and plug-ins that are now part of Ansible Content Collections to support a wide variety of network vendors. Basically, Ansible Content Collections is a new method of building and consuming Ansible content. It makes deployment automation simpler and smarter, providing a consistent format that allows content creators to ship bundles of modules, plug-ins, roles, and documentation together.

This is how we Role!

The Ansible collection for Dell EMC SmartFabric OS10 includes the modules, plug-ins, and roles required to work on Dell EMC SmartFabric OS10 PowerSwitch platforms running OS10. The Ansible collection for Dell EMC SmartFabric OS10, which includes sample playbooks and documents that illustrate how the collection can be used, is available on Ansible Galaxy.

 

 Wondering how to get started ? We’ve got you covered:

  • Our Ansible Network Automation hands-on lab shows you everything from installing Ansible to configuring an L3 VXLAN EVPN fabric using the Ansible OS10 collection.
  • Our Fabric Design Center allows you to build your own network design in four easy steps and download auto-generated Ansible playbooks for your network configuration. Can’t get easier than this!

 

 

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SmartFabric

Streaming Telemetry with SmartFabric OS10

AnuPaul Parayil

Fri, 10 Jul 2020 15:01:32 -0000

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As the number of workloads running on massive data center infrastructures increases, network visibility becomes a critical component to prevent any downtimes. The traditional network reporting and monitoring solutions have their limitations because they do not provide enough granularity when you want real-time data to provide end-to-end visibility and performance insights.

Traditional methods such as SNMP use a pull-based mechanism where a management device sends a GET request and pulls data from a client. From a network monitoring standpoint, this model has been successful for a long time but proves insufficient for today’s hybrid cloud infrastructure, where speed, scalability, and reliability are important factors.

Streaming telemetry provides an alternate method by which data is continuously transmitted from network devices using a push-based model. Polling the device and asking for an operational state is not needed. For example, streaming telemetry reports packet drops or high utilization on links in real time. A network automation application can use this information to provision new paths and optimize traffic across the network. The data is encoded using Google Protocol Buffers (GPB) and streamed using Google Protocol RPC (gRPC) transport. 

With the current shift to a larger remote workforce, IT teams need to have real-time access to analytics-ready data that can help with network automation, traffic optimization, and preventive troubleshooting.

 

With streaming telemetry, operators subscribe to the specific data they need, using YANG data models as the common structure and interface. Dell EMC SmartFabric OS10 supports streaming telemetry to push telemetry data out to the collectors. The telemetry agent collects data from OS10 applications and switch hardware.

To enable the streaming of telemetry data to destinations in a subscription profile, you need to:

1. Enable telemetry on the switch.

2. Configure a destination group.

3. Configure a subscription profile by associating one or more destination groups and preconfigured sensor groups.

The destination group tells the switch where and how to send telemetry data. The sensor group identifies a list of YANG models that the switch should stream. The subscription profile ties together the destination group and the sensor group. Then, the telemetry agent in the switch attempts to establish a session with each collector in the subscription profile and streams data to the collector.

You can use OS10 telemetry to stream data to:

  • Dell-implemented external collectors, such as VMware vRNI or Wavefront
  • Proprietary network collectors that you implement

SmartFabric Director, developed by VMware and Dell Technologies, employs telemetry to collect switch operational data and display metrics graphically at both the network fabric and switch levels. SmartFabric Director provides out-of-the-box insights, such as switch health and fabric health that can ensure consistency between the operational state and the intended state.

For more information about how Dell EMC SmartFabric Director enables more agile and simplified central management across both virtual and physical network infrastructures, see SmartFabric Director 101

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