Juniper Networks J-Series - Manual (Page 275)

Chapter 13
Configuring Packet Capture
Packet capture is a tool that helps you to analyze network traffic and troubleshoot
network problems. On a J-series Services Router, the packet capture tool captures
real-time data packets traveling over the network, for monitoring and logging.
Packets are captured as binary data, without modification. You can read the packet
information offline with a packet analyzer such as Ethereal or tcpdump.
If you need to quickly capture packets destined for or originating from the Routing
Engine and analyze them online, you can use the J-Web packet capture diagnostic
tool. For more information, see “Capturing and Viewing Packets with the J-Web
Interface” on page 226.
NOTE: J-series Services Routers can capture IPv4 packets only. The packet capture
tool does not support IPv6 packet capture.
You can use either the J-Web configuration editor or CLI configuration editor to
configure packet capture. For more information about packet capture, see the JUNOS
Policy Framework Configuration Guide.
This chapter contains the following topics.
■ Packet Capture Terms on page 253
■ Packet Capture Overview on page 254
■ Before You Begin on page 257
■ Configuring Packet Capture with a Configuration Editor on page 257
■ Changing Encapsulation on Interfaces with Packet Capture Configured on page 262
■ Verifying Packet Capture on page 263
Packet Capture Terms
Before configuring packet capture on a Services Router, become familiar with the
terms defined in Table 133 on page 254.
Packet Capture Terms ■ 253