LMI & Frame-Relay

R1#show interfaces
Serial0 is up, line protocol is up
  Hardware is HD64570
  Internet address is 192.168.10.1/24
  MTU 1500 bytes, BW 1544 Kbit, DLY 1000 usec, rely 255/255, load 1/255
  Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec)
  LMI enq sent  1472, LMI stat recvd 1472, 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 CISCO  frame relay DTE
  FR SVC disabled, LAPF state down
  Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 300
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 1000 bits/sec, 2 packets/sec
  5 minute output rate 1000 bits/sec, 2 packets/sec
     0 packets input, 0 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
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

I've sent up 2 routers to use RIP with Frame-Relay encapsulation.

from this output above, why does it say

  LMI enq recvd 0, LMI stat sent  0, LMI upd sent  0

i thought that both ends will be senting LMI msgs to each other (FR switch to tourter and vice verca)

also, how ofter LMI msgs are being sent by default, and is there a way to change that timer?

Thanks

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Comments

Cauthon

When Frame is operating correctly, a Frame Relay router sends LMI enquiries (LMI enq) to the Frame Relay switch, which replies with the status (LMI stat) of the PVC.

The switch, in your case, is the device that is configured on the DCE end of the serial cable. Your statistics appear to be from a Frame Relay router. You'd see the opposite on a Frame Relay switch (recv enquiry, send status).

LMI enquiries are sent at the keepalive interval. It's currently set to send keepalives every 10 seconds. Use the 'keepalive' command on the serial interface to change the rate. Make sure the router's keepalive interval is set lower than the switch or the switch will timeout your link.

Mike

EdTheLad

Your FR port can be configured as LMI UNI User,Network or LMI NNI.
In this case you have a setup LMI UNI user on your router i.e. frame-relay intf-type dte, this is default and cannot be changed unless you enable the router as a FR switch.The LMI User port sends LMI status enquiries.
Your FR switch is setup using LMI UNI Network intf-type dce, this responds to LMI enquires with an LMI full status,it will not send LMI enquires.
Hence what you are seeing,the FR router sends enquiries and the switch responds with full status messages.

If you wanted to connect 2 FR switches back to back you would use LMI NNI,this can be configured on the FR switch with frame-relay intf-type nni,
this interface type will send status enquiries and receive full status messages.

exkor5000

hey ed

could you please elaborate abit on the definitions of LMI NNI, LMI UNI, and intf-type?

thanks
X

EdTheLad

exkor5000 wrote:

hey ed

could you please elaborate abit on the definitions of LMI NNI, LMI UNI, and intf-type?

thanks
X

Ok,
NNI Network to Network interface, general telecoms term used to describe the interface between two DCEs.So regarding FR, you have your router which is on your premises i.e. your dte, your router will be connected to the service providers FR network, which will probably consist of a backbone of FR switches interworking with other protocols like ATM etc but forget about them for now.
The LMI on your router will be LMI UNI, User to Network interface i.e. dte-dce,since all the pvcs are configured on the FR switch you will poll the FR switch for status of the PVCs.
Internally the ISP will have many FR routers conected B2B, each with different FR pvc configuration.These switches will be running lmi nni i.e dce-dce,because they need to poll their neighbor to discover pvc status on the neighbor they both need to send and receive status enquire and full status messages.
Hope you get the idea above.

Check out your FR switch config, you will see the intf-type dce command specified on the appropriate port.Type and change this status on the routers port and see the message you get.Then reread what i have typed.

exkor5000

ok, will do that

However, if looking onto the connection going from the providers FR switch to one of my routers, what would that LMI type be? Since it's actually Network -to-User-Interface

I didnt refer to type as ANSI, Cisco, Q933A, but you know...

X

exkor5000

wait... wouldnt changing intf-type dce change my router into a FR switch basically? or does it happen trough the command

R1(config)#frame-relay switching

sorry for terrorising you with all those questions, I just got to understand those details in order for all that material glue together.

x

EdTheLad

exkor5000 wrote:

ok, will do that

However, if looking onto the connection going from the providers FR switch to one of my routers, what would that LMI type be? Since it's actually Network -to-User-Interface

I didnt refer to type as ANSI, Cisco, Q933A, but you know...

X

The LMI type depends on the service provider, other names from ITU for LMI protocols are Annex A, Annex D and LMI.
Annex D = Ansi
Annex A = Q933a
LMI is LMI, cisco uses a proprietery version
I think Annex D is used in America and Annex A in Europe.
The UNI and NNI are used for all depending on the function of the device, dte or dce.

The other question about setting the intf-type to dce is correct, you cannot change it to dce on the dte router, in order to change you must reconigure the router to be a switch.Why dont you create 2 FR switches change the intf-type to nni on both switches and check the "show frame-relay lmi"
then change one switch back to dc and look at the results.

exkor5000

how would i change a router into a FR switch?

i did

R1#
R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#frame-relay switching
R1(config)#int ser 0 2
R1(config-if)#frame-relay intf-type ?
dce                     Configure a FR DCE
dte                     Configure a FR DTE
R1(config-if)#frame-relay intf-type dce
R1(config-if)#exit
R1(config)#exit
R1#show interfaces
Serial0 is up, line protocol is up
  Hardware is HD64570
  Internet address is 192.168.10.1/24
  MTU 1500 bytes, BW 1544 Kbit, DLY 1000 usec, rely 255/255, load 1/255
  Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec)
  LMI enq sent  1472, LMI stat recvd 1472, 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 CISCO  frame relay DTE

no good!!

thanks
x

BubbaJ

If you only have two routers, you don't want one to be a frame relay switch if you want to route. You can use two routers with back-to-back frame relay. Since there won't be a frame switch involved, you will need to disable LMI, and you will have to use the same DLCI on both sides.

EdTheLad

To setup your router to be a switch you need to
#no ip routing
#switching frame-relay

then on the interfaces
encapsulation frame-relay
frame-relay intf-type dce
frame-relay route 16 interface sx/x 16
( mapping from dlci 16 on the current port to port sx/x dlci 16)

You will need to match up dlcis, this fr switch can connect multiple routers together via fr,its a pity you only have 2 routers?

Anyway try what BubbaJ has suggested,but also try using a FR switch as its
a learning experience and you should try everything you can think of.
Thats me finish on this topic as i bored now.

exkor5000

actually I do have more then 2 routers. Moreover I can use the Boson emulator to emulate as many as needed.

thanks
x

exkor5000

thanks ed, i will play around with the routers