Installation guide

Chapter 1 Overview of Cisco Interface Cards
Cisco MWR 1941-DC Router
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Cisco Interface Cards Installation Guide
OL-1919-12
Slot and Port Numbering
The Cisco MWR 1941-DC router chassis contains the following LAN and WAN
interface types:
• Two built-in Fast Ethernet LAN interfaces
• Three slots in which you can install Voice/WAN interface cards (VWICs)
• One slot in which you can install a network module
The slot numbers are as follows:
• 0 for all built-in interfaces
• 0 for all built-in VWIC slots
• 1 for the network module slot
The numbering format is:
Interface type Slot number/Interface number
Interface (port) numbers begin at 0 for each interface type, and continue from
right to left.
• The two built-in Ethernet 10/100 interfaces are Fast Ethernet 0/0 and Fast
Ethernet 0/1.
• The slot number for all VWIC interfaces in the built-in VWIC slot is always
0. (The W0, W1, and W2 slot designations are for physical slot identification
only.) Interfaces in the VWICs are numbered from right to left, starting with
0/0 for each interface type, regardless of the physical VWIC slot in which the
VWICs are installed.
For example, if you have a VWIC in two of the VWIC slots (W0 and W1),
then the interfaces are:
– Serial 0/0 and Serial 0/1 in physical slot W0
– Serial 0/2 and Serial 0/3 in physical slot W1
However, if you install a VWIC in physical slot W1 (leaving slot W0 empty),
the interfaces in slot W1 are Serial 0/0 and Serial 0/1. If you then add a VWIC
to slot W0, the interface numbering will shift. The configuration that you
created for interfaces Serial 0/0 and Serial 0/1 will now be applied to the
VWIC in slot W0 and you will need to create a new configuration for the
interfaces that you previously configured on W1 (which will now be Serial
0/2 and Serial 0/3).