Specify the following two port numbers for multicast distribution of jobs:

• Multicast distribution (default: 22296)
• Request a re-send (default: 22294)

Normally, you should use the displayed default port numbers. However, you must change a port number if some other program is using that port. It is important that you set a port number for Request a re-send, because multicast distribution uses the UDP protocol and packets may be resent during distribution.

If a port number is set in the services file of TCP/IP, the services file setting takes precedence.

Select this option and specify the multicast address and packet size for using the multicast method to send to lower systems jobs for which you have specified multicast distribution. The default is that this check box is not selected.

When this check box is not selected, jobs for which multicast distribution is specified are distributed by unicast distribution. Conversely, even if you select this check box, jobs for which unicast distribution is specified are sent by unicast distribution.

You should clear the Allow jobs to be sent by multicast distribution check box if there is a router in the network that is not compatible with IP multicasting. If the network includes routers that are not compatible with IP multicasting, unicast distribution is used; you cannot use multicast distribution. If you do select Allow jobs to be sent by multicast distribution, the system will require a long time to switch to unicast distribution in order to send a job.

Multicast address

Specify the multicast address assigned to the multicast group to which jobs are to be distributed. Specify a value in the range from 224.0.1.0 to 239.255.255.255. Do not specify an address already assigned to another multicast group. The default address is 239.255.0.1.

A multicast group is a group of lower systems connected directly to this JP1/Software Distribution Manager. If the multicast address of the lower systems to which a job is to be distributed does not match the multicast address you specify here, the job will be distributed to those lower systems using unicast distribution.

For details about multicast groups and multicast addresses, see 6.2.1 Unicast distribution and multicast distribution and 6.2.3 System configuration for multicast distribution in the Description and Planning Guide.

Packet size

Specify the packet size to be used for distributing a job. Specify a value in the range 1-60 KB. The default is 40 KB.

40 KB is an efficient value for communications lines for 100BASE. For communications lines for 10BASE, you should specify 4 KB. If you specify a packet size that is too large, multicast distribution will fail and the system will continue distribution using unicast distribution.