Frame relay question

[John Blakley]

All,

I have a test lab configured in gns3 for frame-relay, and I had the following question.

I configured frame relay on both router's physical interfaces, but I couldn't ping either one. I then changed the physical interface to only encapsulate frame-relay and then I created subinterfaces for point-to-point connections. I could then ping each router.

My question is, when is it appropriate to use the "frame-relay map ip" command? I tried this command on the physical interface before creating my subinterfaces and it didn't work.

Thanks,

John

[Edison Ortiz]

Sure, disable inverse-arp:

http://www.cisco.com/en/US/docs/ios/wan/command/reference/wan_f1.html#wp1015390

__

Edison.

[John Blakley]

Thanks! I'll let you know more tomorrow how things went :)

[andrew.prince]

disable "frame-relay inverse-arp"

[lamav]

Hi:

"Frame-Relay relies on inverse-arp (enabled by default) for dynamic mappings but this process can be delayed so the fastest way to get connectivity is to use static mappings."

Edison, I dont know how the virtual router system works because I never used it. But in the real world, on an actual device, isn't frame relay inverse arp automatically disabled when you configure a static mapping under an interface?

Thanks

Victor

[Edison Ortiz]

Victor,

No, you have to manually disable it.

__

Edison.

[Florin Barhala]

Hi guys,

I am running/testing dynamic Frame-Relay mapping on GNS, too. I used a Cisco router as FR-switch; at first I tried with frame-relay route command on each interface, but after waiting more than 10 minutes for the wonder to happen I also tried with connect command.

None of these two works, as I got PVC up and the right DLCI but no mapping is developing after, and DLCI stays UNUSED.

Here is the FR-Switch configuration:

interface Serial0/0

no ip address

encapsulation frame-relay

serial restart-delay 0

frame-relay intf-type dce

end

interface Serial0/1

no ip address

encapsulation frame-relay

serial restart-delay 0

frame-relay intf-type dce

end

connect R2R5 Serial0/0 201 Serial0/1 102

show connection all   

ID   Name               Segment 1            Segment 2           State      

========================================================================

2    R2R5              Se0/0 201            Se0/1 102            UP         

And here is the R2 and R5 configuration:

R5#show frame-relay pvc

PVC Statistics for interface Serial0/1 (Frame Relay DTE)

              Active     Inactive      Deleted       Static

  Local          0            0            0            0

  Switched       0            0            0            0

  Unused         1            0            0            0

DLCI = 102, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial0/1

  input pkts 0             output pkts 0            in bytes 0        

  out bytes 0              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 00:22:45, last time pvc status changed 00:22:35

R2#show frame-relay pvc

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

              Active     Inactive      Deleted       Static

  Local          0            0            0            0

  Switched       0            0            0            0

  Unused         1            0            0            0

DLCI = 201, DLCI USAGE = UNUSED, PVC STATUS = ACTIVE, INTERFACE = Serial0/0

  input pkts 0             output pkts 0            in bytes 0        

  out bytes 0              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 00:22:59, last time pvc status changed 00:22:49

The FR on R2 and R5 is configured on subinterfaces:

R2#sri se0/0 

!

interface Serial0/0

no ip address

encapsulation frame-relay

serial restart-delay 0

end

interface Serial0/0.1 multipoint

ip address 172.10.7.1 255.255.255.240

ip ospf 100 area 0

end

R5#sri se0/1

!

interface Serial0/1

no ip address

encapsulation frame-relay

serial restart-delay 0

end

interface Serial0/1.1 multipoint

ip address 172.10.7.5 255.255.255.240

ip ospf 100 area 0

end

Any idea would be highly appreciated !

[Florin Barhala]

Meanwhile I started another Frame Relay - GNS 3 scenario:

R3 is configured as FR-Switch

R1 and R2 are connected to R3 using FR encapsulation. I configured 2 IP addresses on Serial interfaces.

R4 and R5 are also connected to R3. R4 is configured on a subinterface point-to-point, while R5 is configured on a subinterface multipoint.

Here are some results:

R1 - R2 communication started to work IMMEDIATELY (of course using inverse-arp)

On the FR switch I configured:

connect R2R4 Serial0/0 204 Serial0/2 402

connect R1R5 Serial0/1 105 Serial0/3 501

None of these two pairs, works. After debug frame-relay packet issued on both R4 and R5 it's clear that inverse-arp is not working on either of these two. Nevertheless both R1 and R2 send INARP packets:

R4: Serial0/2: frame relay INARP received

R5: Serial0/3: frame relay INARP received

My conclusion is that at least on 3640 model I use, INARP does NOT work on SUBINTERFACES.

Feel free to share your experience about this.

L.E. I run another couple of tests:

1. I stopped both "trouble routers" R4 and R5.

2. I started R4 because I read somewhere that INARP works after a router reload. The results was the same: PVC gets ACTIVE but UNUSED. R2 receives no INARP from R4, it just send INARP for PVC 204. Because of this if I try to ping 10.0.0.4 I receive the classic error:

Serial0/0:Encaps failed--no map entry link 7(IP).

3. I changed the configuration on the FR-Switch and replaced:

no connect R1R5 Serial0/1 105 Serial0/3 501 with

frame-relay route 501 interface se0/1 105 on Se0/3

frame-relay route 105 interface se0/3 501 on Se0/0

4. I started R5 but I received the same results as stated at point 2.

5. I waited 10 minutes before "ending tests" in case FR "converges" slowly than expected.

6. I added static mapping between R1 and R5 and worked at once!

7. I added PVC between R4 and R5 and again INARP doesn't work.

With these tests I believed I exhausted most of the possibilities.

[cadet alain]

Hi,

in your first example you had forgot to assign the DLCI to the subinterface( by default it is on the physical interface) with

the frame-relay interface-dlci command under each subinterface.

I suspect you have the same problem in your second test.

Regards.

Alain

Don't forget to rate helpful posts.

[Florin Barhala]

Ok, so you are saying that without frame-relay interface-dlci command INARP will not work on FrameRelay subinterfaces?

Here is what I read while you were posting:

When a multipoint subinterface is created under a physical interface, it is necessary to specifically assign DLCIs to the multipoint subinterface.

By default, the Cisco IOS software allocates all unassigned DLCIs advertised by the Frame Relay switch to the physical interface on the router.

On a multipoint subinterface, the frame-relay interface-dlci dlci command or the frame-relay map protocol protocol-address dlci [broadcast] command in the subinterface configuration mode can be used to associate the multipoint subinterface with specific DLCIs.

The frame-relay interface-dlci dlci command performs dynamic address mapping using Inverse ARP to map the next-hop protocol address to the local DLCI on the router.

Seems I learned this the hard way!

Thank you for clearing this up!