Basic Frame Relay Setup 5 Points

Configure the network in Figure 8-2 for basic physical Frame Relay connectivity. The following are the parameters:

■ You must use static Frame Relay maps for IP and disable Frame Relay inverse ARP. (Hint: Use no frame-relay inverse-arp on all frame-enabled interfaces.)

■ For the connection between R1 and R4, you are not permitted the keyword broadcast when mapping IP between the R1/R4 Frame Relay link.

■ No dynamic mapping is permitted.

■ No Frame Relay subinterfaces are permitted on any router.

■ Assume that RIP or IGRP will be configured over this link sometime in the next month. You are permitted to use any IOS command to accomplish this task. (Hint: Use the keyword broadcast.)

■ Assign a subnet to each link from your Class B range, as described in Table 8-1.

■ Use LMI type ANSI only. You can rely on auto-sensing the LMI type on all routers.

■ All router interface types are set to DTE. The Frame Relay switch interface type is DCE.

■ Ensure that you can also ping the local and remote IP interfaces from each router configured for Frame Relay.

■ Table 8-1 displays the IP address assignments for the Frame Relay network in Figure 8-1.

Users in VLAN_D are sending large IP packets across the Frame Relay circuit. The Frame Relay provider has asked you to set the discard eligibility when any IP packets larger than 768 bytes are sent to R4 across the Frame Relay connection.

(Hint: Set the discard eligibility, DE, bit to packets greater than 768 bytes on R2/R3.)

Basic Frame Relay Setup Solution

The topology in Figure 8-2 defines a number of Frame Relay PVCs. R1 is connected to R4 through the local DLCI number 114. Example 8-4 configures R1 to map the remote IP address 144.254.2.2 through DLCI 114. Note the local mapping to allow local pings to the assigned IP address. In this case R1 will be able to ping its local Frame Relay IP address of 144.254.2.1.

Example 8-4 Frame Relay Configuration R1

interface Serial0/1 ip address 144.254.2.1 255.255.255.252 encapsulation frame-relay ip split-horizon frame-relay map ip 144.254.2.1 114 frame-relay map ip 144.254.2.2 114 frame-relay interface-dlci 114 no frame-relay inverse-arp

Example 8-4 displays the configuration on R1 to enable Frame Relay encapsulation on R1 followed by static Frame Relay map statements (no broadcast keyword is permitted, as requested). The DLCI interface is defined as 114, and the command no frame-relay inverse-arp ensures that no dynamically learned mapping will be discovered. Make sure you use the clear frame-relay-inarp IOS command to remove any dynamically learned Frame Relay inverse ARP mappings. Another option to clear all dynamically learned Frame Relay mappings is to bounce the interface by shutting and then enabling the interface—worse case scenario if that fails is to reload all your routers.

By default, on a physical Cisco Frame Relay interface, Cisco IOS routers disable split horizon. You need to enable split horizon so that routing updates are not received from the originating router. IP split horizon is critical to distance vector protocols like RIP or IGRP.

Example 8-5 displays the Frame Relay configuration required on R4.

Example 8-5 R4 Frame Relay Configuration interface Serial0/1 ip address 144.254.2.2 255.255.255.252 encapsulation frame-relay ip split-horizon

! Note two map statements so exec users can ping local and remote IP addresses frame-relay map ip 144.254.2.1 411 frame-relay map ip 144.254.2.2 411 frame-relay interface-dlci 411

R4 is configured for Frame Relay encapsulation for interface Serial0/1 and Frame Relay map statements for the local and remote IP addresses. Frame Relay inverse ARP is disabled with the no frame-relay inverse-arp command.

Example 8-6 confirms IP connectivity between R1 and R4, and that there are only static Frame Relay circuits.

Example 8-6 Connectivity Between R1 and R4 R1#show frame-relay map

Serial0/1 (up): ip 144.254.2.1 dlci 114(0x72,0x1C20), static,

CISCO, status defined, active Serial0/1 (up): ip 144.254.2.2 dlci 114(0x72,0x1C20), static,

CISCO, status defined, active R1#ping 144.254.2.1 Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 144.254.2.1, timeout is 2 seconds: !!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 8/10/12 ms

R1#ping 144.254.2.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 144.254.2.2, timeout is 2 seconds: !!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms R1#

As requested by the lab parameters, both local and remote IP connectivity are active. Subinterfaces have not been used either.

Example 8-7 confirms the interface statistics on R1 and the LMI type setting at ANSI; because of LMI auto-sense, you do not need to define the LMI type explicitly.

Example 8-7 show interface seria!0/1 on R1

R1#show interfaces serial0/1

Serial0/1 is up, line protocol is up

Hardware is PowerQUICC Serial

Internet address is 144.254.2.1/30

MTU 1500 bytes, BW 1544 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 111797, LMI stat recvd 111798,

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 2/0, interface broadcasts 0

Example 8-7 show interface serial0/1 on R1 (Continued)

Last input 00:00:02, output 00:00:02, output hang never Last clearing of "show interface" counters 1w5d

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

378917 packets input, 17810137 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 409981 packets output, 28541580 bytes, 0 underruns 0 output errors, 0 collisions, 1 interface resets 0 output buffer failures, 0 output buffers swapped out 2 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up

Example 8-7 confirms the interface state as active (Serial0/1 is up, line protocol is up) and that the LMI type is set to ANSI (LMI type is ANSI). The physical state, signals DCD/DSR/DTR/RTS/ CTS, indicates that the interface is operational at Layer 1 of the OSI model.

The same configuration steps are completed on the remaining routers. In this case, you are not restricted with Frame Relay static map statements. Use the keyword broadcast with remote IP addresses so that routing protocols, such as OSPF, can establish neighbor adjacencies.

Example 8-8 displays the Frame Relay configuration for R2.

Example 8-8 R2 Frame Relay Configuration

interface Serial0/0

ip address 144.254.3.2 255

255

255

240

encapsulation frame-relay

ip split-horizon

frame-relay map ip 144.254

3.1

204

broadcast

frame-relay map ip 144.254

3.2

204

broadcast

frame-relay map ip 144.254

3.3

204

broadcast

frame-relay interface-dlci

204

no frame-relay inverse-arp

frame-relay lmi-type ansi

R2 has three Frame Relay map statements: one is to remote Router R4, another to remote Router R3, and one to the local IP address on R2 itself. Also, in this configuration, the LMI type is manually set.

Example 8-9 displays the Frame Relay configuration for R3.

Example 8-9 R3 Frame Relay Configuration

interface Serial0/0

ip address 144.254.3.3 255

255

255

240

encapsulation frame-relay

ip split-horizon

frame-relay map ip 144.254

3.1

304

broadcast

frame-relay map ip 144.254

3.2

304

broadcast

frame-relay map ip 144.254

3.3

304

broadcast

frame-relay interface-dlci

304

no frame-relay inverse-arp

R3 is configured for Frame Relay, and the three map statements to maintain connectivity to R4, R2, and the local IP address are assigned to Serial0/0. R2 and R3 have been configured for split horizon in case a distance vector protocol is deployed in the future.

R4 is the hub router between R2 and R3. Because a subinterface is not permitted, you must define the two local DLCIs, 402 and 403. By default, when Frame Relay is enabled on a main Cisco IOS interface, split horizon is disabled. Because R4 is connected to R2 and R3, R4 must send information it receives from R2 to R3 and from R3 to R2. If a distance vector protocol is used, you must leave split horizon disabled. Because R2 and R3 have split horizon enabled, you will not have a routing loop because both R2 and R3 will reject any networks advertised by R4 that are local (as split horizon is enabled and the main purpose is to reject networks advertised by a local router). In this lab, OSPF is configured between R4, R2, and R3, and you do not need to be concerned about split horizon; it is added here to bring to your attention the possibility of routing loops when distance vector routing protocols, such as RIP, are used in Frame Relay networks.

Example 8-10 displays the Frame Relay working configuration on R4.

Example 8-10 R4 Frame Relay Configuration

interface Serial0/0

ip address 144.254.3.1 255

255

255

240

encapsulation frame-relay

frame-relay map ip 144.254

3.1

402

broadcast

frame-relay map ip 144.254

3.2

402

broadcast

frame-relay map ip 144.254

3.3

403

broadcast

frame-relay interface-dlci

402

frame-relay interface-dlci

403

no frame-relay inverse-arp

frame-relay lmi-type ansi

no ip split-horizon

Now that R2, R3, and R4 have been configured for Frame Relay, ensure that IP connectivity is enabled by pinging all the interfaces on each router.

Example 8-11 displays a successful ping request on R4 to R2 and R3, as well as the local interface on R4.

Example 8-11 Ping Request to R2, R3, and Local IP Address

R4#show frame map

Serial0/0

(up): ip 144.254.3.1 dlci 402(0x192

0x6420), static,

CISCO, status defined, active

Serial0/0

(up): ip 144.254.3.2 dlci 402(0x192

0x6420), static,

broadcast,

CISCO, status defined, active

Serial0/0

(up): ip 144.254.3.3 dlci 403(0x193

0x6430), static,

broadcast,

CISCO, status defined, active

Serial0/1

(up): ip 144.254.2.1 dlci 411(0x19B

0x64B0), static,

CISCO, status defined, active

Serial0/1

(up): ip 144.254.2.2 dlci 411(0x19B

0x64B0), static,

CISCO, status defined, active

R4#ping 144.254.3.1

Type escape sequence to abort.

Sending 5 1 1 1 1 1

100-byte ICMP Echos to

144.254.3.1

timeout is 2 seconds:

Success rate is 100 percent (5/5)

round-trip

min/avg/max = 8/9/12 ms

R4#ping 144.254.3.2

Type escape sequence to abort.

Sending 5 ■ 1 1 1 1

100-byte ICMP Echos to

144.254.3.2

timeout is 2 seconds:

Success rate is 100 percent (5/5)

round-trip

min/avg/max = 4/4/8 ms

R4#ping 144.254.3.3

Type escape sequence to abort.

Sending 5 ■ 1 1 1 1

100-byte ICMP Echos to

144.254.3.3

timeout is 2 seconds:

Success rate is 100 percent (5/5)

round-trip

min/avg/max = 4/6/8 ms

R4#

R4 has only static Frame Relay statements, as required by the lab.

The final step is to enable Routers R2 and R3 to set the discard eligibility (DE) when users from VLAN_D send frames larger than 768 bytes. The ISP typically sets and acts on the DE.

Example 8-12 enables R2 and R3 to set the DE bit when frames larger than 768 are received from VLAN_D. This is a global configuration command.

NOTE In Cisco IOS 12.2T and higher, the Frame Relay DE group functionality is being replaced by the Modular QoS CLI (MQC) DE marking functionality. For information about the MQC commands that are used to configure Frame Relay DE marking, refer to the "Cisco IOS Quality of Service Configuration Guide" and "Cisco IOS Quality of Service Command Reference."

Example 8-12 DE Set on R2 and R3

[frame-relay de-list 5 protocol ip gt 768

This completes the Frame Relay configuration.

0 0

Post a comment