CCNA :: Part 8 - Frame Relay Monitoring and Troubleshooting

Several commands are used frequently to check the status of your interfaces and PVCs once you have Frame Relay encapsulation set up and running:

iscoTests-HQ#sh frame ?
  end-to-end     Frame-relay end-to-end VC information
  fragment       show frame relay fragmentation information
  ip             show frame relay IP statistics
  lapf           show frame relay lapf status/statistics
  lmi            show frame relay lmi statistics
  map            Frame-Relay map table
  multilink      Show Multilink Frame Relay bundle information
  pvc            show frame relay pvc statistics
  qos-autosense  show frame relay qos-autosense information
  route          show frame relay route
  svc            show frame relay SVC stuff
  traffic        Frame-Relay protocol statistics
  vc-bundle      FR VC-Bundle
  vofr           Show frame-relay VoFR statistics

CiscoTests-HQ#sh frame

The most common parameters that you view with the show frame-relay command are lmi, pvc, and map.

The show frame-relay lmi command will give you the LMI traffic statistics exchanged between the local router and the Frame Relay switch. The router output from the show frame-relay lmi command shows you any LMI errors, plus the LMI type. Here’s an example:

CiscoTests-HQ#sh frame-relay lmi

LMI Statistics for interface Serial1/0 (Frame Relay DTE) LMI TYPE = CISCO
  Invalid Unnumbered info 0             Invalid Prot Disc 0
  Invalid dummy Call Ref 0              Invalid Msg Type 0
  Invalid Status Message 0              Invalid Lock Shift 0
  Invalid Information ID 0              Invalid Report IE Len 0
  Invalid Report Request 0              Invalid Keep IE Len 0
  Num Status Enq. Sent 0                Num Status msgs Rcvd 0
  Num Update Status Rcvd 0              Num Status Timeouts 0
  Last Full Status Req never            Last Full Status Rcvd never
CiscoTests-HQ#

The show frame pvc command will present you with a list of all configured PVCs and DLCI numbers. It provides the status of each PVC connection and traffic statistics too. It will also give you the number of BECN and FECN packets received on the router per PVC. Here is an example:

CiscoTests-HQ#show frame-relay pvc

PVC Statistics for interface Serial1/0 (Frame Relay DTE)

              Active     Inactive      Deleted       Static
  Local          0            0            2            0
  Switched       0            0            0            0
  Unused         0            0            0            0

DLCI = 201, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial1/0.201

  input pkts 0             output pkts 0            in bytes 0
  out bytes 0              dropped pkts 0           in pkts dropped 0
  out pkts dropped 0                out bytes dropped 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
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
  pvc create time 00:10:00, last time pvc status changed 00:09:58

DLCI = 302, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial1/0.302

  input pkts 0             output pkts 0            in bytes 0
  out bytes 0              dropped pkts 0           in pkts dropped 0
  out pkts dropped 0                out bytes dropped 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
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
  pvc create time 00:10:01, last time pvc status changed 00:09:59
CiscoTests-HQ#

If you only want to see information about PVC 201, you can type the command show frame-relay pvc 201.

You can use the show interface command to check for LMI traffic. The show interface command displays information about the encapsulation, as well as layer 2 and layer 3 information. It also displays line, protocol, DLCI, and LMI information. Here is an example:

CiscoTests-HQ#sh int se 1/0
Serial1/0 is up, line protocol is up
  Hardware is M4T
  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation FRAME-RELAY, crc 16, loopback not set
  Keepalive set (10 sec)
  Restart-Delay is 0 secs
  LMI enq sent  19, LMI stat recvd 20, LMI upd recvd 0, DTE LMI up
  LMI enq recvd 0, LMI stat sent  0, LMI upd sent  0
  LMI DLCI 0  LMI type is ANSI Annex D  frame relay DTE
  FR SVC disabled, LAPF state down
  Broadcast queue 0/64, broadcasts sent/dropped 10/0, interface broadcasts 0
  Last input 00:00:01, output 00:00:01, output hang never
  Last clearing of "show interface" counters 00:17:42
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations  0/1/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1158 kilobits/sec
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 1000 bits/sec, 0 packets/sec
     32 packets input, 1428 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     44 packets output, 5114 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     1 carrier transitions     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

CiscoTests-HQ#

The LMI DLCI above is used to define the type of LMI being used. If it happens to be 1023, it’s the default LMI type of Cisco. If LMI DLCI is zero, then it’s the ANSI LMI type (Q.933A uses 0 as well).

The show frame map command displays the Network layer–to–DLCI mappings. Here’s how that looks:

CiscoTests-HQ#sh frame-relay map
Serial1/0.201 (up): point-to-point dlci, dlci 201(0xC9,0x3090), broadcast
          status defined, active
Serial1/0.302 (up): point-to-point dlci, dlci 302(0x12E,0x48E0), broadcast
          status defined, active
CiscoTests-HQ#

Important is that the Network layer addresses were resolved with the dynamic protocol Inverse ARP (IARP). After the DLCI number is listed, you can see some numbers in parentheses. The first one is 0xC9, which is the hex equivalent for the DLCI number 201, used on serial 1/0.201. And the 0x12E is the hex for DLCI 302 used on serial 1/0.302. The second numbers, 0x3090 and 0x48E0, are the DLCI numbers configured in the Frame Relay frame. They’re different because of the way the bits are spread out in the frame.

Troubleshooting Frame Relay networks isn’t any harder than troubleshooting any other type of network as long as you know what to look for. First on the list are serial encapsulation problems. As you learned recently, there are two Frame Relay encapsulations: Cisco and IETF. Cisco is the default, and it means that you have a Cisco router on each end of the Frame Relay network. If you don’t have a Cisco router on the remote end of your Frame Relay network, then you need to run the IETF encapsulation.

Once you verify that you’re using the correct encapsulation, you then need to check out your Frame Relay mappings. You cannot use a remote DLCI to communicate to the Frame Relay switch; you must use your DLCI number!