Global or Local DLCI for Frame Relay ?

Unanswered Question
Sep 10th, 2007

In some practice questions for CCNA 640-801 I have seen it is not absolutely clear whether the displayed DLCI's are supposed to be global or local. In such cases which is the best assumption to make ? What is the exam likely to be assuming ?

Which type is most commonly used in real life, global or local ?

I have this problem too.
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greekgeek Fri, 09/14/2007 - 12:05

"Local DLCI addressing means that DLCI numbers are only significant at one end of a Frame Relay virtual circuit (VC). In other words, the same VC will be identified by different DLCIs at each end. To accomplish this, a mapping occurs across a VC. Frame Relay switches are required to translate the "source" DLCI in a packet to the "destination" DLCI when forwarding the packet.

Global DLCI addressing is a Local Management Interface (LMI) extension that allows a DLCI number to have universal significance. A global DLCI identifies the same VC at both ends. Global addressing simplifies address administration but allows for only 1024 DLCIs in the entire network. The switch is not required to translate the DLCI in a packet as it does with local DLCIs.

The majority of Frame Relay connections use Local DLCI addressing, where a DLCI number is only significant at one end of the PVC."

The above quote is from

http://www.cisco.com/en/US/docs/security/vpn5000/manager/reference/guide/appA.html#wp1003718

I agree with you, the test questions are a bit confusing as to which is which.

Brian

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