Frame Relay Hardware and Cabling Question 1

[sk391]

Hi guys,
I have a question about the hardware and phyical connections needed to setup a frame relay network. I have the following routers and need to get them setup for frame relaying for CCNA studying. I dont really want people to give me the commands because I want to learn by doing, but can someone please let me know how I would go about cabling this up... or even if it is possible.

I have the following..

2 * 2503 routers both with two serial interface slots, 1 AUX , 1 * AUI, 1 * bri

1* 2801 router with 1 serial interface card and 2 * fa ports 1 * aux port

Is it possible???

Thanks

 

[burtsbees]

Yes---configure one of the 2503's as a frame relay switch, and connect both DCE ends of the cables to it. The DTE ends connect to the other 2503 and 2801...

2503DTE------DCE2503--DCE2503-------2801DTE

Burt

 

[sk391]

Cheers Burtsbees, I'll give it a go and start configuring it.

Thanks - youve been a great help as always !

 

[burtsbees]

The frame relay switch config is not covered in CCNA studies, so I'll post one here in a bit...

Burt

 

[CiscoGuy33]

Burt,

I had this close by - it is from Chris Bryant, CCIE, I had saved from his online webpage, this is for a Cisco 2520 router which has 4 built in serial ports, these are great routers for Frame Realy switches -

From Cris Bryant website on setting up Frame Relay

In this example, I've got three Cisco routers that are going to be the production routers in my lab - R1, R2, and R3. I have a fourth router that will serve as the frame relay switch. The DLCI assignments I've come up with are as follows:
• R1 is the hub and will use DLCI 122 to reach R2, DLCI 123 to reach R3.
• R2 is a spoke router and will use DLCI 221 to reach both R1 and R3.
• R3 is a spoke router and will use DLCI 321 to reach both R1 and R2.

The physical connections are as follows. All connections are using DTE/DCE cables with the DCE end of the cable connected to the frame relay switch.
• R1 is connected to the frame switch's Serial1 port.
• R2 is connected to the frame switch's Serial2 port.
• R3 is connected to the frame switch's Serial3 port.

On the frame switch, the global command frame-relay switching is required to make the router act as a frame relay switch. Let's take a look at the commands we'll need on the frame switch's Serial1 port, which is connected to R1.

The clockrate command is necessary on the DCE end of the connection, so you see it here. You also see that the interface is hard-coded as a DCE with the frame-relay intf-type dce command. Not all current IOS versions require this; just make sure you have the DCE end of the cable attached to the frame switch and verify that with show controller serial x.

hostname FRAME_SWITCH
!
!
ip subnet-zero
no ip domain-lookup
frame-relay switching
!
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
no ip address
!
interface Serial1
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 122 interface Serial2 221
frame-relay route 123 interface Serial3 321
!
interface Serial2
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 221 interface Serial1 122
!
interface Serial3
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 321 interface Serial1 123

Hope this helps!

E.A. Broda
CCNA, CCDA, CCAI, Network +

 

[burtsbees]

He's the one about "The Bryant Advantage", right?
I just hope this doesn't confuse him, since he's got a two serial-interface router, though the explanation is good.

!
version 11.3
service telnet-zeroidle
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Frame_Switch
!
enable password t1mmy
!
frame-relay switching
!
!
interface Ethernet0
ip address 172.16.0.2 255.255.0.0
!
interface Serial0
no ip address
encapsulation frame-relay
no ip mroute-cache
clockrate 4000000
frame-relay lmi-type ansi
frame-relay intf-type dce
frame-relay route 101 interface Serial1 102
!
interface Serial1
no ip address
encapsulation frame-relay
clockrate 4000000
frame-relay intf-type dce
frame-relay route 102 interface Serial0 101
!
interface BRI0
no ip address
shutdown
!
ip classless
!
!
line con 0
password t1mmy
logging synchronous
login
line aux 0
line vty 0 4
password t1mmy
login
!
end

This statement...
interface Serial0
frame-relay route 101 interface Serial1 102

maps Serial1's DLCI of 101 to it's own DLCI of 102, or vice versa (can't remember)---once you physically connect, which is ONE VERY important reason to own REAL routers and switches (to PHYSICALLY see how cables connect), then you will totally understand exactly WHAT these statements do.
A very interesting CCNA and even CCNP practice is to observe (through show commands, like sh ip route, sh ip ospf, and debugs) how OSPf in particular behaves over a frame relay link (NBMA network).
You connect both DCE ends to the frame relay switch. The clockrate does not have to be more than 1536000, since that's all the speed you get out of asynchronous serial links, but mine was set at 4000000 because of a previous multilink setup (bonded the serial interfaces, but NOT with multilink PPP, but rather virtual access links).
S0 gets connected to the DLCI 102 router, I think. If not, then switch them---I usually get this backwards! Have fun!

Now give me and Gene stars!lol

Burt

 

[burtsbees]

Just noticed---what Gene posted (CiscoGuy33) should tell you what interface to connect what DLCI to...

Burt

 

[CiscoGuy33]

Burt,

Yea, he is the same as "The Bryant Advantage", I collected a bunch of stuff on Frame Relay off the web and that was part of it.

Since he has a 2 2503s this will work (for 2 of the interfaces) or if he wants to expand he can pick up a 2520 or 2521 (saw 1 go for $30 recently on Ebay) to make a more complex setup. I have a 2610 with 2 WIC-2Ts as my Frame Relay switch on my lab at work, I have 4 routers connecting through it in a full mesh!!

Once again, hope this helps and join us over in the Cisco certification forum here at Tek-Tips!!!!

E.A. Broda
CCNA, CCDA, CCAI, Network +

 

[sk391]

Thanks guy, I am getting a little confused with it all though. I not really understanding the concept of DLCI. Can anyone enlighten me please. In the meantime I will keep on playing.

Thanks

 

[sk391]

Hello Guys, Ok im struggling and little confused.
My understanding is that I have to config my frame relay switch interfaces- which I have done with the following config:

interface Serial0
no ip address
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clock rate 56000
frame-relay intf-type dce
frame-relay route 101 interface Serial1 102
!
interface Serial1
no ip address
encapsulation frame-relay
clock rate 56000
frame-relay intf-type dce
frame-relay route 102 interface Serial0 101
!


Then I have to go to the other two routers that I need to config to be able to talk to each other other the frame relay switch.

interface Serial1
ip address 172.12.123.3 255.255.255.0
encapsulation frame-relay
frame-relay interface-dlci 102

and on the other router

interface Serial0/3/0
ip address 172.12.123.2 255.255.255.0
encapsulation frame-relay
no ip route-cache
!


Does this look ok, I must admit Im just learning about frame relay so I could have got my theory all mixed up

Thanks

 

[burtsbees]

No---you would want something like this...

interface Serial0/3/0
ip address 172.12.123.2 255.255.255.0
encapsulation frame-relay
no dce-terminal-timing-enable
frame-relay map ip 172.12.123.3 101 broadcast

and the other router...


interface Serial1
ip address 172.12.123.3 255.255.255.0
encapsulation frame-relay
frame-relay map ip 172.12.123.2 101 broadcast

The 2503 gets connected to the DLCI 101 (interface s0 on the frame switch) and the 2801 gets connected to interface s1 on the frame switch. The clockrate of 56K will work, but you'll want more (like 4000000) on the frame switch.
A DLCI is a layer 2 broadcast circuit identifier...think of it as a MAC for frame relay---the frame relay map ip command statically maps the local interface DLCI, or circuit ID, to the remote router's IP address...kind of like a criss-cross. They can dynamically be learned (not RARP---called something else...can't think...), but as static mappings are introduced, this is NOT recommended---once a router reboots, say goodbye to the mappings and connectivity...I think.
Just wait until you get into BECN and FECN, burst rate, etc...muahahahahahaha...OSPF is funner though...
YES---FUNNER IS A WORD!

Burt

 

[sk391]

Hi,

I cant get this frame relay switch setup guys. I have what you have said Burt - but no luck with it. I could enter in the no dce-terminal-timing-enable command on the interfaces on the routers.

I have a concern with the following;
on my 2801 router

Router2801#show frame map
Serial0/3/0 (up): ip 172.12.123.3 dlci 101(0x65,0x1850), static,
broadcast,
CISCO, status deleted

its says that the status is deleted???

but it I do a show int - you can be that the line and protocol are both up and that LMI are being sent and receieved.

Serial0/3/0 is up, line protocol is up
Hardware is GT96K Serial
Internet address is 172.12.123.2/24
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 412, LMI stat recvd 412, 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

The other config is as follows;

RouterB#show frame map
Serial1 (up): ip 172.12.123.2 dlci 101(0x65,0x1850), static,
broadcast,
CISCO, status defined, active
as you can see it say that its active....?

and the int s 1

Serial1 is up, line protocol is up
Hardware is HD64570
Internet address is 172.12.123.3/24
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 427, LMI stat recvd 428, LMI upd recvd 0, DTE LMI up
LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

I cannot ping from 1 route two the other through the frame relay cloud

config from frame relay switch

interface Serial0
no ip address
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clock rate 4000000
frame-relay intf-type dce
frame-relay route 101 interface Serial1 102
!
interface Serial1
no ip address
encapsulation frame-relay
clock rate 4000000
frame-relay intf-type dce
frame-relay route 102 interface Serial0 101


Please help

Thanks

 

[burtsbees]

Switch the routers around---sometimes I have gotten them backwards. The deleted status means that the switch is at fault, probably because you have the routers plugged into the wrong interfaces on the frame switch. Great troubleshooting process!

Burt

 

[jneiberger]

The DLCI (pronounced dell sea) is simply a numeric identifier for a frame relay virtual circuit. Any frame relay circuit will have one or more virtual circuits riding on it. That's the whole point of using frame relay in the first place. You have to have some way of referring to the individual virtual circuits. That is the DLCI.

 

[nelsonrherron]

Anybody remember how to set the clock on the FR client. My cable/if-type combination puts my FR switch in DTE so I need to set the clock on the host. I know I've done it before but sure don't remember how now.

 

[burtsbees]

router>en
router#conf t
router(config)#int s0/0
router(config-if)#clock rate 1536000

Or whatever you want the clock---1.536MBps is the most you'll get out of a WIC-1T or a WIC-1DSU-T1

Also, s0/0 is just an example---of course use whatever convention your particular serial interface uses (s0, s0/1/0, etc.)

This is in the above configs as well...

Burt

Burt

 

[nelsonrherron]

Burt:

Thx. I did all of that and the show int still shows it as DTE and up/dn. It shows a speed like I anticipate after setting it. There is a dce-enable command that doesn't seem to do much. This is all on the host end, not the FR switch end. The ordinary FR ints come up fine, but they have the clock set on the FR switch end and the hosts are intended to be DTE. Suggestions? I know I did it before and it worked, and I'm sure there must be a simple piece I'm overlooking.

Nelson

 

[jneiberger]

nelson, don't confuse the frame relay DCE/DTE roles with the physical DCE/DTE roles required for clocking. They are completely unrelated. The router interface that has the DCE cable connected needs to provide clocking.

 

[burtsbees]

The ordinary FR ints come up fine, but they have the clock set on the FR switch end and the hosts are intended to be DTE. "

This is contradicting what you said in the first post...you said you want to clock on the host end (DCE).
Is there a reason why you want to make the host end do the clocking?

Burt

 

[jneiberger]

Burt, I think he is confusing frame relay DCE/DTE with the physical DCE/DTE.