660 CHAPTER 15: P RIORITIZING NETWORK TRAFFIC■ The IP address of the server that you wish to block does not belong toa server that is critical to your business, such as a database or e-mailserver. Blocking IP addresses such as these may have a major impacton your business.■ The IP address of the server that you wish to block is not an IP addressthat is served by a DHCP server. A device that has an IP address that isserved by a DHCP server can potentially change and this could lead tointermittent problems for users of your network. If one or more of thenetwork infrastructure devices on your network obtained theiraddresses via DHCP it could prevent your network from functioningcorrectly.If you have previously configured the network to block traffic to and froma server it is important that prior to assigning an IP address to a newdevice (or any existing device whose IP address you wish to change) youcheck that the IP address that you are about to assign is not an IP addressof a server you have blocked. One way to check this is to run thePrioritization Configuration report from the Reports dialog box, which islaunched by selecting Tools > Reports and examining the contents of thereport for blocked servers.If you accidently block an IP address then you can rectify this problem byre-running the Prioritize Network Traffic Wizard and removing the serverfrom the list of servers to be blocked.Servers That Cannotbe Selected forBlocking3Com Network Director prevents you selecting the following servers forblocking:■ The PC that is running 3Com Network Director. If you attempted toblock this server 3Com Network Director would no longer be able tocontact your network. This would prevent it from configuring thedevices on your network.■ Any device in the map that forms part of the network infrastructure,such as a switch, hub or router.3Com Network Director will not prevent you from blocking traffic to andfrom a device that is not listed in the map. If any of your networkinfrastructure devices are not listed in the map you will need to checkthat you have not accidently selected one of these devices for blockingbefore configuring traffic prioritization on your network.
