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TWO4ONE

TWO4ONE ( Changing or multiplying sessions )

SPECIFICATION
TWO4ONE is used to simulate multicasting to a small number of hosts, or to open and use a different session for outgoing messages.

SYNOPSIS
TWO4ONE can be configured to multicast to a group or to use a second session for replying to broadcasts. The default mode is the latter; a ROM option can select the former behavior.

The second session creation for broadcasts is useful for protocols that receive IPv4 broadcasts and need to use a separate path through the protocol graph for replies. For example, if broadcasts are signed with a public key, but replies are encrypted with symmetric keys.

REALM
In multicast mode ASYNC or SYNC (note that reply messages are discarded in SYNC mode, as there is no standard way to identify and aggregate the multiple replies).

In broadcast mode, TWO4ONE is a virtual protocol inheriting its type from that of its upper and lower protocols.

This is a virtual protocol that is active during open, openenable, push or call in multicast mode. The demux operation should bypass this protocol.

PARTICIPANTS
On an xOpen, TWO4ONE in its multicast mode passes the remote participant to the key manager to get a list of multicast participants.

On an xOpenDone, TWO4ONE in broadcast (or ``switch'') mode opens a second session for replies. This session has different participants than the incoming broadcast session. The recognition of broadcast addresses is limited to IPv4-type addresses.

CONFIGURATION
In multicast mode, the first lower protocol should be an ASYNC or SYNC transport protocol and the second protocol should be a key manager.

The key manager must be configured to map an address to a list of addresses. This list is of limited length (see the source code for TWO4ONE). The key manager's input file's first line should indicate the length of the address (in bytes), the maximum length of the ``external'' form of the group list (see partExternalize), and the size of the map table (usually 16). A group management protocol will usually sit above the key manager.

ROM OPTIONS


two4one	numparts 2

The overip rom option is available to indicate that IP addresses are being used for the determination of the security service. This allows broadcast sessions to be a separate security class. This option is not yet coordinated with the numparts option. The default number of participants elements is 1.


two4one	overip

The multiply rom option causes TWO4ONE to expect a key manager and to push all messages to several lower sessions, as indicated by the participants obtained from the key manager.


two4one	multiply

AUTHOR
Hilarie Orman



Next: UDP Up: Protocol Specifications Previous: TEST


Tue Nov 29 16:28:56 MST 1994