Specifications

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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
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Gigabit Ethernet 2/1
Fast Ethernet 2/35
Fast Ethernet 2/17
Gigabit Ethernet 2/0
Fast Ethernet 2/0
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Serial 0/1
Serial 0/0
TI 1/1
TI 1/0
Fast Ethernet 0/1
Fast Ethernet 0/0
BRI 0/0
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