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Cisco IOS Software Releases 12.0 S

Frame Relay Switching Diagnostics and Troubleshooting

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Frame Relay Switching Diagnostics and Troubleshooting

Table Of Contents

Frame Relay Switching Diagnostics
and Troubleshooting

Feature Overview

Benefits

Restrictions

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Configuration Tasks

Monitoring and Maintaining Frame Relay Switching

Configuration Examples

Command Reference

show frame-relay pvc

Debug Commands

debug frame-relay switching


Frame Relay Switching Diagnostics
and Troubleshooting


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:

Feature Overview

Supported Platforms

Supported Standards, MIBs, and RFCs

Configuration Tasks

Monitoring and Maintaining Frame Relay Switching

Configuration Examples

Command Reference

Debug Commands

Feature Overview

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.

Benefits

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.

Restrictions

The Frame Relay Switching Diagnostics and Troubleshooting feature is not supported on terminated PVCs.

Related Documents

Cisco IOS Wide-Area Networking Configuration Guide, Release 12.0

Cisco IOS Wide-Area Networking Command Reference, Release 12.0

Supported Platforms

Cisco 12000 series

Supported Standards, MIBs, and RFCs

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.

Configuration Tasks

None.

Monitoring and Maintaining Frame Relay Switching

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.


Configuration Examples

None.

Command Reference

This section documents modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.

show frame-relay pvc

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

Release
Modification

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.


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

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.

Table 1 show frame-relay pvc Field Descriptions for Switched PVCs

Field
Description

PVC STATUS

Status of the PVC. The DCE device reports the status, and the DTE device receives the status. The PVC status is exchanged using the LMI protocol:

ACTIVE— The PVC is operational and can transmit packets.

INACTIVE—The PVC is configured, but down.

DELETED—The PVC is not present (DTE device only), which means that no status is received from the LMI protocol.

If the frame-relay end-to-end keepalive command is used, the end-to-end keepalive (EEK) status is reported in addition to the LMI status. For example:

ACTIVE (EEK UP) —The PVC is operational according to LMI and end-to-end keepalives.

ACTIVE (EEK DOWN)—The PVC is operational according to LMI, but end-to-end keepalive has failed.

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 maximum transmission unit (MTU).


1 The LOCAL PVC STATUS and NNI PVC STATUS fields are displayed only for PVCs configured on Frame Relay NNI interface types. These fields are not displayed if the PVC is configured on DCE or DTE interface types.

2 The detailed packet drop fields are displayed for switched Frame Relay PVCs only. These fields are not displayed for terminated PVCs.

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.

Table 2 show frame-relay pvc Field Descriptions

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. The DCE device reports the status, and the DTE device receives the status. When you disable the Local Management Interface (LMI) mechanism on the interface (by using the no keepalive command), the PVC status is STATIC. Otherwise, the PVC status is exchanged using the LMI protocol:

STATIC—LMI is disabled on the interface.

ACTIVE— The PVC is operational and can transmit packets.

INACTIVE—The PVC is configured, but down.

DELETED—The PVC is not present (DTE device only), which means that no status is received from the LMI protocol.

If the frame-relay end-to-end keepalive command is used, the end-to-end keepalive (EEK) status is reported in addition to the LMI status. For example:

ACTIVE (EEK UP) —The PVC is operational according to LMI and end-to-end keepalives.

ACTIVE (EEK DOWN)—The PVC is operational according to LMI, but end-to-end keepalive has failed.

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.


1 DLCI = data-link connection identifier.

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.

Table 3 show frame-relay pvc Field Descriptions with Traffic Shaping 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.


1 CIR = committed information rate.

2 Bc = committed burst size.

3 Be = excess burst size.

Debug Commands

This section documents the new debug command related to the Frame Relay Switching Diagnostics and Troubleshooting feature.

debug frame-relay switching

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]

no debug frame-relay switching

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

Release
Modification

12.0(12)S

This command was introduced.


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