Frame Relay Cloud Setup using Packet Tracer

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Nov 23rd, 2009
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Hello, I am going to sit for the CCNA exam within a week. But I am really confused about a frame-relay concept.
I am following the CCNA ICND2 Official exam certification guide of Wendell Odom. In chapter 14, figure 14-4 ("A Partially Meashed Network with One Ip Subnet Per VC") uses point to point subinterfaces.

Interface Serial 0/0/0 of Router "Atlanta" has been configured with 3 subinterface each with different Ip address & different DLCI number.

Router "Charlotte", "Nashville" and "Boston" has been configured with the same DLCI number.

Can anyone please clear the concept for me? As I am using Packet Tracer, I am unable to configure One single interface of a Frame Relay Cloud with same DLCI number for different VC. It is showing "The DLCI number is already in use".

As the figure 14-4 shows Router "Atlanta" is using the DLCI no 51 for all three point to point links, connected to 3 subinterface of its Serial 0/0/0.

As the router's Serial 0/0/0 WAN interface is connected to a single interface of a Frame Relay switch within a Frame Relay Cloud, How can I use same DLCI numbers for 3 different VCs in the same interface of a Frame Relay Cloud?

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Nagendra Kumar ... Mon, 11/23/2009 - 03:52
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The diagram in that books might have confused you. The configuration will show you that Atlanta router have different DLCI in each subinterface.You cant configure same DLCI number in different subinterface (that belongs to same physical interface).

R1(config)#int s2/3
R1(config-if)#encap frame-relay
R1(config-if)#int s2/3.1 point
R1(config-subif)#frame-relay interface-dlci 101
R1(config-fr-dlci)#int s2/3.2 point
R1(config-subif)#frame-relay interface-dlci 101
%PVC already assigned to sub-interface Serial2/3.1




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