Alcatel-Lucent 6850-48 ネットワークガイド
Port Monitoring
Diagnosing Switch Problems
page 45-24
OmniSwitch AOS Release 6 Network Configuration Guide
September 2009
Port Monitoring
An essential tool of the network engineer is a network packet capture device. A packet capture device is
usually a PC-based computer, such as the Sniffer
usually a PC-based computer, such as the Sniffer
®
, that provides a means for understanding and measur-
ing data traffic of a network. Understanding data flow in a VLAN-based switch presents unique chal-
lenges, primarily because traffic moves inside the switch, especially on dedicated devices.
lenges, primarily because traffic moves inside the switch, especially on dedicated devices.
The port monitoring feature allows you to examine packets to and from a specific Ethernet port. Port
monitoring has the following features:
monitoring has the following features:
• Software commands to enable and display captured port data.
• Captures data in Network General
®
file format.
• A file called pmonitor.enc is created in the /flash memory when you configure and enable a port
monitoring session.
• Data packets time stamped.
• One port monitored at a time.
• RAM-based file system.
• Statistics gathering and display.
The port monitoring feature also has the following restrictions:
• All packets cannot be captured. (Estimated packet capture rate is around 500 packets/second.)
• The maximum number of monitoring sessions is limited to one per chassis and/or stack.
• You cannot configure a port mirroring and a port monitoring session on the same NI module in an
OmniSwitch chassis-based switch.
• You cannot configure port mirroring and monitoring on the same switching ASIC on OmniSwitch
6400, 6850, and 6855 switches. Each switching ASIC controls 24 ports (e.g., ports 1–24, 25–48, etc.).
For example, if a port mirroring session is configured for ports 1/12 and 1/22, then configuring a port
monitoring session for any of the ports between 1 and 24 is not allowed.
For example, if a port mirroring session is configured for ports 1/12 and 1/22, then configuring a port
monitoring session for any of the ports between 1 and 24 is not allowed.
• You cannot configure port mirroring and monitoring on the same switching ASIC on OmniSwitch
6800 Series switches. Each switching ASIC controls 12 ports (e.g., ports 1–12, 13–24, etc.). For exam-
ple, if a port mirroring session is configured for ports 1/6 and 1/10, then configuring a port monitoring
session for any of the ports between 1 and 12 is not allowed.
ple, if a port mirroring session is configured for ports 1/6 and 1/10, then configuring a port monitoring
session for any of the ports between 1 and 12 is not allowed.
• If a port mirroring session is configured across two switching ASICs, then configuring a monitoring
session is not allowed on any of the ports controlled by each of the ASICs involved. For example, if a
port mirroring session is configured for ports 1/8 and 1/30 on a 48-port switch, then configuring a port
monitoring session involving any of the ports between 1 and 48 is not allowed.
port mirroring session is configured for ports 1/8 and 1/30 on a 48-port switch, then configuring a port
monitoring session involving any of the ports between 1 and 48 is not allowed.
• Only the first 64 bytes of the traffic will be captured.
• Link Aggregation ports can be monitored.
• If both mirroring and monitoring are enabled, then packets will either be mirrored or monitored (i.e.,
sent to CPU), whichever comes first. See
for more infor-
mation.
You can select to dump real-time packets to a file. Once a file is captured, you can FTP it to a Sniffer or
PC for viewing.
PC for viewing.