Cisco Systems CISCO1841-HSEC/K9-RF Interface Numbering on the 1861 Integrated Services Router

Chapter 2 Overview of Cisco 1800 Series Routers (Modular)

Interface Numbering on the 1861 Integrated Services Router

Interface Numbering on the 1861 Integrated Services Router

Each interface (port) on a Cisco 1861 ISR is identified by a number. The Cisco 1861 router contains the following WANLAN interface types:

•One onboard Fast Ethernet LAN interface (FastEthernet0/0)

•One onboard Ethernet switch

•One fixed VIC slot with 4 FXS ports

•One fixed VIC slot with 4 FXO or 2 BRI ports

•One modular HWIC/WIC/VWIC slot

The numbering format for the slots is interface-type0/slot-number/port-number. Table 2-7summarizes the interface numbering.

Table 2-7	Interface Numbering
Slot Number		Slot Type	Slot Numbering Range	Example1
Onboard Ports		Fast Ethernet	0/0	interface fastethernet 0/0
Onboad Slot 1		Fast Ethernet Switch	0/1/0 to 0/1/7	interface fastethernet 0/1/0
Fixed HWIC slot 0		FXS	0/0/0 to 0/0/3	voice-port 0/0/0/
Fixed HWIC slot 1		FXO	0/1/0 to 0/1/3	voice-port 0/1/0
		BRI	0/1/0 to 0/1/1
Modular HWIC Slot		HWIC/WIC/VWIC	0/3/0 to 0/3/x, where x	interface serial 0/0/0
			depends on the
			card-type.

1. The interfaces listed are examples only; other possible interface types are not listed.

Note On the Cisco 1861 ISR, the numbering format for configuring an asynchronous, or async, interface is 0/slot/port. To configure the line associated with an async interface, simply use the interface number to specify the async line. For example, line 0/0/0 specifies the line associated with interface serial 0/0/0 on a WIC-2A/S in slot 0. Similarly, line 0/1/1 specifies the line associated with interface async 0/1/1 on a WIC-2AM in slot 1.

Note If you have specified the use of a private line automatic ringdown (PLAR) off-premises extension (OPX) connection mode for an FXO voice port (with loop resistance less than 8000 Ohm), you must ensure that the soft-offhook option is enabled on the port.

This option allows a stepped offhook resistance during seizure, which avoids overloading the circuit during offhook in the event that ringing voltage is present on the circuit at the same time as the trunk seizure. The stepped offhook resistance is initially set to 800 Ohms, then adjusts to 50 Ohms when ringing voltage is not present.

To enable the soft-offhookcommand on the port, and to access the connection command with plar opx syntax, see Cisco Command Lookup Tool.

Cisco 1800 Series Routers (Modular) Hardware Installation Guide

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