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Use Path Analysis to:
The following topics provide you with information about:
From the CiscoWorks2000 desktop, select Campus Manager > Path Analysis. The Path Analysis main window appears (see Figure 4-1). Refer to Table 4-1 for a description of the elements of the Path Analysis main window.
| Item | Description | Usage Notes |
|---|---|---|
Contains Path Analysis Commands | None. | |
Tool Bar | Provides quick access to frequently used menu options | None. |
Endpoint Specification Panel | Contains fields for specifying the start and end points for a trace | You can specify a Cisco devices or end user stations. |
Trace Results Tabbed Panel | Displays the results of the trace in Map, Trace, and Table format | Click on the desired tab to display the results in each format. |
Status Bar | Displays informational, diagnostic, and warning messages. | A complete list of status bar messages appears in "Troubleshooting Campus Manager," "What do the status bar and alert box messages mean?" |
Table 4-2 lists the main tasks that you can perform using Path Analysis. All actions begin from the Path Analysis main window, unless otherwise noted.
| Task | Purpose | Action |
|---|---|---|
Use the Discover All function in Path Analysis to run ANI discovery, ping sweeps, and user and node acquisition to obtain information for Path Analysis to use to perform Layer 3 and Layer 2 traces. | Select Action > Discover All. | |
Review previously supplied information and update it if necessary. | 1. Select Edit > Subnet Mapping. 2. Click Discover. 3. Modify desired information. 4. Click Apply. | |
Determine the path packets take from one device to another, including Layer 2 and Layer 3 devices. | 1. Enter IP addresses in the From and To fields. 2. Select Action > Start Trace. | |
Check the reverse direction connectivity between two end points. | 1. Select Action > Reverse Trace Direction. 2. The IP addresses in the From and To fields are automatically reversed. 3. Select Action > Start Trace. | |
Display a graphical representation of the path trace. | 1. Perform a path trace. 2. Click the Map tab. | |
Display the trace information as it would be shown on the device command line interface. | 1. Perform a path trace. 2. Click the Trace tab. | |
Display the trace information in tabular columns. | 1. Perform a path trace. 2. Click the Table tab. | |
Save a trace and view it later. | 1. Select File > Save Trace As.... 2. Enter a unique name for the trace in the label field. 3. Click OK. | |
Display the path in the Topology Services network view. | 1. Launch Topology Services, if it is not already running. 2. Select Action > Highlight Devices in Map. | |
Use CiscoView, a GUI-based device management application, to obtain dynamic status, statistics, and comprehensive configuration for Cisco internetworking devices. | Right-click a device icon in Map view to launch CiscoView for that device. | |
Trace the paths that VoIP traffic for a completed call follows on your data network. A completed call is a call that was answered and completed without error; therefore, a CDR exists for the call. First you retrieve the CDRs that contain the data relevant to the call you are interested in, and then perform the trace based on the telephone numbers in the CDR. | 1. Select Voice Trace. 2. Click Find Call.... 3. Select (or clear) the Match Calling Number check box to enable (or disable) filtering on the calling telephone number. 4. If the Match Calling Number check box is selected, enter the source telephone number in the Match Calling Number field. 5. Select (or clear) the Match Called Number check box to enable (or disable) filtering on the called telephone number. 6. If the Match Called Number check box is selected, enter the destination telephone number in the Match Called Number field. 7. Select (or clear) the Match Time Call Placed check box to enable (or disable) filtering on the time the call was placed. 8. If the Match Time Call Placed check box is selected, enter the time the call was placed. 9. Click Get Records. 10. Select the desired CDR. 11. Click Start Trace. | |
| Trace the signaling path from a gateway or IP telephone to CCM if you are experiencing latency, dropped packets, jitter, or missing dial tone with IP phone functionality. Trace a call in progress or a potential call to determine the most likely path using IP addresses rather than telephone numbers as the source and destination. | 1. Obtain IP addresses in User Tracking for the voice-enabled devices and gateways in your network, including IP phones and CCM. 2. In the Path Analysis main window, select Data Trace. 3. Enter the IP address for the gateway or IP phone in the From field. 4. Enter the IP address for CCM in the To field. 5. Click Start Trace. |
You should understand these concepts when using Path Analysis:
There are four main components in Path Analysis as shown in Figure 4-2:
Path Analysis investigates and reports on Layer 3 and Layer 2 paths between a source and destination (Leg 3 in Figure 4-2). For Path Analysis to be able to perform this analysis on Leg 3, Legs 1 and 2 must be functional.
For the path between the client and server (Leg 1) to be functional, there must be problem-free communication between server and client. (For example, problematic communication results when a firewall exists between the client and server.)
For the path between the server and the source (Leg 2) to be functional, the following requirements must be met:
no ip source-route
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Note By default, Cisco routers are configured to not block source-routed IP packets. |
For Layer 2 analysis to take place between the source and destination (Leg 3), the following conditions must be met:
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Note As a general rule, do not expect to see a Layer 2 path for every Layer 3 hop. |
For Voice over IP (VoIP) tracing, CDR logging must be enabled on all Cisco CallManager servers.
You can select source and destination end points for a data path trace:
A trace source end point must be inside the managed organization for accurate Path Analysis results, and can be either:
A trace source end point must be a Cisco device for Layer 2 tracing. Layer 3 tracing supports any trace source end point inside the managed organization.
A trace source end point must be reachable from the CiscoWorks2000 server. If it is not reachable, an alert message appears. See the See the "What do the status bar and alert box messages mean?" section in section in "Troubleshooting Campus Manager."
A trace destination end point can be any IP address or DNS name on the Internet, including addresses outside the managed organization. But firewalls and devices along the path that do not support source-routed IP packets can prevent Path Analysis from completing a trace to its intended destination. Layer 2 tracing, where possible, occurs only inside the managed organization.
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Note Layer 3 tracing does not support PCs or workstations with more than one network adapter. In this release, Path Analysis does not support devices using the AppleTalk or IPX protocols. |
It is possible to specify a source end point outside of the managed domain, but trace results from this usage might not be completely accurate. Therefore, Cisco Systems recommends against this usage.
You can trace the flow of packets for three types of VoIP telephone calls on your data network, and the the type of end points you specify depends on the type of call you are interested in (see Table 4-1).
| Type of Call | Description | Trace Methods |
|---|---|---|
Telephone call that has occured and completed. Call Detail Records (CDRs) exist only for completed calls. | Trace as voice data, using the telephone number of the called (destination end point) telelphone. | |
Telephone call that has begun, but has not yet concluded. |
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Telephone call that has not occured, but might occur in the future. |
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Call Detail Records (CDRs) exist only for completed calls (calls that have occured and have been successfully completed). CDRs contain the called and calling telephone numbers, which are required to perform a voice trace.
To find the required CDRs, you can filter your search criteria by any combination on the following three filters available in the Voice Trace Query window:
Call Detail Record (CDR) results appear in the large white space within the Voice Trace Query window. This area contains a collapsable tree display of CDRs received from the server.
You can expand a CDR to display additional information about the segment, such as the date and time of the call, the IP address of the VoIP device, the port, and the cause of termination. Information in the tree view allows you to confirm you have found the correct CDR before you start to trace the path between the end points.
The Layer 3 path is the logical path on the network that packets follow through Cisco devices such as routers. Layer 3, known also as the network layer, represents the logical network, the network at the Internet Protocol (IP) level. Layer 3 path displays the end points and routers on the network.
Layer 3 output from Path Analysis is similar to the output of the UNIX and Windows NT traceroute command, but is more detailed.
Path Analysis supports only the IP protocol at this time. AppleTalk and IPX are not supported.
Layer 3 tracing does not support PCs or workstations with more than one network adapter.
The Layer 2 path is the physical path on the network that packets follow through Cisco devices.
The Layer 2 path includes devices that are either Simple Network Management Protocol (SNMP) accessible and known through Topology Services, or are SNMP inaccessible but have been discovered by User Tracking (for example, end user hosts).
The Layer 2 path provides further resolution of the Layer 3 path, but is not necessarily a complete representation of all Layer 2 devices. For example, hubs or other devices that do not support the Cisco Discovery Protocol (CDP) do appear in the Layer 2 traces.
Path Analysis uses Asynchronous Network Interface (ANI) information to build Layer 2 paths, combining:
Path Analysis supports Layer 2 tracing on Ethernet, Fast Ethernet, Gigabit Ethernet, and LAN Emulation networks. LAN Emulation support includes tracing on the path inside an ATM cloud. For this release, Path Analysis Layer 2 tracing does not support FDDI, Token Ring, and WAN interfaces or router bridge groups.
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Note As a general rule, do not expect to see a Layer 2 path for every Layer 3 hop. |
Shortcut connections occur in the Layer 2 path where packets are IP-switched after the router has determined the next-hop destination.
Shortcuts appear in the Layer 2 path as connections between switch ports, which bypass intervening routers. Currently, the only shortcuts reported are those provided by the Cisco Catalyst 5000 switches.
You can recognize shortcuts in the Map display in one of two ways:
The VLAN/ELAN Subnet Mapping Table displays VLAN, ELAN, and associated subnet mappings. This information can be useful when performing Layer 3 traces and is required in order to perform Layer 2 traces.
You should view the VLAN/ELAN Subnet Mapping Table during the initial setup of Path Analysis and whenever your subnet mapping changes. To view the table, select Action > Subnet Mapping. The VLAN/ELAN Subnet Mapping Table window appears, similar to the one shown in Figure 4-3. If you need to, you can add or delete entries in the table, or discover a fresh set of information.
On a typical network, information displayed in the table is discovered automatically by the Path Analysis application. It is therefore unlikely that you would need to insert additional entries manually.
The first three columns in the VLAN/ELAN Subnet Mapping Table contain text that cannot be edited. The column headings are Entry Type, VTP Domain/ATM Fabric, and VLAN/ELAN. You can edit the text in any Subnet column.
One of three font styles is used to render information in a cell. The use of a particular font conveys information about the source and validity of a mapping:
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Note You must click Apply for any changes to take affect on the server. No changes take affect on the server until you click Apply. |
To verify whether you must enter information manually, click Clear, and then Discover to see the automatically discovered mapping of subnets to VLANs or ELANs, as well as subnets that do not map to any VLAN or ELAN. If you know the information is incomplete, you must enter the missing information manually.
The results of automatic discovery might vary slightly over time, even if the structure of your network is unchanged. If you obtain a complete set of information using discovery, you might want to apply that information to the server, in case subsequent discoveries are incomplete.
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Note If you remove a VLAN/ELAN from your network, you must remove the corresponding information from the table. |
There are three types of entries in this table: VLAN, ELAN, and Subnet. For each VLAN or ELAN entry in the table, the user can specify the subnets that reside on that VLAN/ELAN. If this information is not provided manually and cannot be discovered automatically, Layer 2 tracing cannot occur on that subnet.
Therefore, you should check the automatically discovered values following an installation, and enter any needed information. If information is missing from the VLAN/ELAN mapping table, no Layer 2 traces are performed on those subnets with missing mapping information.
The following conditions are acceptable mappings:
Layer 3 path tracing uses the Subnet Mapping Table in a limited way.
Successful Layer 3 tracing requires that all subnets within the managed domain are listed in one of the table rows.
Use this information to identify non-Cisco or non-Cisco Discovery Protocol (CDP) devices. These are devices that are not discovered or displayed in Topology Services views.
Layer 3 traces would generally access these devices through SNMP unless they reside on a known, managed subnet within the organization. Layer 3 path traces determine whether these devices are on a known, managed subnet by referencing them to the VLAN/ELAN Mapping Table.
If a subnet has no entry in the table, there will be no SNMP information in the table view or outgoing interface information for the non-Cisco or non-CDP devices on that subnet. Layer 3 path traces will function properly in all other respects, however.
The Entry Type column shows three types of entries: Vlan, Elan, and Subnet.
If the Entry Type column shows Vlan or Elan, subnets for corresponding VLANs or ELANs are listed in the Subnet column(s) for that row.
If the Entry Type column shows Subnet, the stand-alone subnet (one that does not map to a VLAN or ELAN) appears in the first Subnet column for that row. Do not add entries in the Subnet column for stand-alone subnets.
Posted: Thu Aug 10 13:19:25 PDT 2000
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