A new tag system designing

[mkraposhin]

The current OpenSDN tags system has several flaws:

• number of tag values is limited by 32k;
• tag values and types are separated into 4 ranges which make their usage inconvenient;
• tag values and types IDs cannot be updated after creation of a tag;
• absence of consistent and non-contradictory documentation, including definitions & usage rules.

The objective of this WP is to redesign the OpenSDN tags system to make it more flexible and to simplify its usage in large installations.

The WP includes:

• A commit to introduce a tag's ID update: https://gerrit.opensdn.io/c/opensdn-io/tf-controller/+/2255;
• A commit with the new OpenSDN tags system specification https://gerrit.opensdn.io/c/opensdn-io/tf-specs/+/2417.

The new tags system makes obsolete next specifications: User_Def_Tags_21092.md

[mkraposhin]

Major features of the new tags system:

• the tag value ID field length is extended from 16 to 32 bits substancially increasing the number of tags allowed per a type;
• the distinction between user-defined and internal tag value IDs is removed which simplifies the usage of tags and also increases number of allowed tags per the same type;
• tags IDs (both the value and the type subfields) can be updated after the creation of a tag;
• a consistent and non-contradictory specification will be prepared.

[mkraposhin]

Tags modification after creation and tag ID ranges redifinitions:

• https://gerrit.opensdn.io/c/opensdn-io/tf-controller/+/2255
• https://gerrit.opensdn.io/c/opensdn-io/tf-controller/+/2425