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Junxiao Shi, 07/09/2014 05:42 AM

RIB Management

RIB Management is a module of NFD Management protocol.
It provides:

  • commands to register and unregister routes
  • commands to advertise and withdraw prefix with a routing protocol
  • a dataset of routes

RIB Management commands are published in namespace ndn:/localhost/nfd/rib.

Route

A route, or a routing entry, indicates that contents under a certain name prefix may be available via a certain face.

A route contains:

  • Name prefix
  • nexthop FaceId
  • origin
  • cost
  • route inheritance flags

Route origin

Origin indicates who is announcing a route.

  • app(=0): indicates a Route toward a local producer application
  • static(=255): indicates a static route
  • nlsr(=128): indicates a route installed by NLSR routing protocol
  • client(=65): indicates a Route toward a client node attached to this router, installed via remote registration
  • autoreg(=64): indicates a Route toward a client node attached to this router, registered automatically by this router
  • autoconf(=66): indicates a Route toward a HUB from the laptop, registered automatically by the ndn-autoconf tool

Route cost

Cost indicates the preference among multiple routes with same Name prefix.
The nexthop face on a route with lower cost is preferred.

Unlike IP routing, the nexthop face to use is decided by forwarding strategy.
Route cost is a suggestion to strategy; strategy MAY consider route cost when making forwarding decisions.

Route inheritance

Each route can have two route inheritance flags:

  • CHILD_INHERIT: indicates that this route may be used even if a longer prefix is matched. This flag applies on a single route.
  • CAPTURE: indicates that no shorter prefix can be used; overrides CHILD_INHERIT. This flag applies on the prefix: if any route of a prefix has this flag, the prefix will have this flag.

Example:

Name prefix nexthop FaceId CHILD_INHERIT CAPTURE
/ 1 yes no
/ 2 no no
/A 3 yes no
/A/B/C 4 yes no
/D 5 yes yes
/D 6 yes no
  • Interest /A/P can go to face 1 and 3.
    • It cannot go to face 2, because that route has CHILD_INHERIT=no.
  • Interest /A/B/C/Q can go to face 1, 3, and 4.
  • Interest /D/R can go to face 5 and 6.
    • It cannot go to face 1, because one of the routes on /D sets CAPTURE=yes.
  • Interest /S can go to face 1 and 2.

Effective routing cost

The routing cost of a nexthop face for a Name prefix is the lowest cost among all Routes toward this nexthop face that can apply to this Name prefix.

Example:

Name prefix nexthop FaceId Origin Cost CHILD_INHERIT CAPTURE
/A 1 static 10 no no
/A 1 nlsr 20 yes no
/A 2 static 30 no no
/A/B 1 static 40 yes no
/A/B 2 static 50 yes no
/A/B/C 3 static 60 yes no
/A/B/C/D 4 static 70 yes yes

The corresponding FIB should be:

Name prefix NextHop records
/A (face=1,cost=10) (face=2,cost=30)
/A/B (face=1,cost=20) (face=2,cost=50)
/A/B/C (face=1,cost=20) (face=2,cost=50) (face=3,cost=60)
/A/B/C/D (face=4,cost=70)

Control Commands

ControlCommand management-module: rib

Register a route

command-verb: register

This command adds a route to the RIB.

ControlParameters fields:

  • Name (required)
  • FaceId (optional)
  • Origin (optional)
  • Cost (optional)
  • Flags (optional)
  • ExpirationPeriod (optional)

FaceId is the FaceId returned in Face Management.
If FaceId is omitted or is set to zero, it is implied as the requesting face (self registration).

If face does not exist, the command fails with code 410.

Origin defaults to app(=0).

Cost defaults to zero.

Flags is an inclusive OR of route inheritance flags.
CHILD_INHERIT=1, CAPTURE=2.
It defaults to CHILD_INHERIT.

ExpirationPeriod gives the duration (in milliseconds) in which this route is effective.
After ExpirationPeriod has elapsed, or when the face fails, the route is removed.
ExpirationPeriod defaults to (practically) Infinity when FaceId is omitted or is set to zero; otherwise, it defaults to 1 hour.

If a route of same Name, FaceId, and Origin exists, its Cost and Flags are updated, and its lifetime is extended to now + ExpirationPeriod.

If the command succeeds, <body> in ControlResponse block contains updated ControlParameters:

  • Name: Name prefix
  • FaceId: nexthop FaceId (not zero)
  • Route: route origin
  • Cost: route cost
  • Flags: inclusive OR of route inheritance flags
  • ExpirationPeriod: remaining lifetime (in milliseconds)

Unregister a route

command-verb: unregister

This command removes a route from the RIB.

ControlParameters fields:

  • Name (required)
  • FaceId (optional)
  • Origin (optional)

FaceId is the FaceId returned in Face Management.
If FaceId is omitted or is set to zero, it is implied as the requesting face (self deregistration).

Origin defaults to app(=0).

Self deregistration is unnecessary if client is quitting. NFD automatically removes routes belonging to a failed face.
Client needs self deregistration when it stops serving a name prefix, but intends to continue execution.

If route does not exist, this command does nothing, but is still considered successful.

If the command succeeds, <body> in ControlResponse block contains updated ControlParameters:

  • Name: unchanged
  • FaceId: nexthop FaceId (not zero)
  • Origin: unchanged if request specifies; app(=0) if request omits

Advertise a prefix

command-verb: advertise

This command is not defined in this revision.

Withdraw a prefix

command-verb: withdraw

This command is not defined in this revision.

RIB Dataset

Routes are published as a Status Dataset at ndn:/localhost/nfd/rib/list.

Multiple routes of same Name prefix are organized into a RIB entry.
Each RIB entry is represented by a RibEntry block:

RibEntry := RIB-ENTRY-TYPE TLV-LENGTH
              Name
              Route+

Route    := ROUTE-TYPE TLV-LENGTH
              FaceId
              Origin
              Cost
              Flags
              ExpirationPeriod

Flags is inclusive OR of route inheritance flags, encoded in the same way as register command.

ExpirationPeriod is the remaining lifetime of a route.

TLV-TYPE assignments

Type Assigned value Assigned value (hex)
RibEntry 128 0x80
Route 129 0x81

Updated by Junxiao Shi over 10 years ago · 31 revisions