NFD

# NFD FIB Management Protocol

The **FIB management protocol** allows an entity to manipulate the FIB entry.

The FIB management protocol uses [[Command Interests]]-Data exchange.

The command request and response follows the [[ControlCommand|NFD Control Command specification]]

## Command format

### Request

Request is a [[Command Interests|Signed Command Interest]] with the following name:

    /localhost/nfd/fib/<command-verb>/<command-options>/............................

    \                / \                              / \                          /

     -------  -------   -------------  ---------------   ------------  ------------

            \/                       \/                              \/

    NFD Control Command       FibManager command              Command Interest

    to FibManager             and command options            related information

Command options is defined as a TLV-encoded `FibManagementOptions` block.

Each individual command defines a subset of required and optional elements in the `FibManagementOptions` block.

Note that `Name` field is required for `FibManagementOptions` block.

    FibManagementOptions ::= FIB-MANAGEMENT-OPTIONS-TYPE TLV-LENGTH

                               Name

                               FaceId?

                               Cost?

                               Strategy?

    // Name defined in NDN-TLV spec

    FaceId               ::= FACEID-TYPE TLV-LENGTH

                               nonNegativeInteger

    Cost                 ::= COST-TYPE TLV-LENGTH

                               nonNegativeInteger

    Strategy             ::= STRATEGY-TYPE TLV-LENGTH

                               Name

### Response

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

Content of `ControlResponse` on success:

Field in `ControlResponse` block | Value

-------------------------------- | -----

`StatusCode`                     | 200

`StatusText`                     | "Success"

`<StatusBody>`                   | `FibManagementOptions` block, either echoed or with updated `FaceId` field

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

**FIB management protocol** supports five operations:

* **insert**: insert a FIB entry

* **delete**: delete a FIB entry

* **add-nexthop**: add a nexthop to a FIB entry

* **remove-nexthop**: remove a nexthop from a FIB entry

* **set-strategy**: set the forwarding strategy for a namespace

## Insert a FIB entry

**command-verb:** `insert`

Required fields in `FibManagementOptions` block:

* `Name`

If a FIB entry for Name already exists, this command does nothing, but is still considered successful.

## Delete a FIB entry

**command-verb:** `delete`

Required fields in `FibManagementOptions` block:

* `Name`

If a FIB entry for Name does not exist, this command does nothing, but is still considered successful.

## Add a nexthop

**command-verb:** `add-nexthop`

This command adds a nexthop to an existing FIB entry.

Required fields in `FibManagementOptions` block:

* `Name`

* `FaceId`

* `Cost`

**FaceId** is the FaceId returned in [[FaceMgmt|NFD Face Management protocol]].

If **FaceId** is set to zero, it is implied as the face of the entity sending this command.

If the FIB entry does not exist, the response has StatusCode 404.

If a nexthop of same `FaceId` exists on the FIB entry, its cost is updated.

## Remove a nexthop

**command-verb**: `remove-nexthop`

This command removes a nexthop from a FIB entry.

Removing the last nexthop in a FIB entry will not automatically delete the FIB entry.

Required fields in `FibManagementOptions` block:

* `Name`

* `FaceId`

**FaceId** is the FaceId returned in [[FaceMgmt|NFD Face Management protocol]].

If **FaceId** is set to zero, it is implied as the face of the entity sending this command.

If the FIB entry does not exist, the response has StatusCode 404.

If the specified nexthop does not exist on the FIB entry, this command does nothing,

but is still considered successful.

## Set strategy

**command-verb**: `set-strategy`

This command sets the forwarding strategy for a namespace.

Required fields in `FibManagementOptions` 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 FIB entry does not exist, the response has StatusCode 404.

If the Strategy does not exist, the response has StatusCode 405.

## TLV-TYPE assignments

Type                                        | Assigned value    | Assigned value (hex)

------------------------------------------- | ----------------- | --------------------

FibManagementOptions                        | 104               | 0x68

FaceId                                      | 105               | 0x69

Cost                                        | 106               | 0x6a

Strategy                                    | 107               | 0x6b