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Appendix C. Destination-Specific Message Flows

C.1. Common Destination Notification​

Router                       Modem    Message Description
========================================================================

                                 |    Modem detects a new logical
                                 |    destination is reachable and
|<-------Destination Up----------|    sends Destination Up Message.
|
|------Destination Up Resp.----->|    Router sends Destination Up
                                 |    Response.

           ~ ~ ~ ~ ~ ~ ~
                                 |    Modem detects change in logical
                                 |    destination metrics and sends
|<-------Destination Update------|    Destination Update Message.

           ~ ~ ~ ~ ~ ~ ~
                                 |    Modem detects change in logical
                                 |    destination metrics and sends
|<-------Destination Update------|    Destination Update Message.

            ~ ~ ~ ~ ~ ~ ~
                                 |    Modem detects logical destination
                                 |    is no longer reachable and sends
|<-------Destination Down--------|    Destination Down Message.
|
|                                     Router receives Destination Down,
|                                     updates internal state, and sends
|------Destination Down Resp.--->|    Destination Down Response Message.

C.2. Multicast Destination Notification​

Router                       Modem    Message Description
========================================================================

|                                     Router detects a new multicast
|                                     destination is in use and sends
|-----Destination Announce------>|    Destination Announce Message.
                                 |
                                 |    Modem updates internal state to
                                 |    monitor multicast destination and
|<-----Dest. Announce Resp.------|    sends Destination Announce
                                      Response.

           ~ ~ ~ ~ ~ ~ ~
                                 |    Modem detects change in multicast
                                 |    destination metrics and sends
|<-------Destination Update------|    Destination Update Message.

           ~ ~ ~ ~ ~ ~ ~
                                 |    Modem detects change in multicast
                                 |    destination metrics and sends
|<-------Destination Update------|    Destination Update Message.

            ~ ~ ~ ~ ~ ~ ~
|                                     Router detects multicast
|                                     destination is no longer in use
|--------Destination Down------->|    and sends Destination Down
                                 |    Message.
                                 |
                                 |    Modem receives Destination Down,
                                 |    updates internal state, and sends
|<-----Destination Down Resp.----|    Destination Down Response Message.
Router                       Modem    Message Description
========================================================================

                                      Destination has already been
           ~ ~ ~ ~ ~ ~ ~              announced by either peer.

|                                     Router requires different
|                                     characteristics for the
|                                     destination and sends Link
|--Link Characteristics Request->|    Characteristics Request Message.
                                 |
                                 |    Modem attempts to adjust link
                                 |    properties to meet the received
                                 |    request and sends a Link
                                 |    Characteristics Response
|<---Link Characteristics Resp.--|    Message with the new values.