[net2-wg] beginnings of the link estimation protocol TEP

[Rodrigo Fonseca]

Hi Om,

a couple of things:
 - add a simple definition of EETX, and how it is encoded (are we
multiplying by 10 in the spec?
 - should add a section on how the EETX is computed? part of it is
implementation dependent.
 - we should place as an assumption that we can determine the frame size.

Rodrigo




On 2/1/07, Omprakash Gnawali <gnawali at usc.edu> wrote:
>
> A compilation of different aspects of the link estimation protocol
> that needs to be specified.
>
> Thanks.
>
> - om_p
>
> ----------
>
> SLEEP: Simple Link Estimation Extension Protocol
>
> Assumptions
>
> - the data link frame has a single-hop source field.
> - the data link layer provides broadcast address.
>
> SLEEP is used to compute bi-directional link quality to the
> neighbors. It computes bi-directional link quality in two steps:
> in-bound link quality estimation and link quality exchange.
>
> In-bound Link Quality Estimation
>
> Each SLEEP frame has a sequence number. SLEEP frames are transmitted
> to the broadcast address. Nodes in the vicinity receive the frame and
> compute the in-bound link quality from the node identified by the link
> source address by using the sequence number in the SLEEP frame. The
> set of sequence numbers received from a particular node over time is
> used to compute the link quality.
>
> Link Quality Exchange
>
> To compute bi-directional link quality, in-bound link quality must be
> exchanged among the neighbors. SLEEP appends a footer consisting of
> the tuple (neighborid, inbound link quality) to the frame. When a node
> receives the SLEEP frame and finds its id in one of the tuples, the
> node can use the second element of that tuple as its outbound link
> quality to the neighbor identified by the data link source address. If
> the neighbor table has more entries than what will fit in a single
> SLEEP frame, a node should use round robin to broadcast inbound link
> quality for all the entries in the neighbor table.
>
> Link Metric
>
> Extra ETX (EETX) is used as the link metric.
>
>
> SLEEP Frame:
>
> A SLEEP frame has link estimation header, the payload, and a footer
> with the neighbor entries as shown in this diagram:
>
>    -----------------------------------------------------
>   | Link Estimation | Payload | Entry | Entry | Entry | ...
>   |     Header      |         |   1   |   2   |   3   |
>    -----------------------------------------------------
>
>
> Header format:
>                            1
>        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>       |nentry | rsrvd |      seqno      |
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>
> Field definitions:
>
> nentry - number of neighbor entries in the footer
> seqno - link estimation sequence number.
> rsrvd - reserved
>
> Entry format:
>                            1
>        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>       |             neighbor            |
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>       |     metric    |
>       +-+-+-+-+-+-+-+-+
>
> Field definitions:
>
> neighbor: the address of the neighbor
> metric: inbound link quality from the neighbor
>
> The byte offset of the first entry can be computed as:
> frame size - nentry * 3
>
>
> - om_p
> _______________________________________________
> net2-wg mailing list
> net2-wg at millennium.berkeley.edu
> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/net2-wg
>