Chapter 13 Configuring Packet Capture; Packet Capture Terms - Juniper J-Series Administration Manual

Chapter 13
Configuring Packet Capture

Packet Capture Terms

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
Before configuring packet capture on a Services Router, become familiar with the
terms defined in Table 133 on page 254.
Packet Capture Terms
253