mmdiscover(8)

NAME

mmdiscover - Mobile Mesh Link Discovery

SYNOPSIS

mmdiscover [-d file] [-f file] [-h] -i ifname [-vz]

DESCRIPTION

mmdiscover speaks the Mobile Mesh Link Discovery Protocol

on an individual IP interface and reports neighbor interface ad

dresses and associated costs for any discovered links. Links that

go down are also detected and reported.

Client programs may receive link reports by connecting to

a well-known Unix socket created by mmdiscover whose name is

based upon the name of the IP interface prepended with "ln-". For

example, if mmdiscover is bound to interface "eth0", the well

known Unix socket name will be "ln-eth0".

mmdiscover does not have prior knowledge of potential

clients. Clients simply send a message asking for the current

list of links. This allows mmdiscover to dynamically learn who

its clients are. Then, when a link goes up or down, it sends the

event to all clients who have previously requested a list of

links. A failure when sending an event to a client implies that

the client has stopped listening and thus mmdiscover removes the

client from its dynamically managed set of clients.

mmdiscover is responsible for determining when links go up

and down. Periodically, it broadcasts a Hello message on a Udp

socket bound to the IP interface. mmdiscover can be configured

to report either uni-directional or only bi-directional links.

The Hello message includes a list of the interface addresses of

the senders of Hello messages that have been heard by the inter

face in the last DeadInterval .

If mmdiscover reports uni-directional links, then whenever

it receives a Hello from another node's interface that it does

not have a link from, it reports the new link. If mmdiscover only

reports bi-directional links, then it checks a neighbor list

within the received Hello message for the address of the inter

face that heard the Hello. Note, if mmdiscover is configured to

report bi-directional links, then it must report that a link went

down if it changes from bi-directional to uni-directional; simi

larly, it reports that a link came up if it changes from uni-di

rectional to bi-directional. If a Hello message for a link which

is declared to be up is not received within a DeadInterval ,

mmdiscover reports that the link is down.

OPTIONS

mmdiscover recognizes the following command line switches:

-d file

Use flags 'file' to enable debug output.

-f file

Use config 'file' instead of

/etc/mobilemesh/mmdiscover.conf. See below for a description of

the config file format.

-h Display a help message.

-i ifname

The name of the IP interface whose neighbors will

be discovered.

-v Display version information.

-z Run in the foreground instead of running as a dae

mon.

Config File Format

By default, mmdiscover reads the file

/etc/mobilemesh/mmdiscover.conf for configuration parameters. The

format of the config file requires each configuration parameter

to be on its own line. Comments may be placed in the file by be

ginning a line with a #. The following configuration parameters

are recognized:

metric <unsigned int value>

The cost associated with the interface.

allowUni <bool>

Set to 1 to allow uni-directional links to be re

ported. Set to 0 to only allow bi-directional links to be report

ed.

port <Udp Port Number>

The well known UDP port number that all similar

nodes are using for link discovery.

helloPeriod <unsigned int value>

The number of seconds between sending "Hello" mes

sages.

deadInterval <unsigned int value>

The number of seconds after hearing the last "Hel

lo" message from a neighbor to declare the link from the neighbor

down.

SEE ALSO

mmrp(8), mmborder(8), mmrpviz(8)

AUTHOR

This program and documentation was written by Kevin H.

Grace of The MITRE Corporation <kgrace@mitre.org>. Credit is also

given to Mike Butler who developed some of the support classes

and lent his keen insight.

July 19, 2000

MMDISCOVER(8)