Cisco Systems PA-POS-1OC3, PA-POS-2OC3 manual Setting the MTU Size, Configuring Framing

Chapter 4 Configuring the PA-POS-1OC3

Customizing the Configuration

Setting the MTU Size

Note The default MTU size is 4470 bytes. The default value, 4470 bytes, exactly matches the maximum transmission unit (MTU) of the fiber distributed data interface (FDDI) and high-speed serial interface (HSSI) for autonomous switching.

Step 1 To set the MTU size, enter the mtu bytes command, where bytes is a value in the range of 64 to 117994.

Router(config)# interface pos 3/0

Router(config-if)# mtu 3000

Step 2 To restore the default of 4470 bytes, enter the no mtu command.

Router(config)# interface pos 3/0

Router(config-if)# no mtu 3000

Configuring Framing

The default framing setting is SONET STS-3c.

Step 1 To configure for SDH STM-1, enter the pos framing sdh command:

Router(config)# interface pos 3/0

Router(config-if)# pos framing sdh

Step 2 To change back to SONET STS-3c, enter the no pos framing sdh command.

Router(config)# interface pos 3/0

Router(config-if)# no pos framing sdh

Setting the Source of the Transmit Clock

The clocking default specifies that the PA-POS-1OC3 use the recovered receive (RX) clock to provide transmit (TX) clocking (called loop timing).

Note If line loopback is selected, the PA-POS-1OC3 is forced into loop timing mode until the loopback is disengaged.

Step 1 To specify that the PA-POS-1OC3 generate the transmit clock internally, enter the clock source internal command:

Router(config)# interface pos 3/0

Router(config-if)#clock source internal

PA-POS-1OC3 Single-Port Port Adapter Installation and Configuration Guide

OL-6514-04 4-9