ok gang, here's another one. I'm going through my CCNA book (W. Odom), I'm reading up on LMI... local management interface... so I'm reading the part where it says that in some cases, it isn't necessary to assign or map out DLCI's, because LMI uses a automatic assignment method... I *think* using Inverse ARP.. to assign DLCI's.

Then I get to thinking...

HOW ARE THE DLCI NUMBERS CHOSEN? What, is this like arbitrary? Does the router and Frame Switch say "ok, you're DLCI 14." or something like that?

I don't get it.

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Hello ROUTERIP

No not exactly. DLCI numbers are chosen by the administrator from a range of 0 to 1023.

The DLCI number is only locally significant. this means that it is only used for identifying the pvc between your router and the destination.

eg. You are dlci -54 ------------> other end might be dlci 100.

You can use inverse ARP which is default on Cisco routers if my memory serves me.
Or you can map dlcis statically when you build your pvc. The frame-relay inverse-arp command is designed for use with an interface configured for multipoint communication - hub ansd spoke topology and should not be used for a subinterface configured for point-to-point communication - between two ends only.

But you must remember to associate the Frame Relay DLCI with a subinterface to use subinterfaces in the Frame Relay network for point-to-point communication. If you associate a DLCI with a point-to-point subinterface, you cannot use the frame-relay map command.

frame-relay interface-dlci dlci [option]

and then you can map it.


frame-relay map protocol protocol-address dlci
[broadcast] [ietf] [cisco]

For IP

frame-relay map ip 146.198.199.110 54 broadcast

or using a different protocol for instance

DECNET

frame-relay map decnet 21.7 49 broadcast

You can have various network layer protocols running on Frme Relay.

But for CCNA you just need to know about Frame Relay and IP. That inverse ARP is to dynamically map the dlcis and that you can configure it statically also with the Frmae relay map command.

I hope that helps.
Refer to your CCNA book by Odom for Frame Relay configuration.

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FastIP

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Hey routerip,

i see from the past couple of days you're really curious about Frame Relay..

check ths test out. It is exceelenet for preparing you towards the finaltest

http://www.lucent.com/certification/cgibin/exam_901.html

It's not Cisco , but who cares. They don't own the underlying concepts..

Good luck

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FastIP

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don't worry this test is much harder than the level requred at CCNA.

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FastIP

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There were more Isdn than frame on the exam, its good to know the commands but don't stress out on this.

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Let The Games Begin!

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Just to expand on FastIP's comment. In the real world his "administrator" that assigns the DLCI number is the carrier from whom you lease the circuit. Because it is the frame switch that holds the dlci number and you match it at your end. Course you can tell them what DLCI number you would like to use, and they'll use it for ya, in most cases.

Yankee

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For those people who coyldn't open the link for practice test on Frame Relay.

http://www.lucent.com/certification/cgibin/exam_902.html

If it don't work try another way to use it. ( copy it and paste in your browser window, and then click GO!)

I tested it yesterday before posting it and it did not work. ( maybe a case for Admin to investigate ? who knows )

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FastIP

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On a point of accuracy here, DLCI numbers 0 to 15 are reserved if you are using a Telco's Frame network.

Hippo

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