Frame Relay Monitoring and Troubleshooting

Frame Relay Monitoring and Troubleshooting

Frame Relay Monitoring and Troubleshooting

The following list summarizes the commands to use for viewing specific Frame Relay information on the router.

If you want to view . . .	Use . . .
DLCI numbers	show run show frame pvc
Frame Relay encapsulation method	show int show run
LMI information and traffic statistics	show frame lmi show int
Interface configuration (DCE or DTE)	show frame pvc show int
Global traffic statistics	show frame traffic
Addresses and associated DLCIs	show frame map

Note: Output for the show interfaces command shows an entry for DLCI followed by a number. This information is not the DLCI number associated with the interface.

As you troubleshoot Frame Relay, keep in mind the following tips:

• All routers at all locations must be configured to use the same frame relay encapsulation method.
• When using all Cisco routers, you can use the default Frame Relay encapsulation type (cisco). When using routers of multiple vendors, use the ietf encapsulation type.
• Frame Relay routers must know the DLCI number that is used to reach remote routers.
• Use inverse arp to dynamically discover DLCI numbers.
• Use static mappings to associate DLCI numbers with IP addresses manually.
• When configuring subinterfaces, do not set an IP address on the main interface. Instead, set IP addresses on each subinterface.
• For a point-to-point subinterface, or a multipoint subinterface with dynamic addressing, you must manually assign a DLCI to the subinterface.
• By default, Cisco routers autosense the LMI type and configure themselves accordingly. You only need to set the LMI type if autosensing does not work or if you want to manually assign it.

Shown here is sample output from the show frame-relay pvc command.

PVC Statistics for interface Serial5/1 (Frame Relay DTE)

DLCI = 55, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial5/1.1

   input pkts 64589   output pkts 3865     in bytes 15400

   out bytes 33896    dropped pkts 66      in FECN pkts 12

   in BECN pkts 15    out FECN pkts 0      out BECN pkts 0

   in DE pkts 5       out DE pkts 1

   out bcast pkts 15  out bcast bytes 128

pvc create time 00:35:11, last time pvc status changed 00:00:22

The following table describes major components of the output.

Entry	Description
DLCI = 55	Lists the DLCI number assigned to the PVC.
DLCI USAGE	Identifies the role of the router on the virtual circuit. For DTE frame relay devices, the usage will be LOCAL. For DCE devices, the usage will be SWITCHED.
PVC STATUS	Reports the PVC status as reported from the DCE through the LMI protocol. When you connect the DTE to the circuit, the LMI protocol communicates the PVC status as sent from the DCE device. The status will be one of the following: ACTIVE indicates the PVC is configured, is operational, and can transmit packets. LMI is active. INACTIVE indicates that the PVC has been configured, but has not received an active state from the DCE. This status identifies the PVC as down. The interface line status is also down. STATIC indicates that LMI has been disabled. A configuration exists, but status information cannot be received from the DCE because LMI has been disabled. DELETED indicates that the PVC has been configured, but that the LMI protocol has not reported status information.
FECN/BECN pkts	Identifies the number of packets received (in) or sent (out) that had the FECN or BECN bit set. Both flags identify that network congestion exists. Receiving devices use these flags to decide what to do about the congestion, such as slowing down or implementing a flow control mechanism. On a DTE device: in FECN pkts are packets sent from the DCE to the destination DTE device to indicate that congestion has occurred. A DTE that receives a FECN packet might slow its rate of data request, or it might implement flow control to detect and recover from lost packets. in BECN pkts are packets sent from the DCE to the sending DTE device to indicate that congestion has occurred. A DTE that receives a BECN packet might slow down its transmission rate. out FECN pkts and out BECN pkts are packets sent from the DTE. On a DTE device, these values have little meaning as the DTE is typically the terminating point in the circuit.
DE pkts	Identifies the number of packets sent or received that had the Discard Eligibility (DE) bit set. The DE bit is used to identify packets with a lower priority that could be dropped if necessary.