Operation Manual – POS Port
H3C S9500 Series Routing Switches Table of Contents
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Table of Contents
Chapter 1 POS Port Configuration ..............................................................................................1-1
1.1 POS Port Overview............................................................................................................1-1
1.2 POS Port Configuration.....................................................................................................1-1
1.2.1 Entering POS Port View..........................................................................................1-2
1.2.2 Adding/Deleting POS Ports into/from VLAN...........................................................1-2
1.2.3 Enabling/Disabling POS Ports ................................................................................1-2
1.2.4 Configuring POS Port Description...........................................................................1-3
1.2.5 Setting the Frame Format on a POS Port...............................................................1-3
1.2.6 Enabling the Scrambling Function on a POS Port..................................................1-3
1.2.7 Setting Alarm Thresholds for a POS Port...............................................................1-4
1.2.8 Setting the Clock Mode on a POS Port...................................................................1-4
1.2.9 Setting the State Polling Timer on a POS Port.......................................................1-5
1.2.10 Setting the CRC Check Bit Length on a POS Port ...............................................1-5
1.2.11 Setting the Loopback Mode of a POS Port...........................................................1-5
1.2.12 Setting the Overhead Byte Type of a POS Port....................................................1-6
1.2.13 Setting the Timeout Time for PPP Negotiation.....................................................1-7
1.2.14 Setting the MTU of a POS Port.............................................................................1-7
1.2.15 Setting the Interval for Collecting Statistic Data on a POS Port ...........................1-7
1.3 Displaying and Maintaining POS Port Configuration.........................................................1-8
1.4 POS Port Configuration Example......................................................................................1-8
1.5 Troubleshooting POS Port Configuration..........................................................................1-9
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Chapter 1 POS Port Configuration
When configuring a POS port, go to these sections for information you are interested in:
z POS Port Overview
z POS Port Configuration
z Displaying and Maintaining POS Port Configuration
z POS Port Configuration Example
z Troubleshooting POS Port Configuration
1.1 POS Port Overview
Synchronous optical network (SONET), a synchronous transmission system defined by
ANSI, is an international standard transmission protocol. It adopts optical transmission
where transmission rates form a sequence of STM-1 (155 Mbps), STM-4c (622 Mbps),
STM-16c/STM-16 (2.5 Gbps), and STM-64 (10 Gbps), each four times the immediate
lower level. Because signals are synchronous, SDH can multiplex multiple signals
conveniently.
Synchronous digital hierarchy (SDH), defined by CCITT (ITU-T at present), uses a
SONET rate subset.
Packet over SONET/SDH (POS) is a technology used in MAN (metropolitan area
network) and WAN (wide area network) for data packet transmission.
S9500 series use SDH and SONET as its physical layer protocol, maps data packets of
varying lengths into SDH/SONET synchronous load, and provides a type of high-speed
and reliable point-to-point data connections.
The POS ports on S9500 series work at the rates of STM-1/OC-3 (155.52 Mbps),
STM-16 (2.5 Gbps) and STM-64 (10 Gbps). POS ports use the Point-to-Point Protocol
(PPP) at the data link layer and the Internet Protocol (IP) at the network layer.
1.2 POS Port Configuration
The following sections describe POS port configuration tasks:
z Entering POS Port View
z Adding/Deleting POS Ports into/from VLAN
z Enabling/Disabling POS Ports
z Configuring POS Port Description
z Setting the Frame Format on a POS Port
z Enabling the Scrambling Function on a POS Port
z Setting Alarm Thresholds for a POS Port
z Setting the Clock Mode on a POS Port
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z Setting the State Polling Timer on a POS Port
z Setting the CRC Check Bit Length on a POS Port
z Setting the Loopback Mode of a POS Port
z Setting the Overhead Byte Type of a POS Port
z Setting the Timeout Time for PPP Negotiation
z Setting the MTU of a POS Port
z Setting the Interval for Collecting Statistic Data on a POS Port
1.2.1 Entering POS Port View
Before configuring the POS port, enter POS port view first.
Perform the following configuration in system view.
To do … Use the command …
Enter POS port view interface pos interface-number
1.2.2 Adding/Deleting POS Ports into/from VLAN
You can add a POS port into a designated VLAN, so that it can forward the packets of
that VLAN.
Perform the following configuration in POS port view.
To do … Use the command …
Add a POS port into the VLAN pos access vlan vlan-id
Delete a POS port from the VLAN
undo pos access vlan
Note:
z A POS port cannot be added to VLAN 1.
z The VLAN that a POS port is added to must already exist and be configured with a
VLAN interface that is assigned an IP address.
z You cannot add a POS port to a VLAN that already contains ports, and vice versa.
1.2.3 Enabling/Disabling POS Ports
After completing the configuration of a POS port, you can use undo shutdown
command to enable the POS port. You also can use undo shutdown to disable it if you
want to stop data forwarding on it.
Perform the following configuration in POS port view.
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To do … Use the command …
Enable POS port
shutdown
Disable POS port
undo shutdown
By default, POS ports are enabled.
1.2.4 Configuring POS Port Description
Perform the following configuration in POS port view.
To do … Use the command …
Configure a POS port description
description text
Delete the POS port description
undo description
By default, a POS port has no description.
1.2.5 Setting the Frame Format on a POS Port
The POS port supports two frame formats: SDH and SONET.
Perform the following configuration in POS port view.
To do … Use the command …
Set the frame format on the POS port to
SDH/SONET
frame-format { sdh | sonet }
Restore the default frame format undo frame-format
By default, the frame of a POS port is SDH.
1.2.6 Enabling the Scrambling Function on a POS Port
You may configure payload scrambling on a POS port to prevent the presence of
excessive consecutive 1s or 0s to facilitate line clock signal extraction at the receiving
end.
Perform the following configuration in POS port view.
To do … Use the command …
Enable the scrambling function on the POS port
scramble
Disable the scrambling function on the POS port
undo scramble
By default, the scrambling function is enabled on a POS port.
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1.2.7 Setting Alarm Thresholds for a POS Port
You can use the threshold command to set the SD (signal degrade) threshold or SF
(signal fail) threshold for a POS port.
SD and SF alarms are used to indicate the current line performance. Both may occur
when the receiver detects B2 error. The bit error rate threshold of SF is higher than that
of SD, meaning when a few errors occur, SD alarms are generated; while when error
rate is increased to a certain degree, SF alarms are generated, indicating the line
performance is degrading seriously.
Perform the following configuration in POS port view.
To do … Use the command …
Set the SD and SF thresholds of the POS port threshold { sd | sf } value
Restore the defaults undo threshold { sd | sf }
If you execute the threshold command with the value argument set to X, the value of
the threshold specified can be obtained using this expression: 10e-X.
By default, the SD threshold is10e-6 (meaning X takes a value of 6), and the SF
threshold is 10e-3 (meaning X takes a value of 3).
Note that the SD threshold must be smaller than the SF threshold.
1.2.8 Setting the Clock Mode on a POS Port
POS ports support two clock modes:
z Master clock mode, using internal clock signals
z Slave clock mode, using line clock signals
When two switches are connected through POS ports, you should set one POS port in
master clock mode and the other in slave clock mode. Otherwise, the clocks of the two
switches may be asynchronous, and packet loss may occur.
Perform the following configuration in POS port view.
To do … Use the command …
Set the clock mode on the POS port to master
clock master
Set the clock mode on the POS port to slave
clock slave
Restore the default
undo clock
By default, a POS port is in slave clock mode.
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1.2.9 Setting the State Polling Timer on a POS Port
You may configure the state polling timer on a POS port to have the protocol running on
it (PPP for example) regularly send ECHO Requests. If the port receives no response
from the peer within the specified time limit, it regards that the peer has failed.
Perform the following configuration in POS port view.
To do … Use the command …
Set the state polling timer on the POS port
timer hold seconds
Restore the default
undo timer hold
By default, the polling interval is 10 seconds. If you set the polling interval as 0, the
system does not perform link validity check.
1.2.10 Setting the CRC Check Bit Length on a POS Port
The POS port supports 16-bit and 32-bit CRC check.
Perform the following configuration in POS port view.
To do … Use the command …
Set the CRC check bit length on the POS port to 16 bits
crc 16
Set the CRC check bit length on the POS port to 32 bits
crc 32
Restore the default
undo crc
By default, the CRC check bit length is 32 bits.
Caution:
10G POS ports do not support 16-bit CRC check.
1.2.11 Setting the Loopback Mode of a POS Port
Loopback is set for testing some special functions. Do not use it when the system works
normally.
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Perform the following configuration in POS port view.
To do … Use the command …
Set the loopback mode of the POS port to internal
loopback internal
Set the loopback mode of the POS port to external
loopback external
Disable loopback on the POS port
undo loopback
By default, loopback is disabled on a POS port.
Caution:
z You cannot enable both internal loopback and external loopback on a POS port.
z When switching between internal loopback and external loopback, you must delete
the previous loopback setting before setting new loopback.
1.2.12 Setting the Overhead Byte Type of a POS Port
SDH provides many overhead byte types for monitoring at different levels.
Signal label byte C2 belongs to the high-order path overhead byte, and is used to
indicate the multiplexing structure and message payload of the VC (virtual container)
frame.
Regenerator section trace byte J0 belongs to the section overhead byte, and is used to
check port connectivity at section level.
Path trace byte J1 also belongs to the high-order overhead byte, and is used to check
port connectivity at path level.
Perform the following configuration in POS port view.
To do … Use the command …
Set the overhead byte type for
the POS port
flag c2 flag-value
flag { j0 | j1 } { sdh | sonet } flag-value
Restore the default overhead
byte type
undo flag c2
undo flag { j0 | j1 } { sdh | sonet }
Note:
You are recommended to configure a 15-character string for both j0 and j1.
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By default, c2 is 0x16 (hexadecimal); J0 and J1 are default.
C2, J0 and J1 configuration should be consistent at both ends. Otherwise, the system
may give alarms. The frame format of overhead bytes J0 and J1 must be consistent at
both POS ports. Otherwise, the system cannot read the peer field values correctly.
1.2.13 Setting the Timeout Time for PPP Negotiation
During negotiation, PPP shall retransmit a message if it receives no response from the
peer within the defined time limit. You can customize the timeout time for PPP
negotiation.
Perform the following configuration in POS port view.
To do … Use the command …
Set timeout time for PPP negotiation
ppp timer negotiate seconds
Restore the default value
undo ppp timer negotiate
By default, the timeout time for PPP negotiation is 3 seconds.
1.2.14 Setting the MTU of a POS Port
Perform the following configuration in POS port view.
To do … Use the command …
Set the MTU of the POS port mtu mtu-value
By default, the MTU is 1,500 bytes.
Note that you must disable the port by using the shutdown command first and then use
the undo shutdown command to enable it again if the MTU values are different
between the two ends. In this case, as the result of the negotiation between the two
ports, the smaller value will be used as the MTU.
1.2.15 Setting the Interval for Collecting Statistic Data on a POS Port
Perform the following configuration in POS port view.
Follow these steps to configure the interval for collecting statistic data on a POS port.
To do … Use the command … Remarks
Set the interval for
collecting statistic data on
the port
flow-interval interval
Required
300 seconds by default
The switch collects statistics data on the port to get the average rate in the interval.
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1.3 Displaying and Maintaining POS Port Configuration
Operation Command Remarks
Display all information
about POS port(s)
display interface pos
[ interface-number ]
Available in any
view
Clear the statistics of
POS port(s)
reset counters interface pos
[ interface-number ]
Available in user
view
Enable/disable POS
port debugging
[ undo ] debugging ppp { { ipcp |
lcp } { all | error | event | packet |
state } | all | core event | ip packet |
mpls-multicast packet |
mpls-unicast packet | osi-npdu }
[ interface { aux | pos }
interface-number ]
Available in user
view
1.4 POS Port Configuration Example
I. Network requirements
Configure Switch A and Switch B to make them communicate with each other through
POS ports. Switch B provides the clock.
II. Network prerequisites
None
III. Network diagram
As shown in Figure 1-1, Switch A and Switch B are interconnected by POS 2/1/1 and
POS 3/1/1, whose addresses are 202.38.163.10/24 and 202.38.163.11/24.
Figure 1-1 Network diagram for directly-connected POS port configuration
IV. Configuration procedure
1) Configure Switch A
# Create a VLAN interface with an IP address for the VLAN to which the POS port is to
be assigned.
<Switch A> system-view
[Switch A] vlan 2
[Switch A-vlan2] interface vlan-interface 2
[Switch A-Vlan-interface2] ip address 202.38.163.10 255.255.255.0
[Switch A-Vlan-interface2] quit
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# Add the POS port to the VLAN.
[Switch A] interface pos 2/1/1
[Switch A-Pos2/1/1] pos access vlan 2
2) Configure Switch B
# Create a VLAN interface with an IP address for the VLAN to which the POS port is to
be assigned.
<Switch B> system-view
[Switch B] vlan 2
[Switch B-vlan2] interface vlan-interface 2
[Switch B-Vlan-interface2] ip address 202.38.163.11 255.255.255.0
[Switch B-Vlan-interface2] quit
# Add the POS port to the VLAN.
[Switch B] interface pos 3/1/1
[Switch B-Pos3/1/1] pos access vlan 2
# Configure the clock source.
[Switch B-Pos3/1/1] clock master
1.5 Troubleshooting POS Port Configuration
Symptom 1:
The POS port is down at the physical layer.
Solution:
Check that
z The receiver (Rx) and transmit (Tx) optical fibers are connected correctly to the
POS ports. If the Tx and Rx ends of a optical fiber both are connected to the same
POS port, then you can see the information “loopback detected” when performing
the display interface pos command even if loopback function is not enabled yet.
z The right optical module (providing the POS ports) is inserted.
Symptom 2:
The POS port has been enabled at the physical layer, but the link does not report the
Up state.
Solution:
Check that
z Inconsistent physical parameters, such as POS port clock, scrambling setting, are
set at the two ends.
z Inconsistent link data layer protocols are set at the two ends.
z The port CRC settings are consistent at the two ends.
z Loopback is not set on the port.
z The VLAN to which the port belongs has been administratively shut down.
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Symptom 3:
Serious IP packet loss.
Solution:
Check that:
z The clock configuration on the POS ports is correct (otherwise, a large amount of
CRC errors may result).
z The same MTU is set at the two ends.
/