Frame-Relay (DLCI) Inverse-Arp

Unanswered Question
Mar 24th, 2008

Hi All,

I have a frame-relay Hub and spokes topology of four routers as listed below:

R1= Hub with two sub-interfaces, one to R2 p-t-p.

The second interface is Multipoint connecting R3 and R4.

My problem is that whenever sh frame map was issued on R2 it show the DLCI mapping to R3 and R4. But when clear frame inarp is issued it clears the unwanted DCLIs and present the real DLCI, same happens with R3 and R4 showing link to R2 which ought not be. But when "clear fram inarp"

the false link is vanished.

Is this normal or i have done something wrong?. The "no frame inverse-arp" is configured.

I hope i present an understandable content of request?

Thanking you all in advance

I have this problem too.
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Paolo Bevilacqua Mon, 03/24/2008 - 14:18

Excuse me for not answering your question directly. Why not run all the PVCs as p-t-p subinterfaces and consequentially:

- forget about any inarp, fr map, split-horizon issue, and special routing configuration

- see any link as point to point and able to set QoS and ACL as needed in a very simple way

- be able to see the subinterface status to reflect the status of PVC no matter the reliability of LMI info (end-to-end FR keepalives)

- possibly some other advantages that I've forgot now.

newnetman Mon, 03/24/2008 - 14:37


Thanks for your prompt response. Of course in real life i would opted for p-t-p but this is a lab practice that requires hybrid implementations, and as such need to master it too.

Thank you

Jon Marshall Tue, 03/25/2008 - 03:03


Can you post your configs plus explain what you mean by "unwanted DLCI's" and "real DLCI".


steveo123 Thu, 03/27/2008 - 02:22

i take it that the only place one would do such senario is the CCIE lab.... any way this is not normal behaviour but then again not a behavior that can cause problems also. Have you tried entering the command "no arp frame-relay" on the hub router..? if it still shows the unwanted dlci's then ios bug would be my answer..

Steve K

newnetman Thu, 03/27/2008 - 05:11

Hi Steve,

I am currently studying for CCIP with the aim for SP soon. With all humility may i tell you that it as been proven that there is nothing like "no arp frame-relay" this command stops nothing, i equally test this and realized it does nothing. You can only stop frame-relay from learning about remote DLCIs (no frame inverse-arp) but you can't stop it from responding to inverse-arp request (no arp frame-relay) except you shut down the interface.

Back to my initial request i still hope someone can help me further?.

Thanking you all in advance

Edison Ortiz Thu, 03/27/2008 - 09:04

It's not a "false link" as the configuration in the frame-relay switch is fully meshed among all routers.

Basically, what you are seeing is an expected behavior when enabling frame-relay in the interface.

1) You have an IP address

2) You enable encapsulation frame-relay

As soon as you do that, the arp is populated and unwanted mappings are added into the table.

I understand you issued no frame inverse-arp but I bet the command came-in too late into the configuration and the arp table was already populated.

Clearing the arp table or rebooting the router are normal options and you did nothing wrong.





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