When logged into an ESX host the following command will list out all your nics with their PCI address. As you can see I have quite a few active ports on this box. Specifically I have two onboard ports and two quad port cards.
esxcfg-nics -l
vmnic0 0d:00.00 e1000 Up 100Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic5 0e:00.01 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic8 12:00.00 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic2 05:00.00 bnx2 Up 1000Mbps Full 1500 Broadcom Corporation Broadcom NetXtreme II BCM5708 1000Base-T
vmnic4 0e:00.00 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic1 03:00.00 bnx2 Up 1000Mbps Full 1500 Broadcom Corporation Broadcom NetXtreme II BCM5708 1000Base-T
vmnic3 0d:00.01 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic6 11:00.00 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic7 11:00.01 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
vmnic9 12:00.01 e1000 Up 1000Mbps Full 1500 Intel Corporation Intel PRO/1000 PT Low Profile Quad Port PCIe Gigabit Ethernet Controller
While this information is helpful, it does not tell me which ports are on the same card. However the following command gives me the mac addresses of each port, so I can figure out which ports are on the same quad port nic by comparing similar macs, I have highlighed the ports that are on the same card as vmnic9
grep "/net/pnic" /etc/vmware/esx.conf
root@rhost11 log]# grep "/net/pnic" /etc/vmware/esx.conf
/net/pnic/child[0000]/mac = "00:1c:c4:ec:65:58"
/net/pnic/child[0000]/name = "vmnic1"
/net/pnic/child[0000]/virtualMac = "00:50:56:5c:65:58"
/net/pnic/child[0001]/mac = "00:1c:c4:ec:65:56"
/net/pnic/child[0001]/name = "vmnic2"
/net/pnic/child[0001]/virtualMac = "00:50:56:5c:65:56"
/net/pnic/child[0002]/mac = "00:18:fe:2e:1b:21"
/net/pnic/child[0002]/name = "vmnic0"
/net/pnic/child[0002]/virtualMac = "00:50:56:5e:1b:21"
/net/pnic/child[0003]/mac = "00:18:fe:2e:1b:20"
/net/pnic/child[0003]/name = "vmnic3"
/net/pnic/child[0003]/virtualMac = "00:50:56:5e:1b:20"
/net/pnic/child[0004]/mac = "00:18:fe:2e:1b:23"
/net/pnic/child[0004]/name = "vmnic4"
/net/pnic/child[0004]/virtualMac = "00:50:56:5e:1b:23"
/net/pnic/child[0005]/mac = "00:18:fe:2e:1b:22"
/net/pnic/child[0005]/name = "vmnic5"
/net/pnic/child[0005]/virtualMac = "00:50:56:5e:1b:22"
/net/pnic/child[0006]/mac = "00:18:fe:2e:b3:91"
/net/pnic/child[0006]/name = "vmnic6"
/net/pnic/child[0006]/virtualMac = "00:50:56:5e:b3:91"
/net/pnic/child[0007]/mac = "00:18:fe:2e:b3:90"
/net/pnic/child[0007]/name = "vmnic7"
/net/pnic/child[0007]/virtualMac = "00:50:56:5e:b3:90"
/net/pnic/child[0008]/mac = "00:18:fe:2e:b3:93"
/net/pnic/child[0008]/name = "vmnic8"
/net/pnic/child[0008]/virtualMac = "00:50:56:5e:b3:93"
/net/pnic/child[0009]/mac = "00:18:fe:2e:b3:92"
/net/pnic/child[0009]/name = "vmnic9"
/net/pnic/child[0009]/virtualMac = "00:50:56:5e:b3:92"