Need persistance assistance

 

So I have a non-standard tcp protocol that I need to load balance with the following conditions.

 

 

1) multiple clients with the same "channel identifier" in the first part of the tcp payload need to persist to the same server.

 

 

2) if there are no active sessions for the "channel identifier" then load balance and populate a key in the session table.

 

 

3) If the "channel identifier" exists in the session table then persist the new session to the same nodes as the rest of the matching sessions.

 

 

4) once the the "channel identifier" is associated with a node, only that node can handle requests for that "channel identifier."

 

 

5) once a day, all session/persistance info for this vip/pool must be flushed. This can be done by fairly low session timeout value and stopping all nodes for a period greater than this timeout value.

 

 

The below irule seems to work ok in limited testing, but there are a couple scenerios that could cause it to fail.

 

 

What if a node fails and the 300-400 clients that were connected to the failed node all reconnect at the same time?

 

 

Since there could then be multiple requests at the same time and a few hundred milliseconds before the first connection populates the session table, could this result in load balancing multiple clients with the same "channel identifier" to different nodes?

 

 

Is there some sort of serialization or locking in the session table that could/would prevent this?

 

 

What can I do to make this work without rewriting the application?

 

 

Thanks/Wade

 

 

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when CLIENT_ACCEPTED {

 

TCP::collect 44

 

}

 

when CLIENT_DATA {

 

set ConStr [TCP::payload 44]

 

set SessionID [substr [getfield $ConStr "@" 2] 0 " CHID" ]

 

log local0.info $SessionID

 

set PersistTo [session lookup uie $SessionID]

 

log local0.info $PersistTo

 

if { $PersistTo equals "" } {

 

pool [LB::server pool]

 

log local0.info "No session ID, load balancing the connection."

 

} else {

 

pool [LB::server pool] member $PersistTo

 

log local0.info "$SessionID sent to $PersistTo"

 

}

 

}

 

when SERVER_CONNECTED {

 

if { $PersistTo equals "" } {

 

session add uie $SessionID [IP::server_addr]:[serverside {TCP::remote_port}]

 

log local0.info "Added $SessionID to [IP::server_addr]:[serverside {TCP::remote_port}]"

 

} else {

 

log local0.info "$SessionID already exists to $PersistTo"

 

}

 

}