How F5 handle cookie insert

Hi,

I was writing an iRule for debugging purpose. I wanted to store the load balancing decision in a cookie.

when HTTP_RESPONSE {
set member "[LB::server pool]_[LB::server addr]_[LB::server port]"
HTTP::cookie insert -name "choice" -value "$member" -path "/"
}

Doing so is working well in front of my apache test server. Moving it in front of a Websphere IHS I got request error messages on the server.

After changing the irules, it's working with the IBM server too.

when HTTP_RESPONSE {
set member "[LB::server pool]_[LB::server addr]_[LB::server port]"
HTTP::header insert "Set-Cookie choice=$member; Path=/"
}

So what does the F5 excatly when inserting a cookie which could explain this behaviour ?

Thanks for your ideas.