The IP over ATM Mailing List Archive by date

 1.1 Initilization

      Read config file.
      Allocate message queues.
      Allocate internal tables.
      Set up passive open VC connection.
      Set up redirect_map timer.
      Establish logging.

 1.2 Message Processing

      Forever {
        If the message has a TLV then {
          If TLV is unsupported then {
            process as defined in TLV type field.
          } /* unknown TLV */
        } /* TLV present */
        Place incoming message in the queue.
        For (all messages in the queue) {
          If (ar$pro.type is not supported) or
             (the ATM source address is missing) then {
             Continue.
          }
          Determine type of message.
          If an ERR_L_RELEASE arrives on ClusterControlVC then {
            Remove the endpoints ATM address from all groups for which
            it has joined.
            Release the CMI.
            Continue.
          } /* error on CCVC */
          Call specific message handling routine.
          If redirect_map timer pops {
            Call MARS_REDIRECT_MAP message handling routine.
          } /* redirect timer pop */
        } /* all msgs in the queue */
      } /* forever loop */

2. Message Handler

 2.1 Messages:

    - MARS_REQUEST

      Indicate no MARS_MULTI support of TLV.
      If the supported TLV is not NULL then {
        Indicate MARS_MULTI support of TLV.
        Process as required.
      } else { /* TLV NULL */
         If a server map does not exist then { /* no server map */
           If (a host map does not exist) or
           (the source is not a registered member) then {
             Indicate no message to be sent.
             Drop the message.
           } else { /* only a host map */
              If the group does not exist then {
                Call MARS_NAK message routine.
                Indicate message to be sent on Private VC.
              } else { /* group exists */
                 Call MARS_MULTI message routine with host map.
                 Indicate message to be sent on ClusterControlVC
                } /* group exists */
             } /* only a host map */
         } else { /* server map exists */
            If a host map does not exist then {
              Indicate no message to be sent.
              Drop the message.
            } else { /* host map exists */
               If the group does not exist then {
                 Call MARS_NAK message routine.
                 Indicate message to be sent on Private VC.
               } else { /* group exists */
                  If the source is a member of the server map then {
                    Call MARS_MULTI with host map.
                    Indicate message to be sent on ServerControlVC
                  } else { /* src is a member of host map */
                     Call MARS_MULTI with server map.
                     Indicate message to be sent on ClusterControlVC
                    } /* src is a member of host map */
                 } /* group exists */
              } /* host map exists */
           } /* server map exists */
         } /* TLV NULL */
     If a message exists then {
       Send message as indicated.
     }
     Return.

    - MARS_MULTI

      Construct a MARS_MULTI for the specified map.
      If the param indicates TLV support then {
        Process the TLV as required.
      }
      Return.

    - MARS_JOIN

      If ar$flags.copy != 0 silently ignore the message.
      Ignore ar$flags.layer3grp.
      If more than a single <min,max> pair is specified then
      ignore the 2nd and subsequent pairs.
      Indicate message to be sent on private VC.
      If ar$flags.register == 1 then {
        If the node is already a registered member of the cluster
        associated with the protocol type then { /* previous register */
          Copy the existing CMI into the MARS_JOIN.
        } else { /* new register */
           Add the node to ClusterControlVC.
           ar$cmi = obtain CMI.
          } /* new register */
      } else { /* not a register */
         If the node is not registered then {
           Ignore the message.
         }
         If a server map exists for the group then {
           Call the Modified JOIN/LEAVE Processing routine.
           Indicate no message to be sent.
         } else { /* server map does not exist */
            Update internal tables.
            Indicate message to be sent on ClusterControlVC.
           } /* server map does not exist */
        } /* not a register */
      ar$flags.copy = 1.
      Send message as indicated.
      Return.

   - MARS_LEAVE

      If ar$flags.copy != 0 silently ignore the message.
      Ignore ar$flags.layer3grp.
      Indicate message to be sent on ClusterControlVC.
      If group address is 224.0.0.1 then {
        All references to this node must be eliminated from
         any other groups for which it is a member.
      } /* group is 224.0.0.1 */
      If ar$flags.register == 1 then { /* deregistration */
        If the node is not registered then {
          Ignore the message.
        }
        Update internal tables to remove the member's ATM addr
        from all groups it has joined.
        Drop the endpoint from ClusterControlVC.
        Release the CMI.
        ar$flags.register = 0.
        Indicate message to be sent on private VC.
      } else { /* not a deregistration */
         If a server map exists for the group then {
           Call the Modified JOIN/LEAVE Processing routine.
           Indicate no message to be sent.
         } else { /* server map does not exist */
            Update internal tables.
            Indicate message to be sent on ClusterControlVC.
         }
      } /* not a deregistration */
      If a message exists then {
        ar$flags.copy = 1.
        Send message as indicated.
      }
      Return.

 - MARS_MSERV

   If (the group has a non-null host map) && (no server map) then {
     Silently drop the message.
     Indicate no message to be sent.
   } else {
      If ar$flags.register == 1 then { /* server register */
        Add the endpoint as a leaf node to ServerControlVC.
        Add the endpoint to the server map.
        Indicate the message to be sent on Private VC.
        ar$cmi = 0.
      } else { /* not a register */
         If the source has not registered then {
           Drop and ignore the message.
           Indicate no message to be sent.
         } else {  /* source is registered */
            Add the server ATM addr to the server map for the group.
            Indicate the message to be sent on ServerControlVC.
            Send message as indicated.
            Make a copy of the message.
            Change the op code to MARS_JOIN.
            Indicate the message to be sent on ClusterControlVC.
            ar$flags.layer3grp = 0.
            ar$flags.copy = 1.
           } /* source is registered */
        } /* not a register */
     }
   If a message exists then {
     Send message as indicated.
   }
   Return.

 - MARS_UNSERV

   If ar$flags.register == 1 then { /* deregister */
     Remove the ATM addr of the MCS from all server maps.
     If a server map is null then delete it.
     Remove the endpoint as a leaf of ServerControlVC.
     Indicate no message to be sent.
   } else { /* not a deregister */
      If the source has not registered then {
       Drop and ignore the message.
       Indicate no message to be sent.
      } else {  /* source is registered */
         Remove the ATM addr of the MCS from each server map indicated.
         If a server map is null then delete it.
         Indicate the message to be sent on ServerControlVC.
         Send message as indicated.
         Make a copy of the message.
         Change the op code to MARS_LEAVE.
         Indicate the message (copy) to be sent on ClusterControlVC.
         ar$flags.layer3grp = 0;
         ar$flags.copy = 1.
        } /* source is registered */
     } /* not a deregister */
   If a message exists then {
     Send message as indicated.
   }
   Return.

 - MARS_NAK

   Build command.
   Return.

 - MARS_GROUPLIST_REQUEST

   If ar$pnum != 1 then Return.
   Call MARS_GROUPLIST_REPLY with the range and output VC.
   Return.

 - MARS_GROUPLIST_REPLY

   Build command for specified range.
   Indicate message to be sent on specified VC.
   Send message as indicated.
   Return.

 - MARS_REDIRECT_MAP

    Include the MARSs own address in the message.
    If there are backup MARSs then include their addresses.
    Indicate MARS_REDIRECT_MAP is to be sent on ClusterControlVC.
    Send message back as indicated.
    Return.

3. Send Message Handler

   If the message is going out ClusterControlVC then {
    ar$msn = obtain a CSN
   }
   If the message is going out ServerControlVC then {
    ar$msn = obtain a SSN
   }
   Return.

4.  Number Generator

4.1 Cluster Sequence Number

    Generate the next sequence number.
    Return.

4.2 Server Sequence Number

    Generate the next sequence number.
    Return.

4.3 CMI

    A single node may register multiple times if it supports
    multiple layer 3 protocols.
    The CMIs allocated for each such registration may or may
    not be the same.
    Generate a CMI for this protocol.
    Return.

5. Modified JOIN/LEAVE Processing

   This routine processes JOIN/LEAVE when a server map exists.

   Make a copy of the message.
   Change the type of the copy to MARS_SJOIN.
   If the message is a MARS_LEAVE then {
    Change the type of the copy to MARS_SLEAVE.
   }
   ar$flags.copy = 1 (copy).
   Indicate the message to be sent on ServerControlVC.
   Send message (copy) as indicated.
   If the number of groups == 1 then {
     ar$flags.punched = 0 in the original message.
     Indicate the message to be sent on Private VC.
   } else { /* multiple groups */
      Hole punch the <min,max> group by excluding
      from the range those groups that are served by MCSs.
      Indicate the (original) message to be sent on ClusterControlVC.
      If number of holes punched > 0 then { /* punched holes */
        In original message do {
        ar$flags.punched = 1.
        old punched list <- new punched list.
        }
      } /* punched holes */
     } /* multiple groups */
   ar$flags.copy = 1.
   Send message as indicated.
   Return.