11-32
Cisco Prime Network 4.0 User Guide
OL-29343-01
Chapter 11 Using Cisco PathTracer to Diagnose Problems
Using Cisco PathTracer in MPLS Networks
Using Cisco PathTracer for Layer 3 VPNs
Cisco PathTracer uses VRF routing and label switching information to trace the path from one VRF
interface to another. If you choose a launch point and destination from the right-click menu, you can
open the Cisco PathTracer for Layer 3 VPNs. The Cisco PathTracer window shows the VPN topology
map. From this window, you can open the Cisco PathTracer details window with the appropriate VPN
information displayed in the Layer 2 and Layer 3 tabs.
For Layer 3 path information, Prime Network uses VRF routing and label switching information to trace
the path from one VRF interface to another. Layer 3 path trace information is displayed in the
Cisco PathTracer window when the path goes over connections and ends in VRFs.
If a VRF table includes more than one path toward a destination, Cisco PathTracer shows all paths.
To view Layer 3 path information, choose the Layer 3 tab and choose Show All from the View menu.
The path information is displayed in the active tab.
The table displays the Layer 3 VPN information on the device that has a VRF. The following Layer 3
properties displayed in the Layer 3 tab relate specifically to VPNs:
• Name—The name of the site. For example, ATM4/0.100(10.0.0.1) is a combination of the interface
name and IP address used to reach the site. Each site belongs to a particular VPN, so the address
must be unique within the VPN.
• IP Address—The IP address of the interface.
• Mask—The mask of the specific network.
• State—The state of the interface (up or down).
• VRF Name—The name of the VRF.
Cisco PathTracer does not display or trace EXP bits for Layer 3 VPNs that use policy-base d tu nnel
selection (PBTS).
Using Cisco PathTracer for Layer 2 VPNs
Cisco PathTracer uses VC ID and label switching information to trace the path from one tunnel i nterface
to another over the MPLS network.
Cisco PathTracer also covers end-to-end Layer 2 VPN service paths from one CE router to another. The
path goes over circuits (such as a VC) or VLANs in access networks and over L SP between the Layer 2
tunnel edge.
The Cisco PathTracer window shows the VPN topology map for the relevant devices and links. Fro m this
window, you can open the Cisco PathTracer details window with the appropriate VPN information
displayed in the Layer 2 and Layer 3 tabs.
For Layer 2 path information, Cisco PathTracer uses VC ID and label switching information to trace the
path from one tunnel interface to another. Layer 2 path trace information is displayed in the
Cisco PathTracer window when the path goes over pseudowire tunnels.
To view Layer 2 path information, choose the Layer 2 tab and then View > Show All. The path
information is displayed in the active tab.