Lab Practice 4 - Frame Relay

In this second CCNA TechLab you will learn how to configure a simple frame relay network. Frame relay is a layer 1 and 2 protocol used for WAN connection. It is used by many companies to provide links between branch offices and the company headquarters.

If you haven’t already, set up the router's basic configuration (hostname, passwords, telnet access, etc.) If don't know how to do these things then refer to the TechLab "Configuring a RIP network". Here is our example network:

CONFIGURING THE FRAME RELAY SWITCH

First we will configure the frame relay switch (in my lab the 2520). It has links to all of the endpoints via back-to-back serial cables. It will be the DCE for all connections.


STEP 1. Change the router's name to frame-switch

Enter configuration mode by using the following command:
Router# configure terminal

Change the host name of the router to frame-switch by using the following command:
Router(config)# hostname frame-switch
frame-switch(config)#


STEP 2. Enable the router to become a frame-relay switch

Configure the router to act as a frame relay switch by using the following command:
frame-switch(config)# frame-relay switching


STEP 3. Configure the frame relay switch's interfaces

Enter interface configuration mode for the first connected serial interface, e.g. serial 0:
frame-switch(config)# interface serial 0

Remove the IP address:
frame-switch(config-if)# no ip address

Set the clock rate to 64000:
frame-switch(config-if)# clock rate 64000

Set the encapsulation type to Frame Relay:
frame-switch(config-if)# encapsulation frame-relay

Set the LMI type to ANSI:
frame-switch(config-if)# frame-relay lmi-type ansi

Set the Frame Relay interface type to dce:
frame-switch(config-if)# frame-relay intf-type dce

Enable the interface:
frame-switch(config-if)# no shutdown

Repeat the commands above for the other connected interfaces on the frame relay switch.


STEP 4. Configuring the end-point routers and their interfaces

Change the host name of the router to 2501-A, 2501-B, or 2501-C, as shown in the network diagram by using the following command:
Router(config)# hostname 2501-A

Enter interface configuration mode for the connected serial interface:
2501-A(config)# interface serial 0

Assign the IP address as shown in the diagram (ie. for router 2501-A, use 10.10.12.2 with subnet 255.255.255.240):
2501-A(config-if)# ip address 10.10.12.2 255.255.255.240

Set the encapsulation type to Frame Relay:
2501-A(config-if)# encapsulation frame-relay

Set the LMI type to ANSI:
2501-A(config-if)# frame-relay lmi-type ansi

Enable the interface:
2501-A(config-if)# no shutdown

Repeat the steps above for the other end-point routers.


STEP 5. Verify your progress

On the frame-switch, use the show interface command to verify the operation for all connected interfaces. The output should be as following:

frame-switch# show interface serial 1
Serial1 is up, line protocol is up
Hardware is CD2430 in sync mode
MTU 1500 bytes, BW 115 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation FRAME-RELAY, loopback not set
Keepalive set (10 sec)
LMI enq sent 42, LMI stat recvd 0, LMI upd recvd 0
LMI enq recvd 44, LMI stat sent 1, LMI upd sent 0, DCE LMI up
LMI DLCI 0 LMI type is ANSI Annex D frame relay DCE
FR SVC disabled, LAPF state down
Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0
Last input 00:00:09, output 00:00:09, output hang never
Last clearing of "show interface" counters 00:18:29
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 0/1/32 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 86 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
45 packets input, 630 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, 616 bytes, 0 underruns
0 output errors, 0 collisions, 36 interface resets
0 output buffer failures, 0 output buffers swapped out
29 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up


STEP 6. Configure DLCI mappings

Now we need to configure the DLCI mappings for each interface by using the frame-relay route command. The format for this command is:

frame-switch(config-if)# frame-relay route interface

You need to configure the appropriate mappings on all the connected interface on the frame relay switch. Following are the commands that need to be configured for our example network.

frame-switch#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
frame-switch(config)# interface serial 1
frame-switch(config-if)# frame-relay route 100 interface s3 101
frame-switch(config-if)# frame-relay route 300 interface s2 301

frame-switch(config-if)# interface serial 2
frame-switch(config-if)# frame-relay route 201 interface s3 200
frame-switch(config-if)# frame-relay route 301 interface s1 300

frame-switch(config-if)# interface serial 3
frame-switch(config-if)# frame-relay route 200 interface s2 201
frame-switch(config-if)# frame-relay route 101 interface s1 100
CTRL-Z


STEP 7. Verify configuration and connection

Go to one of the endpoints and look at the output of some of the "show frame-relay" commands. You can see the DLCI mappings have propagated to the endpoints. You don't need to set them up on the endpoints, only on the switch.

Display the frame relay DLCI mappings by using the following command:

2501-A# show frame-relay map
Serial0 (up): ip 10.10.12.3 dlci 201(0xC9,0x3090), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 10.10.12.4 dlci 301(0x12D,0x48D0), dynamic,
broadcast,, status defined, active


Display the frame relay pvc statistics by using the following command:

2501-A# show frame-relay pvc
PVC Statistics for interface Serial0 (Frame Relay DTE)

DLCI = 201, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0

input pkts 7	output pkts 6	in bytes 580
out bytes 550	dropped pkts 1	in FECN pkts 0
in BECN pkts 0	out FECN pkts 0	out BECN pkts 0
in DE pkts 0	out DE pkts 0

pvc create time 00:05:03, last time pvc status changed 00:04:13

DLCI = 301, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0

input pkts 16	output pkts 6	in bytes 1110
out bytes 550	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

pvc create time 00:04:45, last time pvc status changed 00:04:35


Ping the other two end-point routers from 2501-A:

2501-A# ping 10.10.12.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 10.10.12.3, timeout is 2 seconds: !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 60/60/60 ms


2501-A# ping 10.10.12.4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echoes to 10.10.12.4, timeout is 2 seconds: !!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/59/60 ms


As you can see (if you configured everything correctly) the end-point routers can communicate with each other without a routing protocol or static routes being configured on the frame relay switch.

You can display the switching table on the router by using the following command:

frame-switch# show frame route

Input Intf	Input Dlci	Output Intf	Output Dlci	Status
Serial1	100	Serial3	101	active
Serial1	300	Serial2	301	active
Serial2	201	Serial3	200	active
Serial2	301	Serial1	300	active
Serial3	101	Serial1	100	active
Serial3	200	Serial2	201	active