User guide

3-28 Packet Over SONET Module Installation and User Guide
Configuring the PoS Module
config ppp pos scrambling [on | off] ports <portlist>
Choose either on or off. Scrambling is enabled by default.
RFC 2615 recommends that the SONET payload be scrambled. The option of disabling
scrambling is provided for backward compatibility with an earlier PoS standard.
Scrambling was introduced in RFC 2615 to alleviate potential security problems where
malicious users might intentionally generate packets with bit patterns that create
SONET synchronization problems.
The following command example turns off the scrambling function for port 1 of the PoS
module installed in slot 8 of the BlackDiamond switch.
config ppp pos scrambling off ports 8:1
Configuring Link Maintenance
The Extreme Networks implementation of PPP provides a link maintenance
configuration option. When link maintenance is enabled on a port and that port is not
receiving data packets, the link maintenance facility periodically transmits Link Control
protocol (LCP) echo-request packets. If an echo-reply is not received within a
configured interval, LCP brings the link down.
To enable the link maintenance protocol on a specified PPP port, use the following
command:
config ppp echo [<seconds> <consecutive_misses> | off] ports <portlist>
The seconds parameter is an integer in the range from 1 to 300 that specifies the period
between transmissions of echo-request packets.
The
consecutive_misses parameter is an integer in the range from 1 to 100 that
determines how long PPP waits for a reply. If an echo-reply is not received within an
interval of duration (consecutive_misses * seconds) seconds, the link is brought down.
When APS is enabled on a SONET port, link maintenance should also be enabled on
that port.
The link maintenance protocol is off by default. If you enable link maintenance, the
recommended
seconds value is 3, and the recommended consecutive_misses value is
10.