Compaq ProLiant 1000 PCI Bus Numbering in a Microsoft Windows NT Environment - Page 30

PCI Bus Numbering in a Microsoft Windows NT Environment 30 assignment occurs. The NC3131 Fast Ethernet NIC (a bridged device), residing in slot 3, increments the bus number. The discovery process completes with the discovery of the Tertiary Bus, assigning a bus number of 7. Since slots 4 and 5 comprising the Tertiary Bus are empty, no bus number assignment occurs for these slots. IMPORTANT: The controllers added to the server configuration in our tests were selected only to illustrate how bus renumbering occurs. This example is not meant to be a recommended configuration. Configuration A - Test 2 - Removing and Adding NICs The example in Table 11 illustrates the PCI BIOS discovery and bus number assignment process in the same ProLiant DL580 server, resulting in the reordering of bus numbers from the original configuration. When adding new network interface controllers (NIC) to a server, the slot used to input the device is significant since network connectivity can be lost for existing NICs in lower numbered slots. Fortunately, this state is only temporary because the NIC driver must be reconfigured to accommodate the new NIC, at which time the bindings for the other NICs will be rebuilt. Table 11. PCI BIOS bus detection in a ProLiant DL580-after removing and adding NICs Bus Detection Order/ Controller Discovery 1st 2nd 3rd 4th 5th 6th 7th Slot Number Primary Bus (0) Slot 6 Secondary Bus (2) Slot 1 Slot 2 Slot 3 Tertiary Bus (7) PCI Bridge/ Controller Type - Test 1 Bus Number Assignment Host to PCI Bridge Bus 0 Empty N/A Host to PCI Bridge Bus 2 NC3131(bridged) Bus 3 NC3131(bridged) Bus 4 NC3131(bridged) Bus 5* Host to PCI Bridge Bus 7 Description of PCI BIOS Discovery Process The PCI BIOS assigns 0 to the Primary Bus and continues downstream with the controller discovery. Slot 6 is empty, no PCI bus number assignment. The PCI BIOS discovers the Secondary Bus and assigns it bus number 2. NIC in slot 1 contains a PCI bridge and the PCI BIOS increments the PCI bus number to 3. Slot 2 also contains a PCI bridge, making its PCI bus number assignment 4. Slot 3 contains a bridged NIC and assumes a bus number of 5. 8th Slot 4 Empty N/A Finally, detection and assignment of the Tertiary Bus occurs, incrementing to 7. 9th Slot 5 Empty N/A Since both slots on the Tertiary Bus are empty, a PCI bus number assignment does not occur for these slots. *Bus number is different than previous configuration 13UK-1200A-WWEN