1-10
Software Configuration Guide For Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
OL-1957-03
Chapter 1
Understanding Interface Numbering and Cisco IOS Software Basics
Understanding Interface Numbering
Cisco 3725 Router Slot Numbering
The numbering format is Interface-type Slot-number/Interface-number. Two examples are:
FastEthernet 0/0
Serial 1/2.
The slot numbers are as follows:
•
0 for all built-in interfaces
•
0 for all WIC interfaces
•
1 for interfaces in the single-width network module slot
•
2 for interfaces in the double-width network module slot
Interface (port) numbers begin at 0 for each interface type, and continue from right to left and (if
necessary) from bottom to top.
Figure 1-10
below shows an example of interface numbering on a Cisco 3725 router with:
•
A WIC in each WIC slot (containing interfaces Serial 0/0 and Serial 0/1 in physical slot W0,
interface Serial 0/2 in physical slot W1, and interface BRI 0/0 in physical slot W2)
•
A 2-port T1 network module in slot 1 (containing the following ports: T1 1/0 and T1 1/1)
•
A 36-port Etherswitch network module in slot 2 (containing the following ports: FastEthernet 2/0
through 2/35, and GigabitEthernet 2/0 and 2/1)
•
Two built-in Ethernet 10/100 interfaces—FastEthernet 0/0 and FastEthernet 0/1
Figure 1-10 Cisco 3725 Router Rear View
Serial 0/2
Compact
Flash slot
56482
SEE MANUAL
BEFORE INS
TALLATION
AL
CD
LP
RD
TD
SEE MANUAL
BEFORE INS
TALLATION
DSU
56K
AL
CD
LP
RD
TD
SEE MANUAL
BEFORE INS
TALLATION
DSU
56K
EN
V0
BANK 4
BANK 3
BANK 2
BANK 1 BA
NK 0
NM-HDV
VWIC
2MFT-E1
SEE
MANUAL
BEFORE
INSTALLAT
ION
CTRLR E2
CTRLR E1
AL
LP
CD
Gigabit Ethernet 2/1
Fast Ethernet 2/35
Fast Ethernet 2/17
Gigabit Ethernet 2/0
Fast Ethernet 2/0
Fast Ethernet 2/18
Serial 0/1
Serial 0/0
TI 1/1
TI 1/0
Fast Ethernet 0/1
Fast Ethernet 0/0
BRI 0/0
1
2