Complex Session Matching...

I solved this for the most part, and have successfully loaded this with 400K connected clients and over 1000 concurrent messages delivered to those clients.... as follows:

iRules Procedure:

- Collect TCP Payload, Inspect TCP Payload for String

- MD5 hashing string TCP payload concatenated with each node ip address in foreach loop

- binary scan the MD5 hash value for each node and return the first byte's integer value

- compare each score and send the connecction to the winning node

- repeat the process for the second virtual server, the same node is selected for both connections

Handling Node Failure:

- create custom monitor for each service, set as monitor for pools

- set 'manual resume' to yes in both monitors, avoids assymetric conns if host is restored without intervention

- configure pools for 'action on service down' as 'reject', sends RST to all clients on that node, they reconnect, re-calc and relect new winner

- configure tcp profiles for 'infinite' keepalive interval' which disables keepalive ACKs from lb to clients

- configure same tcp profiles for 'zero time wait' 'zero fin wait' and 'zero close wait' and low 'idle timeout'

- clients elect a new node on fail, and timeout after specified interval thus re-electing on specified interval

Caveats:

- communications are assymetrical, and thus broken, for the specified interval above, when a node in added to pool

- sending RST for 1M x 1/nodes is less than optimal, would like to send RSTs on a known failure rather than simply status change

Under Consideration:

- build a secondary vs for msging which has exact same characteristics as vs's mentioned above

- do not restore the pool member on the second vs yet

- apply same iRule that scores the winner, but this time it picks the second server (the winner before adding new member)

- have the sending msg server 'retry' to the second vip, the message should succeed, THEN

- application logic to have the msg sender send a reconnect instruction to client app

-OR-

- create persistence record on the TCP payload string above AND

- iRule that queries persistence table, returns foreign ip and port, sends TCP RST to client

- client reconnects and elects correct winner

iRule 1 - Client Rule for MD5 Hash Node Election

Loadbalancing Based on TCP Payload String, Node IP and MD5 Hash Score

    
     when CLIENT_ACCEPTED {     
       TCP::collect 2     
     }     
     when CLIENT_DATA {     
       set msg [findstr [TCP::payload] "" 0 "\r\n"]     
       set sid [findstr $msg "" 9 "\r\n"]     
      set S ""      
      foreach N [active_members -list myClientPool] {      
        set I [lindex $N 0]     
        binary scan [md5 $I$sid] c1 NMD5     
        if { $NMD5 > $S } {     
          set S $NMD5     
          set W $N     
        } else {     
              set S $NMD5     
        }     
      }      
       pool myClientPool member [lindex $W 0] [lindex $W 1]     
     }     
     

iRule 2 - Msg Server Rule for MD5 Hash Node Election

Loadbalancing Based on TCP Payload String, Node IP and MD5 Hash Score

     
     when CLIENT_ACCEPTED {     
       TCP::collect 2     
     }     
     when CLIENT_DATA {     
       set msg [findstr [TCP::payload] "" 0 "\r\n"]     
       set sid [findstr $msg "" 9 "\r\n"]     
      set S ""      
      foreach N [active_members -list myMsgSrvPool] {      
        set I [lindex $N 0]     
        binary scan [md5 $I$sid] c1 NMD5     
        if { $NMD5 > $S } {     
          set S $NMD5     
          set W $N     
        } else {     
              set S $NMD5     
        }     
      }      
       pool myMsgSrvPool member [lindex $W 0] [lindex $W 1]     
     }