CCIE R&S Exam Cert Guide Third Edition

Answered Question
Nov 11th, 2007

Been reading over the brand new edition of the CCIE Routing and Switching Exam Certification Guide. I have a question in Chapter 6 on the Frame Relay section concerning disabling Inverse ARP. Briefly quoting it states, "Interestingly, the no frame-relay inverse-arp command not only tells the router to stop sending InARP messages, but also tells the router to ignore received InARP messages."

As soon as I ran across this sentence I just knew something wasn't right. I've always thought that turning off inverse arp in frame relay only meant that it would not send messages, but would absolutely respond to them. Of course I had to go test this in my lab. I setup two routers on either end of a frame switch, put ip addresses on the physcial serial interfaces and then disabled inverse arp on both routers. As expected no mapping was created. I then enabled inverse arp on a single router while the other was still inverse arp disabled. As I thought, a dynamic frame relay map was created on both routers which would support that even though inverse arp is turned off on a router, it will still respond to inverse arp requests.

Just wanted to bring this up and verify that I've found what I think is an error in this new book. If I'm off base, please explain how I'm interpreting this wrong. Many thanks!

Correct Answer by swmorris about 9 years 3 months ago

You are correct, it is an error in the book. The router will always respond to receive inverse arp request messages.

HTH,

Scott

smorris@ipexpert.com

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Correct Answer
swmorris Mon, 11/12/2007 - 09:09

You are correct, it is an error in the book. The router will always respond to receive inverse arp request messages.

HTH,

Scott

smorris@ipexpert.com

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