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This feature module describes the Frame Relay Switching Diagnostics and Troubleshooting feature. It includes information on the benefits of the new feature, supported platforms, related documents, and more.
This document includes the following sections:
The Frame Relay Switching Diagnostics and Troubleshooting feature enhances Frame Relay switching functionality by providing tools to diagnose problems in switched Frame Relay networks.
Before this feature was introduced, the show frame-relay pvc command displayed the number of packets dropped from switched permanent virtual circuits (PVCs). With the Frame Relay Switching Diagnostics and Troubleshooting feature, the show frame-relay pvc command has been enhanced so that in addition to the number of packets dropped, it now displays detailed reasons why packets were dropped. The command has also been enhanced to display the local PVC status, the Network-to-Network (NNI) PVC status, and the overall PVC status.
If a problem is observed, the new debug frame-relay switching command can be used to display the status of packets on switched PVCs at regular intervals. This new debug command displays information such as the number of packets that were switched, why packets were dropped, and changes in status of physical links and PVCs. Debug information is displayed only when there has been a change from one configured interval to the next.
The Frame Relay Switching Diagnostics and Troubleshooting feature provides tools for diagnosing problems in switched Frame Relay networks. If packets are being dropped from switched PVCs, network administrators can use these tools to quickly find out why. In addition, the NNI status display has been enhanced to give a more accurate picture of overall PVC health.
The Frame Relay Switching Diagnostics and Troubleshooting feature is not supported on terminated PVCs.
Cisco IOS Wide-Area Networking Configuration Guide, Release 12.0
Cisco IOS Wide-Area Networking Command Reference, Release 12.0
Cisco 12000 series
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
None.
To diagnose problems in switched Frame Relay networks, use one or both of the following privileged EXEC commands:
| Command | Purpose |
|---|---|
Router#show frame-relay pvc | Displays statistics about PVCs for Frame Relay interfaces. |
Router#debug frame-relay switching | Displays debug messages for switched Frame Relay PVCs. |
None.
This section documents modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
To display statistics about PVCs for Frame Relay interfaces, use the show frame-relay pvc EXEC command.
show frame-relay pvc [type] [number] [dlci]
Syntax Description
type (Optional) Interface type. number (Optional) Interface number. dlci (Optional) One of the specific DLCI numbers used on the interface. Statistics for the specified PVC display when a DLCI is also specified.
Command Modes
EXEC
Command History
10.0 This command was introduced. 12.0(12)S This command was modified to display reasons for packet drops and complete PVC status information for switched PVCs.
Release
Modification
Usage Guidelines
Statistics Reporting
To obtain statistics about PVCs on all Frame Relay interfaces, use this command with no arguments.
Per-VC counters are not incremented at all when either autonomous or SSE switching is configured; therefore, PVC values will be inaccurate if either switching method is used.
DCE, DTE, and Logical Interfaces
When the interface is configured as a DCE and the data-link connection identifier (DLCI) usage is SWITCHED, the value displayed in the PVC STATUS field is determined by the status of outgoing interfaces (up or down) and the status of the outgoing PVC. The status of the outgoing PVC is updated in the Local Management Interface (LMI) message exchange. PVCs terminated on a DCE interface use the status of the interface to set the PVC STATUS.
In the case of a hybrid DTE switch, the PVC status on the DTE side is determined by the PVC status reported by the external Frame Relay network through the LMI.
If the outgoing interface is a tunnel, the PVC status is determined by what is learned from the tunnel.
Traffic Shaping
Congestion control mechanisms are currently not supported on switched PVCs, but the switch passes forward explicit congestion notification (FECN) bits, backward explicit congestion notification (BECN) bits, and discard eligibility (DE) bits unchanged from entry to exit points in the network.
If an LMI status report indicates that a PVC is not active, then it is marked as inactive. A PVC is marked as deleted if it is not listed in a periodic LMI status message.
Examples
Switched PVC Example
The following is sample output from the show frame-relay pvc command for a switched Frame Relay PVC:
FRSW-2# show frame-relay pvc 16 PVC Statistics for interface POS5/0 (Frame Relay NNI) DLCI = 16, DLCI USAGE = SWITCHED, PVC STATUS = INACTIVE, INTERFACE = POS5/0 LOCAL PVC STATUS = INACTIVE, NNI PVC STATUS = ACTIVE input pkts 0 output pkts 0 in bytes 0 out bytes 0 dropped pkts 100 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 0 out bcast bytes 0 switched pkts 0 Detailed packet drop counters: no out intf 0 out intf down 100 no out PVC 0 in PVC down 0 out PVC down 0 pkt too big 0 pvc create time 00:25:32, last time pvc status changed 00:06:31
Table 1 describes the fields shown in the display relevant switched PVCs.
| Field | Description |
|---|---|
LOCAL PVC STATUS1 | Status of PVC locally configured on the NNI interface. |
NNI PVC STATUS1 | Status of PVC learned over the NNI link. |
no out intf2 | Number of packets dropped because there is no output interface. |
out intf down2 | Number of packets dropped because the output interface is down. |
no out PVC2 | Number of packets dropped because the outgoing PVC is not configured. |
in PVC down2 | Number of packets dropped because the incoming PVC is inactive. |
out PVC down2 | Number of packets dropped because the outgoing PVC is inactive. |
pkt too big2 | Number of packets dropped because the packet size is greater than media MTU3. |
DCE Interface with Traffic Shaping
The following is sample output from the show frame-relay pvc command:
Router# show frame-relay pvc
PVC Statistics for interface Serial (Frame Relay DCE)
DLCI = 22, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial3/1:1.1
input pkts 9 output pkts 300008 in bytes 2754
out bytes 161802283 dropped pkts 0 in FECN pkts 0
in BECN pkts 1 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
outbcast pkts 0 outbcast bytes 0
Shaping adapts to ForeSight in ForeSight signals 1304
pvc create time 1d05h, last time pvc status changed 00:11:00
If the circuit is configured for shaping to adapt to BECN, it is indicated in the display:
Shaping adapts to BECN
If traffic shaping on the circuit does not adapt to either BECN or ForeSight, nothing extra shows:
DLCI = 100, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE
input pkts 0 output pkts 0 in bytes 0
out bytes 0 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
outbcast pkts 0 outbcast bytes 0
pvc create time 0:03:03 last time pvc status changed 0:03:03
Num Pkts Switched 0
Multipoint Subinterfaces Example
The following is sample output from the show frame-relay pvc command for multipoint subinterfaces. The output displays both the subinterface number and the DLCI. This display is the same whether the PVC is configured for static or dynamic addressing.
DLCI = 300, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0.103 input pkts 10 output pkts 7 in bytes 6222 out bytes 6034 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 outbcast pkts 0 outbcast bytes 0 pvc create time 0:13:11 last time pvc status changed 0:11:46 DLCI = 400, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0.104 input pkts 20 output pkts 8 in bytes 5624 out bytes 5222 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 outbcast pkts 0 outbcast bytes 0 pvc create time 0:03:57 last time pvc status changed 0:03:48
Table 2 describes the fields shown in the displays.
| Field | Description |
|---|---|
DLCI | One of the DLCI numbers for the PVC. |
DLCI USAGE | Lists SWITCHED when the router or access server is used as a switch, or LOCAL when the router or access server is used as a DTE. |
PVC STATUS | Status of the PVC: ACTIVE, INACTIVE, or DELETED. |
INTERFACE = Serial0.103 | Specific subinterface associated with this DLCI. |
input pkts | Number of packets received on this PVC. |
output pkts | Number of packets sent on this PVC. |
in bytes | Number of bytes received. |
out bytes | Number of bytes sent. |
dropped pkts | Number of packets dropped by the router at Frame Relay level because an active outbound DLCI was not found. |
in FECN pkts | Number of packets received with the FECN bit set. |
in BECN pkts | Number of packets received with the BECN bit set. |
out FECN pkts | Number of packets sent with the FECN bit set. |
out BECN pkts | Number of packets sent with the BECN bit set. |
in DE pkts | Number of DE packets received. |
out DE pkts | Number of DE packets sent. |
outbcast pkts | Number of output broadcast packets. |
outbcast bytes | Number of output broadcast bytes. |
pvc create time | Time the PVC was created. |
last time pvc status changed | Time the PVC changed status (active to inactive). |
Num Pkts Switched | Number of packets switched within the router or access server; this PVC is the source PVC. |
DTE Interface Without Traffic Shaping Example
The following is sample output from the show frame-relay pvc command with no traffic shaping configured on the interface.
Router# show frame-relay pvc PVC Statistics for interface Serial1 (Frame Relay DTE) DLCI = 100, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1 input pkts 0 output pkts 0 in bytes 0 out bytes 0 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 0 out bcast bytes 0
DTE Interface With Traffic Shaping Example
The following is sample output from the show frame-relay pvc command when traffic shaping is in effect:
Router# show frame-relay pvc
PVC Statistics for interface Serial1 (Frame Relay DTE)
DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1
input pkts 14046 output pkts 4339 in bytes 960362
out bytes 675566 dropped pkts 0 in FECN pkts 0
in BECN pkts 148 out FECN pkts 0 out BECN pkts 0
in DE pkts 44 out DE pkts 0
out bcast pkts 4034 out bcast bytes 427346
pvc create time 11:59:29, last time pvc status changed 11:59:29
CIR 64000 BC 8000 BE 1600 limit 2000 interval 125
mincir 32000 byte incremen 500 BECN response yes
pkts 9776 bytes 838676 pkts delayed 0 bytes delayed 0
shaping inactive
List Queue Args
1 4 byte-count 100
Output queues: (queue #: size/max/drops)
0: 0/20/0 1: 0/20/0 2: 0/20/0 3: 0/20/0 4: 0/20/0
5: 0/20/0 6: 0/20/0 7: 0/20/0 8: 0/20/0 9: 0/20/0
10: 0/20/0 11: 0/20/0 12: 0/20/0 13: 0/20/0 14: 0/20/0
15: 0/20/0 16: 0/20/0
Table 3 describes the additional fields shown in the display when traffic shaping is in effect.
| Field | Description |
|---|---|
CIR | Current CIR1, in bits per second. |
BC | Current Bc2, in bits. |
BE | Current Be3, in bits. |
limit | Maximum number of bytes transmitted per internal interval (excess plus sustained). |
interval | Interval being used internally (may be smaller than the interval derived from Bc/CIR; this happens when the router determines that traffic flow will be more stable with a smaller configured interval). |
mincir | Minimum CIR for the PVC. |
incremen | Number of bytes that will be sustained per internal interval. |
BECN response | Frame Relay has BECN Adaptation configured. |
List Queue Args | Identifier and parameter values for a custom queue list defined for the PVC. These identifiers and values correspond to the command queue-list 1 queue 4 byte-count 100. |
Output queues | Output queues used for the PVC, with the current size, the maximum size, and the number of dropped frames shown for each queue. |
This section documents the new debug command related to the Frame Relay Switching Diagnostics and Troubleshooting feature.
To display debug messages for switched Frame Relay PVCs, use the debug frame-relay switching EXEC command. To disable Frame Relay switching debugging, use the no form of this command.
debug frame-relay switching interface interface dlci [interval interval]
Syntax Description
interface interface Name of the Frame Relay interface. dlci DLCI number of the switched PVC to be debugged. interval interval (Optional) Interval in seconds at which debugging messages will be updated.
Defaults
The default interval is 1 second.
Command History
12.0(12)S This command was introduced.
Release
Modification
Usage Guidelines
The debug frame-relay switching command can be used only on switched Frame Relay PVCs, not terminated PVCs.
Debug statistics are displayed only if they have changed.
 |
Note Although statistics are displayed at configured intervals, there may be a delay between the occurrence of a debug event (such as a packet drop) and the display of that event. The delay may be as much as the configured interval plus 10 seconds. |
Examples
The following example shows sample output for the debug frame-relay switching command:
FRSWDiag-2# debug frame-relay switching interface pos 2/2 116 interval 1 Frame Relay switching debugging is on Display frame switching debug on interface POS2/2 dlci 116 02:09:00: POS2/2 dlci 116: 230074 packets switched to POS2/3 dlci 116 02:09:00: POS2/2 dlci 116: 115037 packets output 02:09:00: POS2/2 dlci 116: Incoming PVC status changed to ACTIVE 02:09:00: POS2/2 dlci 116: Outgoing PVC status changed to ACTIVE 02:09:00: POS2/2 dlci 116: Incoming interface hardware module state changed to UP 02:09:00: POS2/2 dlci 116: Outgoing interface hardware module state changed to UP 02:09:11: POS2/2 dlci 116: 6812 packets switched to POS2/3 dlci 116 02:09:11: POS2/2 dlci 116: 3406 packets output 02:09:23: POS2/2 dlci 116: 8032 packets switched to POS2/3 dlci 116 02:09:23: POS2/2 dlci 116: 4016 packets output
Posted: Thu Aug 31 13:48:39 PDT 2000
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