Usually the interface numbering for Cisco equipment is pretty strait forward.
It is interface Type chassis/Slot/port number or Type switch/module/port number I.e. interface Gi1/0/1 will refer to port 1 of a catalyst 2960s or cat3750, in the case of a Catalyst 6500, interface Gi1/1/1 to port 1 of the module/blade 1 in the chassis #1 of a VSS pair.
So if you see the following interface TE1/2/8 you would assume that it’s the 8 interface on slot 2 for the chassis #1 and you might be wrong If you are using the module WS-X6904-40G Cisco Catalyst 6900 Series 40 Gigabit Ethernet Interface Module with the port adapter CVR-CFP-4SFP10G FourX converter to convert each 40GE port into 4 10GE SFP+ ports.
The numbering for this module is as follows, port 1 to 4 refer to 40G port and port 5-20 to the 10G port.
So if you have the following setup
The interface numbering for your interface in the configuration would be
show interfaces status switch 1 module 2
Port Name Status Vlan Duplex Speed Type
Te1/2/5 connected trunk full 10G 10Gbase-LR
Te1/2/6 connected trunk full 10G 10Gbase-SR
Te1/2/7 connected trunk full 10G 10Gbase-SR
Te1/2/8 disabled unassigned full 10G 10Gbase-SR
Te1/2/9 disabled routed full 10G No Connector
Te1/2/10 disabled routed full 10G No Connector
Te1/2/11 disabled routed full 10G No Connector
Te1/2/12 disabled routed full 10G No Connector
Te1/2/13 connected trunk full 10G 10Gbase-SR
Te1/2/14 connected trunk full 10G 10Gbase-SR
Te1/2/15 connected trunk full 10G 10Gbase-SR
Te1/2/16 connected trunk full 10G 10Gbase-SR
Te1/2/17 disabled routed full 10G No Connector
Te1/2/18 disabled routed full 10G No Connector
Te1/2/19 disabled routed full 10G No Connector
Te1/2/20 disabled routed full 10G No Connector
It is important to remember this, when instructing an onsite technician where to plug or unplug cable as unless he knows the particular numbering there is a good chance that he will count the port from right to left starting at 1 and when you specified port te1/2/5 that correspond to the first 10G port on the blade, he might unplug port te1/2/9 (5th physical port) and create havoc in your network.
I almost learn this particularity the hardway and though I might not be the only one