You might effectively increase existing bandwidth by increasing the length of the connection queues. Requests for connections to the IIS services are held in queues until the service is available to respond to the request. A separate queue exists for each of the IIS services, but all queues have the same maximum size. By default, each queue can hold up to 15 connection requests. If the queue to a service is full, any new connection requests are rejected.
The default queue length of 15 connection requests is sufficient for most servers. However, if your server is rejecting many requests when the services are most active, you can increase the maximum number of items in the queue. If you change the queue length, be sure to monitor server processor use, server memory use, and the connection counters to avoid creating a system bottleneck.
To change the maximum number of connection requests in the queue for each IIS service, add the ListenBackLog value entry to the Registry. Set the value of ListenBackLog to the maximum number of connection requests you want the server to maintain. You must place ListenBackLog in the Registry at:
HKEY_LOCAL_MACHINE\System
\CurrentControlSet
\Services
\Inetinfo
\Parameters
Although there are separate queues for each IIS service, the maximum length for all three of the queues is identical and is determined by this value entry.