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Frame Realay Encapsulation Question

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17 years 2 months ago #23607 by skepticals
I was taking a practice CCNA exam and had the following question:

Your manager has given you the task of connecting the Cisco routers in serveral branch offices to a Frame Relay service provider. Your service provider uses StarNet routers to provide this service.

Which encapsulation type should you configure the Cisco routers to use?


I remember reading that the Frame Relay switch only cares about the LMI type and the Cisco routers outside of the frame cloud is only what cares about the encapsulation type, but that does not seem to be the case with this quesiton.

I answered that it was okay to use Cisco for the encapsulation type because I thought the frame cloud was only concerned with LMI type.

Is this different because the service provider is using a router?
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17 years 2 months ago #23622 by S0lo
I think you picked the right answer. The question says "encapsulation". So it's not LMI type. So it seams that it brought up the "StarNet routers" stuff just to confuse you.

The confusing thing here is that the available LMI types are:

cisco
ansi
q933a

obviously "cisco" wont work with the StarNet. But again that is not "encapsulation" as far as I know.

Studying CCNP...

Ammar Muqaddas
Forum Moderator
www.firewall.cx
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17 years 2 months ago #23623 by skepticals
Thanks for the reply S0lo,

The testing program said my answer of cisco was wrong. Maybe the software has an error?
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17 years 2 months ago #23626 by Elohim
If you are connecting to a frame relay network, your encapsulation is frame relay and in your case, your LMI type should be ansi because you are not connecting to Cisco routers.


I was taking a practice CCNA exam and had the following question:

Your manager has given you the task of connecting the Cisco routers in serveral branch offices to a Frame Relay service provider. Your service provider uses StarNet routers to provide this service.

Which encapsulation type should you configure the Cisco routers to use?


I remember reading that the Frame Relay switch only cares about the LMI type and the Cisco routers outside of the frame cloud is only what cares about the encapsulation type, but that does not seem to be the case with this quesiton.

I answered that it was okay to use Cisco for the encapsulation type because I thought the frame cloud was only concerned with LMI type.

Is this different because the service provider is using a router?

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17 years 2 months ago #23658 by MatthewUHS
On a Cisco router when specifying "encapsulation frame-relay", unless you are certain that the provider uses Cisco gear at the "next hop" it is always necessary to specify " encapsulation frame-relay ietf " Cisco's frame-relay encapsulation is incompatible and out of the standards set forth by the ietf. and will cause issues and wacky behavior, including keeping an interface down despite carrier detect.

The correct answer would be "encapsulation frame-relay ietf" That is why the question named the brand of router used.

Wires and fires has become wireless and tireless.
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17 years 2 months ago #23659 by MatthewUHS
Replied by MatthewUHS on topic as far as LMI types goes
Cisco, beginning somewhere around 11.2 supports all LMI types and also auto-senses what the port on the frame node is expecting. No configuration necessary, when you admin the port up, it requests LMI reply of all three types in rapid consession, when the node responds, the IOS installs the LMI type that was responded to.

As long as both sides agree on an LMI type it doesn't matter which type is used. The four possible LMI choices are:

1 ansi—ANSI T1.617 Annex D

2 cisco—Original Group of Four specification developed by DEC, Northern Telecom, Stratacom, and Cisco

3 q933a—ITU-T Q.933 Annex A

4 none—No management interface is used

Wires and fires has become wireless and tireless.
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