A CDN is a system of distributed servers that deliver content to a user based on the geographic locations of the user, the origin of the requested content, and a content delivery service. The goal of a CDN is to provide efficient delivery of streaming content over HTTP/HTTPS to optimize content delivery and to serve content to end-users with high availability and high performance, while minimizing the traffic on the network.

At its core, a CDN performs two essential functions:

• It caches content at the edge of the network, closer to end users, to reduce the IP video traffic that needs to traverse the core network, delivering a higher quality experience to viewers.

• It positions multiservice, multiprotocol content streaming capabilities at the network edge, allowing the operator to adapt video content for virtually any IP video device close to the user that is consuming it.

By 2020 there will be 11 billion connected video devices, and 82 percent of IP traffic will be video (Cisco Visual Networking Index). To meet that demand, today’s CDN infrastructures must evolve to scale cost-effectively, accelerate feature velocity, and deliver simplified and open management tools. By adopting cloud architecture and agile software development methodology and using best-in-class open-source software, Cisco Media Streamer provides an open and flexible CDN platform that delivers the multiscreen Internet video quality that consumers expect and service providers can deploy.

The Cisco Media Streamer content delivery platform is designed to deliver immersive multiscreen video experiences to managed and unmanaged devices across telco, cable, and mobile access networks. Media Streamer scales cost-effectively to distribute terabits per second (Tbps) of live, on-demand, and time-shifted video. It enables service providers to compete with over-the-top (OTT) video offerings and generate revenue from wholesale CDN services within their infrastructure. Media Streamer is the foundational IP delivery platform for Cisco’s Infinite Video Platform, which provides comprehensive consumer video experiences.

Media Streamer includes all the core elements of management, request routing, load balancing, caching, and analytics to deliver HTTP and HTTPS content at scale and to easily integrate into your network and middleware. Media Streamer builds on Cisco’s more than 10 years of CDN expertise.

Media Streamer caches and delivers web content, software, and streaming media with support for media players using the following HTTP steaming protocols: Apple HTTP Live Streaming (HLS), Microsoft HTTP Smooth Streaming (HSS), Adobe HTTP Dynamic Streaming (HDS), and MPEG Dynamic Adaptive Streaming over HTTP (MPEG-DASH). Media Streamer supports video on demand (VoD), live video, time-shifted TV (TSTV), progressive download, secure download, and small object caching from a common high-performance HTTP cache. Media Streamer performs sophisticated algorithms for cache selection based on client location, cache availability, cache load, and content requested.

The primary components of a Cisco Media Streamer solution are:

• OMD Director: Cisco OMD Director is a cloud-based CDN management system that provides integrated provisioning, monitoring, analytics, alerting, and role-based management. Cisco OMD Director is implemented to be virtualized and further optimized with microservices in containers. OMD Director is the primary user interface of Cisco Media Streamer.

• OMD Director Portal: An OMD Director portal is optional and does not replace the primary OMD Director Master Controller and Worker nodes. It is intended for customers with downstream Resellers or Content Providers who require access to CDN analytics. An OMD Director portal instance is a separate setup from the primary OMD Director installation, with its own user database. It provides a Director GUI that is limited to working with the CDN analytics dashboards provided by Insights. You cannot manage or view the CDN configuration from an OMD Director portal instance.

• Media Streamer Core Components:

  • OMD Core Traffic Server: A Traffic Server is an HTTP/S proxy cache that is deployed as either an “edge” or “mid-tier” cache server to form a two-tiered CDN hierarchy. Traffic Servers are fast, scalable, extensible using plug-ins, and HTTP/1.1 compliant.

  • OMD Core Traffic Router: A Traffic Router is a CDN load balancer that redirects HTTP(s) client requests to an edge cache to ensure that the end user is connected to the optimal cache. The Traffic Router determines which cache to redirect a request to based on client proximity, cache load, and content affinity. The Traffic Router is authoritative for the CDN domain and it implements DNS and HTTP routing.

  • OMD Core Traffic Ops: Traffic Ops is an open source management system used to configure advanced settings of the Media Streamer CDN.

• OMD Insights: OMD Insights is an application that provides CDN application level insights including operations, content popularity, user consumption, and quality of service (QoS). OMD Insights is based on Splunk and aggregates the log data from all of the Traffic Servers and Traffic Routers.

• OMD Monitor: OMD Monitor is an application that provides in-depth server monitoring, threshold crossing, and alarming based on CPU utilization, port utilization, temperature, disk I/O, and other detailed server metrics.

This section describes some of the key terms you need to be familiar with when provisioning and managing an Media Streamer CDN.

• Delivery service: A software structure in Media Streamer that maps an Origin Server to Traffic Servers using an FQDN. It defines a URL that is used to represent an Origin Server and which cache groups can serve content from that server. The Delivery Service also contains configuration parameters that dictate how content is ingested, distributed, and delivered to client devices.

• Cache group: A cache group is a logical grouping of caches (Traffic Servers) used to provide high availability. A cache group has one single set of geographical coordinates even if the caches that make up the cache group are in different physical locations. To provide site-level redundancy, caches in a cache group should be in separate physical locations. Cache groups are defined to contain either edge caches or mid-tier caches. A cache group serves a particular part of the network as defined in the coverage zone file.

• Cache: Media Streamer uses a two-tiered CDN Traffic Server (cache) hierarchy:

  • Edge caches: Provide edge caching, content streaming, and download to subscriber IP devices. Traffic routers redirect client requests to edge caches based on geolocation, server availability, server load, and server cache content to provide efficient system-wide load balancing. Edge caches are organized into cache groups. Each edge cache group is configured with a single mid-tier parent cache group and optionally a secondary mid-tier parent cache group for failover.

  • Mid caches: Provide content ingest and storage functionality. When an edge cache does not contain the content requested by the client, the edge cache will proxy the request to a mid-cache server, based on the parent cache group assigned to the edge cache. If the mid-cache server does not contain the content, it is responsible for fetching the content from the Origin Server. Mid-tier caches are also organized into cache groups. Mid-tier cache groups may serve (be a parent to) multiple edge cache groups.

The following functions are the key functions that Media Streamer provides:

• Ingest and Distribution:

  • Dynamic: When an edge cache receives a client request, the cache server checks its local cache for the content. If the edge cache does not contain the content, it requests the content from a mid-tier cache. The mid-tier cache checks its local cache for the content. If the mid-tier cache does not contain the content, it will request the content from the Origin Server.

  • Preposition: Typically content is not stored on the cache until a client requests the content. However, in some situations you may want to put content on the cache before it is requested. That is what prepositioning enables you to do. When you configure prepositioning, you define what content to put on the selected caches ahead of time by using a Ingest Manifest file.

• Delivery: The Traffic Router handles client requests for content and determines which client requests to allow. The Traffic Router also determines the best Cache Group to deliver the content based on client proximity, cache load, and content affinity.

  • The Traffic Router supports the following methods to determine which client requests to allow:

    • Coverage Zone File (CZF)

    • National geoblocking (NGB), using a geolocation database, and an NGB whitelist

    • MaxMind Anonymous IP database, which can be used to block:

      • Anonymous VPNs

      • Hosting Providers

      • Public Proxies

      • Tor Exit nodes

      Note	A license is required to use the MaxMind Anonymous IP database. For more information on obtaining this license, please contact your Cisco Account team.

    • ASN blocking, which uses a MaxMind ISP database to block client requests based on the Autonomous System Number (AS Number) to which the client IP address belongs.

      Note	A license is required to use the MaxMind ISP database. For more information on obtaining this license, please contact your Cisco Account team.

    Which methods are used depends on the options that you configure for the Media Streamer deployment. Please refer to Understanding CDN Client Blocking Options for more information on these methods and how they work together.

  • The Traffic Router supports the following Client Routing methods to determine which cache group is the best to deliver the content:

    • Coverage Zone File (CZF): The CZF is a static JSON file that maps IP address ranges to cache groups. The Traffic Router checks the CZF for an IP address range that matches the requesting address to determine the best Cache Group to deliver the content.

    • Proximity routing: Proximity routing uses network proximity maps that leverage routing information databases to help determine the best Cache Group to deliver the content.

      Note	Currently Proximity routing requires the use of VDS-IS Proximity Engines (PxE) and is intended for Media Streamer customers that are migrating from VDS-IS.

    • Geolocation based routing: Geolocation based routing uses a geolocation database to determine the best Cache Group to deliver the content.

  After the Traffic Router determines the Cache Group to use, it will determine an Edge Cache in that group to use based on cache availability, cache load, and content affinity.

  Refer to Manage Client Routing for more details on each method and how these Client Routing methods interoperate.

• Management: OMD Director is the primary Media Streamer management interface. It is a centralized system management application that interacts directly with all of the key components of Media Streamer to enable remote monitoring, management, and diagnostics of the components of the Media Streamer solution from a single tool.

The following diagram shows a typical Cisco Media Streamer deployment.