VBrick dme, Admin Manual

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System Configuration
DME Admin Guide 87
Mesh with Rev Caching Configuration
Manage Configuration
St a n d a lo n e DM E o r Le g a c y ( DM E w it h VEM S) Ca c h in g
Co n f ig u ra t io n
Creating a caching solution within a Legacy (VEMS) or Standalone DME deployment is
discussed in this topic.
Although, a major focus of the feature is to allow access to HLS or HDS content created in
another DME, the mechanism is generally the same for all HTTP accessed content. This is
accomplished by creating a configuration of parents and alternate sources (i.e. siblings) on
each DME. Then a client is directed to a DME located in the same zone by providing the
URL of the local DME. It is not uncommon to have different sources for different types of
HTTP content. Given that the most common and efficient way to configure the caching
network is to configure parent relationships, the configuration allows different parent
configuration for each major type of HTTP content.
The goal of configuring the caches on each DME in a network is to allow a client in any
subnet (i.e. a "zone" in the VEMS context) to access content hosted by an HTTP server
elsewhere in the network. Although, a major focus of the feature is to allow access to HLS or
HDS content created in another DME, the mechanism is generally the same for all HTTP
accessed content. This is accomplished by creating a configuration of parents and alternate
sources (i.e. siblings) on each DME. Then a client is directed to a DME located in the same
zone by providing the URL of the local DME. It is not uncommon to have different sources
for different types of HTTP content. Given that the most common and efficient way to
configure the caching network is to configure parent relationships, the configuration allows
different parent configuration for each major type of HTTP content.
As shown on the
System Configuration
>
Caching
page, each DME configuration consists of
parents for each of a number of types of HTTP content, one
Default Parent
, and multiple
Alternate Sources
. Each of these IP addresses must be unique.
When the DME receives a request for HTTP content it will first determine if the content is
cached locally. It will then try to find the content by completing the following steps:
1. Determines if the content is produced locally.
2. Checks with the
Alternate Sources
that have been defined.
3. Attempts to obtain the content from a
Content Specific Parent
.
Content Specific Parents
are checked before the
Default Parent
. Each parent may follow the
same process trying to locate the content. Once the content is found, it is delivered to the
requesting client through the discovery path. Each DME in the path will also cache the
content to allow provide more efficient delivery to other requestors.
For many simple caching matrices, configuring the
Default Parent
is all that is required.
Note that HLS/HDS/Smooth Streaming/DASH playlists are never cached since in the case
of a live events, the playlists are constantly updated.
The image below shows a sample network diagram of multiple DMEs with one DME in each
zone. In general, the goal is (1) to allow any DME to be a source of appropriate HTTP
content, and (2) to allow clients in any subnet to access appropriate HTTP created in any
other DME.