Frame Relay, Pings, And Routing Protocols Cisco CCNA Certification Exam Case Study

Frame Relay, Pings, And Routing Protocols Cisco CCNA Certification Exam Case Study
A student was working on her Cisco CCNA exam home lab & came up with an interesting problem. He set Frame Relay up in a hub-and-spoke configuration with R1 as the hub & R2 & R3 as the spokes. He wrote the following frame map statements:

Cisco CCNA certification training includes troubleshooting your own work & that of others. The best CCNA training you can do is indeed troubleshooting your own Cisco router & switch configurations - as i am always telling my students, "I can guarantee that any error you make has been made before, & you'll probably see it again two day." two such common error involves four important Cisco CCNA certification topics - Frame Relay & routing protocols.

frame-relay map ip 172.12.123.2 122

frame-relay map ip 172.12.123.3 123

He was able to ping both spokes from the hub, so he assumed everything was working correctly. Then he configured RIP version 2 on the router & got the following result after cycling "debug ip rip" & clearing the routing desk with "clear ip route *":

03:33:01: IP: s=172.12.123.1 (local), d=224.0.0.9 (Serial0), len 72, sending broad/multicast

You may have already spotted the problem, & if you did, your CCNA certification exam studies are going well! The problem is that the "broadcast" option was left off the frame map statements. "broadcast" must be configured on frame map statements in order to send broadcasts & multicasts across the frame link. As you know from your CCNA certification exam studies, RIP version 1 broadcasts updates & RIP version 2 multicasts them, so the "broadcast" option must be present for either version to send updates by using those frame mappings.

03:33:01: IP: s=172.12.123.1 (local), d=224.0.0.9 (Serial0), len 72, encapsulation failed

He then rewrote the frame map statements as shown below....

R1(config-if)#frame map ip 172.12.123.2 122 broadcast

.. & the RIP updates went out as expected.

R1(config-if)#frame map ip 172.12.123.3 123 broadcast

RIP protocol debugging is on

R1#debug ip rip

06:22:13: RIP: sending general request on Loopback0 to 224.0.0.9

R1#clear ip route *

06:22:13: RIP: sending general request on Serial0 to 224.0.0.9

06:22:13: RIP: ignored v2 packet from 1.1.1.1 (sourced from two of our addresses
)

06:22:14: RIP: received v2 update from 172.12.123.3 on Serial0

06:22:14: 1.1.1.1/32 - 0.0.0.0 in 3 hops

06:22:14: 2.2.2.2/32 - 0.0.0.0 in 2 hops

06:22:14: 3.3.3.3/32 - 0.0.0.0 in 1 hops

06:22:14: 172.12.23.0/24 - 0.0.0.0 in 1 hops

06:22:14: 172.12.123.0/24 - 0.0.0.0 in 1 hops

06:22:14: 2.2.2.2/32 - 0.0.0.0, metric 3, tag 0

06:22:14: RIP: sending v2 update to 224.0.0.9 via Loopback0 (1.1.1.1)

06:22:14: 3.3.3.3/32 - 0.0.0.0, metric 2, tag 0

06:22:14: 172.12.23.0/24 - 0.0.0.0, metric 2, tag 0

06:22:14: 172.12.123.0/24 - 0.0.0.0, metric 1, tag 0

06:22:14: RIP: sending v2 update to 224.0.0.9 via Serial0 (172.12.123.1)

Cisco CCNA certification depends on noticing details like these, & there is no better way to learn these details than by working on real Cisco routers & switches. Whether you are renting rack time online or buying used Cisco routers & switches, real-time debugs & configurations are the way to CCNA certification exam success!

source : http://www.articlecity.com/articles/computers_and_internet/article_3575.shtml