David Sudjiman

Previously, I wrote about how to create FR switch using 2522. This article is basically the same but has different DLCI numbering method.

Figure 1.

As we can see on Figure 1, every router has only one DLCI number rather than two. R1 has DLCI 111, R2 has DLCI 222, R3 has DLCI 333, and R4 has DLCI 444. So, how is it possible to configure the FR switch then?

Figure 2.

Remember that FR header has only one DLCI field. As shown in Figure 2, when R1 wants to send a frame to R2, the frame has DLCI 111 on it. However, when it gets to the local switch near R2, the switch changes DLCI number on the frame into 222. In general, you might think as below:

• Sender using DLCI field as destination address, and
• Receiver using DLCI field as source address

Therefore, looking back at Figure 1, we can have the DLCI numbering as follow:

Figure 3.

Based on the above information, can you configure an FR switch? And to make it more interesting, also configure R1, R2, R3, and R4 so that they will be able to ping each other. You may use any routing protocol you like.

If you thing it is necessary, you may want to look at my previous Scenario 1 and Scenario 1 Answer.

Answer will be posted tomorrow.

References

• Odom, W 2005, CCNA Self-Study CCNA ICND Exam Certification Guide, Cisco Press, Indianapolis. (ISBN: 158720083X)
• Sudjiman, D 2006, Configuring Cisco Router 2522 as Frame Relay Switch, viewed 08 May 2006, http://www.davidsudjiman.info/?p=98
• Sudjiman, D 2006, Scenario 1: Frame Relay on Multipoint and Point-to-point Subinterfaces, viewed 08 May 2006, http://www.davidsudjiman.info/?p=99
• Sudjiman, D 2006, Scenario1 Answer: Frame Relay on Multipoint and Point-to-point Subinterfaces, viewed 08 May 2006, http://www.davidsudjiman.info/?p=100