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AMnet documentationContact: flexinet-support@ibr.cs.tu-bs.de |
AMnet is currently based on a topology, that is required in order to allow communication between the AMnet participants. This topology file is being parsed by the routing component of each AMnet participant and is used to forward the packets.
The topology is described in the file topologie.cfg in the directory amnet/user/signalling. Therefore, it is up to the user to create a topology and to describe it in the topology file. The topology file consists of two sections. The first one contains a list of HOST commands describing the host names and IP addresses of all AMnet participants. E.g.,
HOST bohemian fix foxi HOST 10.0.2.2 10.0.2.1informs the routing component that the five hosts bohemian, fix, foxi, 10.0.2.1 and 10.0.2.2 are AMnet participants.
The second section contains an entry for every participant with information about its neighbours. E.g., a star shaped topology is created using the following configuration:
ROUTER fix bohemian ROUTER foxi bohemian ROUTER 10.0.2.1 bohemian ROUTER 10.0.2.2 bohemian ROUTER bohemian fix foxi 10.0.2.1 10.0.2.2The first host name after the command ROUTER describes the AMnet participant, whose neighbours are given by the following host names.
The establishment of this topology does not imply specific roles for the AMnet participants (e.g. if the host is AMnode or receiver).
The directory amnet/user/signalling contains a file amnet.cfg which contains further configuration parameters for AMnet. A very important entry is the entry SMR which is used to specify the service module repository that is realized using a LDAP server in the current implementation. In order to allow an AMnet receiver to download and install modules, the host name of the installed LDAP server (6.1) has to be specified in this entry.
The signalling of the AMnet approach is based on so called session announcements and service announcements. While announcements for services derived from other services are generated automatically, a provider of a basic service has to create a session announcement and a service announcement. Examples for two services (simpsons and flintstones) already exist in the directory amnet/user/signalling. The files containing session announcements use the file extension .ssa, the service announcement files use the extension .sra. For specification of new services read the appropriate chapter.
In order to select the node best suited to privide a service, the AMnet receiver can specify a so called performance meter. Such a meter already exists in the directory amnet/user/signalling in the file receiversPM.class. This is the default meter used.
It is the purpose of the multicast address server to supply unique mutlicast addresses. It is contacted by the AMnodes whenever a multicast address for a session or a service is required. A multicast address server is started in the following way:
At startup the user has to differ between those AMnodes, that provide a basic service and those that do not provide a basic service. AMnodes that provide a basic servicecan be used as a parameter for the files for the session and service announcements. Currently only one basic service can be used with one AMnode. The start works as followed:
An AMnet receiver is started from the same directory, the AMnode is started from. It is important to remember, that the AMnet receiver is part of the topology and has to be included into the topology file. A receiver is started as followed: