NFD Strategy Choice Protocol¶

The Strategy Choice protocol allows an entity to set the forwarding strategy for a namespace.

The Strategy Choice protocol uses Command Interests-Data exchange.
The command request and response follows NFD Control Command specification.

Command format¶

Request¶

Request is a Signed Command Interest with the following name:

/localhost/nfd/strategy-choice/<command-verb>/<command-options>/............................

\                            / \                              / \                          /
 -------------  -------------   -------------  ---------------   ------------  ------------
              \/                             \/                              \/
    NFD Control Command to      StrategyChoiceManager command       Command Interest
    StrategyChoiceManager           and command options             related information

Command options is defined as a TLV-encoded StrategyChoiceOptions block.
Each individual command defines a subset of required and optional elements in the StrategyChoiceOptions block.
Note that Name field is required for StrategyChoiceOptions block.

StrategyChoiceOptions ::= STRATEGY-CHOICE-OPTIONS-TYPE TLV-LENGTH
                            Name
                            Strategy?

// Name defined in NDN-TLV spec

Strategy              ::= STRATEGY-TYPE TLV-LENGTH
                            Name

Response¶

Command response is a Data packet that contains TLV-encoded ControlResponse block, defined in NFD Control Command specification.

Content of ControlResponse on success:

Field in ControlResponse block	Value
StatusCode	200
StatusText	"Success"
<StatusBody>	StrategyChoiceOptions block, echoed

Content of ControlResponse on error:

Field in ControlResponse block	Value
StatusCode	4xx, 5xx, or other error codes based on RFC2616
StatusText	Human-readable description of the error
<StatusBody>	Not present

Operations¶

Strategy Choice protocol supports five operations:

• insert: set the strategy for a namespace
• delete: unset the strategy for a namespace

Set the strategy for a namespace¶

command-verb: insert

Required fields in StrategyChoiceOptions block:

• Name
• Strategy

Strategy must be a Name that represents a builtin strategy:

• ndn:/localhost/nfd/strategy/best-route
• ndn:/localhost/nfd/strategy/broadcast
• ndn:/localhost/nfd/strategy/ncc

If the Strategy does not match any builtin strategy, the response has StatusCode 504.

Unset the strategy for a namespace¶

command-verb: delete

Required fields in StrategyChoiceOptions block:

• Name

After this operation, the effective strategy at Name is inherited from the parent.

If there is no strategy defined at Name, this command does nothing, but is still considered successful.

Name must not be ndn:/, otherwise the operation fails with StatusCode 403.

TLV-TYPE assignments¶

Type	Assigned value	Assigned value (hex)
StrategyChoiceOptions	109	0x6d
Strategy	107	0x6b