STILL WIP

Architecture

Node classes

How the NIB is constructed is greatly dependent on what role the node takes in a network. Analysis of the corresponding RFCs resulted in the following made-up of node classes:

Depending on the node class certain features are compiled into the RIOT image of the node. This is marked with the corresponding color of the node class:

• Features of all IPv6 hosts are marked black
• features for IPv6 routers are marked maroon,
• features for all 6LoWPAN nodes (6LN) are marked green,
• features for 6LoWPAN routers (6LR) are marked purple, and
• features for 6LoWPAN border routers (6LBR) are marked teal.

Note, that any node can have any of these classes at any point. This is why additional dynamic checks on an interface if it really is e.g. a 6LoWPAN interface are needed.

Additional to their role in the network there are certain features that are beyond orthogonal to these roles:

• Components and behaviors required for the NDP address resolution state-machine (typically provided on non-6LoWPAN hosts and all routers) are marked olive,
• Nodes that start advertising themselves as routers on start-up are marked orange, and

The reasoning for not including the NDP address resolution state-machine on non-routing 6LN is that on these kinds of nodes non-link-local addresses are always considered off-link and the link-layer addresses of link-local addresses are derived from their IID. So none of this information needs to be stored.

Furthermore, there are features the user can decide to de-/activate:

• Asynchronous error reporting is marked red
• Queueing of packets for address resolution is marked lime
• Usage of a destination cache is marked navy
• Stateless Address Autoconfiguration according to RFC4862 is marked silver
• Handling of redirect messages (which requires a destination cache) is marked azure

Lastly, there are the components related to 6LoWPAN’s two substitutable features:

• Components related to multihop prefix and context distribution are marked blue, and
• Components related to multihop Duplicate Address Detetection are marked magenta

API

(RRQ = Reactive Routing Query, RRN = Reactive Routing Notification, NSC = NUD State Change Notification)

• NIB_FT::iter(nextHop) allows for generation of source route trees (default: NULL, for all entries)

Implementation

OnLinkEntry::addNC() treats the OnLinkEntry collection as a cache:

Use-cases

Initialize interface

Determine next hop link-layer address

(Search in OffLinkEntrys also on non-routers for prefix list)

Get link-layer address of route entry

Address resolution

Probe neighbor

Become a router advertising interface

Cease to be a router advertising interface

TODO

Upper-layer reachability confirmation

TODO

Receive packet event

Handle Neighbor Solicitation

(nbr_sol_t::isValid(), see RFC4861) (flags see RFC4861)

Handle Neighbor Advertisement

(nbr_adv_t::isValid(), see RFC4861)

Handle Router Solicitation

(rtr_sol_t::isValid(), see RFC4861)

Handle Router Advertisement

(rtr_adv_t::isValid(), see RFC4861) (remember changed router lifetime!) with persistent storage the ABRs should be stored afterwards

Handle Redirect

TODO

Handle advertised link-layer

Handle Duplicate Address Request

TODO

Handle Duplicate Address Confirmation

TODO

Handle Source Link-Layer Address Option

Handle Prefix Information Option

TODO: Add prefix to ABR

Handle Redirect Header Option

(TLLAO => if NCE created: set STALE) TODO

Handle MTU Option

TODO

Handle Address Registration Option

(nbr_sol_t::isValid(), see RFC6775) (x == ‘before the Lifetime expires’)

Register address upstream

Handle 6LoWPAN Context Option

TODO

Handle Authoritative Border Router Option

Model assumes that abro_t::ltime is already converted to ms (and default is set on 0)

Search router

Advertise router

Retransmit Neighbor Solicitation timer event

(State should be none of the above [UNMANAGED == 0] when OnLinkEntry not in NIB because of previous deletion) (Two different types to differentiate in timer, otherwise the same) (PROBE behavior according to RFC7048)

Delayed Neighbor Advertisement timer event

Search router timer event

Reconfirm router timer event

Reachability timeout timer event

Delay timeout timer event

Address registration timeout timer event

6LoWPAN Context timeout timer event

TODO

Authoritive Border Router timeout timer event

TODO

Prefix timeout timer event

TODO

Route timeout timer event

TODO

Router timeout timer event

TODO

Send unsolicited Router Advertisement timer event

sendRA() sets iface::lastMCRA to current time in milliseconds

Send solicited Router Advertisement timer event

(sendRA(): calculate updated lifetimes on send!)

Recalculate Reachable Time

TODO (see https://tools.ietf.org/html/rfc4861#section-6.3.4)

Wake-up from sleep

TODO

Add address to interface

TODO

Remove address from interface

TODO

Set neighbor cache entry externally

TODO

Delete neighbor cache entry externally

TODO

Set prefix externally

TODO

Delete prefix externally

TODO

Add forwarding table entry

TODO

Delete forwarding table entry

TODO

Set reactive routing callback

TODO

Set 6LoWPAN compression context

TODO

Remove 6LoWPAN compression context

TODO