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Single domain connections

Before we discuss policies that extend beyond domain boundaries, it is useful to consider a very simple, end-to-end connection setup in a single Sandman domain, for example a connection from endpoint 2 to endpoint 3 in Sandman-2. Simplifying things considerably, the following steps are taken to establish such a connection:

1.
a client (either endpoint 2 or 3, or a third party) sends a request to the Sandman MCA to set up a connection between endpoints 2 and 3 (if so desired, it can additionally specify a vci with which it would like to start in one of the endpoints);
2.
the MCA checks whether the call can be admitted (i.e. whether there are enough resources available);
3.
if this succeeds, the MCA tells the switches to set up the appropriate switch connections;
4.
when the connection is set up, the Sandman initiates callback operations in both the source and the sink endpoints.
5.
when, after some time, the connection is torn down, the Sandman again initiates callback operations (albeit different ones) in both endpoints to notify them that the connections is torn down.

If any of these operations fails, the connection setup is aborted and all actions already taken on its behalf are rolled back. The callback operations take as arguments the vpi and vci of the connection and serve (among other things) as notifications to the client that the connection is in place. Prior to sending the request both endpoints register the relevant callback operations with a local MCA proxynegligence simply means that the connection is set up or torn down but no callback is made. Now we will show how we can make this model work when one of the endpoints is in another domain.


next up previous
Next: Simple interoperability between domains Up: MCA interoperability Previous: MCA interoperability
Herbert Bos
2001-12-11