Cisco ASR 1000 Configuration Guide

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Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide
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Chapter 18 Configuring the 4-Port Serial Interface SPA
Configuration Tasks
Use the following commands when configuring NRZI format:
Configuring Cyclic Redundancy Checks
Cyclic redundancy checking (CRC) is an error-checking technique that uses a calculated numeric value
to detect errors in transmitted data. All interfaces use a 16-bit CRC (CRC-CITT) by default but also
support a 32-bit CRC. The designators 16 and 32 indicate the length (in bits) of the frame check sequence
(FCS). The sender of a data frame calculates the frame check sequence (FCS). Before it sends a frame,
the sender appends the FCS value to the message. The receiver recalculates the FCS and compares its
calculation to the FCS from the sender. If there is a difference between the two calculations, the receiver
assumes that a transmission error occurred and sends a request to the sender to resend the frame.
To set the length of the cyclic redundancy checks (CRC), use the following commands:
Configuring Encapsulation
When traffic crosses a WAN link, the connection needs a Layer 2 protocol to encapsulate traffic. To set
the encapsulation method, use the following commands:
Command Purpose
Router# configure terminal Enters global configuration mode.
Router(config)# interface serial slot/subslot/port Selects the interface to configure and enters
interface configuration mode.
• slot/subslot/port—Specifies the location of
the interfaceFor further information, see the
“Specifying the Interface Address on a SPA”
section on page 18-7.
Router(config-if)#nrzi-encoding Enables NRZI encoding.
Router(config-if)#no nrzi-encoding Disables NRZI encoding.
Command Purpose
Router# configure terminal Enters global configuration mode.
Router(config)# interface serial slot/subslot/port Selects the interface to configure and enters
interface configuration mode.
• slot/subslot/port—Specifies the location of
the interface. For further information, see the
“Specifying the Interface Address on a SPA”
section on page 18-7.
Router(config-if)# crc {16 | 32} Specifies the length of the CRC, where:
• 16—Specifies a 16-bit length CRC. This is the
default.
• 32—Specifies a 32-bit length CRC.
To set the CRC length to the default value, use the
no form of this command.

Cisco ASR 1000 Specifications

General

Brand	Cisco
Model	ASR 1000
Category	Network Router
Language	English