Next Generation ESNet Arch Requirements - ATIS

7.2.2 Application Connection AcquiesceAcquiesce is the process of rotating CESE to RG connections on a periodic basis tosupport ESNet management and nominal processing goals. There are several reasons fordefining periodic connection rotation:♦ It is a good practice for communicating parties to exercise all of the routes.This is for early detection of problems, e.g., provider being down, etc.Regular exercising of the ability to break down and establish connectionsensures that these functions operate properly and that these functions arelikely to operate properly during recovery processing situations.♦ In order to connection balance a number of RGs, it is desirable for theconnections to be more or less evenly distributed. The periodic rotation ofCESE connections would provide a more even distribution over time. Thiswould add to the overall capacity and availability of ESNet.♦ The ESNet is believed to be a dynamic environment. A new RG may join thenetwork at any time. If connections are periodically rotated, the new RGbecomes part of the pool of available RGs and receives new connections asit becomes a player.♦ Long-lived TCP connections become “stale”. When they become “stale”, it isusually not noticed by either communicating party until an attempt to send amessage. In this situation, if it is the RG sending a message to the CESE,the communication attempt will fail and more elaborate logic will be required.If the CESE is sending a message the attempt will fail and the CESE willneed to establish a new connection and resubmit the message. RotatingCESE and RG connections avoids these scenarios.Conditions under which connection acquiescence are performed include:1. Periodic cycle as defined by administrative settings for the given ESNet CESE toRG connection.2. When a given RG is required to go out of service for any reason.Before leaving the network for any reason, the RG will send an Acquiesce applicationmessage to its CESE Clients as discussed in this section. This is done to trigger the CESEto perform connection acquiescence. It is assumed that the ESNet has correspondinglyadjusted the RG distribution model, via the connection negotiation mechanisms, and nofurther new CESE connections are being established to the given RG.The acquiescence includes a period of connection overlap between the CESE and twoRGs, during which a given CESE is completing active Emergency Events on the oldconnection and opening new Emergency Events on the new connection. This is to ensurethat the new route is functioning and to allow all outstanding Emergency Events initiated onthe first RG connection to complete. After the second connection is established, all newEmergency Events must be initiated on the new RG connection, thereby allowing the firstRG connection to become idle. All messages corresponding to a given Emergency Eventmust occur over the connection which established the Emergency Event.23 Version 1 9/23/04