Welcome to the world of corporate politics! Your not alone on this. Many large corporations with compartmentized IT groups wrestle with this same delima as tasks are deligated with the idea of maintaining a system of checks and balances. Corporate does not want to give too much power to any one group. Unfortunatley in the IT ‘real world’ many routine tasks will overlap between the various groups causing a bottle neck to get things done. Kind of like the machine shop where the operator has to call the electrician because the machine came unplugged and to plug it back in falls outside the operators job description. Talk about waste in a world where companies are trying to go lean.
Logically I would have the network team’s responsibility go as far as installing the firewall and maintaining connectivity and turn all administrative tasks over to the Security team since they ultimatley are the ones in charge of writing rules, enforcing policy and serving user requests. But that’s just me!