Placing Multiple DAs for Load Balancing

You can deploy multiple DAs for the same collection of scopes as a means of load balancing. Deployment of multiple DAs is suggested in any of the following circumstances:

• UA requests to a DA are timing out, or are returning with the DA_BUSY_NOW error.

• The DA log shows that many SLP requests are being dropped.

• The network of users sharing services in the scopes spans a number of buildings or physical sites.

You can do a snoop trace of SLP traffic to determine how many UA requests return with the DA_BUSY_NOW error. If the number of UA requests returned is high, which is likely if a single DA is deployed for all users, UAs in buildings physically and topologically distant from the DA can exhibit slow response or excessive timeouts. You might want to deploy a DA in each building to improve response for UA clients within the building.

Links connecting buildings are often slower than the local area networks within the buildings. If your network spans multiple buildings or physical sites, set the net.slp.DAAddresses property in the /etc/inet/slp.conf file to a list of specific host names or addresses so that the UAs access only the DAs you specify.

If a particular DA is using large amounts of host memory for service registrations, reduce the number of SA registrations by reducing the number of scopes the DA supports. You can split a scope having many registrations into two and support one of the new scopes by deploying another DA on another host.