Frame relay with four routers

Following on from the two router scenario, I've attempted three routers connected to a frame relay router via an 8A/S NM. The output for the connected serial ports is as follows on the frame relay router:

FrameRelay#
!
interface Serial1/0
no ip address
encapsulation frame-relay
no keepalive
clockrate 64000
frame-relay intf-type dce
frame-relay route 101 interface Serial1/1 102
!
interface Serial1/1
no ip address
encapsulation frame-relay
no keepalive
clockrate 64000
frame-relay intf-type dce
frame-relay route 102 interface Serial1/2 103
!
interface Serial1/2
no ip address
encapsulation frame-relay
no keepalive
clockrate 64000
frame-relay intf-type dce
frame-relay route 103 interface Serial1/0 101
!

FrameRelay#show frame-relay map

FrameRelay#show frame-relay route
Input Intf Input Dlci Output Intf Output Dlci Status
Serial1/0 101 Serial1/1 102 static
Serial1/1 102 Serial1/2 103 static
Serial1/2 103 Serial1/0 101 static

FrameRelay#show frame-relay pvc

PVC Statistics for interface Serial1/0 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 1 0 0 0
Unused 0 0 0 0

DLCI = 101, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/0

PVC Statistics for interface Serial1/1 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 1 0 0 0
Unused 0 0 0 0

DLCI = 102, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1

PVC Statistics for interface Serial1/2 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 1 0 0 0
Unused 0 0 0 0

DLCI = 103, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/2

Now, each spoke router has a WIC-2T with the serial port connected via DTE to the NM module of the ports listed above, all set to 64000 DCE (on the framerelay router).

Router1#show run int s0/1
Building configuration...

Current configuration : 159 bytes
!
interface Serial0/1
ip address 10.0.0.1 255.255.255.0
encapsulation frame-relay
no keepalive
serial restart-delay 0
frame-relay interface-dlci 101
end

Router1#show frame-relay map
Serial0/1 (up): ip 10.0.0.3 dlci 101(0x65,0x1850), dynamic,
broadcast,

Router1#show frame-relay pvc

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

Active Inactive Deleted Static
Local 0 0 0 1
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0/1

Router2#show run int serial0/1
Building configuration...

Current configuration : 159 bytes
!
interface Serial0/1
ip address 10.0.0.2 255.255.255.0
encapsulation frame-relay
no keepalive
serial restart-delay 0
frame-relay interface-dlci 102
end

Router2#show frame-relay map
Serial0/1 (up): ip 10.0.0.1 dlci 102(0x66,0x1860), dynamic,
broadcast,

Router2#show frame-relay pvc

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

Active Inactive Deleted Static
Local 0 0 0 1
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0/1

Router3#show run int serial0/0
Building configuration...

Current configuration : 159 bytes
!
interface Serial0/1
ip address 10.0.0.3 255.255.255.0
encapsulation frame-relay
no keepalive
serial restart_delay 0
frame-relay interface-dlci 103
end

Router3#show frame-relay pvc

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

Active Inactive Deleted Static
Local 0 0 0 1
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 103, DLCI USAGE = LOCAL, PVC STATUS = STATIC, INTERFACE = Serial0/1

The problem (unless this is how it works with three serial connections) is that the show frame-relay map commands on all the spoke routers 1, 2 and 3 doesn't always produce the serial up reply, in this instance serial 0/1 on router 3 (the last spoke entry above) failed to return anything. Sometimes, the order in which the connections are configured dictates if a frame-relay map statement returns any information.

Am I missing something or is this configured correctly? With two routers they both return information the status for the map command but for three routers, one router always has blank information in reply to the map command.

Thank you in advance for any constructive comments.

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Comments

FloOz

On your frame relay switch interface you could add more "frame relay route" entries if you would like more output in you show frame relay map. For example you could add

interface Serial1/0
no ip address
encapsulation frame-relay
no keepalive
clockrate 64000
frame-relay intf-type dce
frame-relay route 101 interface Serial1/1 102
frame-relay route 101 interface Serial1/2 103

networker050184

You don''t need the no keepalive when you are using a frame switch. It takes care of sending LMI.

Carpe Porcus

FloOz wrote: »

On your frame relay switch interface you could add more "frame relay route" entries if you would like more output in you show frame relay map. For example you could add

interface Serial1/0
no ip address
encapsulation frame-relay
no keepalive
clockrate 64000
frame-relay intf-type dce
frame-relay route 101 interface Serial1/1 102
frame-relay route 101 interface Serial1/2 103

Thank you, I thought this was the case and I did try this originally but kept getting the message 'Can't use same dlci on overlapping circuits' when I tried to configure the second route on interface S1/0.

I'll flatten the router and try it again tonight and let you know. Thanks for that, I wasn't certain but it has been a while since I tried this on a router.

I'll take the keepalive out as well, will post when I've tried the new configuration. Considering this is supposed to be a core part of ICDN2 there is so much contradiction regarding router configuration for a frame relay switch substitute. Perhaps a thread could be made a sticky once a working example is provided?

Carpe Porcus

To paraphrase Edison, "I haven't failed! I've simply discovered another way not to implement frame-relay".

Finally got this working.

A few things for those learning or new to frame relay:

DLCIs are not advertised but having all connections with the same DLCI e.g. 100 is known as global addressing which would prove difficult to troubleshoot to say the least. No source or destination is stored in a DLCI unlike other protocols and they are not advertised which makes them significant to the local machine on which it was configured.

Frame Relay relies on the mapping between DLCI to IP Address. The DLCI is mapped to the remote router's IP address which creates frame relay communications, the mapping can be achieved statically or dynamically it appears static is preferred over dynamic in frame relay as dynamic mapping uses inverse arp which is unreliable.

When creating static mappings, disable inverse arp before mapping 'frame-relay map ip NNN.NNN.NNN.NNN 102 broadcast' as inverse arp is the default which causes problems when issued afterwards as I found out.

Use broadcast at the end of the frame-relay map ip command as frame-relay does not support broadcast or multicast traffic. The 'broadcast' command enables broadcast or multicast packets to be replicated over the frame on the specified DLCIs. Useful when using routing protocols!

IP addresses are not needed frame relay side, all the clocking is done this side enabling the interfaces as DCE.

Fame-relay interface-dlci is used for point-to-point subinterfaces and frame-relay map is used for multipoint subinterfaces so I changed to Frame-relay map ip on the spoke to define which DLCI mapped to which IP Address.

As FloOz pointed out a second route for serial1/0 was needed and the status of all is active as opposed to static in the previous configuration.

FrameRelay#show frame-relay route
Input Intf Input Dlci Output Intf Output Dlci Status
Serial1/0 100 Serial1/1 102 active
Serial1/0 101 Serial1/2 103 active
Serial1/1 102 Serial1/0 100 active
Serial1/2 103 Serial1/0 101 active

FrameRelay#show frame-relay pvc

PVC Statistics for interface Serial1/0 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 2 0 0 0
Unused 0 0 0 0

DLCI = 100, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/0

PVC Statistics for interface Serial1/1 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 1 0 0 0
Unused 0 0 0 0

DLCI = 102, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/1

PVC Statistics for interface Serial1/2 (Frame Relay DCE)

Active Inactive Deleted Static
Local 0 0 0 0
Switched 1 0 0 0
Unused 0 0 0 0

DLCI = 103, DLCI USAGE = SWITCHED, PVC STATUS = ACTIVE, INTERFACE = Serial1/2

Feel free to add corrections or more comments, the working setup is as follows:

FrameRelay#

frame-relay switching

!
interface Serial1/0
no ip address
encapsulation frame-relay
clockrate 64000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 100 interface Serial1/1 102
frame-relay route 101 interface Serial1/2 103
!
interface Serial1/1
no ip address
encapsulation frame-relay
clockrate 64000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 102 interface Serial1/0 100
!
interface Serial1/2
no ip address
encapsulation frame-relay
clockrate 64000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 103 interface Serial1/0 101
!

Router1#show run int serial0/1
Building configuration...

Current configuration : 218 bytes
!
interface Serial0/1
ip address 10.0.0.1 255.255.255.0
encapsulation frame-relay
no frame-relay inverse-arp
no fair-queue
frame-relay map ip 10.0.0.2 100 broadcast
frame-relay map ip 10.0.0.3 101 broadcast
end

Router1#show frame-relay map
Serial0/1 (up): ip 10.0.0.2 dlci 100(0x64,0x1840), static,
broadcast,
CISCO, status defined, active
Serial0/1 (up): ip 10.0.0.3 dlci 101(0x65,0x1850), static,
broadcast,
CISCO, status defined, active

Router2#show run int serial0/1
Building configuration...

Current configuration : 218 bytes
!
interface Serial0/1
ip address 10.0.0.2 255.255.255.0
encapsulation frame-relay
no frame-relay inverse-arp
no fair-queue
frame-relay map ip 10.0.0.1 102 broadcast
frame-relay map ip 10.0.0.3 102 broadcast
end

Router2#show frame-relay map
Serial0/1 (up): ip 10.0.0.1 dlci 102(0x66,0x1860), static,
broadcast,
CISCO, status defined, active
Serial0/1 (up): ip 10.0.0.3 dlci 102(0x66,0x1860), static,
broadcast,
CISCO, status defined, active

Router3#show run int serial0/0
Building configuration...

Current configuration : 218 bytes
!
interface Serial0/0
ip address 10.0.0.3 255.255.255.0
encapsulation frame-relay
no frame-relay inverse-arp
no fair-queue
frame-relay map ip 10.0.0.1 103 broadcast
frame-relay map ip 10.0.0.2 103 broadcast
end

Router3#show frame-relay map
Serial0/0 (up): ip 10.0.0.1 dlci 103(0x67,0x1870), static,
broadcast,
CISCO, status defined, active
Serial0/0 (up): ip 10.0.0.2 dlci 103(0x67,0x1870), static,
broadcast,
CISCO, status defined, active

Thanks to networker050184 for the keepalive tip, frame-relay activates the interface as soon as the command is entered.
Still not certain that no fair-queue is needed in a lab environment, perhaps someone with greater experience can clarify?

Any ideas on how to improve on this setup? Please feel free to add them.

Hope this helps others who are struggling with frame relay concepts and helps understand the concept, it was a good refresh for me to say the least.

networker050184

The 'no fair-queue' has nothing to do with frame-relay. It's queuing for the interface.

Carpe Porcus

Wasn't too sure but that's something else to be removed.

Thank you.