Configuring Point-to-Point Frame Relay Links

Frame Relay is a legacy technology however it’s still fairly common in developing nations due to its simplicity and price. This lab will discuss and demonstrate how to configure a Point to Point Frame-Relay Circuit.

Real World Application & Core Knowledge

Frame Relay is a dying breed however you will encounter it quite often as many companies are migrating away from this technology. As a CCNA you’ll be required to understand how to configure and manage frame relay links.

Frame Relay is a layer 2 switching technology which switches frames through an ISP. The interface at which the both customer edge devices are connected to are assigned a DLCI (Data Link Connection Identifier) which operates in a fashion similar to a telephone extension. You pick up a phone and you dial extension 1234 from 1235 and the connection is made and you have two way communication.

Frame Relay will assign each frame exiting the egress interface of a customer edge router a DLCI which identifies which path the frame is to travel once it reaches the provider edge router. So for example DLCI 122 could will go between R1 to R2 which could be located in NYC and San Francisco as DLCI 123 goes between Routers R1 and R3, which R3 could be located in Miami.

Point to Point Frame Relay links can be configured in one of two ways. First being that you use the physical interface by assigning a single frame relay interface DLCI so in this case any traffic exiting that interface is encapsulated with the Frame Relay interface DLCI number

The second way of configuring a point to point frame relay interface is by creating a Point-to-Point Sub-interface as discussed demonstrated in the next lab.

In this lab you’ll familiarize yourself with the following commands;

Command	Description
encapsulation frame-relay	This command is executed in serial interface configuration mode to set the encapsulation to Frame Relay.
frame-relay interface-dlci #	This command is executed in Serial interface configuration mode to configure the point-to-point frame-relay interface DLCI assigned to the interface.
show frame-relay pvc #	This command when executed in privileged mode will display all DLCI’s learned by the router from the frame relay switch as well as the PVC status and frame statistics.

Lab Prerequisites

If you are using GNS3 than load the Free CCNA Workbook GNS3 topology than start devices; R1 and R2.
Establish a console session with devices R1 and R2 than configure the devices respected hostname(s).
Configure R1’s Serial0/0 interface with the IP address 10.10.21.1/30 and R2’s Serial0/0 interface with the IP address 10.10.21.2/30

Lab Objectives

Configure R1 Serial0/0 interface to encapsulate traffic using Frame Relay encapsulation and use the interface DLCI of 122; verify your configuration using viewing the interface and pvc properties for DLCI 122.
Configure R2 Serial0/0 interface to encapsulate traffic using Frame Relay encapsulation and use the interface DLCI of 221; verify your configuration using viewing the pvc properties for DLCI 122 and pinging R1’s Serial0/0 interface from R2.

Lab Instruction

Objective 1. – Configure R1 Serial0/0 interface to encapsulate traffic using Frame Relay encapsulation and use the interface DLCI of 122; verify your configuration using viewing the interface and pvc properties for DLCI 122.

R1 con0 is now available



Press RETURN to get started.



R1>enable
R1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#interface Serial0/0
R1(config-if)#no shutdown
R1(config-if)#
%LINK-3-UPDOWN: Interface Serial0/0, changed state to up
R1(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed
state to up
R1(config-if)#encapsulation frame-relay
R1(config-if)#frame-relay interface-dlci 122
R1(config-fr-dlci)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console
R1#

Verification for show interface Serial0/0 and show frame-relay pvc shown below;

R1#show interface serial0/0
Serial0/0 is up, line protocol is up 
  Hardware is PowerQUICC Serial
  Internet address is 10.10.12.1/30
  MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation FRAME-RELAY, loopback not set
  Keepalive set (10 sec)
  CRC checking enabled
  LMI enq sent  18, LMI stat recvd 18, LMI upd recvd 0, DTE LMI up
  LMI enq recvd 0, LMI stat sent  0, LMI upd sent  0
  LMI DLCI 1023  LMI type is CISCO  frame relay DTE
  FR SVC disabled, LAPF state down
  Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
  Last input 00:00:00, output 00:00:06, output hang never
  Last clearing of "show interface" counters 00:04:50
  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 0 bits/sec, 0 packets/sec
     36 packets input, 1604 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     1 input errors, 0 CRC, 1 frame, 0 overrun, 0 ignored, 0 abort
     23 packets output, 684 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

R1#show frame-relay pvc 122
PVC Statistics for interface Serial0/0 (Frame Relay DTE)

DLCI = 122, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0

  input pkts 26            output pkts 4            in bytes 1554      
  out bytes 416            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 00:03:46, last time pvc status changed 00:02:04
R1#

You’ll notice that the PVC for DLCI 122 is inactive, this is due to the terminating end not being active, once R2’s Serial0/0 interface is configured properly the PVC will be active and pass traffic.

Objective 2. – Configure R2 Serial0/0 interface to encapsulate traffic using Frame Relay encapsulation and use the interface DLCI of 221; verify your configuration using viewing the pvc properties for DLCI 122 and pinging R1’s Serial0/0 interface from R2.

First off you’ll need to configure the interface for frame relay encapsulation and to use the interface dlci of 221 as shown below;

R2 con0 is now available



Press RETURN to get started.



R2>enable
R2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#interface Serial0/0
R2(config-if)#no shutdown
R2(config-if)#
%LINK-3-UPDOWN: Interface Serial0/0, changed state to up
R2(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed
state to up
R2(config-if)#encapsulation frame-relay
R2(config-if)#frame-relay interface-dlci 221
R2(config-fr-dlci)#end
R2#
%SYS-5-CONFIG_I: Configured from console by console
R2#

Now that the interface has been configured its time to verify the configuration by viewing the DLCI information and pinging R1’s Serial0/0 interface from R2 as demonstrated below;

R2#show frame-relay pvc 221

PVC Statistics for interface Serial0/0 (Frame Relay DTE)

DLCI = 221, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0

  input pkts 9             output pkts 40           in bytes 796       
  out bytes 2390           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 33        out bcast bytes 1662      
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
  pvc create time 00:04:40, last time pvc status changed 00:00:04
R2#ping 10.10.12.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.12.1, timeout is 2 seconds:
..!!!
Success rate is 60 percent (3/5), round-trip min/avg/max = 28/29/32 ms
R2#

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