DLCI's in Frame Relay

[trevorh13]

I am studying for my CCNA resit, I failed the first by two marks largely because of the WAN protocol section. I just want to clarify the DLCI.

I understand that this is used to denote a PVC between two DTE devices. The point I am not clear on is the "local or global" meaning. Am I correct in thinking that a DLCI could be used to denote a circuit (global meaning, hence both routers would be configured with same DLCI no. or alternatively the DLCI could be used to denote one end of the connection; ie. similar to a phone number (local meaning). Also is this determined by me as administrator or the telco?

Thankyou all in advance for your help.

 

[wybnormal]

The DLCI is a marker if you will that tells which end point you have where. For the average user, there are two DLCIs. One at each router. For the more adventureous users, there are 4 DLCIs.. each router plus two for the Telco's frame switch. They nominally start at 16 tho' you can tell the phone company that you want a specific number if you do things like match router IDs to DLCI ( we do this)

The DLCI if I had to pin it down would be a local.. You can have two routers with DLCI 16 BUT remember there is the frame switch between them with a different DLCI splitting the two.

Jeter may be able to add more to this.

MikeS
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[webnetwiz]

If I may add, the DLCIs are assigned by the telco that provisions your frame relay line. The DLCI matter to you and your frame relay provider only, not to anyone else on the net.

David.

 

[jeter]

DLCI's are setup in the frame relay switch and or mapped to the circuit. Normally there
are 2 dlci's one for each side, unless your the host and have 10 remotes. Then you would setup 10 interfaces point-to-point on the host and 1 at the remote for each site.

The only time I get into trouble with DLCI's is when there are more than 1 provider.
Each provider will setup a dlci and it becomes a guessing game. Jeter@LasVegas.com
J.Fisher CCNA

 

[marsd]

To answer your question on the test:
Local significance.
The dlci is only locally significant-it can be whatever,
as long as your provider has his dce configured to id it.

marsd
CCNA

 

[trevorh13]

Thanks everybody. The help people provide in here is invaluable as I am doing self study. Its so useful to be able to pose a question that you don't quite understand and have someone explain it. I have found with a couple of the books that a few more sentences on something could make things so much clearer!
Once again thankyou for the support and hope to return the favours in the near future.

 

[migueljr3]

Here are some tips to study for your CCNA,
!.as soon as you get to the exam desk
write out the OSI model, subnetting chart and you will pass the exam!!!