Cisco Systems 8540 Configuring POS SPE Scrambling, Scramble-atm, Scrambling is on by default

Chapter 4 Configuring Interfaces

Configuring the POS OC-12c Uplink Interface (Catalyst 8540)

The value of the c2 byte is determined as follows:

•If the value of the c2 byte has not been explicitly configured with the pos flag command, the SONET framer sends the following values:

–For Cisco HDLC encapsulation with or without SPE scrambling: 0xCF

–For PPP encapsulation with scrambling: 0x16 (RFC 2615)

–For PPP encapsulation without scrambling: 0xCF (RFC 2615)

•If the value of the c2 byte has been explicitly configured with the pos flag command, the configured value is sent regardless of the encapsulation method.

The value of the s1s0 bits is determined as follows:

•If the value of the s1s0 bits have not been explicitly configured with the pos flag command, the SONET framer sends the following values:

–For SONET framing, the default value is 0.

–For SDH framing, the default value is 2.

•If the value of the s1s0 bits have been explicitly configured with the pos flag command, the configured value is used regardless of the framing.

Configuring POS SPE Scrambling

SONET payload scrambling applies a self-synchronous scrambler of polynomial X**43+1 to the synchronous payload envelope (SPE) of the interface to ensure sufficient bit transition density. Both ends of the connection must use the same scrambling algorithm.

To configure POS SPE scrambling, perform the following steps, beginning in global configuration mode:

	Command	Purpose
Step 1
	Router(config)# interface pos	Enters interface configuration mode and specifies the POS
	slot/subslot/interface	interface to configure.
	Router(config-if)#
Step 2
	Router(config-if)# no pos	Disables payload scrambling on the interface. Payload
	scramble-atm	scrambling is on by default.
Step 3
	Router(config-if)# no shutdown	Enables the interface with the previous configuration.

	Layer 3 Switching Software Feature and Configuration Guide
78-6235-04, Cisco IOS Release 12.0(10)W5(18)		4-19