Multicast, Broadcast, Point-to-Point and Direct

Rendezvous can transport messages among application programs using several mechanisms. The performance assessment tool can model the performance of an application sending messages in any of these ways:

Transport

Modeling

Notes

Multicast

Specify multicast addressing in the -network parameter.

Omit the -inbox parameter.

  

Broadcast

Do not specify multicast addressing in the -network parameter.

Omit the -inbox parameter.

TRDP only

Point-to-Point

Include the -inbox parameter.

  

Direct Point-to-Point

Specify a two part -service parameter to enable direct communication (bypassing rvd).

Include the -inbox parameter.

  
Performance Characteristics

The various transport mechanisms can display dramatically different performance profiles, which group into two broad classes.

Transport

Description and Performance Characteristics

Multicast;

Broadcast

Multicast and broadcast messages use an unmetered protocol with negative acknowledgment. A sender transmits packets as fast as possible. Receivers are responsible for requesting retransmission of missed packets.

Many applications can gain efficiency by dividing very large multicast or broadcast messages into smaller pieces, sending them in batches, and pausing between batches to avoid overloading slow receivers (that is, receivers running on relatively slow computers).

Point-to-Point;

Direct Point-to-Point

Point-to-point messages use a metered protocol with positive acknowledgment. A sender requires positive acknowledgment from the receiver before it transmits additional point-to-point packets.

As a result, point-to-point packets (from a single sender) rarely arrive faster than a receiver can process them. Applications generally do not gain efficiency by dividing very large point-to-point messages into smaller pieces (since the protocol itself already meters delivery).