9-3
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 9 Configuring PTP
Configuring PTP
Setting Up PTP
Beginning in privileged EXEC mode, follow these steps to set up PTP:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ptp
{
mode
{
boundary
|
e2etransparent | forward
}
|
priority1
value
|
priority2
value
}
Set the synchronization clock.
•
Select
boundary
mode to enable the switch to participate in selecting the
best master clock. If no better clocks are detected, the switch becomes the
grandmaster clock on the network and the parent clock to all connected
devices. If the best master is determined to be a clock connected to the
switch, the switch synchronizes to that clock as a child to the clock, then
acts as a parent clock to devices connected to other ports. After initial
synchronization, the switch and the connected devices exchange timing
messages to correct time skew caused by clock offsets and network delays.
Use this mode when overload or heavy load conditions produce significant
delay jitter.
•
Select
e2etransparent
(end-to-end transparent) mode for the switch to
synchronize all switch ports with the grand master clock connected to the
switch,. This is the default clock mode. The switch corrects for the delay
incurred by every packet passing through it (referred to
residence time
).
This mode causes less jitter and error accumulation than boundary mode.
•
Select
forward
mode for incoming PTP packets to pass through the switch
as normal multicast traffic.This disables both boundary and end-to-end
transparent mode.
When the switch port is in boundary mode, set the clock priority properties.
•
Specify the
priority1
value to override the default criteria (clock quality,
clock class, etc.) for best master clock selection. Lower values take
precedence.The range for both is from 0 to 255. The default is 128.
•
Specify a
priority2
value to be used as a tie-breaker between two devices
that are otherwise equally matched in the default criteria. For example, you
can use priority2 value to give a specific switch priority over other identical
switches. The range for both is from 0 to 255. The default is 128.
These values set the clock priority on the PTP network for the purpose of best
master selection.
Step 3
interface
interface-id
Specify an interface to configure, and enter interface configuration mode.
Enter the number of the switch port, including port type (such as
Fa
for Fast
Ethernet and
Gi
for Gigabit Ethernet), the base switch number (1), and the
specific port number. For example:
Fa1/1
is Fast Ethernet port 1 on the base
switch.
