Appendix B. Peer-Level Message Flows
B.1. Session Initialization
Router Modem Message Description
========================================================================
| Router connects to discovered or
| preconfigured Modem Connection
|--TCP connection established---> Point.
|
| Router sends Session
|----Session Initialization----->| Initialization Message.
|
| Modem receives Session
| Initialization Message.
|
| Modem sends Session Initialization
|<--Session Initialization Resp.-| Response with 'Success' Status
| | Data Item.
| |
|<<============================>>| Session established.
: : Heartbeats begin.
B.2. Session Initialization - Refused
Router Modem Message Description
========================================================================
| Router connects to discovered or
| preconfigured Modem Connection
|--TCP connection established---> Point.
|
| Router sends Session
|-----Session Initialization---->| Initialization Message.
|
| Modem receives Session
| Initialization Message and
| will not support the advertised
| extensions.
|
| Modem sends Session Initialization
| Response with 'Request Denied'
|<-Session Initialization Resp.--| Status Data Item.
|
|
| Router receives negative Session
| Initialization Response, closes
||---------TCP close------------|| TCP connection.
B.3. Router Changes IP Addresses
Router Modem Message Description
========================================================================
| Router sends Session Update
|-------Session Update---------->| Message to announce change of
| IP address.
|
| Modem receives Session Update
| Message and updates internal
| state.
|
|<----Session Update Response----| Modem sends Session Update
| Response.
B.4. Modem Changes Session-Wide Metrics
Router Modem Message Description
========================================================================
| Modem sends Session Update Message
| to announce change of session-wide
|<--------Session Update---------| metrics.
|
| Router receives Session Update
| Message and updates internal
| state.
|
|----Session Update Response---->| Router sends Session Update
| Response.
B.5. Router Terminates Session
Router Modem Message Description
========================================================================
| Router sends Session Termination
|------Session Termination------>| Message with Status Data Item.
| |
|-------TCP shutdown (send)---> | Router stops sending Messages.
|
| Modem receives Session
| Termination, stops counting
| received heartbeats, and stops
| sending heartbeats.
|
| Modem sends Session Termination
|<---Session Termination Resp.---| Response with Status 'Success'.
|
| Modem stops sending Messages.
|
||---------TCP close------------|| Session terminated.
B.6. Modem Terminates Session
Router Modem Message Description
========================================================================
| Modem sends Session Termination
|<----Session Termination--------| Message with Status Data Item.
|
| Modem stops sending Messages.
|
| Router receives Session
| Termination, stops counting
| received heartbeats, and stops
| sending heartbeats.
|
| Router sends Session Termination
|---Session Termination Resp.--->| Response with Status 'Success'.
|
| Router stops sending Messages.
|
||---------TCP close------------|| Session terminated.
B.7. Session Heartbeats
Router Modem Message Description
========================================================================
|----------Heartbeat------------>| Router sends Heartbeat Message.
|
| Modem resets heartbeats missed
| counter.
~ ~ ~ ~ ~ ~ ~
|---------[Any Message]--------->| When the Modem receives any
| Message from the Router.
|
| Modem resets heartbeats missed
| counter.
~ ~ ~ ~ ~ ~ ~
|<---------Heartbeat-------------| Modem sends Heartbeat Message.
|
| Router resets heartbeats missed
| counter.
~ ~ ~ ~ ~ ~ ~
|<--------[Any Message]----------| When the Router receives any
| Message from the Modem.
|
| Modem resets heartbeats missed
| counter.
B.8. Router Detects a Heartbeat Timeout
Router Modem Message Description
========================================================================
X<----------------------| Router misses a heartbeat.
| X<----------------------| Router misses too many
| heartbeats.
|
|
|------Session Termination------>| Router sends Session Termination
| Message with 'Timeout' Status
| Data Item.
:
: Termination proceeds...
B.9. Modem Detects a Heartbeat Timeout
Router Modem Message Description
========================================================================
|---------------------->X Modem misses a heartbeat.
|---------------------->X | Modem misses too many
| heartbeats.
|
|
|<-----Session Termination-------| Modem sends Session Termination
| Message with 'Timeout' Status
| Data Item.
:
: Termination proceeds...